Scientists Amazed by Monkfish’s Bizarre Feeding Habits
An international team of biologists studying monkfish has found that the bottom-dwelling creature can prey on a small Arctic seabird called dovekie, the smallest member of the puffin family.
Monkfish (Lophius americanus), also known as American anglerfish, goosefish or all-mouth, are highly opportunistic predators. The fish are typically partially buried on soft bottom habitats and attract a variety of prey by using a modified dorsal fin ray that resembles a fishing pole and lure.
Dovekie (also known as the Little Auk, Alle alle) is a small black and white puffin species. It lives in the open ocean and can dive to depths of more than 100 feet to prey on small fish, crustaceans, and zooplankton.
Remains of 14 dovekie were recovered from the stomachs of 14 monkfish caught during the winters between 2007 and 2010. The monkfish were captured in gillnets deployed at depths between 275 and 495 feet in waters 65 to 95 miles south of Chatham, Massachusetts.
The team led by Dr Peter Osenton from the USGS Patuxent Wildlife Research Center in Laurel wanted to know how the birds could be captured so far from shore by a fish that lives on the ocean bottom in deep water. Their findings, published in the journal Northeastern Naturalist, suggest that it is all a matter of timing.
Left: a dovekie, also known as the Little auk (Chris Melrose / NEFSC / NOAA). Right: a monkfish is measured at sea (NOAA)
The team members said tagging studies that they have conducted reveal that monkfish swim considerable vertical distances from the bottom to near the surface, especially during their spring and fall migrations onshore and offshore in response to water temperatures and related factors. Monkfish leave the bottom to use the currents during migration periods or to spawn at the surface. If prey items are encountered during their vertical movements, the monkfish take advantage. Hence, timing may be the key factor in bringing dovekies and monkfish together in the same place.
“It is not surprising to find birds in monkfish stomachs, but it is surprising to find that this predation occurs over deep water. Monkfish do not actively seek out the dovekies, but when such tasty morsels are available in the water column, the fish are going to consume them,” explained co-author Dr Anne Richards of NOAA’s Northeast Fisheries Science Center.
Another source of data used in the study is the NOAA NEFSC food-habits database, which contains decades of predation information collected from the stomachs of fish that are caught during regular research vessel surveys. While not a particularly good measure of how often or how many birds are eaten by fish, these data confirm that not only monkfish, but also spiny dogfish, Atlantic herring, pollock, Atlantic cod, red hake, and fourspot flounder will eat birds.
First author Dr Matthew Perry from the USGS Patuxtent Wildlife Research Center said he became interested in monkfish predation when he learned from a sea scalloper on Nantucket that Chatham gillnetters were finding birds inside monkfish stomachs.
“I was studying long-tailed ducks and thought, to avoid being eaten, these birds fly 30 to 50 miles to Nantucket Sound each night and return to the ocean in the morning,” Dr Perry said. “People ask why don’t dovekies fly to Nantucket Sound at night like the long-tailed ducks to avoid monkfish? My explanation is that dovekies have small wings and can’t make the routine flight.”
“One thing we know is that dovekies cannot dive to the bottom in 300 to 400 feet of water,” Dr Perry said. “Monkfish probably come up from the ocean bottom to within 10 to 20 feet of the water surface at night. As dovekies dive for amphipods, small crustaceans, in the morning at first light, monkfish seize the opportunity and might use their ‘fishing lure’ to simulate one of these prey species by attracting the dovekies with their typical ‘sit and wait’ behavior.”
Bibliographic information: Matthew C. Perry et al. 2013. Predation on Dovekies by Goosefish over Deep Water in the Northwest Atlantic Ocean. Northeastern Naturalist, vol. 20, no. 1, pp. 148–154