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Flyfishing in Saltwaters, March/April 2006
WHAT’S UP WITH BLUEFIN TUNA?
Atlantic stocks continue to decline but there is hope.
Bluefin tuna are perhaps the most sought after fish in the world commanding top prices on the sushi market and targeted by anglers world wide. Fairly recently, bluefin tuna have gained popularity in the flyfishing world and are considered to be one of the most challenging targets. But, while pacific bluefin tuna seem to be relatively healthy, Atlantic bluefin have been in serious decline for a long time. The International Commission for the Conservation of Atlantic Tunas (ICCAT) which manages Atlantic bluefin internationally estimates that Atlantic Bluefin populations are at 10 to 20% of what they were in the early 1970’s. The most recent assessment indicates that the stock is continuing to decline and fishing effort and mortality remains high. Many scientists believe that unless some changes are made rather quickly this fish could be headed to extinction in a short period of time. There are most certainly solutions to the problems Atlantic Bluefin are facing, but whether or not the managing authorities have the backbone to ensure this species doesn’t go the way of the American buffalo is most certainly in question. While space doesn’t allow for a through examination of the problems bluefin tuna face, the following is a brief synopsis.
East vs. West
Past and recent data indicate that there are two distinct populations of Atlantic Bluefin: A western stock that spawns in the Gulf of Mexico and an eastern stock which reproduces in the Mediterranean Sea. Back in 1982 ICCAT set up two management zones separated by a line in the mid-Atlantic Ocean at longitude 45 degrees West. This decision was based on the best science available at the time which suggested that the two stocks were separate and rarely if ever intermingled.
Stock assessments have indicated for some time that the western stock is in serious decline, but the eastern stock while still waning is considerably healthier. Today ICCAT limits the annual tuna catch in the western Atlantic to 3,000-tons while allowing a whopping 32,000-ton quota in the Eastern Atlantic. Not only is the eastern quota 12-times that of the western quota, it is widely known that many European countries fail to report their catch accurately if at all. Officials acknowledge that the Eastern Atlantic catch most likely exceeds 40,000 tons. .
Dr. Barbara Block, professor of Marine Science at Stamford, founder and Co-Director of Tuna Research Conservation Center and a leading expert on Atlantic Bluefin tuna has been putting electronic tags in Atlantic bluefin in the Gulf of Mexico and off the shores of North Carolina, Nantucket and Ireland for the last decade. In a report published in the journal Nature last spring she summarized her findings proving that the two “separate” stocks frequently ignore the longitude 45W boundary and intermingle regularly at productive feeding grounds.
Block’s tagging results raise serious questions about whether ICCAT quotas protect our vulnerable western bluefin that cross the imaginary 45W line into eastern waters to feed. Tagging data shows that the big breeding bluefin weighing 300 pounds or more, which have a remarkable capacity to stay warm, are traveling to and feeding in the productive subpolar seas throughout the North Atlantic, and are more likely to cross the boundary, exposing them to oceanic longlines fished by eastern Atlantic boats that are subject to much higher eastern quotas.
To put it simply, bluefin from the east coast, where fishing regulations are strict and quotas relatively small are crossing the ocean to areas where quotas are higher and regulations are often ignored. Fishing the mixed fishery as though it is a strong stock depletes the fishery and could cause the weaker Atlantic stock to go extinct. Big bluefin ignore international boundaries and European fishermen are thwarting recovery by catching western bluefin that regularly stray into the eastern Atlantic.
The US must convince ICCAT to extend low-quota restrictions from the current mid-Atlantic boarder east toward Europe where the mixing occurs. This would protect some of the largest tuna with the greatest reproductive potential. Closing productive feeding grounds where the two stocks mix may also be warranted. Furthermore, the US needs to insist on tighter quotas in the Eastern Atlantic. Trade sanctions and other economic measures should be implemented by the US to push eastern countries to end routine violations of size and catch limits by their fleets.
Gulf Spawning Area Protection
Block’s tagging data confirmed previous studies which showed that during the winter months large bluefin spawn over the continental slope of the Gulf. Block found that the region’s powerful eddies bring nutrients to the surface creating “hotspots” for spawning giant.
