Fish Feature

Atlantic Halibut – Don’t Let the Googly Eyes Fool You

Low biomass and slow growth rates leave Atlantic halibut susceptible to overexploitation. Image via Mass. Executive Office of Energy and Environmental Affairs.

Today, we’re talking about a monstrous flatfish – the voracious, predacious Atlantic halibut.

Big, Bad Beasties

Does this image reflect the intimidating sea beast you had in mind? Probably not. Like all flatfish, Atlantic halibut (Hippoglossus hippoglossus) lie on their left sides, giving them a goofy, almost crooked appearance. But don’t be fooled – their mouths gape all the way back to their eyes and are lined with sharp, curved teeth. Atlantic halibut range in color from dark chocolate to an olive brown with a blotchy, clouded gray lower side. Lying flat on the ocean floor, these fish are nearly invisible as they wait to ambush their prey. Starting to sound a little more predacious, right?

Now let’s dig into the “voracious” part. Atlantic halibut eat practically everything: other fish including cod, cusk, haddock, redfish, sculpins, hake, wolffish, and mackerel; as well as invertebrates like lobsters and crab. They’ve even reportedly eaten sea birds. Oh, and indigestible materials like iron, wood, and drift ice. These guys are pretty much the definition of opportunistic feeders – they’re out to eat whatever is most readily available. In the Gulf of Maine, though, they prefer to feed chiefly on other fish. And don’t worry, as opportunistic as they are, they are completely harmless to humans.

This is lucky, considering how “monstrous” they are…or at least were. Reports of 600 to 700 lb. Atlantic halibuts are often viewed as exaggerations, but at least one account of a fish in this weight class, caught about 50 miles off of Cape Ann by Capt. A. S. Ree in 1917, has been confirmed. The world record according to the International Game Fish Association (est. 1939) stands at 418 lbs., caught off the Norwegian coast in 2004.

Today, however, “large” Atlantic halibut hauled into New England docks range from about 50 to 200 lbs. It is believed that fully-grown females average between 100 and 150 lbs., while males weigh significantly less. Now, a 150 lb. fish is still pretty ginormous in my book, but why aren’t we finding the 600+ lb. whoppers of the 19th and early 20th centuries?

Here Today, Gone Tomorrow

That seems to be the motto of the commercial Atlantic halibut industry. Before 1820, these colossal fish were considered to be a nuisance. They hindered cod fishermen’s efforts by eating and chasing away their catch, often snapping some fishing gear in the process. However, a market for Atlantic halibut meat arose in Boston sometime between 1820 and 1825, and that was the beginning of the end.

The Atlantic halibut fishery was a boom and bust deal. The fish were first pursued inshore. As with most fisheries, the biggest fish were the first to go, resulting in smaller average body size and dramatically reduced biomass. When stocks began noticeably declining (around 1839), fishermen moved offshore. By 1850, there were so few halibut left that it was no longer profitable for small boats to fish. In a last-ditch, desperate effort, the fishery was extended to deeper waters (600 – 1200 ft.) on Georges Bank in 1875. The only populations that maintained their numbers lived on even deeper slopes, out of the reach of fishing gear.

In 1996, the International Union for the Conservation of Nature classified Atlantic halibut as endangered. NOAA followed suit in 2004 with a “Species of Concern” listing, acknowledging severe population decline, but withholding Endangered Species Act protections due to species data deficiencies. Today, thanks to careful fishing regulations under the Northeast Multispecies Fishery Management Plan, populations have stabilized enough to be identified as vulnerable.

Atlantic halibut are bottom-oriented fish that have been able to survive by seeking refuge from human exploitation on deep sea slopes, such as Cashes Ledge. These areas, which were historically fished less intensively than more easily accessible regions, provide vital feeding and breeding grounds to Atlantic halibut and offer them the chance to persist – to sustain viable populations and to recover from a dramatically overfished past. Yet, low existing biomass and slow growth rates mean that this species is still extremely susceptible to overexploitation. We must continue to maintain vigilance in our protections.

To preserve deep sea mountains and canyons is to protect monstrous majesties like the Atlantic halibut.

 


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