How much does a pound of halibut cost in your neighborhood grocery store? If you can even find halibut for sale, it probably costs more than $20 per pound, and if you decided to buy it, you expect your butcher to hand you a perfect chunk of pristine, white fish. Pacific halibut is one of the most sought-after food fish in the world. When cooked, halibut has a subtle flavor and a flaky texture, but when fishermen report catching halibut with sub-prime flesh conditions, the news alarms sport and commercial fishermen, fish processors, chefs, and consumers. Chalky and mushy flesh conditions are the two biggest concerns for halibut caught in Alaska.
What is the difference between chalky and mushy halibut, and can a human safely eat the meat of a fish afflicted with either condition? The two flesh conditions might both look unappetizing, but they are very different from each other. One is caused by the rigors of an athlete trying to stay in the ocean and out of your boat, while the other is a sign of a malnourished fish. Let me explain in more detail.
Chalky Halibut
When an animal exerts itself, it uses oxygen to break down glucose and produce energy. During intense exercise, such as when a sprinter runs a race, he might not be able to breathe enough oxygen to complete the chemical process to produce energy. When the body does not have sufficient oxygen, it produces lactic acid, which your body can convert anaerobically (without oxygen) into energy. Producing anaerobic energy works great in the short term, but during prolonged physical exertion, lactic acid can build up in the bloodstream and muscles faster than the animal can burn it, lowering the pH of the muscle tissue.
The blood and muscles of a healthy athlete, as well as those of a healthy fish, will slowly dump excess lactic acid once the athlete or fish stops exerting and begins breathing normally again. When a fish is killed at the end of a long fight, though, the excess lactic acid stays in its flesh. Small halibut in the 10 lb. to 15 lb. range, caught during the warmest part of the summer, are the most susceptible to excess lactic acid in their tissues.
The meat from a halibut with a build-up of lactic acid often looks white and cooked as soon as you fillet the fish, but it sometimes takes several hours before the flesh turns chalky. Instead of the semi-translucent appearance of normal halibut meat, chalky halibut is white and opaque. Chalky halibut looks like raw halibut after the meat has marinated in lemon juice for several hours. Chalky halibut is safe to eat, but the meat often tastes tough and dry when cooked.
Mushy Halibut Syndrome
As the name implies, halibut with this syndrome have large sections of flesh which are soft instead of firm, and sometimes the flesh is so mushy, it feels like jelly. A mushy halibut is often obvious even before you fillet it because the fish looks emaciated, and indeed, biologists think malnourishment causes this condition.
Mushy halibut syndrome is most prevalent in halibut in the 15-20-lb. range. Although fish pathologists have yet to pinpoint the cause of this condition, they have not found parasites or infectious agents in affected fish, and they do not believe it is a disease that can be transmitted from fish to fish. Microscopic examination of the tissues of mushy halibut reveal a severe loss of muscle mass, and the affected muscles resemble those of animals known to have nutritional deficiencies of vitamin E and selenium.
The muscle atrophy in mushy halibut causes weakness in the fish and compromises the halibut’s ability to capture prey, leading to further malnutrition and weakness. This syndrome is most common in areas where populations of prey fish have declined, and the stomach contents of mushy halibut show many have consumed small crabs instead of the forage fish they normally eat. Researchers wonder if crab lacks some of the nutrients necessary for halibut to thrive.
Mushy halibut is safe to eat, but when cooked, it falls apart and resembles oatmeal.
According to the International Halibut Commission, neither chalky nor mushy halibut are common, but the prevalence of these conditions varies between years and locations. As the oceans warm, researchers worry these conditions will become more common.
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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.