Why don't fish get hurt with so many sharp fish bones?

Why don't fish get hurt with so many sharp fish bones?

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Why don't fish get hurt with so many sharp fish bones? And why don't fish feel pain when they swim? Don't those sharp fish bones stick into the flesh while swimming?

Connective tissues prevent fish from being hurt by its bones. They surround the sharp bones so that the bones do not hurt its organs/flesh.

However Of course the bones can hurt the fish, but the situation is quite imaginable.

If a fish is smashed or gets too much force, its connective tissues cannot protect its organs much(like our clothes cannot protect us from bullets, or our broken bones penetrating our organs when we encounter a serious car accident despite our connective tissues covering the bones - the bones just damage our connective tissues and organs, and so on… ) and its organs get hurt.

Your worry can happen in human case too (but much weaker version), we can think of our hip bones sometimes pressing our flesh between the bones and the chair we are on.


Needlefish (family Belonidae) or long toms [2] are piscivorous fishes primarily associated with very shallow marine habitats or the surface of the open sea. Some genera include species found in marine, brackish, and freshwater environments (e.g., Strongylura), while a few genera are confined to freshwater rivers and streams, including Belonion, Potamorrhaphis, and Xenentodon. [3] Needlefish closely resemble North American freshwater gars (family Lepisosteidae) in being elongated and having long, narrow jaws filled with sharp teeth, and some species of needlefishes are referred to as gars or garfish despite being only distantly related to the true gars. In fact, the name "garfish" was originally used for the needlefish Belone belone in Europe and only later applied to the North American fishes by European settlers during the 18th century. [4]


The puffer, which is also called swellfish, or blowfish, is any member of a group of about 90 species of fishes of the family Tetraodontidae, noted for their ability when disturbed to inflate themselves so greatly with air and water that they become globular in form. Puffers are found in warm and temperate regions around the world, primarily in the sea but also, in some instances, in brackish or fresh water. They have tough, usually prickly skins and fused teeth that form a beaklike structure with a split in the center of each jaw. The largest puffers grow about 90 cm (3 feet) long but most are considerably smaller.
Many species are poisonous a highly toxic substance, tetraodontoxin, is especially concentrated in the internal organs. Although this substance can cause death, puffers are sometimes used as food. In Japan, where the fishes are called fugu, they must be carefully cleaned and prepared by a specially trained chef.

Fish-friendly solutions

According to Lee Baumgartner, a fish ecologist from Charles Sturt University, Dr Pflugrath's research has revealed big pressure changes can occur even at small weirs.

"Unfortunately, when a lot of infrastructure was built, we had no idea this would be a problem," he said.

The good news is that there are engineering solutions that could minimise or eliminate these impacts.

Dr Pflugrath's research in the US has already been used in the design of fish-friendly hydro turbines, Dr Baumgartner said.

He said other options included using a screen to lift fish up to the surface of the upstream side of the weir, or using gates that tilt forward rather than lift up, giving a chance for fish to adjust to shallower depths before they go through the weir.

"The solutions are so straightforward when you think of it," Dr Baumgartner said.

Fish-friendly hydro turbine designs also minimise the possibility of fish being struck by blades, or being injured by turbulence, added Dr Pflugrath.

And what about reducing barotrauma to fish caused by fishing?

Research over a decade ago by marine scientist Chris Lowe at California State University, Long Beach found that if a fish with barotrauma were quickly sent back to the depths they came from, they would likely recover.

To this end, all manner of "descending devices" have been developed to help get fish back down to safety.

For example, if someone has to throw back in an undersized fish they've just caught, they can attach a weight to its lip, using a special attachment that can be easily released.

But Dr Fairclough from the Western Australian government said it's tricky making sure this happens.

Barotrauma isn't always visible, so the weight would need to be applied to all undersized fish captured and then released, he said.

Even if fishing boats are required to have ⟞scending devices' on board, it is difficult to enforce their use, said Dr Fairclough.

"If the release rate is very high and we know that a particular species dies when it's released then it's probably better restricting the number of fish being caught and kept rather than having a size limit."

Goldfish Care Guide: Tips And Advice For Your Tank!

As you can see, goldfish are far more diverse than the equally popular Betta, and this leads to a challenge when creating a comprehensive care guide. Some types thrive in outdoor ponds while other goldfish can live in warm water. Since ponds are a whole separate topic, I’m going to focus on caring for goldfish in aquariums.

Setting Up Your Goldfish Habitat

While single-tailed goldfish, like the Common and Comet, are hearty and easy to accommodate in a variety of tank set-ups, fancy types with telescope eyes and pom poms are more delicate. The specific set-up you’ll need will vary depending on your type of goldfish.

Aquarium Size

Goldfish need plenty of room to swim, eat and explore, and since they can grow from 6 to over 12-inches in length a fishbowl is never appropriate for a goldfish! The size of your tank will depend on which types of fish you’ve decided upon and how many you plan to keep.

While you can certainly start a juvenile goldfish out in a 10-gallon tank, they will outgrow it within months, and being cramped can limit their adult size. To give your goldfish the best start you’ll need at least a 20-gallon long-style tank, and should consider going bigger if you’re keeping more than a single fish.

How many gallons per goldfish do you need? It depends, but usually adding 10 to 20 gallons per goldfish gives you enough room for your fish to reach their maximum potential.

Water Quality And Filtration

Let’s talk about your water quality and what kind of conditions you’ll need to have a lively goldfish tank. The most important factors are cleanliness and consistency. Goldfish produce a lot of waste since they are constantly eating, and their tanks often suffer from toxic ammonia spikes. Filtration is a must for goldfish tanks!

You should invest in at least one high-quality 3-stage HOB or canister filtration system for your tank. I’d recommend one that can hold additional ammonia-absorbing filter media. You may need to adjust the filter to provide the minimal current goldfish prefer since they will avoid areas with high flow.

What Kind Of Water Conditions Do Goldfish Need?
  • Goldfish are freshwater fish and do well over a wide range of water temperatures and conditions as long as they are stable fluctuations cause goldfish stress.
  • They are not terribly sensitive to water hardness and can adjust to either hard or soft water aquariums.
  • They aren’t picky about their pH levels goldfish do well from pH 6.0 to 8.0.
  • They avoid areas with heavy currents and prefer still-to-low water flows.
  • Goldfish need very clean, filtered water to remain healthy.

Does Your Goldfish Tank Need A Heater?

While goldfish can live in warm water over 75°F, many of the hearty single-tail types prefer cooler water and suffer in the warmer temperatures. It may make them lethargic and cause them to stop eating. You may not need a heater for a tank of hearty goldfish if your home’s temperature is stable year-round.

Fancy goldfish almost always do best right around 75°F, and while some can survive lower temperatures it may predispose them to illness and infections. I recommend using a heater to maintain a stable temperature for these delicate goldfish. A sudden drop of a few degrees could be all that’s needed to make your goldfish sick.

Hoods, Lids And Lights

Single tail goldfish can swim very fast and could certainly leap out of your aquarium, so a lid, cover or hood is a good idea. They can be helpful for fancy tanks too, since they slow the rate of water evaporation. For lighting, LED aquarium lights are ideal for goldfish tanks and won’t add any heat to your habitat.

Too much light can boost algae growth, though. I recommend between 8 and 12 hours of light per day maximum. Cut back further if algae becomes a problem, and do several water changes to reduce the nutrient levels in your tank water.

Plants, Decorations And Substrate

Goldfish love to eat and uproot plants, so I don’t recommend keeping them in planted aquariums. But you can certainly give them some plastic plants and other decorations like rocks, caves and sticks to explore! Leave plenty of open areas for swimming and place the decorations along the back and sides of your tank.

You don’t need to worry much about your decor if you’re keeping single tail goldfish, but for fancy types you may need to take other precautions. Fantail and Veiltail goldfish can hurt their long fins on hard gravel or cut them on your decor. You may be better off using soft aquatic sand or a fine gravel substrate.

Telescopic-eyed goldfish and types with fluid-filled bubbles and pom poms are very delicate and can’t swim very well. You’ll want to avoid using decorations that could poke or puncture their eyes/bubbles/poms. Long, open tanks with fewer plastic plants and rounded decorations are safest.

Goldfish Diet And Feeding In Aquariums

I’ve already mentioned that goldfish have voracious appetites and are always hunting for food. There is a ton of confusion on the internet about what to feed, how often and how much to feed goldfish. It does not have to be this confusing, so let’s lay out some basic rules!

What To Feed Goldfish

First, most pet goldfish are fed too much, too often and suffer from health problems related to their weight and diet. Fancy goldfish, with their squat, round bodies often have trouble with constipation, especially if they are fed too many treat foods.

