In 1991, he found, the probability of landing a C+ fish (A being the highest grade) was 16 percent and 9 percent for August and September, respectively. By 2004, the probability increased to 68 percent and 76 percent in the C+ category for August and September, respectively. He also found that the bluefin are leaner on arrival to the Gulf of Maine; the probability of catching a poor quality fish (grade C or worse) in June 1991 was 30% compared with 70% in 2004. Good quality fish, such as B or better, now comprise less than one percent of the commercial catch at this New Hampshire cooperative.
For scientists like Golet and his collaborators at UNH, this research is less about tasty tuna than about understanding and promoting this overexploited fishery. One of the big consequences of not fattening as much is the potential impact it could have on reproduction, says Golet. Reduced energy stores can often force a fish to skip spawning in a particular year.
Jennifer Goldstein, also a Ph.D. student in the Large Pelagics Research Lab, looked at this link between bluefin body composition and reproductive status in an article published in the July 2007 Marine Biology journal (http://www.springerlink.com/content/q21417091803m56u/fulltext.pdf).
The researchers hypothesize this change in energy or fat acquisition could also shift the bluefin tunas migration patterns.
Now that the researchers have documented the decline of bluefin quality, theyre looking into the reasons behind it. One obvious cause would be a decline in their food supply; bluefin are voracious predators with a high
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| Contact: Beth Potier beth.potier@unh.edu 603-862-1566 University of New Hampshire Source:Eurekalert |