Fish tagging gets underway in the Gulf of Maine

Halibut head shot Ben Neal

Modern marine science has increasingly sought to involve fishermen and their knowledge in research programs, and for some fishermen this summer, that could mean encountering fish and lobsters carrying tracking tags. A number of tracking studies are underway for different species, and all of them rely on commercial and recreational fishermen to report any tags they run across.

Halibut

The Maine Department of Marine Resources is managing an Atlantic halibut experimental fishery in federal waters (more than three miles offshore), which requires the six commercial fishermen participating to tag and release any fish under 36 inches. These fishermen will be tagging fish from Vinalhaven to Beals Island during a two-month season. If fish greater than 36 inches are caught, they may be retained, and the fisherman will provide the Department with biological samples (including the gonads and the otoliths, which are small bones in the ear that can be used to determine the age of the fish) that will be used to understand the growth of this large fish. For fish that are not retained, the tag number should be recorded and the fish should be released again as quickly as possible.

To date there has been one tag returned, from a fish released in April, 2000. The young halibut had been at sea for approximately one year, and had grown five inches in that time. Halibut are the largest of the flatfishes in our waters, with at least one documented specimen weighing over 700 pounds, taken in 1917. In the Gulf of Maine only swordfish, tuna and some sharks reach a comparable size. This particular fish was a giant of its species, but 100- to 300-pound fish were once common. Halibut was once an economic mainstay of the handline fishing fleet, but inshore and Georges Banks stocks were quickly fished out by the turn of the last century. Currently the population of halibut in the Gulf of Maine remains very depressed, and recreational fishermen or commercial fishermen with halibut permits can retain only one fish over 36 inches per day. (For more information on the program or to report a tagged halibut, please contact Kohl Kanwit, Fishery Biologist, Department of Marine Resources West Boothbay Laboratory, PO Box 8, West Boothbay Harbor, ME 04575, (207) 633-9535.)

Lobsters

Lobsters in lower Penobscot Bay will be tagged this summer by Dr. Richard Wahle of the Bigelow Laboratory for Ocean Sciences. This project aims to use tag and recapture techniques to develop better methods for estimating the population of lobsters. In cooperation with a research vessel of the Island Institute and a local project intern, Wahle will catch lobsters with 50 to 60 modified, ventless lobster traps deployed in a limited area near Vinalhaven. Divers will also operate as a part of the experiment, counting lobsters on the bottom and comparing this information to the abundance estimates developed from the trap portion of the project. Both legal and juvenile lobsters will be tagged through the shell and musculature with plastic streamer tags, applied with a sharp needle. These tags will remain in place through the summer molt. Some tags will be recaptured in the study traps, but it is anticipated that the majority of the returns will be from the large amount of commercial gear in and around this area.

Fishermen are requested to record the tag number, location and date of recapture, and size of the lobster, and to call this information in on a toll-free line. The study will tend the traps and tag lobsters for approximately ten weeks, beginning in June, and is supported by the Maine/New Hampshire Sea Grant Program. Wahle conducted a similar project last winter in the area of Monhegan Island, and tags were recovered. (For more information or to report a tagged lobster please contact Dr. Richard Wahle, Bigelow Laboratory for Ocean Sciences, McKown Point Road, West Boothbay Harbor, ME 04575, or call Bigelow Lab at (207) 633-9600, or call 1-800-339-9209, extension 125 to report a tag.)

Cod

Cod will be tagged this summer and fall in a study conducted by the Island Institute. This investigation will gather information about the migration and mixing of fish in a limited area in the mouth of Penobscot Bay, south of Vinalhaven. This area has in the past been a noted cod spawning and groundfishing area, but the abundance of many species of groundfish in these inshore waters has declined, and there is no longer much fishing for these species. In the last two years some lobstermen have reported increasing numbers of small codfish in their traps. It is hoped that these populations will recover, and that a commercial fishery will redevelop, and when such a fishery redevelops, changes in fishery management could insure that stocks are not depleted again. Information gathered through tagging could assist in understanding where the fish are all through the year, and would be helpful in estimating total fishing pressure.

