Sharks
Shark [class Chondrichthyes subclass Elasmobranchii superorder Selachimorpha]

Sharks are very different from other fish. When the modern fish (teleosts - bony fish) came on the scene, they rapidly pushed their predecessors toward extinction. Under severe stress some of these older fish back evolved features of their own primitive ancestors while adding some very advanced features as well. So successful were these adaptions the following era is called "The Age of Sharks" and modern fish had to struggle to survive.   Photo © i0089.

Sharks have much larger brains than modern fish and a more complex social structure. They generally give live birth instead of laying eggs and many are warm blooded and very energetic. They have no bones but a skeleton of light weight cartilage, allowing them to grow very large and still float. Their scales are formed like teeth rather than the removable flakes on modern fish (thus shark is not kosher).

Many sharks are now IUCN Red Listed as VU (Vulnerable) due to slow birth rates and Chinese demand for shark fins. Finning sharks is illegal in US waters and posession of shark fins or shark fin products is now illegal in California and Hawaii, states with the largest Chinese communities.

More on Varieties of Fish (very large page).


Culinary Varieties of Shark

Spiny Dogfish - [Piked Dogfish, Mud Shark, Spurdog; Cape Shark (market); Palombo (Sicily); Squalus acanthias   |   Pacific Spiny Dogfish; Squalus suckleyi]
Whole Dogfish 01d

There are many small sharks called "Dogfish", but the Spiny Dogfish has always been the most common and perhaps the most common of all sharks. It inhabits cooler waters worldwide, except the North Pacific, where the very similar S. suckleyi replaces it. This fish can grow to a little over 5 feet long and 20 pounds but it is commonly a little over 3 feet. This fish is IUCN Red Listed as VU (Vulnerable) worldwide, and CR (Critically Endangered) in Northern Europe, where effective controls are late being implemented.   Details and Cooking   Photo by U.S. National Oceanic and Atmospheric Administration = Public Domain.

Thresher Shark - [Common Thresher; Alopias vulpinus | Big Eye Thresher; Alopias superciliosus | Pelagic Thresher; Alopias pelagicus]
Whole Fish

Common Thresher is found in temperate and tropical waters worldwide and can grow to nearly 25 feet and over 760 pounds. It is a warm blooded shark, thus very energetic, and that tail is used to herd and stun prey. Thresher is fished commercially and commonly sold as frozen shark steaks. There was a major fishery in California in the 1980s but populations collapsed within a decade from overfishing. Now under strict fisheries regulation the populations are recovering, but most thresher is now caught as bycatch from other fishery operations. Due to the California experience, all three Thresher sharks are now IUCN Red Listed as VU (vulnerable).   Photo by U.S. National Oceanic and Atmospheric Administration = public domain.

Big Eye Thresher and Pelagic Thresher are tropical and subtropical fish and not warm blooded. The Big Eye, a night hunter, is found worldwide, while the Pelagic is an Indo Pacific fish absent from the Atlantic. Both are caught primarily as bycatch from other fishery operations.

Great White Shark - [Carcharodon carcharias]
Live Shark

This is one of a very few sharks where the eating can go the wrong way. Great whites don't consider humans particularly edible, but in the surf or murky waters they can mistake a person for something tastier. They live in temperate and tropical waters worldwide and can grow to nearly 26 feet and nearly 7500 pounds. This is quite large, but dwarfed by the extinct C. megalodon which grew up to 55 feet and over 121,000 pounds (it ate mostly whales). How closely the Great White and Megalodon are related is currently subject to fierce scientific debate. Great White Sharks can be used for human consumption just like any other shark - their fins are in demand in China, their livers by the supplement industry and their hides by fashion houses. IUCN Red Listed as VU (vulnerable).   Photo by Terry Goss distributed under license Creative Commons Attribution-ShareAlike 3.0 Unported.

Blue Shark - [Prionace glauca]
Live Shark

Blue Sharks have the widest range of any animal, inhabiting all oceanic waters between the arctic circles. .They can grow to 13 feet and 450 pounds. This is the most widely caught shark in commercial fisheries, usually as bycatch in other fisheries, and a major source of shark fins. They are known to occasionally attack humans, probably mostly by mistake. IUCN Red Listed as NT (near threatened).   Photo by U.S. National Oceanic and Atmospheric Administration = public domain.

