Changes in relative abundance of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing
Changes in relative abundance of sharks and rays on Australian South East Fishery trawl grounds after twenty years of fishing
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DOI：
10.1071/mf99174
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发表时间：
2001-01-01
影响因子：
1.8
通讯作者：
Hodgson, KE
中科院分区：
文献类型：
--
作者：
Graham, KJ;Andrew, NL;Hodgson, KE
1976-77 年（商业开发初期）和 1996-97 年，使用相同的船只和拖网渔具以及类似的采样方案对新南威尔士州附近的上大陆坡拖网渔场（200-650 m 深）进行了调查。 1996-97 年主要 15 个物种（或物种组）的鲨鱼和鳐鱼平均捕获率与 1976-77 年平均值的 20% 相似。 1996-97 年，15 个物种或物种组中有 13 个的个体捕获率显着降低。减少幅度最大的是 Centrophorus 属的狗鲨，它们在 1976-77 年数量最多，但 20 年后很少被捕获。相比之下，1996-97 年尖刺鲨（Squalus megalops）和（较小程度上）白鳍鲨（Cephaloscyllaum sp. A）的捕获率与 1976-77 年相似。 1979-81 年期间的拖网捕捞提供了 9 个物种的数据，尽管没有针对较大的渔具尺寸进行校正，并且在 300-525 m 深度范围内鲨鱼和鳐鱼的汇总平均捕获率与 1976-77 年平均值的 28% 相似。结果表明，随着渔业的发展，大多数鲨鱼和鳐鱼物种的生物量迅速下降，目前处于非常低的水平。
Upper continental slope trawling grounds (200-650 m depth) off New South Wales were surveyed with the same vessel and trawl gear and similar sampling protocols in 1976-77 (during the early years of commercial exploitation) and in 1996-97. The 1996-97 mean catch rate of sharks and rays, pooled for the main 15 species (or species groups), was similar to 20% of the 1976-77 mean. Individual catch rates were substantially lower in 1996-97 for 13 of the 15 species or species groups. The greatest decline was observed for dogsharks of the genus Centrophorus, which were most abundant in 1976-77 but rarely caught 20 years later. In contrast, 1996-97 catch rates of spiky dogshark (Squalus megalops) and, to a lesser extent, whitefin swell shark (Cephaloscyllaum sp. A) were similar to those in 1976-77. Trawling during 1979-81 provided data for nine species, albeit not corrected for larger gear size, and the pooled mean catch rate for sharks and rays in the depth range 300-525 m was similar to 28% of the mean for 1976-77. The results suggest that the biomass of most species of sharks and rays declined rapidly as the fishery developed and is now at very low levels.