|
New Electronic Tagging Of School Bluefin
by Rich Ruais, Executive Director, East Coast Tuna Association
The speculating will soon be over for small bluefin here in the U.S. with an explosion of migration and other biological data about to be produced from a new tagging program initiated in June, 2005, by the Large Pelagic Research Lab of the University of New Hampshire together with researchers from the Virginia Institute of Marine Science and Massachusetts Division of Marine Fisheries. The program called “Tag a Tiny” has now deployed 100 data logging tags on juvenile bluefin off the coasts of Massachusetts and Virginia. A $500 reward is being offered to fishermen returning the tag and fish to researchers. Short History of Bluefin Tagging In the western Atlantic U.S., fishermen and researchers began regular conventional tagging of small bluefin tuna in 1954. These initial tagging efforts allowed confirmation of the impressive migrations and trans-Atlantic swimming capabilities of these fish. One early U.S. tagging scientist, Frank Mather, provided the International Commission for the Conservation of Atlantic Tunas (ICCAT) at only its third regular meeting in 1974 with the most comprehensive description of documented bluefin migrations through that time. Among the more notable bluefin migrations published by Mather were the following: • 40 small bluefin crossings from southern New England/Mid-Atlantic fishing grounds to the Bay of Biscay off France/Spain and two documented similar east-to-west migrations with only a handful (54) of eastern fish tagged; • seven giants tagged off the Bahamas recaptured in Norwegian waters; four of these seven fish were recaptured only 50 to 120 days after being tagged! That’s a 5,000 mile migration in 50 days or 100 miles a day average swim!; • two giants tagged off Bahamas, later recaptured in the South Atlantic off Brazil and Argentina; • several large Nova Scotia and Newfoundland tagged fish recaptured in Massachusetts waters. Although Mather’s and other early bluefin tagging scientists work was important to show the intermixing of fish in the west and east, the limited data could not be used for statistical analysis on the impacts of fisheries in the east on the west and vice-versa. This inability to prove a link between the health of western bluefin fisheries with eastern fisheries has been the excuse for the bluefin tragedy of the past 30 years: western fisheries carry all the conservation burden while eastern Atlantic and Mediterranean fisheries remain essentially unregulated with resulting outrageous catch levels of large and illegal size fish. East and Mediterranean Sea Continuing Slaughter Although scientists have recommended a precautionary quota of 26,000 metric tons since 1998, scientists and managers believe from market information that catches from eastern fishing grounds continue to be in the 40,000 to 50,000 metric ton range since 1996. Even basic catch information from eastern fisheries is being withheld from ICCAT scientists by the European Community (EC) and other Mediterranean fishing nations. This prevents reliable stock assessments. As poor as the quota violations have been, the situation with catches of illegal size (<6.4 kg or 14 lbs.) bluefin has been worse. ICCAT scientists have been strongly critical of European nations continuing significant commercial fisheries for age 0 and age 1 bluefin (<3.2 kg or about 7 lbs.) in the Mediterranean Sea and the Bay of Biscay. Tired of the repeated criticism in ICCAT science documents, in 2002 the EC simply reported to ICCAT’s Compliance Committee that there were zero catches of bluefin by Spain and France. There was a problem for the EC: the following Spring at a meeting in Marseille, France, I purchased and brought to the meeting a 5 lb. bluefin (see picture) still available every day at the head of the harbor from local fishermen! ICCAT Response to Electronic Tag Data Fast forward the tagging scene from Mather’s conventional tags to the 1990s and a much different scenario is taking place with the advent of electronic pop-up satellite tags and implantable archival tags. Two teams of researchers led by Dr. Barb Block (Standford University) and Dr. Molly Lutcavage (University of New Hampshire, Large Pelagic Research Lab) have been successful in deploying almost 900 of the new smart tags on mostly large mediums and giants. This new generation of tags is shedding much more detailed information on seasonal mixing of fish tagged in the west to eastern fishing grounds, migration highways or corridors, breeding behaviors and physical oceanographic patterns important to northern bluefin tuna. The new electronic tags have now already proven the 1981 ICCAT management strategy (i.e. the “two stock hypothesis with limited mixing” and arbitrary boundary at 45-degree W. Longitude) to be biologically unrealistic and incredibly unfair to U.S. and Canadian fishermen. The electronic tags prove that anywhere from 30 to 58 percent of the fish in the west may well be migrating to eastern fishing grounds every year where they are not protected by size limits, bag limits or effective quotas. The exact number of western fish caught in this continuing eastern slaughter remains unknown but the tagging data suggests it is very substantial and clearly undermining the sacrifices of U.S. recreational and commercial tuna fishermen. A process is underway at ICCAT to develop a more biologically realistic program. In place of the one arbitrary management boundary, scientists are looking at the possibility of shifting the line to the east and northeast or establishing a restricted fishing zone in the central Atlantic where mixing is now known to be heavy. Any movement of the line to the east would result in more protection for western fish. The EC continues to stonewall a better conservation plan and the situation is not likely to change until the U.S. State and Commerce Departments get serious and help the U.S. Delegation to ICCAT achieve effective and realistic quotas in the east. UNH “Tag a Tiny” Program |
