Halibut
Halibut is the common name for three flatfish in the genera "Hippoglossus" and "Reinhardtius" from the family of right-eye flounders and, in some regions, and less commonly, other species of large flatfish. The word is derived from "haly" (holy) and "butte" (flat fish), for its popularity on Catholic holy days. Halibut are demersal fish and are highly regarded as a food fish as well as a sport fish. Species. A 2018 cladistic analysis based on genetics and morphology showed that the greenland halibut diverged from a lineage that gave rise to the Atlantic and Pacific halibuts. The common  ancestor of all three diverged from a lineage that gave rise to the genus "Verasper", comprising the spotted halibut and barfin flounder. Physical characteristics. The Atlantic halibut is the world's largest flatfish. The IGFA record was apparently broken off the waters of Norway in July 2013 by a , fish. This was awaiting certification as of 2013. In July 2014, a Pacific halibut was caught in Glacier Bay, Alaska; this is, however, discounted from records because the halibut was shot and harpooned before being hauled aboard. Halibut are dark brown on the top side with a white to off-white  underbelly and have very small scales invisible to the naked eye embedded in their skin. Halibut are symmetrical at birth with one eye on each side of the head. Then, about six months later, during larval metamorphosis one eye migrates to the other side of the head. The eyes are permanently set once the skull is fully ossified. At the same time, the stationary-eyed side darkens to match the top side, while the other side remains white. This color scheme disguises halibut from above (blending with the ocean floor) and from below (blending into the light from the sky ) and is known as countershading. Diet. Halibut feed on almost any fish or animal they can fit into their mouths. Juvenile halibut feed on small crustaceans and other bottom-dwelling organisms. Animals found in their stomachs include sand lance, octopus, crab, salmon, hermit crabs, lamprey, sculpin, cod, pollock, herring, and flounder, as well as other halibut. Halibut live at depths ranging from a few meters to hundreds of meters, and although they spend most of their time near the bottom, halibut may move up in the water column to feed. In most ecosystems, the halibut is near the top of  the marine food chain. In the North Pacific, common predators are sea lions, killer whales, salmon sharks and humans. Halibut fishery. The North Pacific commercial halibut fishery dates to the late 19th century and today is one of the region's largest and most lucrative. In Canadian and US waters, long-line fishing predominates, using chunks of octopus ("devilfish") or other bait on circle hooks attached at regular intervals to a weighted line that can extend for several miles across the bottom. The fishing vessel retrieves the line after several hours to a day. The effects of long-line gear  on habitats are poorly understood, but could include disturbance of sediments, benthic structures, and other structures. International management is thought to be necessary, because the species occupies waters of the United States, Canada, Russia, and possibly Japan (where the species is known to the Japanese as "ohyo"), and matures slowly. Halibut do not reproduce until age eight, when about long, so commercial capture below this length prevents breeding and is against US and Canadian regulations supporting sustainability. Pacific halibut fishing is managed by the International Pacific Halibut Commission. For most of the modern era, halibut fishery operated as a derby . Regulators declared time slots when fishing was open (typically 24–48 hours at a time) and fisherman raced to catch as many pounds as they could within that interval. This approach accommodated unlimited participation in the fishery while allowing regulators to control the quantity of fish caught annually by controlling the number and timing of openings. The approach led to unsafe fishing, as openings were necessarily set before the weather was known, forcing fisherman to leave port regardless of the weather. The approach limited fresh halibut to the markets to several weeks per year, when the gluts would push down the  price received by fishermen. Individual fishing quotas. In 1995, US regulators allocated individual fishing quotas (IFQs) to existing fishery participants based on each vessel's documented historical catch. IFQs grant to holders a specific proportion of each year's total allowable catch (TAC). The fishing season is about eight months. The IFQ system improved both safety and product quality by providing a stable flow of fresh halibut to the marketplace. Critics of the program suggest, since holders can sell their quota and the fish are a public resource, the IFQ system gave a public resource to the private sector. The  fisheries were managed through a treaty between the United States and Canada per recommendations of the International Pacific Halibut Commission, formed in 1923. A significant sport fishery in Alaska and British Columbia has emerged, where halibut are prized game and food fish. Sport fisherman use large rods and reels with line, and often bait with herring, large jigs, or whole salmon heads. Halibut are strong and fight strenuously when exposed to air. Smaller fish will usually be pulled on board with a gaff and may be clubbed or even punched in the head to prevent them from thrashing around on  the deck. In both commercial and sport fisheries, standard procedure is to shoot or otherwise subdue very large halibut over before landing them. As food. Nutrition. Raw Pacific or Atlantic halibut meat is 80% water and 19% protein, with negligible fat and no carbohydrates (table). In a reference amount, raw halibut contains rich content (20% of more of the Daily Value, DV) of protein, selenium (65% DV), phosphorus (34% DV), vitamin D (32% DV), and several B vitamins: niacin, vitamin B6, and vitamin B12 (42–46% DV). Cooked halibut meat – presumably through the resulting dehydration – has relatively increased protein content and  reduced B vitamin content (per 100 grams), while magnesium, phosphorus, and selenium are rich in content. Food preparation. Halibut yield large fillets from both sides of the fish, with the small round cheeks providing an additional source of meat. Halibut are often boiled, deep-fried or grilled while fresh. Smoking is more difficult with halibut meat than it is with salmon, due to its ultra-low fat content. Eaten fresh, the meat has a clean taste and requires little seasoning. Halibut is noted for its dense and firm texture. Halibut have historically been an important food source to Alaska Natives  and Canadian First Nations, and continue to be a key element to many coastal subsistence economies. Accommodating the competing interests of commercial, sport, and subsistence users is a challenge. As of 2008, the Atlantic population was so depleted through overfishing that it might be declared an endangered species. According to Seafood Watch, consumers should avoid Atlantic halibut. Most halibut eaten on the East Coast of the United States is from the Pacific. In 2012, sportfishermen in Cook Inlet reported increased instances of a condition known as "mushy halibut syndrome". The meat of affected fish has a "jelly-like" consistency. When  cooked it does not flake in the normal manner of halibut but rather falls apart. The meat is still perfectly safe to eat but the appearance and consistency are considered unappetizing. The exact cause of the condition is unknown but may be related to a change in diet.