  • You should pick a well-rounded commercial omnivore flake or floating diet as your primary goldfish food.
  • Hearty fast-swimming goldfish can easily eat either, but many of the fancy fish can’t dive for flake foods and often do better with floating pellets.

In terms of treats, I offer my adult goldfish treats once or twice a week. Instead of giving them their usual commercial diet, I substitute it with fresh/frozen/freeze dried:

  • Brine shrimp or bloodworms
  • Daphnia eggs
  • Mosquito larvae
  • Sinking vegetable/algae disk (for single-tail goldfish only).

How Often To Feed Adult Goldfish

When it comes to frequency, while there are times to offer multiple meals, the typical adult goldfish will do well being fed once every 24-hours. They naturally start looking for food at dawn (and dusk), so I usually feed my goldfish tanks right after their lights switch on. Your fish will anticipate their meals if you’re consistent in your timing!

I also fast my adult fish one day out of every 7, so they only get 6 meals a week. Don’t worry, a regular fast won’t hurt your adults. They’ll just spend the day nibbling any algae in your tank and hunting for food scraps!

How Much To Feed Your Goldfish

It’s really easy to overfeed goldfish, because like Bettas, their stomach is about the size of their eyeball. A single pellet or flake of food can be a full meal for a small goldfish! So limit your meals and treat offerings to a portion the size of their eyeball, which is about all the food they can eat in 1 to 2 minutes, and remove any extras.

When To Alter Your Goldfish Feeding Regimen

There are times when goldfish need frequent meals, and conversely other times when you may need to cut back and fast them several days a week. Baby goldfish, called fry, do best eating 3 meals a day for a few weeks after hatching, and then I switch to twice a day feedings until they are mature. They get more treats, too!

If you want to mimic a period of wintertime hibernation, you could let your tank temperature drop for a few months. The specific temperature varies depending on the type, however. Lower temperatures stimulate your fish to go into a suspended, sleep-like state. When their metabolism drops, they eat less and not as often.

When you raise their tank’s temperature after a period of hibernation, your goldfish may naturally begin to spawn. I talk more about breeding goldfish below, but spawning fish need more food and higher protein levels to produce healthy fry. You’ll want to adjust your feeding regimen as well when breeding your fish.


Next time you see your rod tip bumping from an annoying catfish while fishing the flats, don’t get angry, get your live well going…

There are many of old-time fisherman that let their kids and grandkids have fun catching the slimy catfish in the morning, while they go out later and use the catfish to catch monster tarpon and cobia in the afternoon and evening (while the kids are napping from all of the fun).

Let us know if we missed anything in regards to using saltwater catfish for bait, and don’t hesitate to leave a comment with any questions or personal fishing tips on using saltwater catfish as bait.

And if anyone has a great recipe for saltwater catfish, let us know as well.

P.S. – If you think your angler friends would like this article, please Tag them or Share it with them. You Rock! Pa-POW!

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I’d also like to know when the shirt will be available to purchase again. Would have made a perfect father’s day present.

Perfect timing on your question because we’re actually planning on doing a pre-order sale on these shirts soon… most likely next week. So make sure you’re subscribed to our email newsletter and keep an eye out for the notice.

I’d like to buy a saltwater catfish shirt

I am looking to get the shirt posted above, how?

We’re currently not making this design but we’re bringing it back later this year as a limited edition run (as so many anglers have asked for it). Stay tuned!

The hardhead catfish with the head and tail cut off do work pretty well for large tarpon, but have never had any luck with the sail cats. This is just my experience though. Sharks and grouper will eat the sail cats no problem but for whatever reason I’ve never caught a tarpon on sail cats. I prefer mullet chunks of the mid section, live freelined mullet, live freelined mojarra, and Spanish mackerel head halves. But the problem with these baits is that small sharks will pick them apart while, they mostly seem to leave the catfish alone.

I caught a nice Tarpon on a catfish with the head cut off in Tampa Bay.

I plan on giving this a try using the catfish head on a knocker rig. Is there a preference for species when using chunked catfish on the bottom?

This article has mistakes. Neither species of saltwater catfish are “bottom feeders”. They are “full water column” feeders and after eviserating and studying stomach contents of hundreds of both species (and this is verified by a expert with the state of Florida)–over 95% had crab chitin in their stomachs, shrimp parts were the next most commonly found part of their diet and fingerlings of other species were common. When food is scarce they will also consume seagrass. It is not unusual to catch either species on topwater plugs and as their numbers increase (man, and an occasional bull shark are their only predators and, when inshore gillnetting was banned in 1995, they got a free pass to proliferate–and they have) you will be catching a lot more of them.

They are having an impact on recreational species. They can consume a fish that is over 40% of their body length. They are now the dominate species in many areas and their population continues to increase.

It is essential that when they are caught, that they be quickly cooled. Any fish caught in 80º water on a 90º day has a very short window to be properly cooled. After 20 minutes the path to deterioration is very quick and is irreversible.

If you do not have a lot of ice, and even if you do, gutting the fish quickly will do a lot to slow down deterioration. Their strong stomach acid will cause quick spoilage.

Snipping the ends of their spines will prevent getting spiked. You would have to be Hercules to snip the spines close to the body but the ends can be snipped easily.

I use a cheap 1000 psi electric pressure washer with a 25º nozzle to wash the slime off–it is quick and very effectiw boats have a pressure washer on board so an alternative is carrying a bucket of sand and applying it to the fish and then rinsing the fish (even if it means just dipping it back in the water) will reduce sliming up your cooler. I have yet to find an alternative for slime removal–vinegar and salt didn’t work. A rag works some but if you are catching a lot of them you will need a lot of rags.
Another alternative is wrapping the fish in newspaper before putting it the cooler–the paper does absorb some of the slime.

In culinary tests both species rank at the top of the taste tests over their freshwater brethern–most of which are “bottom feeders” and, depending on where caught, can have a muddy taste. I have smoked, pickeled, poached, fried, baked, canned, blackened and used both saltwater species in many dishes. They are delicious. (I do not remove the “bloodline”–the red area on the bone side of the fillet–no one can detect whether this has been done or not). Their bones and heads (gills removed) make an outstanding fish broth

The smaller (less than 12″) “Hardheads” (Ariopsis felis) are hardly worth filleting–but gutting them, removing the heads and fins then frying or baking them (skin on) makes a delicious meal and is easy to do. With the skin on you need no breading.
If skinning them in the conventional manner dipping them for a few seconds in near boiling water seems to make the job easier.

Taking kids fishing? No species will lure a kid into enjoying fishing more than catching a catfish. They are easily caught, fight like hell (especially a larger “Sailcat”–Bagre Marinus) and seldom get off the hook. Kids are fascinated by examining the stomach contents and their experience is completed when their fish is cleaned and they get to eat what they caught.

A tip–they are strong fish and are really fiesty when you try to remove the hook. We use “snaps” –we detach and leave the hook and snell in the fish until we process the fish (or it is sedated). Most spiking injuries come from people trying to remove the hook immediately after landing the fish. This is not a process that the fish cooperate in–they really take offense and hook removal is really difficult. It is reported that when stabbed by one of the spikes putting the wound in water as hot as you can stand brings relief. (Do note that the onset of scalding starts at 120º F–so no boiling water please).

Top 5 facts about Lake Sturgeon, the Great Lakes' most ancient and enormous fish

Are you ready to learn about a true Great Lakes monster?

Lake Sturgeon are the oldest and largest fish in the Great Lakes. They’re enormous, ancient, culturally important, intelligent, and threatened creatures. This World Wildlife Day, learn why Lake Sturgeon are one of the most interesting species in the Great Lakes.

Here are our top 5 facts about Lake Sturgeon:

Lake Sturgeon can grow to be very old and very huge

Lake Sturgeon can live as long as humans. More astonishing still? They never stop growing. On average, Lake Sturgeon live to about 50-80 years old, but males can live to 55, and females to 150.

Did You Know?

Some Lake Sturgeon have grown to be two meters long and have weighed in at a whopping 310 pounds. These fish are so enormous, they’ve been mistaken for various Great Lakes monsters over the centuries.

My grandmother recalls seeing a sturgeon that her father had caught when she was a small child. “I went out to the back shed and saw an enormous shape hanging from the shed door. I thought it was a deer! The thing was so big. But when I got closer I realized that it was a massive Lake Sturgeon.”

Lake Sturgeon are ancient

Lake Sturgeon have inhabited the Great Lakes for 10,000 years. They’re one of the oldest species on the planet, belonging to a fish family that dates back 200 million years (this means that their ancestors lived among the dinosaurs!). Lake Sturgeon are descendants of prehistoric fish, and they definitely look like relics of another era.