Tiger Shark - [Galeocerdo cuvier]
Live Shark

This is one of the most dangerous sharks. While a Great White may bite and say "Yuk!", a tiger shark is more likely to actually eat a human, because they eat just about anything, including things that are not edible. This shark inhabits warmer waters worldwide, staying pretty close to shore, and may even be found in river estuaries. Growing to nearly 25 feet and 1780 pounds, Tiger Shark is fished commercially for its fins, meat, hide, cartilage and liver. IUCN Red Listed as NT (near threatened).   Photo by Albert Kok distributed under license Creative Commons Attribution-ShareAlike 3.0 Unported.


Prep & Cooking

Shark Steaks Shark does not cook at all like other fish. Modern bony fish cook so quickly and flake apart because they have very little of the connective tissue land animals have. Shark has connective tissue, distributed differently from land animals, but connective tissue it is. Shark stays firm when cooked, so firm you may need a knife to slice it. The texture is more like pork than like fish, and the flavor somewhere between pork and fish. The steaks shown in the photo are from thresher shark.

Shark Fins:   Do not buy shark fins or order shark fin soup. "Finning" sharks is inhumane, very wasteful, illegal in US waters and some of the sharks used are rated "threatened". Possession of shark fins and shark fin products is now illegal in California and Hawaii, over the protests of Chinese restaurants that served shark fin soup for US $80 to over $100 per bowl. Prices from $300 to $750 per bowl have been reported from Hong Kong. The sole purpose of shark fin soup is so party hosts can show off their wealth - it isn't really outstanding in any other way.

Catching:   Shark must be bled as soon as caught. Commercially caught shark is generally handled correctly, but if you catch one yourself keep this in mind. Cut off the tail, preferably still alive, and when the bleeding slows cut off the head and gut the fish immediately. Scrape the blood works and green spleen from the under side of the backbone. Rinse well and keep the body from contact with blood. Keep the head and tail so the game warden can measure your fish. Shark meat that has not been properly bled will smell of urine and ammonia.

Buying:   In North America shark is most commonly sold in the form of steaks, about 1-1/2 inch thick. Shark spoils rapidly so use it right away or freeze immediately, or more likely, buy it frozen. As with the related skates and rays you can tell freshness by smell. If there's a distinct smell of ammonia it's not fresh. If there's just a faint trace of ammonia, a soak in milk or water acidulated with citric acid will clear it up, but really fresh shark is better.

Skin:   Shark must be skinned. The skin is completely covered with tiny teeth rather than scales, and they don't scrape off. Some cultures use shark skin as sandpaper.

Cooking:   Shark is generally broiled, baked or grilled. It is considered less desirable for steaming, boiling or frying.


Health and Nutrition

Shark Jaw Being bitten by a shark can be hazardous to your health, and may result in disability or even death. For this reason, exposure to large live sharks, particularly in murky or turbulent water, should be limited to the extent practical. Most sharks, including Great Whites, don't much like the taste of people and usually bite by accident, but the tropical Tiger Shark is much more dangerous, as it will (and does) eat anything, including things that are not edible.   Photo © i0090 .

The only other noted danger from sharks is that, being top predators, they tend to have a higher mercury content than prey fish. This is considered a danger mainly to the fetuses of pregnant women, though the FDA admits their recommended limits are a shot in the dark without substantial relevant scientific data. The only substantial data I know of is the Seychelles Study (1) where no effect on child development was found in a population that eats 10 times as much fish as Americans do. From this I conclude moderate shark consumption is safe.

Shark liver oil from cold water sharks has long been harvested for dietary supplements and has long been a primary source of vitamins A and D. It is also a source for alkylglycerols (also found in mother's milk and bone marrow) pristane, squalene, omega-3 fatty acids, triglycerides, glycerol ethers, and fatty alcohols. Studies of possible anti-cancer benefits are under way, but nothing conclusive so far.

Shark cartilage has been claimed to fight cancerous tumors by slowing the growth of new blood vessels needed to supply the tumor. Most studies on this have been informal and inconclusive. Better studies are under way but most have so far shown no benefit. One study reported that a liquid extract had a positive effect but solid forms did not.

Links

  1. The Seychelles Study - No Detectable Risk From Mercury In Seafood, Study Shows - Science Daily.
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