COMMERCE
Subscriber Services
Classified Ads
Subscribe
Advertise
NEWS
This Month
Editorial
Letters
F/V Safety
Past Issues
ABOUT US
Contact Us
Latest Issue
Subscribe
History
MORE CONTENT
CFN Archives
Links
Each month exclusively in the PRINT edition of CFN
Along the Coast
Ask the Lobster Doc
Bearin’s
Classifieds
Coming Events
Editorial
Enforcement Report
FISH SAFE
Fleet Additions
Letters
Lobster Market Report
New Boats
News Catch
Quahog Market Report
|
Commercial Fisheries News
Volume 37 Number 6
February 2010
Researchers, fishermen tag monkfish; probe north/south mixing rates
WOODS HOLE, MA – It takes a bit of skill to do surgery on a monkfish, especially at sea in the bitter cold.
But several researchers have mastered the art, making delicate incisions in the tail of each fish to surgically implant bullet-shaped data storage tags. They did it 150 times in 2009 aboard commercial fishing vessels and, as the new year opened, were prepping to head out to sea to do it again.
Newport, RI-based fisherman Ted Platz, the industry partner on three of the 2009 trips, said the teams now had the system down pat.
“We’ve figured out ways to get a lot of tags out in a short period of time,” he said.
Aboard Platz’s Gertrude H, researchers and fishermen worked together to tag 18 fish in January, 26 in July, and 54 in December, all in Southern New England, which is considered part of the “southern” area for monkfish management purposes.
Gillnetter Tim Caldwell was the industry partner for the project’s Gulf of Maine trips, carrying researchers aboard his C. W. Griswold. Together, they tagged six fish in October and 46 in November.
Tagging teams were hoping to make a third northern-area trip with Caldwell in late January as Commercial Fisheries News was going to press.
Finding a rhythm
By the third trip in December on Platz’s boat, everyone knew their roles. Platz and a crewman worked to pull burly monkfish from the net, while two, two-person teams carried out surgeries simultaneously.
“The trick for us was hauling the net really, really slow,” Platz said.
That took some getting used to. Commercial fishermen, after all, haul for a living, and slow is not the name of the game.
But slow hauling after a short, one-night soak produced live fish in prime condition – just the right candidates for tag implantation.
At first, the teams tried keeping monkfish in holding tanks on deck, lining up several fish in advance for tagging. But that didn’t work because the fish became stressed.
“They got slimy with mucus when we put them together,” said Platz, who worked with crewman Pavel Ivanov on the first tagging trip and Sergey Yuminov on the second two.
So, going against the grain, the gillnetters gave way to the slow-haul method, only supplying fish as needed, so that each of the sharp-toothed monks could have its own tank.
The teams soon fell into a rhythm. Industry partners handled the net, providing researchers with fish as needed, and researchers did the tag implantations. They injected each fish with oxytetracycline to mark its vertebrae, otoliths (ear bones), and dorsal spines for aging studies that will be done after the fish are recaptured.
Altogether, it took between five and seven minutes to tag and inject each fish and gently put it back overboard.
Jon Grabowski of the Gulf of Maine Research Institute (GMRI) in Portland, ME, one of the tagging program’s project leaders, said, “I watched those fish swim away. They looked very healthy.”
Two tag types
The tagging work is part of a years-long collaboration between gillnetters and three of the region’s most prominent research institutions – the Northeast Fisheries Science Center (NEFSC) in Woods Hole, GMRI, and the University of Massachusetts-Dartmouth’s School for Marine Science and Technology (SMAST).
GMRI and fishermen have been tagging monkfish since 2007 with conventional T-bar tags – the ones that look like antennae sticking out of the fish. This work has been carried out through the Monkfish Research Set-Aside (RSA) Program, which is directly financed by industry. Fishermen collectively give up 500 monkfish days-at-sea per year to help fund research projects through the RSA program.
The T-bar tagging by itself has begun to provide important clues about monkfish movements, but this latest data storage tag (DST) work, also financed by the RSA program with additional support from the Northeast Consortium, goes even further.
“With the conventional T-bar tags, you know where the fish were released and where they were recaptured, but you have no idea where they have been in between,” said Anne Richards of the science center, one of the project leaders for the DST work.
Many questions
With DSTs, commonly called archival tags, researchers can learn much more than the release-and-recapture points of a monkfish’s travels. These remarkable tags additionally record time, temperature, and pressure, roughly every 10 minutes, for up to five years.
The pressure measurement is key because it can be used to estimate how deep a particular monkfish was swimming – all the way down to 1,500 meters, equivalent to 4,950 feet.
And that’s what people really want to know: How deep do these monkfish go? How much time do they spend at depths beyond the reach of trawl surveys and commercial fishing activity? Do they travel from inshore to offshore and back again or visa versa? Do they move from south to north or the other way around? Where do the females go at certain times of the year when they seem to disappear? How deep do they go? Maybe they go very deep.
“These are big, overarching questions,” said Grabowski. “We want to establish migratory patterns. We want to establish how much exchange there is between management areas. Is one area a source of monkfish and the other one a sink? Are there seasonal patterns of migration? Do they vary from the Gulf of Maine to Southern New England to the Mid-Atlantic Bight?”
Grabowski believes that finding answers to these questions is critically important to the commercial fishery.
“It’s a very valuable fish species,” he said. “It’s important that we get it right.”