Lake Sturgeon have bony plates on their backs, long snouts, four whisker-like barbels, prehensile lips, long torpedo-shaped bodies, a shark-like tail, and coarse skin instead of scales.

Lake Sturgeon may grow to be large and fearsome-looking, but their ‘blub’ is worse their bite.

Lake Sturgeon are actually known for being shy and docile. In fact, they don’t even have teeth. Lake Sturgeon use their vacuum-like mouths to eat insect larvae, small crustaceans, and fish from the bottom of the lake.

Lake Sturgeon are an important part of Indigenous culture

Groups like the Huron and Anishnabeg have eaten these fish for centuries, and the northern Ojibwe would sell sturgeon to traders.

Lake Sturgeon were also a key part of social feasts, ceremonies, and customs. Huron fish preachers would summon Lake Sturgeon as part of a fishing ritual to ensure a fruitful catch.

Once caught, no part of the fish was wasted (modern fisheries, take note). First Nations people used Lake Sturgeon bones as needles, spearheads and arrowheads, and isinglass (a gelatin from dried swim bladders) to make glue and paint.

Did You Know?

Lake Sturgeon are playful and intelligent

Some scientists have seen Lake Sturgeon display individual personalities, such as inventive feeding strategies and playfulness. Lake Sturgeon have been seen tail walking (‘walking’ on their tails on water’s surface) and porpoising (jumping up in the air).

They’re basically the dolphins of the Great Lakes!

Sadly, some scientists believe that rather than being an act of joy, this spirited behaviour is intended to shake off Sea Lampreys.

Sea Lampreys are a parasitic invasive species in the Great Lakes. They have rows upon rows of sharp teeth and a razor-sharp tongue. These suction-y little scumbags can kill up to 40 pounds of fish during their year to year-and-half-long feeding periods.

Invasive species are only one of the many threats facing Lake Sturgeon.

Lake Sturgeon need our help

In the Great Lakes and St. Lawrence River region, Lake Sturgeon are classified as at-risk or endangered. The idea that such an archaic and incredible species could one day be lost is unthinkable.

In the past, Lake Sturgeon populations declined due to overharvesting, dams, habitat loss, and poor water quality. Today, the species is threatened by overharvesting, pollution, climate change, habitat degradation, and dams that block access to spawning and rearing sites.

Because Lake Sturgeon live for so long and have precise habitat requirements, their health is an indicator of the health of our lakes. Although Lake Sturgeon still face many threats, populations in the Great Lakes appear to be reviving.

It seems only fitting that members of the Waterkeeper Alliance often use this extraordinary and resilient fish as a symbol of the work they do. Waterkeepers, like our very own Lake Ontario Waterkeeper, strengthen and expand a global movement to safeguard swimmable, drinkable, fishable waters for all.

Lake Sturgeon are living fossils, and they’re a vital part of Great Lakes ecosystems.

If you’re lucky enough to spot one of these fascinating fish, report the sighting to the Natural Heritage Information Center along with where you saw it and and a photo. This will help to support biodiversity conservation efforts.


The consumption of fish is by far the most significant source of ingestion-related mercury exposure in humans and animals. [4] Mercury and methyl mercury are present in only very small concentrations in seawater. However, they are absorbed, usually as methyl mercury, by algae at the start of the food chain. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methyl mercury, but excrete it very slowly. [5] Methyl mercury is not soluble and therefore not excreted. Instead, it accumulates, primarily in the viscera, although also in the muscle tissue. [6] This results in the bioaccumulation of mercury, in a buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish, and so on. [7] The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish within the food chain also consumes the higher level of mercury that the fish have accumulated, including humans. [7] This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. Species on the food chain can amass body concentrations of mercury up to ten times higher than the species they consume. This process is called biomagnification. For example, herring contains mercury levels at about 0.1 parts per million, while shark contains mercury levels greater than 1 part per million. [8]

Terrestrial mercury pollution Edit

There are three types of mercury emission: anthropogenic, re-emission, and natural, including volcanoes and geothermal vents. Anthropogenic sources are responsible for 30% of all emissions, while natural sources are responsible for 10%, and re-emission accounts for the other 60%. While re-emission accounts for the largest proportion of emissions, it is likely that the mercury emitted from these sources originally came from anthropogenic sources. [9]

Anthropogenic sources include coal burning, cement production, oil refining, artisan and small-scale gold mining, wastes from consumer products, dental amalgam, the chlor-alkali industry, production of vinyl chloride, and the mining, smelting, and production of iron and other metals. [9] The total amount of mercury released by mankind in 2010 was estimated to be 1,960 metric tons. The majority of this comes from coal burning and gold mining, accounting for 24% and 37% of total anthropogenic output respectively. [9]

Re-emission, the largest emitter, occurs in a variety of ways. It is possible for mercury that has been deposited in soil to be re-emitted into the mercury cycle via floods. A second example of re-emission is a forest fire mercury that has been absorbed into plant life is re-released into the atmosphere. While it is difficult to estimate the exact extent of mercury re-emission, it is an important field of study. Knowing how easily and how often previously emitted mercury can be released helps us learn how long it will take for a reduction in anthropogenic sources to be reflected in the environment. Mercury that has been released can find its way into the oceans. A 2008 model estimated the total amount of deposition into the oceans that year to be 3,700 metric tons. It is estimated that rivers carry as much as 2,420 metric tons. [9] Much of the mercury deposited in the oceans is re-emitted, however as much as 300 metric tons is converted into methyl mercury. While only 13% of this finds its way into the food chain, that is still 40 metric tons a year. [9]

Much (an estimated 40%) of the mercury that eventually finds its way into fish originates with coal-burning power plants and chlorine production plants. [10] The largest source of mercury contamination in the United States is coal-fueled power plant emissions. [11] Chlorine chemical plants use mercury to extract chlorine from salt, which in many parts of the world is discharged as mercury compounds in waste water, though this process has been largely replaced by the more economically viable membrane cell process, which does not use mercury. Coal contains mercury as a natural contaminant. When it is fired for electricity generation, the mercury is released as smoke into the atmosphere. Most of this mercury pollution can be eliminated if pollution-control devices are installed. [10]

Mercury in the United States frequently comes from power plants, which release about 50% of the nation's mercury emissions. [12] In other countries, such as Ghana, gold mining requires mercury compounds, leading to workers receiving significant quantities of mercury while performing their jobs. Such mercury from gold mines is specifically known to contribute to biomagnification in aquatic food chains. [13]

Elemental mercury often comes from coal power plants, and oxidized mercury often comes from incinerators. Oil-fired power plants also contribute mercury to the environment. [2] The energy industry therefore is a key player in the introduction of mercury into the environment. When addressing the issue of reducing seafood mercury bioaccumulation on a global scale, it is important to pinpoint major energy producers and consumers whose exchange of energy may be the root of the problem.

Aquatic mercury pollution Edit

The farming of aquatic organisms, known as aquaculture, often involves fish feed that contains mercury. A study by Jardine has found no reliable connection between mercury in fish food affecting aquaculture organisms or aquatic organisms in the wild. [14] Even so, mercury from other sources may affect organisms grown through aquaculture. In China, farmed fish species, such as bighead carp, mud carp, and Siniperca chuatsi, carried 90% of total mercury content in all of the measured fish in a study by Cheng. This study also concluded that mercury bioaccumulates through food chains even in controlled aquaculture environments. Both total mercury and methyl mercury absorption was found to be derived from sediments containing mercury, not mainly from fish feed. [3]

The Hawaii Institute of Marine Biology has noted that fish feed used in aquaculture often contains heavy metals such as mercury, lead, and arsenic, and has dispatched these concerns to organizations such as the Food and Agriculture Organization of the United Nations.

Mercury can get into freshwater systems by point sources and extended flooding. [7] In Canada, mercury poisoning in Grassy Narrows was likely caused by a spill at a paper mill, which is a point source. Non-point sources include floods that create hospitable habitats for bacteria that can convert mercury to methylmercury, which is the toxic form that bioaccumulates through aquatic food webs. The effects of these different sources of mercury have been studied at the Experimental Lakes Area in Ontario, Canada, using research procedures including whole-lake ecosystem experiments and non-lethal fish muscle biopsies. [7]

Controlling output of mercury pollution sources Edit

A study that was led by scientists from Harvard University and U.S. Geological Survey has determined that in the next several decades there will be a 50 percent increase in mercury levels. [ citation needed ] The study also shows that the increases are connected through industrial emissions and are not natural as previously thought. [ citation needed ] However, by decreasing emissions from industrial plants, the possibility of decreasing the high level of mercury remains plausible. [15] Several nations are currently implementing systems that will detect and therefore later be able to control the output of mercury into the atmosphere. Air pollution control devices (APCDs) have been implemented in South Korea as the government is starting to take inventory of mercury sources. Mercury pollution can also be removed by electrostatic precipitators (ESPs). Bag-based filters are also used in factories that may contribute mercury to the environment. Flue-gas desulfurization, normally used to eliminate sulfur dioxide, can also be used in conjunction with APCDs to remove additional mercury before exhausts are released into the environment. [2] Even so, countries such as South Korea have only begun to use inventories of mercury sources, calling into question how fast anti-mercury measures will be put into factories.