This study plans to tag cod over 15 inches, and hopes through returned tags to learn if these fish are year-round residents in the area or if they migrate up or down the coast, or offshore to Georges Bank. Because the area of the study has a significant amount of lobster gear, and because tagging has not been done in this area previously, part of the summer investigation will compare the use of fish traps, hook gear and a small net to determine how best to catch viable cod in this area. Fishing will begin in June, and the study hopes to eventually tag up to four thousand fish. Information is requested on location and time of recovery, and size of the fish. No part of the fish itself is needed. (For more information, or to provide information about groundfishing in this area, please contact Ben Neal, Marine Resources Coordinator, Island Institute, PO Box 648, Rockland, ME 04841, (207) 594-9209, or call 1-800-339-9209, extension 126 to report a tag.)

Other species

Several other marked and tracked fish are swimming in the Gulf of Maine, including Atlantic salmon, bluefin tuna and several species of sharks. Due to the migratory nature of these species, and less fishing pressure, they are less likely to make an appearance, but still could be encountered.

750 marked adult Atlantic salmon have been released this year into the St. Croix River system, on the border of Maine and Canada. These fish do not carry an inserted tag, but instead are identified through a clipped dorsal adipose fin. The lack of this small fin, located on the back of the fish between just ahead of the tail, identifies the fish to biologists as a stocked fish. As it is illegal to fish for or retain this species, this program does not rely on returns of fish from anglers. If these 15-pound fish survive, they could return to spawn multiple times. Fish were also released in the Machias and Dennys rivers. (For more information contact Lee Sochasky of the St. Croix Waterway Commission.)

Giant bluefin tuna could also be carrying tags into the Gulf of Maine during their summer migration, from June to September. Capable of reaching well over a thousand pounds, and rocketing along at forty miles an hour, giant bluefin are targeted by both commercial and recreational fishermen. They roam from Newfoundland to Africa, and it is very possible for a fish tagged in the summer in Maine to show up in the winter off Europe or Mexico. These migrations are still not well understood, and with many different countries fishing separately for bluefin, the fish stock has been greatly reduced. Understanding migration patterns could help these separate fishing countries work together for tuna conservation. Both regular and electronic pop-up archival tags are used. Archival tags store information on depth, temperature, and location for an extended period of time, and later detach from the fish and send the information to a satellite. Fishermen and scientists both tag these fish under the National Marine Fisheries Service Cooperative Tagging Program and the Tag-A-Giant project. (For more information contact the Cooperative Tagging Center of the Southeast Fisheries Science Center, National Marine Fisheries Service, 75 Virginia Beach Drive, Miami, FL, 33149, 1-800-437-3936.)

Four species of sharks are common summer residents of the northern Gulf of Maine, and all are currently being tagged as a part of the Cooperative Shark Tagging Project, run by the Apex Predators Program of the National Marine Fisheries Service Northeast Fisheries Science Center. Blue sharks are perhaps the most common, with mako, porbeagle, and perhaps even thresher sharks also potentially present. Other species such as the giant and docile basking shark are also seen occasionally.

Participants in the cooperative program include academic institutions and recreational and commercial fishermen, and other interested individuals. David Power of Dedham, Maine, has been tagging sharks in the Mt. Desert area for five years, and has tagged over 50 sharks, mostly blues and porbeagles. Five of the tags he applied have been returned, one by a recreational fisherman in New York and four by widely scattered commercial longline vessels. The longest time at liberty was over 900 days, for a blue shark taken off the Azores, and another blue was recaptured off Guyana, South America, for a straight-line distance of 2,130 miles from the tagging site. More information on the Cooperative Shark Tagging Program can be requested from the National Marine Fisheries Service Narragansett Laboratory, 28 Tarzwell Drive, Narragansett, RI 02882-1199.