Researchers hope that tagging halibut provides clues to where they are spending their time.
By Lisa Cavanaugh
For several years, Chris McGuire had been hearing anecdotal accounts from local fishermen of greater numbers of halibut, a highly regulated and valuable fish.
“The federal trawl survey wasn’t catching them,” says McGuire, Marine Program Director for Massachusetts at The Nature Conservancy, “and the stock assessment is based on that survey.”
So he proposed a new information source for this “data poor” species in hopes it would improve our understanding of halibut and give regulators additional information to sustainably manage the historically important fish.
The new approach has fishermen at its heart.
“The fishermen know best,” says Crista Bank, a fisheries research technician from the School for Marine Science and Technology at UMass Dartmouth (SMAST). “They know when a fish will make it with a tag and when they won’t, so I rely on their expertise.”
Bank is in the middle of the ambitious halibut research project spearheaded by The Nature Conservancy and funded by a federal NOAA Saltonstall-Kennedy grant. She has been on the water with partnering fishermen from Cape Cod and elsewhere in Massachusetts, placing programmable satellite tags into live halibut in order to learn more about their migration. She is also the lead technician in the biological sampling segment of the program, designed to determine age of maturity.
“I had some of the New Bedford guys bring me halibut at the beginning of the project so I could practice here in lab, and I worked to train quite a few fishermen at the Fishermen’s Alliance last summer to recognize the gonads and take out the otolith,” she says, explaining that an otolith is a shell-like deposit in both sides of the fish’s head that has rings, like a tree trunk, that are used to determine age.
“I heard that Bobby Eldridge, of F/V Unicorn, was catching a lot of halibut so I asked him if I could jump on a trip with him,” Bank continued. “Each vessel comes up with its own routine to get the samples as efficiently as possible. Bobby and his crew did really well. They had a whole system down. I told him that his guys do it better than I do.”
The work is designed to gather a better understanding of halibut stock structure and movement as well as knowledge about their age of sexual maturity. Participating fishermen have been measuring the length and weight of the specimen fish, and removing the otoliths, their gonads, and heart. The samples are first processed at the Fishermen’s Alliance office in Chatham and then shared with collaborators at NOAA’s Northeast Fisheries Science Center in Woods Hole for maturity analysis, and with the Massachusetts Division of Marine Fisheries ageing lab in Gloucester to determine age.
The second part of the research – live tagging – uses pop-up satellite archival tags (PSATs) darted into the dorsal muscles of a halibut. For six months or longer, the tags collect information on water temperatures and depth of the halibut’s various locations until its pre-programmed release date. Once it pops up to the surface each tag will transmit as much data to a satellite as battery life allows, and potentially be retrieved by vessels for complete data recovery.
For both the sampling and tagging to work, Bank needed participating fishermen to catch plenty of halibut, and that has proven challenging.
“The goal was to get 200 bio samples and we’ve probably done about half,” she says. “And we have 20 satellite tags and we think we will get at least 10 in before it’s too late.” To get useful data, they need the tags to stay in the fish for at least six months, preferably longer, with as few gaps in data as possible. Right now they have programmed tags to pop up on two dates next summer: June 26 and August 10. (Check back here for the results.)
“The tags record depths and water temperatures every 10 minutes and we use that data to match up with established ocean models,” Bank says. “This will be a best estimate for where the fish was swimming over the course of the study. It is not as accurate as the tags used on creatures that surface regularly, like sharks and turtles, but it will give us a very good idea of where the fish migrated.”
They want to learn if the fish stayed close to shore, or moved off to the continental shelf and at what time of year they migrated and spawned. “Even if it’s too hard to find out really specific spawning data, our big goal is to see where they go through a whole season,” she says.
Bank was able to get tags into fish starting in the late summer, and has continued working with fishermen through the winter.
The Fishermen’s Alliance has been partnering on the project, hosting intern Rachael Marshall, a marine biology student from University of Rhode Island who assisted in the halibut sampling work, and connected fishermen with the program. Bank has gone aboard several Cape Cod vessels of various gear types, including Jason Amaru’s Joanne A III, the Unicorn, Eric Hesse’s F/V Tenacious and F/V Alicia Ann with captain Greg Walinski. Ever resourceful, Bank also opted to re-use some Data Storage Tags (DSTs) from a previous monkfish research project on weaker seeming fish.
The team triaged the fish caught into three groups: the most vibrant got the expensive pop-up tags, less robust fish were given the DSTs which stay in the fish and are only retrieved if the fish is re-caught, and the weakest fish were dissected for their samples.
Whether hauled from longline gear caught on large circle hooks, or brought aboard in gillnets or trawls, the large flatfish are quickly tagged by Bank, who inserts a dart through the skin near the dorsal fin on the eyed-side of the flat fish. After a tag is securely attached, Bank, often aided by a crew member and using a large foam mat to stabilize the fish, lifts the halibut over the side of the boat and releases it back into the ocean.
Fishermen seem eager to see what the research will show. Walinski thinks it might be a long time coming for a change in halibut fisheries management but “it’s important for scientists to learn where the fish are and where they go throughout the year.”
Both Bank and McGuire value the collaboration with fishermen, since the ultimate goal of the research is to support useful fisheries management. McGuire would love to see a dedicated long line survey for halibut.
“Canada has been conducting a halibut survey since 1998 and they are seeing an increase in the MSC (Marine Stewardship Council) certified stock. Almost every year in the last decade is the highest on record,” he adds. “I’m optimistic about halibut. This could be a positive story of rebuilding, which the groundfishery needs more of.”
Bank has been an on-board federal observer of the commercial fleet, has taught sailing and marine education on tall ships, and loves being on the water.
“A decade ago, when I heard that SMAST does cooperative research with fishermen, I knew I wanted to work there,” she says. “I like working with them, and being on the right end of science. We have to be as flexible and resourceful as fishermen.”