Disparate impacts Edit

Mercury content in fish does not affect all populations equally. Certain ethnic groups, as well as young children, are more likely to suffer the effects of methyl mercury poisoning. In the United States, Wallace gathered data that indicated 16.9% of women who self-identify as Native American, Asian, Pacific Islander, or multiracial exceed the recommended reference dose of mercury. [16] A study done on children of the Faroe Islands in the North Atlantic showed neurological problems stemming from mothers consuming pilot whale meat during pregnancy [17] (see Whaling in the Faroe Islands). A 2020 NBER paper found that in coastal Colombia, those born during periods when fish catches have high mercury content have worse educational and labor market outcomes than those born during periods of low mercury content in fish. [18]

Regulation and health Edit

While various studies have shown high concentrations of mercury accumulated in fish, medical cases often go unreported and pose a difficulty in correlating mercury in fish with human poisoning. Environmental issues cover a broad range of areas, but medical cases that are associated with pollutants released into the environment by factories or construction areas cause public health issues that affect not only the environment but also human well-being. Substances poisonous to the human body in a particular amount or dose may not cause any symptoms over time. While there are limits to how much of anything the body can have, mercury is a particular poison that produces immediate physical symptoms when the body has been accumulating it over a period of time. [ clarification needed ]

In the United States, the Environmental Protection Agency estimates the amount of mercury in human blood that is not likely to pose fatal health outcomes. The agency is in charge of enforcing regulations and policies that cover a range of environmental topics. [19] Analysis of blood mercury concentrations in childbearing women has documented that exposure to methyl mercury (MeHg) occurs primarily through the consumption of fish. [20] The U.S. FDA highly recommends against pregnant women and young children consuming raw fish. Pregnant women and young children often lack strong immune systems and are more at risk for foodborne illnesses. [21]

Medical cases and exposure to mercury Edit

In the United States, the EPA provides advice about the levels of mercury that are non-fatal in humans. Symptoms of exposure to high levels of methyl mercury include disturbed vision, hearing, and speech, lack of coordination, and muscle weakness. Medical studies have examined the correlation of fish consumption and health issues. American studies have presented evidence of fish consumption and its effects on child development. Longitudinal studies agree that human activities release mercury that accumulates in marine life. [22] [ failed verification ] Addressing the issues of fish consumption forces health officials to recognize the sources of mercury in the human body. Specific Native American tribes are vulnerable to a high exposure of mercury. Studies have determined that these native peoples in the United States suffer more from mercury poisoning and illness than any other cohort group in the country. This is due to the fact that fish is a main source of protein. Exposure risk was assessed through a medical study, thus raising judicial issues of whether the public health of these groups is a priority in the United States. [23]

Work and exposure Edit

Most cases that arise are due to work exposure or medicinal poisoning. Environmental justice advocates can relate these mercury cases to the unregulated amount of mercury that enters the environment. Workers can be exposed to mercury through the manufacture of fluorescent tubes, chloralkali, or acetaldehyde among other products. Anthropogenic sources and places where mercury is released or used as a solid or vapor puts these has caused fatigue, dizziness, hyperhidrosis, chest congestion, and loss of motor skills. When taken to the hospital, the neurotoxicity levels had already exceeded the maximum amounts. [24] Over-the-counter medicines have been shown to have traces of mercurous chloride. Medical research reported that the children who received doses of these medicines experienced physical symptoms such as "drooling, irregular arm movements, and impaired gait". [25] Exposures to this result in severe physical impairments unregulated chemicals that are put in products. The intake of laxatives that contained about 120 mg of mercurous chloride has also been cases of mercury's toxicity. [26]

Even in countries, such as Sweden, that have phased out mercury in the dental industry and manufacturing, lingering quantities of mercury still exist in lakes and coastal areas. Moreover, global contributions of mercury to the environment also affect that country. A study in Sweden selected 127 women who had a high level of fish consumption. Around 20% of the women selected, after hair and blood samples, were found to have exceeded the EPA's recommended reference dose of 0.1 micrograms of methyl mercury per kilogram of body weight. Additionally, the study concluded that there was "no margin of safety for neuraldevelopmental effects in fetus[es]" [27] without removing the offending species of fish from the diets of the women. This indicates that families intending to raise children should be especially careful about exposing their unborn babies to toxic mercury via fish.

Children exposed to mercury are particularly susceptible to poisoning since the ratio of food, water, and air intake versus individual body weight is much higher than that of adults. [28] Additionally, children undergo fast growth that causes them to be more susceptible to damaging exposure to methylmercury, as well as the long term consequences of such exposure during childhood development. [28] Young age plays an important role in terms of damage caused by mercury, and much literature on mercury focuses on pregnant women and specific precautions designed to prevent youth mercury exposure. Prenatal methylmercury exposure does cause behavioral problems in infants and worsened cognitive test performance. Additionally, Hughner estimates that 250,000 women may be exposing their unborn babies to levels of methyl mercury above recommended federal levels. [29]

Economically, there does not seem to be a difference in mercury exposure based on socioeconomic bracket and the ability to buy fish from the market. One study shows "no significant differences in mercury levels in tuna, bluefish, and flounder as a function of type of store or economic neighborhood". [30]

By nation Edit

Certain countries have cultural differences that lead to more fish consumption and therefore more possible exposure to seafood methylmercury. In Ghana, the local population traditionally consumes large quantities of fish, leading to potentially dangerous amounts of mercury in the bloodstream. [13] In the Amazonian Basin, during the rainy season, herbivorous fish dominate the diet of 72.2% of the women selected from a particular Amazonian village. Analysis also shows increase of mercury content in the hair of humans who eat fish on a daily basis in the Amazon. [31]

The most serious case of mercury poisoning in recent history was in the Japanese city of Minamata, in the 1950s. Minamata poisoning demonstrated that significant prenatal and postnatal exposure to high levels of methylmercury caused serious neurological problems. Minamata victims also showed higher than normal signs of psychiatric diseases, along with those diseases being caused by underlying neurological issues. [32]

A 2014 USGS survey of mercury levels in the United States water system found that methylmercury concentrations in fish were typically highest in wetland areas including the coastal plain streams in the Southeast. Fish methylmercury levels were also high in the Western US, but only in streams that had been mined for mercury or gold. [33]

Minamata disease Edit

In the 1950s, inhabitants of the seaside town of Minamata, on Kyushu island in Japan, noticed strange behavior in animals. Cats would exhibit nervous tremors, and dance and scream. Within a few years this was observed in other animals birds would drop out of the sky. Symptoms were also observed in fish, an important component of the diet, especially for the poor. When human symptoms started to be noticed around 1956 an investigation began. Fishing was officially banned in 1957. It was found that the Chisso Corporation, a petrochemical company and maker of plastics such as vinyl chloride, had been discharging heavy metal waste into the sea for decades. They used mercury compounds as catalysts in their syntheses. It is believed that about 5,000 people were killed and perhaps 50,000 were to some extent poisoned by mercury. Mercury poisoning in Minamata, Japan, is now known as Minamata disease.

Seafood consumption benefits Edit

The American College of Obstetricians and Gynecologists noted that, considering all the dangers and benefits, the overall result of eating fish in the United States is likely to improve personal health rather than damage it. [17] The College argues that the omega-3 polyunsaturated fatty acids found in fish have a health benefit that outweighs the harm from mercury or polychlorinated biphenyls. Even so, the College suggested limiting fish consumption for pregnant women. A risk-benefit study weighing the risks of mercury consumption against the benefits derived from fish in Alaska showed that the benefits outweigh the risks when consuming salmon for both cardiovascular health and infant neurological development, and that methyl mercury data for non-oily fish need to be of high quality before relative risk can be reliably identified. [34] The Seychelles Child Development Study traced more than seven hundred mother-child pairs for nine years and found no neurological problems in the children resulting from both prenatal and postnatal methylmercury exposure. A study done with marketed fish in Oman concluded that, except in a few rare cases, the fish available for consumption had lower levels of mercury than limits defined by various health organizations. [35] Clearly, these studies call into question whether or not normal everyday consumption of fish is dangerous, and at very least justify the creation of place-based and culturally relevant consumption advisories. [36] They do not take into account cases of severe mercury poisoning, such as that found in Minamata disease.

