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Commercial Fisheries News
Volume 36 Number 1
September 2008
Researchers continue dogfish tagging work
BIDDEFORD, ME – Researchers in Maine and North Carolina are continuing their extensive efforts to learn more about spiny dogfish migration patterns and distribution through both large- and small-scale tagging operations.
The efforts are being headed up by Assistant Professor James Sulikowski of the University of New England’s Marine Science Center in Biddeford and by Senior Scientist and Professor Roger Rulifson at East Carolina University in Greenville, NC.
Both researchers are conducting their own projects with considerable help from graduate students and colleagues, but, collectively, the results of their work are deepening the scientific community’s understanding of where and when spiny dogfish spend most of their time.
Furthermore, researchers are beginning to share data and communicate more effectively through a recently established Spiny Dogfish Research Network.
The network is an offshoot of an August 2007 dogfish workshop sponsored by North Carolina Sea Grant. During that workshop, Richard Beamish of Canada’s Department of Fisheries and Oceans broached the network idea as a way for scientific investigators to better coordinate large-scale projects and reduce competition for scarce research dollars.
Now a viable entity, the network is being coordinated through East Carolina University. And Rulifson, who was chairing an Aug. 19 scientific symposium about dogfish at the American Fisheries Society’s annual meeting in Ottawa, Canada, said he planned to encourage symposium attendees to join the network and contribute to the effort.
Anyone interested in joining or supplying postings to the network should e-mail Jennifer Cudney, an East Carolina University doctoral candidate working on dogfish, at <jlc0213@ecu.edu>.
Gulf of Maine tagging
Commercial and recreational fishermen, deeply frustrated by their inability to avoid dogfish while targeting other species, have helped sponsor and organize three separate dogfish forums in 2008 – one on March 29 in Biddeford, one on May 21 in Hyannis, MA, and one, which is still to come, on Sept. 30 in Philadelphia, PA (see story next page).
Plus, fishermen have been supplying at-sea information to researchers and collaborating on tagging projects at unprecedented levels.
On July 19 from Spring Point Marina in South Portland, ME, 15 recreational boats participated in a dogfish tagging tournament led by Sulikowski.
Recreational fishermen Phil Grondin of South Portland’s Sturdivant Island Tuna Tournament and Mike Jancovic of Maine River and Sea Charters, both staunch dogfish research supporters, were heavily involved in organizing the event, which, among other things, was intended to raise public awareness of growing dogfish interactions.
According to Sulikowski, nine of the 15 participating boats quickly tagged 400 dogfish. At press time, the other six vessels were still putting out 300 additional tags, and another 300 tags were available for further tagging, possibly from commercial vessels off Cape Cod.
More females
Of the dogfish caught and tagged on July 19, Sulikowski said females outnumbered males by 7-to-1. Of the total fish caught, dogfish outnumbered groundfish on the order of 30-to-1.
The tagging teams used rototags, which Sulikowski said stay attached to dogfish longer than the well-known spaghetti tags and are more visible.
The new tag release information, followed up with data from recaptured dogfish, will be entered into a computer imaging program at the University of New England.
The program will generate “track lines” so fishermen can see the distance traveled between where a particular fish was released and where it was recaptured.
Satellite tags
Sulikowski’s team also was continuing to analyze results from three satellite tags attached to dogfish in the fall of 2007. Two of the tags had “popped up” early this winter, giving researchers a chance to present preliminary findings at the March 29 dogfish forum in Biddeford (see CFN May 2008 for details).
Early this spring, the third tag popped up and transmitted its accumulated data to a satellite, making all three tags successful in accomplishing their mission.
“This tells us that these tags can work on this species,” said Sulikowski.
Ensuring that the tags worked was crucial given their cost – $4,200 per tag plus $500 for satellite time.
Expensive, yes, but Sulikowski said the amount of information they provide is astounding.
For one, the research team discovered that the first satellite-tagged fish traveled from the Bay of Fundy down to Virginia in six weeks with numerous twists and turns. The third tagged fish traveled from the Gulf of Maine to Virginia in a matter of days.
“It’s only three fish and we’re still compiling the data, but we’re seeing trends,” said Sulikowski. “These fish are moving fast from a north/south direction, crisscrossing several states, and spending a lot of time off the bottom in the middle of the water column.”
Fishermen repeatedly express concerns that federal trawl surveys are “missing” the dogfish during traditional spring and fall surveys and underestimating biomass, and this is one of the issues Sulikowski and his team hope to get to the root of.
While unable to make any conclusive determinations, the limited accumulated data to date is enough to convince Sulikowski that “these fish are behaving differently than we previously thought.”
He and colleagues now are in the process of seeking additional funding for more satellite tags.
North Carolina tagging
Meanwhile, researchers at East Carolina University have been working steadily to analyze their own tagging data.
Over the past decade, Rulifson and students in his lab, working with commercial fishermen, have tagged and released over 38,000 dogfish – primarily off North Carolina but some in the Bay of Fundy in Canada as well.
So far, 359 of those tags – less than 1% of the total – have been returned.
But Rulifson said the information provided by those 359 returns was extremely valuable, and he encouraged fishermen to keep returning any tags they happen upon.
“We have learned a great deal from these returns,” he said. “We hope that fishermen will continue to help us in understanding dogfish migration patterns and the different gear types in which they are caught.”
As Commercial Fisheries News was going to press, Rulifson and his team were readying to tag another 2,000 dogfish off Massachusetts with the help of local commercial fishermen. Their goal, he said, was to better understand the split between fish going to North Carolina for the winter and those going to Canada.
Information about how to return East Carolina University tags, as well as a chart showing release-and-recapture track lines from returned tags, is available online at <www.spinydogfish.org>.
Acoustic tags
Rulifson’s team was lining up to launch another major research effort this coming winter – one involving acoustic tags.
The team, working with North Carolina fishermen, was planning to insert acoustic tags into 50 dogfish off the Outer Banks of North Carolina and set up a “listening fence” – with sound receiving equipment – just below Cape Hatteras.
The purpose, explained Rulifson, will be to determine the percentage of the dogfish staying above Cape Hatteras compared to those moving south below the Cape.
As part of the project, researchers will work to obtain good information about current speed and direction, as well as water temperature, to help understand dogfish movement patterns.
Janice M. Plante
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