2008 Annual Report
Gulf of Maine Research Institute

Spotlight on Science

Learning About Monkfish

Monkfish will never win any beauty contests, but the toothily menacing groundfish still commands high prices at the market. Gulf of Maine Research Institute (GMRI) scientists work to unravel many mysteries about the Northeast’s most valuable finfish. A reputation as the “poor man’s lobster” has led to significant increases in fishing for monkfish, especially as stocks of other fish have declined. As the New England Fishery Management Council considers changes in how the fishery is managed, GMRI researchers work to ensure that those decisions are made based on the best science available.

Monkfish are currently managed as two separate populations, one inhabiting the Gulf of Maine and the other ranging down to North Carolina. Recent data suggests that these populations might actually be a single group that migrates along the coast. Graham Sherwood, GMRI Fisheries Ecologist, leads a tag, release, and recapture study to monitor monkfish. Over 6,200 monkfish have been tagged to date. Fishermen who catch tagged monkfish report their finds to GMRI, noting the date and location of capture. Some of the tagged monkfish carry a data storage tag, which records when they were tagged and recaptured and what they were doing in between.

Monkfish ear boneKnowing the ages of fish is key to how they are managed. Most scientists use a fish’s otoliths (ear bones) to estimate their ages—new bone is laid down yearly in rings, which can then be counted in the same way as tree rings. Graham employs a multi-method approach to provide a more accurate approximation. One technique involves injecting the fish with a chemical that lightly stains the otoliths, allowing Graham to measure how much growth occurs between the time of injection and recapture. Graham also analyzes microchemicals in the otoliths because these chemicals serve as natural data recorders. Taken together, these methods will result in more accurate estimations of monkfish ages.

The ecological impact of monkfish fishing methods is another area of research. Tie-down gillnets are used to catch monkfish but often catch other species as well. Steve Eayrs, GMRI Research Scientist in Fish Behavior and Gear Technology, works to modify nets to reduce bycatch. Steve is testing nets that are 18 and 30 inches tall instead of the usual 42 inches.

Fishermen are a vital part of monkfish research, providing fish, time on the water, and years of experience to GMRI’s scientific endeavors. They have made generous contributions to GMRI’s efforts to make the monkfish industry both economically and environmentally sustainable.

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