Selenium is an element that is known to counteract some of the dangers of ingesting mercury. [29] Multiple studies have been done, such as those in New Jersey and Sweden, that take into account selenium as well as mercury levels. Fish often do contain selenium in conjunction with bioaccumulated mercury, which may offset some of the dangers associated with the mercury ingested.

Most-contaminated fish species Edit

The danger level from consuming fish depends on species and size. Size is the best predictor of increased levels of accumulated mercury. Sharks, such as the mako shark, have very high levels of mercury. A study on New Jersey coastal fish indicated that one third of the sampled fish had levels of mercury above 0.5 parts per million, a level that could pose a human health concern for consumers who regularly eat this fish. [29] Another study of marketplace fish caught in waters surrounding Southern Italy showed that, undoubtedly, greater fish weight leads to additional mercury found in fish body tissues. Moreover, the concentration, measured in milligrams of mercury per kilogram of fish, steadily increases with the size of the fish. Anglerfish off the coast of Italy were found with concentrations as high as 2.2 milligrams of mercury per kilogram, higher than the recommended limit of 1 milligram of mercury per kilogram. Annually, Italy catches approximately a third of its fish from the Adriatic Sea, where these anglerfish were found. [37]

Fish that consume their prey in a certain manner may contain much higher concentrations of mercury than other species. Grass carp off the coast of China hold far less internal mercury than do bighead carp. The reason for this is that bighead carp are filter feeders, while grass carp are not. Thus, bighead carp gather more mercury by eating large amounts of small plankton, as well as sucking up sediments that collect a sizable amount of methyl mercury. [3]

Mercury levels in commercial fish and shellfish
species Mean
(ppm) [1]
Std dev
(ppm) [1]
(ppm) [1]
Comment Trophic
level [38]
Max age
(years) [38]
Tilefish (Gulf of Mexico) 1.123 n/a n/a Mid-Atlantic tilefish has lower mercury levels
and is considered safe to eat in moderation. [1]
3.6 35
Swordfish 0.995 0.539 0.870 4.5 15
Shark 0.979 0.626 0.811
Mackerel (king) 0.730 n/a n/a 4.5 14
Tuna (bigeye) 0.689 0.341 0.560 Fresh/frozen 4.5 11
Orange roughy 0.571 0.183 0.562 4.3 149
Marlin* 0.485 0.237 0.390 4.5
Mackerel (Spanish) 0.454 n/a n/a Gulf of Mexico 4.5 5
Grouper 0.448 0.278 0.399 All species 4.2
Tuna 0.391 0.266 0.340 All species, fresh/frozen
Bluefish 0.368 0.221 0.305 4.5 9
Sablefish 0.361 0.241 0.265 3.8 94
Tuna (albacore) 0.358 0.138 0.360 Fresh/frozen 4.3 9
Patagonian toothfish 0.354 0.299 0.303 AKA Chilean sea bass 4.0 50+ [39]
Tuna (yellowfin) 0.354 0.231 0.311 Fresh/frozen 4.3 9
Tuna (albacore) 0.350 0.128 0.338 Canned 4.3 9
Croaker white 0.287 0.069 0.280 Pacific 3.4
Halibut 0.241 0.225 0.188 4.3
Weakfish 0.235 0.216 0.157 Sea trout 3.8 17 [40]
Scorpionfish 0.233 0.139 0.181
Mackerel (Spanish) 0.182 n/a n/a South Atlantic 4.5
Monkfish 0.181 0.075 0.139 4.5 25
Snapper 0.166 0.244 0.113
Bass 0.152 0.201 0.084 Striped, black, and black sea 3.9
Perch 0.150 0.112 0.146 Freshwater 4.0
Tilefish (Atlantic) 0.144 0.122 0.099 3.6 35
Tuna (skipjack) 0.144 0.119 0.150 Fresh/frozen 3.8 12
Buffalofish 0.137 0.094 0.120
Skate 0.137 n/a n/a
Tuna 0.128 0.135 0.078 All species, canned, light
Perch (ocean) * 0.121 0.125 0.102
Cod 0.111 0.152 0.066 3.9 22
Carp 0.110 0.099 0.134
Lobster (American) 0.107 0.076 0.086
Sheephead (California) 0.093 0.059 0.088
Lobster (spiny) 0.093 0.097 0.062
Whitefish 0.089 0.084 0.067
Mackerel (chub) 0.088 n/a n/a Pacific 3.1
Herring 0.084 0.128 0.048 3.2 21
Jacksmelt 0.081 0.103 0.050 3.1
Hake 0.079 0.064 0.067 4.0
Trout 0.071 0.141 0.025 Freshwater
Crab 0.065 0.096 0.050 Blue, king and snow crab
Butterfish 0.058 n/a n/a 3.5
Flatfish * 0.056 0.045 0.050 Flounder, plaice and sole
Haddock 0.055 0.033 0.049 Atlantic
Whiting 0.051 0.030 0.052
Mackerel (Atlantic) 0.050 n/a n/a
Croaker (Atlantic) 0.065 0.050 0.061
Mullet 0.050 0.078 0.014
Shad (American) 0.039 0.045 0.045
Crayfish 0.035 0.033 0.012
Pollock 0.031 0.089 0.003
Catfish 0.025 0.057 0.005 3.9 24
Squid 0.023 0.022 0.016
Salmon * 0.022 0.034 0.015 Fresh/frozen
Anchovies 0.017 0.015 0.014 3.1
Salmon * 0.014 0.021 0.010 Canned
Sardine 0.013 0.015 0.010 2.7
Tilapia * 0.013 0.023 0.004
Oyster 0.012 0.035 n/d
Clam * 0.009 0.011 0.002
Shrimp * 0.009 0.013 0.001 6.5 [41]
Scallop 0.003 0.007 n/d
* indicates only methylmercury was analyzed (all other results are for total mercury)
n/a – data not available
n/d – below detection level (0.01ppm)

US government scientists tested fish in 291 streams around the country for mercury contamination. They found mercury in every fish tested, according to the study by the U.S. Department of the Interior. They found mercury even in fish of isolated rural waterways. Twenty-five percent of the fish tested had mercury levels above the safety levels determined by the U.S. Environmental Protection Agency for people who eat the fish regularly. [11]

Japan Edit

Since the Minamata disaster, Japan has improved on its mercury regulation. During the 1970s Japan made strides to reduce mercury demand and production. Chief among these efforts was the reduction of inorganic mercury produced by mines. It was halted by 1974, and demand fell from 2,500 tons per year in 1964, its peak, to 10 tons per year in recent years. [42] Since these initial strides, Japan has introduced a list of regulations governing the mercury content of a variety of materials.

Japan Mercury Regulation [42]
Category Regulation Result
Cosmetics Pharmaceutical Affairs Act Ban the use of mercury and its compounds
Agriculture Agricultural Chemicals Control Act Ban the use of mercury and its compounds as an active ingredient
Household Commodities Act on Control of Household Products Containing Hazardous Substances No mercury in household adhesives, household paints, household wax, shoe polish, shoe cream, diapers, bibs, undergarments, gloves, and socks
Pharmaceutical Products Pharmaceutical Affairs Act No use of mercury compounds in oral preparations. No use of mercury compounds, other than mercurochrome, as an active ingredient. Mercury as a preservative only if no other option is available.
Air Air Pollution Control Law No more than 40 ng/m 3
Water Basic Environment Law and Water Pollution Control Act Environmental quality standard: no more than 0.0005 mg/L in waterway and ground water. Effluent standard: no more than 0.005 mg/L in effluence.
Soil Basic Environment Law and Soil Contamination Countermeasures Act Environmental quality standard: no more than 0.0005 mg/L sample solution. Elution standard: no more than 0.0005 mg/L. Content standard: no more than 15 mg/kg

Regulation of these potential sources of pollution reduces the amount of mercury that ends up in fish and, through biomagnification, in humans. In addition to enacting legislation controlling the mercury levels in potential pollutants, Japan has directly influenced the environment by issuing regulations setting acceptable levels of environmental mercury pollution.

It is Japan's goal to promote international mercury legislation in hopes of preventing any country from experiencing what it did. [42] Despite Japan's extensive regulation and experience with mercury-based disasters, there is still little information provided to the public. The Japanese Federal Fish Advisory's recommendations are less strict than those in America. [43]

United States Edit

The United States has regulated mercury emissions under the authority of the Clean Air Act.