Keep an eye out
So many questions and so much hope for answers, all contained in tiny canisters sutured just under the surface of the tail-skin on 16"-to-20"-long monkfish.
The tags leave a noticeable bulge, an obvious clue that something is different about the fish.
“It looks like someone’s thumb was sewn in,” said Platz. “It’s pretty hard to miss.”
But fearing that busy fishermen might pass by what could be mistaken for a large growth, researchers also attached two, bright pink T-bar tags along the midridge area of the tail. And those pink antennae are practically impossible to overlook.
Furthermore, researchers are hoping that the high reward for returning a DST-tagged monkfish – $500 per fish – will entice fishermen to keep a keen eye on their catches.
DSTs expensive
Getting data storage tags back from recaptured whole monkfish is absolutely crucial to the success of the project, according to every researcher involved.
These tags do not transmit information to satellites like some ultra-high-end archival tags. Instead, they serve as time capsules, storing data for downloading onto a computer after the fish is recaptured.
The tags are wildly expensive, which has limited the number of DSTs the tagging teams can put in the water. Once this current round of tagging is complete, the teams will have implanted a total of 190 high-tech Star-Oddi DST centi-TD loggers at $360 a pop.
They also have on hand an additional 40 or so lower-quality DSTs, courtesy of SMAST, for external attachment. These 40 won’t provide quite as much information and probably won’t record as long as the Star-Oddi tags, but it’s another tagging opportunity that everyone welcomes.
“We’re using every opportunity we can to get as many tags out there as possible,” said Richards.
And that includes more T-bar tagging.
Practice makes perfect
Given that the archival tags are so valuable, researchers wanted to be sure they were right on the money with tag placement and fish survival rates.
So, before any of the at-sea tagging got underway, researchers spent a year honing their surgical skills in the lab with the help of a separate Northeast Consortium grant.
And now, with four trained “surgeons” and a fairly slick tagging system, the tagging teams are ready to keep going as long as they can buy more tags and receive funding for future projects.
“We can learn so much about monkfish behavior from these tags,” said Richards.
She has plenty of questions of her own.
“Where do these fish spawn?” Richards wondered. “At the surface? At the edge of the continental shelf? Could they be riding currents to migrate? They’re hydrodynamically designed. Their pectoral fins are like wings, and there have been sightings of monkfish at the surface. Are these fish going to Canada?”
While the information contained in those tiny canister-like DSTs probably won’t answer all of those questions definitively, the stored data will provide important pieces of a very big puzzle.
T-bar tag results
Promising as it all is, the limiting factor with these remarkable data-rich archival tags is their cost; $360 apiece is a lot of money.
In contrast, conventional T-bar tags run less than a dollar each.
“The trade off is you can put out a lot of T-bar tags really cheap,” said GMRI’s Graham Sherwood.
In 2007 alone, GMRI and fishermen tagged 2,770 fish during the fall. It was the very first monkfish tagging study in the Northeast.
Of the 1,006 fish tagged in the north, 1.7% were recaptured, and of the 1,764 tagged in the south, 3.9% were recaptured. Only fish that were “at liberty” for more than 30 days after being released were counted as “recaptures” in the study, and most of the recaptures occurred within 10 months of release.
The results were intriguing. Contrary to popular thinking, 9.1% of the fish tagged in the northern area were estimated to have moved to the south. However, none of the fish tagged in the south had moved north.
Therefore, the study concluded that mixing rates were “low and unidirectional,” and average movement was to the southwest.
But no one was putting undue weight on these results, especially since researchers strongly suspect that at least some monkfish move from south to north.
“The only data we have so far is from those 2007 fish,” said Sherwood, who headed up the project. “It’s a very preliminary snapshot of what’s going on. No juveniles were tagged, and they may be the ones that are moving north. We need to tag in other seasons and in other areas. Plus, our return rate for the north was very low.”
The study did show that monkfish have the potential to travel great distances. According to Sherwood, one monkfish tagged and released off Boston was recaptured off New Jersey.
More in 2010
During 2010, GMRI hopes to get an additional 5,000 T-bar tags in the water, this time further south into the Mid-Atlantic and further offshore, as well as during the spring instead of the fall.
And, researchers also intend to train fishermen to do the tagging themselves. They’ll meet with participating industry members to ensure they understand tagging methods and what’s needed for data collection.
Yet even before any further training, researchers expressed full confidence that fishermen can take the lead on the at-sea T-bar work. Not only will this save valuable time and resources, but it will allow the tags to be more widely distributed.
Grabowski, a project leader for the 2010 T-bar work, said, “The fishermen involved in this are very interested in the science. They told us, ‘You know, we can do these tags ourselves. You guys don’t have to be on the boat.’”
All of the researchers involved in the tagging project expressed sincere appreciation for the partnerships they have developed with fishermen.
“I cannot emphasize enough how integrally involved the industry has been in all of this,” Grabowski said. “They guide us to where the fish are. We use their vessels. We have been really fortunate to have so much support from industry. That kind of buy-in is invaluable.”
From gillnetter Ted Platz’s perspective, the work is worth the effort.
“It’s what the fishery needs,” he said. “We need to know about the mixing rates from north to south and how these fish move. I think there are a lot of misconceptions about the lives these monkfish lead. We need to do what it takes to get better science.”
Janice M. Plante
Back to story list
|
|
Tell us what you think.
