What Big Teeth You Have!
It’s clear where the wolffish gets its name. Those canines kind of remind you of…an actual wolf, right? But those visible chompers aren’t even the wolffish’s most useful dental feature; they use three sets of crushing teeth on the roofs of their mouths to grind down their hard-shelled prey – so hard that their teeth fall out every year after spawning and are replaced by a new set!
Which one’s the wolf, and which one’s the wolffish? Images via National Park Service (left) and Jonathan Bird (right).
Atlantic wolffish are voracious predators, feeding on mollusks, crustaceans, and echinoderms (think urchins and sea stars). So voracious, in fact, that they serve as keystone species in North Atlantic food webs because they help limit populations of sea urchins and green crabs.
Without the wolffish around, urchin and green crab populations could explode, which would have serious negative impacts on the Gulf of Maine ecosystem.
Can you imagine swimming in 30º to 50ºF (-1.2º to 10.2 ºC) water? That’s cold. The Atlantic wolffish prefers depths of 250 to 400 ft (80 to 120 m), so they live in water that frigid. How do they do it? No, they don’t wear wetsuits; they have something even better – concentrations of an antifreeze compound in their blood! And that’s not the only thing that makes these crazy creatures so unique. Unlike most fish species, which “broadcast spawn” (females release thousands of eggs into the water, and males compete to fertilize them externally), Atlantic wolffish pair up and fertilize the female’s eggs internally (much in the same way mammals mate). The female incubates the eggs for four to nine months (depending on the water temperature) before laying them in large clusters, which the male then aggressively protects for about four months until they hatch.
Image via Jonathan Bird.
Greenland sharks, Atlantic cod, haddock, gray seals, and even spotted wolffish prey on pelagic Atlantic wolffish larvae. And occasionally, the larvae may resort to eating each other . . . not the healthiest sibling relationships. Those that survive to be early juveniles transition to benthic habitats, where they prefer complex substrates such as rocky outcrops and kelp beds. They can grow up to 5 feet (1.5 m), weigh up to 40 pounds (18 kg), and live to be up to twenty years old. Wolffish are slow-growing and don’t reach sexual maturity until about age six, which can make them susceptible to fishing pressure, as stocks recover slowly.
Populations in Peril
Since the 1980s, populations of this deep sea creature have been consistently dropping, and average fish size has decreased by 50%. It’s not like there’s a commercial wolffish fishery – so what’s happening?
The biggest threat to Atlantic wolffish is otter trawling. Wolffish are caught as bycatch, indiscriminately snagged by enormous nets intended for commercially harvested species. To add insult to injury, these nets scrape along the seafloor, crushing fragile corals, disturbing rocky outcrops and kelp beds, and re-suspending bottom sediments that damage the fish’s gills and potentially release settled toxic heavy metals.
Atlantic wolffish were historically found from the Gulf of Maine all the way down to New Jersey. However, after decades of habitat destruction, there are only three populations remaining: the Gulf of Maine, Georges Bank, and the Great South Channel (a passage between Nantucket and Georges Bank). To address population decline, NOAA identified the Atlantic wolffish as “Species of Concern” in 2004 and manages the species under Amendment 16 to the Northeast Fisheries Management Plan. But is that enough?
The fact that current population estimates don’t exist is a huge cause for concern. Direct studies on stock structure are a gaping piece of the puzzle in understanding and managing Atlantic wolffish populations. We know they were declining dramatically until 2009, the last year for which data is available. We need to know more.
Canada has protected their stocks through the country’s Species at Risk Act, but the U.S. has yet to follow suit. In 2009, NOAA’s National Marine Fisheries Service (NMFS) denied CLF’s petition for the Atlantic wolffish to be protected under the Endangered Species Act. What are we waiting for? Let’s get the conversation started about this crazy, rare, toothy, weird, unique deep sea dweller. We want to protect the Atlantic wolffish!