The Environmental Protection Agency (EPA) first attempted to regulate power plant mercury emissions with the Clean Air Mercury Rule in 2005. [44] The George W. Bush administration intended for the regulation to use a cap-and-trade system to control emissions across multiple industries. The rule was challenged in litigation, and in 2008 the U.S. Court of Appeals for the District of Columbia Circuit vacated the rule, stating that EPA had improperly excluded power plants from designation as emitting hazardous air pollutants. [45]

EPA subsequently classified mercury emissions from power plants as hazardous under section 112 of the Clean Air Act. The 2012 Mercury and Air Toxics Standards (MATS) regulation, issued by the Barack Obama administration, targets airborne mercury emissions from power plants and other stationary sources. [46] [47] Airborne mercury is dissolved in the oceans, where microorganisms convert waterborne mercury into methyl mercury, which enters the food chain and is stored in fish tissue.

EPA stated that the MATS regulation would prevent about 90% of power plant mercury. [47] The agency estimated the total expected health benefits are estimated at $37 billion–$90 billion by 2016. [ citation needed ] EPA estimated the economic cost at $9.6 billion annually. [ citation needed ] .

In 2020 the Trump administration attempted to weaken the MATS rule by disavowing EPA's previous calculations and justifications, thereby making the rule subject to legal challenges. [48]

In EU, the regulation (EU) 2017/852 [49] covers the full life cycle of mercury. This legislation prohibits the manufacture, export and import of a large range of mercury-added products puts an end to all uses of mercury catalysts and large electrodes in industrial processes and reduces the use of and pollution from dental amalgamRecently, the EU estimated the Mercury content in the topsoils based on a large Land Cover Survery named LUCAS. [50] The mercury content in EU topsoils has a median of 38 μg per Kg with a total content of around 45,000 tons [51] in the 0–20 cm of EU.

International Edit

Legislation on a global scale is believed by some to be needed for this issue because mercury pollution is estimated to be so far-reaching. Pollution from one country does not stay localized to that country. Despite the need by some, international regulation has been slow to take off. The first forms of international legislation appeared in the 1970s, beginning as agreements about shared bodies of water. [52] The next step was the Stockholm Declaration, which urged countries to avoid polluting the oceans by dumping. [53] The 1972 Oslo Convention and the 1974 Paris Convention were adopted by parts of Europe. Both lessened polluting the ocean with mercury, the former by banning the dumping of ships and aircraft into the ocean and the latter by obligating participants to reduce land-based pollution on coastlines. [54] [55] The first real global legislation regarding mercury pollution was the Basel Convention of 1989. This convention attempts to reduce the movement of mercury across borders and primarily regulates the import and export of toxic chemicals, including mercury. [52] In 1998 the Convention on Long-Range Transboundary Air Pollution was adopted by most of the European Union, the United States, and Canada. Its primary objective is to cut emissions of heavy metals. The convention is the largest international agreement on mercury established to date. [52] In the early 21st century, the focus of mercury regulation has been on voluntary programs. [52] The next phase in legislation is a global effort, and this appears to be what the Minamata Convention hopes to accomplish. The Minamata Convention, named after the Japanese city that suffered horribly from mercury pollution, has taken four years of negotiation but was finally adopted by delegates from over 140 countries. The convention will come into power after 50 countries have signed it. The Minamata Convention will require all participants to eliminate, where possible, the release of mercury from small-scale gold mining. It will also require a sharp reduction in emission from coal burning. [56]

The complexities associated with mercury transport and environmental fate are described by USEPA in their 1997 Mercury Study Report to Congress. [57] Because methyl mercury and high levels of elemental mercury can be particularly toxic to a fetus or young children, organizations such as the U.S. EPA and FDA recommend that women who are pregnant or plan to become pregnant within the next one or two years, as well as young children, avoid eating more than 6 ounces (170g, one average meal) of fish per week. [58]

In the United States, the FDA has an action level for methylmercury in commercial marine and freshwater fish that is 1.0 parts per million (ppm). In Canada, the limit for the total of mercury content is 0.5 ppm. The Got Mercury? website includes a calculator for determining mercury levels in fish. [59]

Species with characteristically low levels of mercury include shrimp, tilapia, salmon, pollock, and catfish (FDA March 2004). The FDA characterizes shrimp, catfish, pollock, salmon, sardines, and canned light tuna as low-mercury seafood, although recent tests have indicated that up to 6 percent of canned light tuna may contain high levels. [60] A study published in 2008 found that mercury distribution in tuna meat is inversely related to the lipid content, suggesting that the lipid concentration within edible tuna tissues has a diluting effect on mercury content. [61] These findings suggest that choosing to consume a type of tuna that has a higher natural fat content may help reduce the amount of mercury intake, compared to consuming tuna with a low fat content. Also, many of the fish chosen for sushi contain high levels of mercury. [62]

According to the US Food and Drug Administration (FDA), the risk from mercury by eating fish and shellfish is not a health concern for most people. [63] However, certain seafood might contain levels of mercury that may cause harm to an unborn baby (and especially its brain development and nervous system). In a young child, high levels of mercury can interfere with the development of the nervous system. The FDA provides three recommendations for young children, pregnant women, and women of child-bearing age:

  1. Do not eat shark, swordfish, king mackerel, or tilefish (Gulf of Mexico) because they might contain high levels of mercury.
  2. Eat up to 12 ounces (2 average meals of 170 g each) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish and shellfish that are low in mercury are: shrimp, canned light tuna, salmon, pollock, and catfish. Another commonly eaten fish, albacore or ("white") tuna depending on its origin might have more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, it is recommended that you should not eat more than up to 6 ounces (one average meal) of albacore tuna per week.
  3. Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal of 170 g) per week of fish you catch from local waters, but consume no other fish during that week.

Research suggests that selenium content in fish is protective against the toxic effects of methylmercury content. [64] Fish with higher ratios of selenium to methylmercury (Se:Hg) are better to eat since the selenium binds to the methylmercury allowing it to pass through the body un-absorbed.

In 2012 the European Food Safety Authority (EFSA) reported on chemical contaminants they found in the food of over 20 European countries. They established that fish meat and fish products were primarily responsible for methylmercury in the diet of all age classes. Particularly implicated were swordfish, tuna, cod, pike, whiting and hake. The EFSA recommend a tolerable weekly intake for methylmercury of 1.3 μg/kg body weight. [65]


Alligator gar are the largest species in the gar family, and among the largest freshwater fishes found in North America. Mature alligator gar commonly measure 6 ft (1.8 m) in length, and weigh over 100 lb (45 kg). However, anecdotal reports suggest they can grow up to 10 ft (3 m) in length, and weigh as much as 350 lb (159 kg). [8] The largest alligator gar officially recorded was inadvertently caught in the net of fisherman Kenny Williams of Vicksburg, Mississippi, while he was fishing the oxbow lakes of the Mississippi River on February 14, 2011. Williams was pulling up his net on Lake Chotard, expecting to find buffalo fish, but instead discovered a large alligator gar tangled in his net. The gar was 8 ft 5 + 1 ⁄ 4 in (2.572 m) long, weighed 327 lb (148 kg), and its girth was 47 in (120 cm). According to wildlife officials, the fish was estimated to be between 50 and 70 years old one report estimated the gar's age to be at least 95. [9] Williams donated it to the Mississippi Museum of Natural Science in Jackson, where it will remain on display. [10] [11] All gars have torpedo-shaped bodies, but some distinguishing characteristics of adult alligator gar include their large size heavy bodies broad heads short, broad snouts large, sharp teeth and double row of teeth on their upper jaws. They are usually brown or olive fading to a lighter gray or yellow ventral surface. The dorsal and anal fins are positioned toward the back of their bodies, and their caudal fins are abbreviate heterocercal, or nonsymmetrical. [8]

Alligator gar have gills, but unlike other species of fish, with few exceptions, they also have a highly vascularized swim bladder lung that supplements gill respiration. [12] The bladder not only provides buoyancy, but also enables them to breathe in air, which is why they are able to inhabit bodies of water in which most other fishes would die of suffocation. The swim bladder is connected to their fore gut by a small pneumatic duct, which allows them to breathe or gulp air when they break the surface, [13] an action seen quite frequently on lakes in the Southern United States during the hot summer.

