Smart tags show unexpected tuna trips.Bluefin tuna power across the Atlantic much more often than scientists had expected, a find that could make life messy for fishing-rights negotiators. The greater mobility of bluefins is just one insight to come from a new generation of fish-tagging experiments, explains Barbara A. Block of Stanford University Stanford University, at Stanford, Calif.; coeducational; chartered 1885, opened 1891 as Leland Stanford Junior Univ. (still the legal name). The original campus was designed by Frederick Law Olmsted. David Starr Jordan was its first president. . Scientists used to rely on tags that merely identify the animal. Now, electronic tags can report much about what a fish does between tagging and recapture. In the Aug. 17 SCIENCE, Block and her colleagues release results for Atlantic bluefins wearing two new models. One of 15 species of tuna, these fish can grow into 10-foot-long, 1,500-pound torpedoes selling for up to $45 a pound. By the early 1980s, bluefin numbers had dropped alarmingly. Recovery of the fish population depends in large part on country-by-country fishing quotas doled out Adj. 1. doled out - given out in portions apportioned, dealt out, meted out, parceled out distributed - spread out or scattered about or divided up by the International Commission for the Conservation of Atlantic Tunas The International Commission for the Conservation of Atlantic Tunas (ICCAT) is an intergovernmental organisation responsible for the management and conservation of tunas and tuna-like species in the Atlantic Ocean and adjacent seas. (ICCAT ICCAT International Commission for the Conservation of Atlantic Tuna ), based in Madrid. "The arguments over these fish are legendary," says Block. To better understand the fish, Block and her colleagues worked with sports and commercial fishers in 1996 to tag 377 bluefins in the western Atlantic. So far, the team has recovered 49. Nearly a third turned up in the eastern Atlantic or the Mediterranean. ICCAT regulates eastern and western fish separately, assuming that only about 2 percent switch sides. John J. Magnuson of the University of Wisconsin-Madison “University of Wisconsin” redirects here. For other uses, see University of Wisconsin (disambiguation). A public, land-grant institution, UW-Madison offers a wide spectrum of liberal arts studies, professional programs, and student activities. , coauthor of a commentary in the same issue, says the discovery of greater mixing emphasizes the two fisheries' interdependence and the need to stop overfishing Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans. More precise biological and bioeconomic terms define 'acceptable level'. in the eastern Atlantic. The two new tag types together provide day-by-day or more frequent records of location, dive depths, and body and water temperatures. Eastern and western fish seem to mingle in food-rich areas but retire to separate spawning zones. Block estimates that travel to the spawning grounds may take 2 weeks or so. She identified shallow dives in warm water that appear to be the first recorded bluefin spawning dives. Also, the data suggest that the fish spawn near the Bahamas, as well as in previously recognized areas of the Gulf of Mexico Noun 1. Gulf of Mexico - an arm of the Atlantic to the south of the United States and to the east of Mexico Golfo de Mexico Atlantic, Atlantic Ocean - the 2nd largest ocean; separates North and South America on the west from Europe and Africa on the east and the Mediterranean. Magnuson, who chaired a National Research Council panel that in 1994 pleaded for more tuna data, calls the new study "a major contribution." |
|
||||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion