Sharks in Research and Industry Report by Shark Info Pathological changes caused by fish hooks on the blue shark Prionace glauca. Blue sharks are often caught as bycatch by longline fisheries. During the catch period between 1993 and 1995 it is estimated that between 50 and 120,000 individuals were caught annually alone in the North Atlantic catch area. Blue shark meat is not deemed commercially interesting, especially since legal catch regulations limit the quotas in the U.S. According to the authors, about 81% of the animals caught on hooks are released alive. Those blue sharks living in the open sea are often caught by sports fishermen off the U.S. coast between Maine and New Jersey, but precise catch statistics from sports fishery are not available. The jaw of a blacktip shark (Carcharhinus limbatus) with ingrown fishing hook. The colored and structurally changed region around the hook marks the intense area of inflammation. © Gaston D. Guex / Shark Foundation For example, during a two-day competitive fishing event in Massachusetts over 2,000 blue sharks were caught, 99% of which were apparently released alive. Unknown is how many of these animals die later on as a consequence of the traumatic catch. In any case many of these sharks have problems with fishing hooks stuck in their jaw, their gullet or intestinal tract. The hooks begin to rust and trigger antibody reactions in their bodies. The authors describe growths (fibroms) in the connective tissue, stomach inflammation (gastritis), inflammation of abdominal cavities (peritonitis), perforated liver resulting in inflammation (hepatitis) and tissue growth, inflammation of the esophagus (esophagitis) and as a mechanical result strong obstructions of the esophagal area. Transported by the fishing hook, bacteria and fungi directly enter the punctured tissue and trigger various inflammations. The 211 animals examined were caught by anglers within four days (July 1999, 81 specimen; June/July 2000, 130 specimen) in Montauk, New York. All blue sharks caught were males. Six of them had old remains of fishing hooks in their bodies and formed the basis of this research. The weight of the respective sharks was in a normal statistical range so they were considered healthy. Source: Journal of Fish Diseases 25 (9), pp 515-521. Borucinska J., Kohler N., Natanson Skomal, G. (2002). Pathology associated with retained fishing hooks in blue sharks, Prionace glauca (L.), with implications for their conservation. | Home | Index | Links |   top   last change: 06-04-2016 11:48