The scales of alligator gar are not like the scales of other fishes, which have flexible elasmoid scales their bodies are protected by inflexible and articulated ganoid scales that are rhomboidal-shaped, often with serrated edges, and composed of a tough inner layer of bone and hard outer layer of ganoin, which is essentially homologous to tooth enamel, making them nearly impenetrable. [14] [15] [16]

Lacépède first described the alligator gar in 1803. The original name was Lepisosteus spatula, but was later changed by E.O. Wiley in 1976 to Atractosteus spatula to recognize two distinct taxa of gars. Synonyms of Atractosteus spatula include Lesisosteus [sic] ferox (Rafinesque 1820), and Lepisosteus spatula (Lacepede 1803). Fossils from the order Lepisosteiformes have been collected in Europe from the Cretaceous to Oligocene periods, in Africa and India from the Cretaceous, and in North America from the Cretaceous to recent times. The Lepisosteidae are the only extant family of gars with seven species, all located in North and Central America. [8] The fossil record traces the existence of gars like the Alligator gar back to the Early Cretaceous over 100 million years ago. [17] [18] Despite being a highly evolved species, alligator gar are often referred to as "primitive fishes" or "living fossils" [19] [20] because they have retained a few morphological characteristics of their earliest ancestors with seemingly few to no apparent changes, such as a spiral valve intestine, which is also common to the digestive system of sharks, an abbreviate heterocercal tail, and a swim bladder lung for breathing in both air and water. [8] [21] [22]

Alligator gar are relatively passive, seemingly sluggish solitary fish, but voracious ambush predators. They are opportunistic night predators and are primarily piscivores, but they also ambush and eat water fowl, turtles, [23] and small mammals that may be floating on the surface. Their method of ambush is to float a few feet below the surface, and wait for unsuspecting prey to swim within reach. They lunge forward, and with a sweeping motion, grab their prey, impaling it on their double rows of sharp teeth. [21]

Diet studies have shown alligator gar to be opportunistic piscivores, and even scavengers depending on the availability of their preferred food source. They occasionally ingest sport fish, but the majority of stomach content studies suggest they feed predominately on forage fishes such as gizzard shad and invertebrates and water fowl. However, brackish water populations of alligator gar are known to feed heavily on blue crabs in addition to fish such as the hardhead catfish (Ariopsis felis). [24] Diet studies have also revealed fishing tackle and boat-engine parts in their stomachs. [25] [26]

As with most ancestral species, alligator gar are long-lived, and sexually late maturing. Most females do not reach sexual maturity until after their first decade of life, while males reach sexual maturity in half that time. The conditions must be precise for a successful spawning to occur. Preparation for spawning begins in the spring with the extended photoperiod and rising water temperatures, but flooding is also necessary to trigger the event. When rivers rise and spread over the floodplain, they create oxbow lakes and sloughs, and inundate terrestrial vegetation, which in turn provides protection and a nutrient-rich habitat for larval fish and fry. Once the water temperature has reached 68 to 82 °F (20 to 28 °C), and all the other criteria are met, gar move into the grassy, weed-laden shallows to spawn. [27] [28]

Actual spawning occurs when males gather around gravid females, and begin writhing, twisting, bumping into, and slithering over the tops of females, an activity which triggers the release of eggs. Males release clouds of milt to fertilize the eggs as they are released into the water column. [27] The sticky eggs then attach to submerged vegetation, and development begins. Only a few days are needed for the eggs to hatch into larval fish, and another 10 days or so for the larval fish to detach from the vegetation and start moving about as young fry. [28] Egg production is variable, and believed to be dependent on the size of the female. A common formula used for predicting the number of eggs a female can produce is 4.1 eggs/gram of body weight, which gives an average of about 150,000 eggs per spawn. The eggs of alligator gar are bright red and poisonous to humans if ingested. [21]

Natural range Edit

Alligator gar inhabit a wide variety of aquatic habitats, but most are found in the Southern United States in reservoirs and lakes, in the backwaters of lowland rivers, and in the brackish waters of estuaries, bayous, and bays. It occurs southward along the Gulf Coast of Texas, into Tamaulipas and northern Veracruz, Mexico, however, records from Nicaragua and Costa Rica are considered "suspect and refuted". [29] They have occasionally been seen in the Gulf of Mexico. [21] In Texas and Louisiana, large gars are commonly seen breaking the surface in reservoirs, bayous, and brackish marshes. They are found throughout the lower Mississippi River Valley and Gulf Coast states of the Southern United States and Mexico as far south as Veracruz, encompassing Texas, Oklahoma, Louisiana, Kentucky, Mississippi, Alabama, Tennessee, Arkansas, Missouri, Illinois, Florida, and Georgia. [30] Reports suggest alligator gar were once numerous throughout much of their northern range, but valid sightings today are rare, and may occur once every few years. [8] Records of historical distribution indicate alligator gar once inhabited regions as far north as central Kansas, Nebraska, Ohio, Iowa, and west-central Illinois, where they are now listed as extirpated. The most northerly verified catch was in Meredosia, Illinois, in 1922. [31] In 2016, there were efforts to reintroduce alligator gar between Tennessee and Illinois as part of an effort to control invasive Asian carp. [32]

Outside natural range Edit

A few notable sightings of alligator gar have been reported outside North America. In November 2008, a broadhead gar, genus Atractosteus, measuring 5.2 to 6.4 ft (1.6 to 2.0 m) was caught in the Caspian Sea north of Esenguly, Turkmenistan, by two officials of Turkmenistan Fishery Protection. [33] Its species is unconfirmed, but is believed to be an alligator gar. [34]

On September 4, 2009, a 3 ft 3 in (0.99 m) alligator gar was found in Tak Wah Park in Tsuen Wan, Hong Kong. Over the next two days, at least 16 other alligator gar, the largest measuring 4.9 ft (1.5 m), were found in ponds in public parks in Hong Kong. [35] Nearby residents reported the alligator gar had been released into the ponds by aquarium hobbyists, and had lived there for several years. However, after a complaint made by a citizen who falsely identified alligator gar as crocodiles, the use of terms like "horrible man-eating fish" had begun appearing in the headlines of some major local newspapers. Officials with Leisure and Cultural Services in Tak Wah Park removed all the alligator gar from the ponds because they were concerned the large, carnivorous fish might harm children. [36] Not unusually, the large, sharp teeth and outward appearance of alligator gar can precipitate unreasonable fear in those unfamiliar with the species. Sensationalized reports have contributed to the misconception of predatory attacks by alligator gar on humans, though none of the reports have been confirmed.

On January 21, 2011, an alligator gar measuring 4 ft 11 in (1.50 m) was caught in a canal in Pasir Ris, Singapore, by two recreational fishermen. The fish was taken to a nearby pond, where the owner confirmed it was an alligator gar rather than an arapaima, as the men had initially thought. [37]

Anecdotal reports have been made of alligator gar captured in various parts of India, but are believed to be the result of incidental releases by aquarium hobbyists and the like. In August 2015, an alligator gar was found entangled in cloth inside a well in Dadar, where it had been living for quite some time. It was rescued by animal activists and returned to the well unharmed. [38] In June 2016, a 3.5-ft alligator gar was caught from Subhash Sarovar Lake in Kolkata. [39] Other incidents over the years have been random, ranging from captures in coastal waters during environmental assessments [40] to captures in private ponds.

On June 27, 2020, an alligator gar measuring 112 cm (3 ft 8in) was reported dead on the shore of Gonyeli Baraji reservoir, North Cyprus. Specialists from Cyprus Wildlife Research Institute collected the fish and explained its species to be alligator gar (Atractosteus spatula). It is suspected that the fish had been released recently and could not cope with the environment and died, however, it could be that the fish was resident there for years. A necropsy will be applied to find out more. [41]

Early history Edit

Native Americans in the South, and Caribbean peoples used the alligator gar's ganoid scales for arrow heads, breastplates and as shielding to cover plows. Early settlers tanned the skins to make a strong, durable leather to cover their wooden plows, and make purses and various other items. Gar oil was also used by the people of Arkansas as a repellent for buffalo gnats. [25]

For nearly half a century, alligator gar were considered "trash fish", [4] or "nuisance species" by state and federal authorities who targeted them for elimination to protect gamefish populations, [6] and to prevent alleged attacks on humans, a claim that remains unsubstantiated with the exception of occasional injuries sustained from captured alligator gar thrashing around on the decks of boats. [21] Fishermen participated in the slaughter of thousands of alligator gar believing they were providing a great service. In 1992, PBS affiliate KUHT channel 8 became the presenting station for a public-outreach program that documented the life history cycle of alligator gar titled The Alligator Gar: Predator or Prey?. It was the first documentary ever produced and televised nationally about alligator gar at a time when it was still being referred to as a trash fish. The half-hour program ran for three years as part of an educational series titled "Exotic and Unusual Fishes", produced by Earthwave Society. It first aired in primetime during the 1992 July sweeps, and drew a 2.8 rating/4 share, making it the number-one rated program of the evening for several PBS affiliates. [21] A decade passed before any significant action was taken to protect and preserve the remaining populations of alligator gar in the United States. [26] Among the first to enact restoration and management practices was the Missouri Department of Conservation in partnership with Tennessee, Arkansas, Kentucky, Illinois, Alabama, Mississippi, Texas, Oklahoma, and Louisiana. [25]