While NOAA Fisheries closed the Gulf breeding grounds to targeted bluefin tuna fishing in 1981, longline vessels are still allowed to keep a certain number of bluefin incidentally taken as bycatch while targeting other species. While tagging fish on a commercial longline boat in the Gulf, Block and her team noted the exceptionally high mortality rate of bluefin released from longlines in this area. While the warm waters of the Gulf are favorable for the development of the eggs and larval stage offspring, they create physically stressful conditions for giant tunas, which have large metabolic demands and die quickly from lack of oxygen in the warm water. So, in other words, just about every tuna caught and released on longlines in the gulf is doomed. According to Block, these are Earth’s largest giant bluefin. The big breeders that produce the most offspring. The stocks we should be trying hardest to protect.
The simple way to stop needlessly killing all these large breeders is to establish a time and area closure in the spawning “hotspots” of the Gulf to all commercial longliners during the bluefin spawning period – Jan to June. Because these hotspots are within US waters NOAA Fisheries could create a “no-fishing” region for spawning giant bluefin to reduce mortalities in short order, but of course they have yet to do so. As one might imagine there is a lot of resistance from the longline industry. Fairly recently, however, Oceana and Earthjustice filed a petition on behalf of the Blue Ocean Institute, the Monterey Bay Aquarium, the Natural Resources Defense Council and the National Coalition for Marine Conservation for a closure of about 125,000 square miles of the northern Gulf. The petition is still under consideration as we go to press.
Purse Seine Boats
Today there are only five purse-seine-boats that are allowed to fish US Atlantic waters. Unfortunately these boats are grandfathered in, and with new technology – spotter planes, satellites, faster boats etc. - these vessels are extremely deadly. Once a school is located, a larger boat deploys a skiff which pays out a net, surrounding the schools of tuna. Lines on the bottom of the net are tightened like purse strings, closing the bottom of the net. Powerful winches on the mother boat pull the net up along with thousands of pounds of adult and juvenile bluefin. For fifteen years these boats did their best to fish down the young school-bluefin that the canaries preferred, making it virtually impossible for sustainable numbers to reach sexual maturity. Then, in 1972 the market for giant bluefin in Japan went berserk. Almost overnight, giant bluefin tuna went from being considered a trash fish to a goldmine and the purse seiners didn’t miss a beat. It doesn’t take a scientist to figure out that hammering the young of the stock and then systematically killing off the big breeders would result in a crash somewhere down the road, but still, despite angler outrage and scientists dire warnings it continues.
When you figure in the inordinate price per pound bluefin are bringing in, then the fact that these five boats receive an unjust 500-ton quota yearly which is approximately 25% of the entire western Atlantic bluefin quota, you can begin to get a sense of the millions the owners of these vessels make off a resource that is supposed to be owned by the public. Their well paid lobbyists and extensive political connections have enabled them to keep that quota despite the obvious over-allocation and misuse of a public resource.
Increasingly, tuna farms are popping up in certain parts of the world but they seemed to be growing in the Mediterranean at a disturbing rate. This may be the biggest threat to Atlantic bluefin at present. School and medium size bluefin are captured by purse-seine boats and subsequently dumped into pens where they are fed exorbitant amounts of forage fish. The harvest of all this feed is becoming a big problem for forage fish stocks that bluefin and other predators feed on like herring, menhaden. which are under a lot of danger of being overfished themselves. But, where the real damage lies is the fact that these fish are taken while still young, thus they don’t have a chance to spawn even once. Furthermore, as with other farmed fish, the waste from the feed and the tuna result in quite a bit of pollution in the surrounding waters. Another particularly troubling aspect of this practice is that these fish which are initially taken via purse-seine boats are not counted against the ICCAT quota. When they are transferred to pens they are classified as aquaculture products rather than “wild fish.” Purse seine boats never technically land the fish so they do not report their catch as landed. It’s a giant loophole in the system that needs to be closed right away if there is to be any hope for the future of bluefin tuna.
The Good News?
Many northeast and mid-Atlantic flyfishes took advantage of the spectacular run of school bluefin tuna we had just a few miles from the shore this year. Why these fish all of the suddenly appeared remains a mystery. However, some scientists, including Block believe that the abundance of small fish were spawned by the big year classes in 94-97. No data exists on these school bluefin at the moment and it could be merely be a redistribution of forage base, or simply changing water temps. Currently an effort is underway by Molly Lukovitch of the Large Pelagic research lab of the University of NH to “Tag a Tiny” which will track movements of juvenile bluefin with tags. But, the question still remains will these fish make it to spawning size before getting harvested to low levels. One thing is for sure, however; there are very few giants around and some serious changes need to be made, before it’s too late.