Sport fish Edit

The long-time public perception of alligator gar as trash fish or a nuisance species has changed, with increasing national and international attention on the species as a sport fish, which some have attributed to features on popular television shows. Oklahoma, Texas, Arkansas, Mississippi, and Louisiana allow regulated sport fishing of alligator gar. Texas has one of the best remaining fisheries for alligator gar, and in concert with its efforts to maintain a viable fishery, imposed a one-per-day bag limit on them in 2009. [42] The Texas state record, and world record for the largest alligator gar caught on rod and reel, is 279 lb (127 kg), taken by Bill Valverde on January 1, 1951, on the Rio Grande in Texas. [43] Alligator gar are also quite popular among bowfishers because of their large size, trophy potential, and fighting ability. The Texas state bowfishing record was set in 2001 by Marty McClellan with a 290 lb (130 kg) alligator gar from the Trinity River. The all-tackle record was a 302 lb (137 kg) alligator gar caught on a trotline in 1953 by T.C. Pierce, Jr. In 1991, fishing guide Kirk Kirkland anecdotally reported catching an alligator gar measuring 9 ft 6 in (2.90 m) on rod and line from the Trinity River. [44]

Commercialization and aquaculture Edit

Declining populations of alligator gar throughout their historic range have resulted in the need to monitor wild populations and regulate commercial harvests. Alligator gar have a high yield of white-meat fillets and a small percentage of waste relative to body weight. Fried gar balls, grilled filets, and fillets boiled in water with crab boil are popular dishes in the southern United States. There is also a small cottage industry that designs and sells jewelry made from the ganoid scales of alligator gar some tan the hides to produce leather for making lamp shades, purses and a host of other novelty items. [21] [25] Historically, the price of wild gar meat sold commercially to wholesale distributors has fluctuated between $1.00/lb [45] up to $2.50/lb. [46] Retail prices in supermarkets and specialty stores have ranged from $3.00 to $3.50/lb. [47] [48]

Atractosteus gars, including alligator gar, tropical gars, and Cuban gars, are considered good candidates for aquaculture, particularly in developing regions, where their rapid growth, disease resistance, easy adaptation to artificial feeds as juveniles, and ability to tolerate low water quality are essential. Their ability to breathe in both air and water eliminates the need for costly aeration systems and other technology commonly used in aquaculture. In the Southern United States, as well as in parts of Mexico and Cuba, broodstocks have already been established, and are being maintained in their respective regions, where they already are a popular food fish. [49]

When to see a doctor

A fishbone sometimes just won’t come out on its own. See your doctor instead.

It can cause real danger if the fishbone is trapped in your oesophagus or elsewhere in your digestive tract for so long. It can cause a rip in your oesophagus, an abscess, infections and life-threatening problems on rare occasions.

Instruction: If your discomfort is severe or does not go down after a few days of trying out all these fishbone home remedies explained above, see your doctor. Seek medical help straight away if you experience: inability to drink or eat, swelling, bruising, chest pain, and excessive drooling.

What a doctor can do

If you can not get a fishbone out by yourself, the doctor usually can easily remove it. If they are unable to see the fishbone at the back of your throat, they will most definitely do an endoscopy.

What is endoscopy?

An endoscope is a large, transparent tube with a small camera at the end. This device may be used by your doctor to remove the fishbone or push it down gently into your stomach.


The swordfish is named after its pointed, flat bill, which resembles a sword. The species name, Xiphias gladius, derives from Greek ξιφίας (xiphias, "swordfish"), itself from ξίφος (xiphos, "sword") and from Latin gladius ("sword"). [4] This makes it superficially similar to other billfish such as marlin, but upon examination, their physiology is quite different and they are members of different families. [6]

Several extinct genera are known, such as a large sized Xiphiorhynchus and Aglyptorhynchus. [7] Unlike modern taxa these have equally long lower jaws. [ citation needed ]

They commonly reach 3 m (9.8 ft) in length, and the maximum reported is 4.55 m (14.9 ft) in length and 650 kg (1,430 lb) in weight. [3] [4] The International Game Fish Association's all-tackle angling record for a swordfish was a 536 kg (1,182 lb) specimen taken off Chile in 1953. [2] Females are larger than males, and Pacific swordfish reach a greater size than northwest Atlantic and Mediterranean swordfish. [4] They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years. [4] The oldest swordfish found in a recent study were a 16-year-old female and 12-year-old male. Swordfish ages are derived, with difficulty, from annual rings on fin rays rather than otoliths, since their otoliths are small in size. [8]

Swordfish are ectothermic animals however, along with some species of sharks, they have special organs next to their eyes to heat their eyes and brains. Temperatures of 10 to 15 °C (18 to 27 °F) above the surrounding water temperature have been measured. The heating of the eyes greatly improves their vision, and consequently improves their ability to catch prey. [9] [10] Of the 25 000+ fish species, only 22 are known to have a mechanism to conserve heat. These include the swordfish, marlin, tuna, and some sharks. [9] [10]

Movements and feeding Edit

The popular belief of the "sword" being used as a spear is misleading. Their nose is more likely used to slash at its prey to injure the prey animal, to make for an easier catch. [4] The use as an offensive spear in case of dangers against large sharks or animals is under review.

Mainly, the swordfish relies on its great speed and agility in the water to catch its prey. It is no doubt among the fastest fish, but the basis for the frequently quoted speed of 97 km/h (60 mph) is unreliable. [11] Research on related marlin (Istiophorus platypterus) suggest a maximum value of 36 km/hr (22 mph) is more likely. [12]

Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 10 m (33 ft) from a neighboring swordfish. They are frequently found basking at the surface, airing their first dorsal fin. Boaters report this to be a beautiful sight, as is the powerful jumping for which the species is known. This jumping, also called breaching, may be an effort to dislodge pests, such as remoras or lampreys. [ citation needed ]

Swordfish prefer water temperatures between 18 and 22 °C (64 and 72 °F), [2] but have the widest tolerance among billfish, and can be found from 5 to 27 °C (41 to 81 °F). [4] This highly migratory species typically moves towards colder regions to feed during the summer. [4] Swordfish feed daily, most often at night, when they rise to surface and near-surface waters in search of smaller fish. During the day, they commonly occur to depths of 550 m (1,800 ft) and have exceptionally been recorded as deep as 2,878 m (9,442 ft). [2] Adults feed on a wide range of pelagic fish, such as mackerel, barracudinas, silver hake, rockfish, herring, and lanternfishes, but they also take demersal fish, squid, and crustaceans. [3] [4] In the northwestern Atlantic, a survey based on the stomach content of 168 individuals found 82% had eaten squid and 53% had eaten fish, including gadids, scombrids, butterfish, bluefish, and sand lance. [13] Large prey are typically slashed with the sword, while small are swallowed whole. [4]

Threats and parasites Edit

Almost 50 species of parasites have been documented in swordfish. In addition to remoras, lampreys, and cookiecutter sharks, this includes a wide range of invertebrates, such as tapeworms, roundworms, Myxozoans and copepods. [4] [14] A comparison of the parasites of swordfish in the Atlantic and in the Mediterranean indicated that some parasites, particularly Anisakis spp. larvae identified by genetic markers, could be used as biological tags and support the existence of a Mediterranean swordfish stock. [15]

Fully adult swordfish have few natural predators. Among marine mammals, killer whales sometimes prey on adult swordfish. [4] The shortfin mako, an exceptionally fast species of shark, sometimes take on swordfish dead or dying shortfin makos have been found with broken-off swords in their heads, revealing the danger of this type of prey. [16] Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish. [4] [17] Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more. [17]

Human fishery is a major predator of swordfishes. The annual reported catch in 2019 of the North Atlantic swordfish amounted to a total of 2.9 million pounds. [18]

Breeding Edit

In the North Pacific, batch spawning mainly occurs in water warmer than 24 °C (75 °F) during the spring and summer, and year-round in the equatorial Pacific. [2] In the North Atlantic, spawning is known from the Sargasso Sea, [19] and in water warmer than 23 °C (73 °F) and less than 75 m (246 ft) deep. [2] Spawning occurs from November to February in the South Atlantic off southern Brazil. [2] Spawning is year-round in the Caribbean Sea and other warm regions of the west Atlantic. [4]

Large females can carry more eggs than small females, and between 1 million to 29 million eggs have been recorded. [2] The pelagic eggs measure 1.6–1.8 mm (0.063–0.071 in) in diameter and 2.5 days after fertilization, the embryonic development occurs. [19] [4] The surface-living and unique-looking larvae are 4 mm (0.16 in) long at hatching. [3] [4] The bill is evident when the larvae reach 1 cm (0.4 in) in length. [3]

Watch the video: Ταχεία κατάψυξη ψαριών - Φιλέτα u0026 Ολόκληρα ψάρια (August 2022).