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《African Journal of Marine Science》2013,35(4):481-491
South Africa lacks a commercial oyster hatchery. To inform the sourcing of seed for future hatchery establishments, we compared half-sib Pacific oyster Crassostrea gigas cohorts from hatcheries in Namibia and Chile. We measured oyster growth, mortality, condition and feeding organ morphology in Algoa Bay (AB, Eastern Cape) and Saldanha Bay (SB, Western Cape), South Africa, from July 2011 to June 2012. Within SB, 14.3% of mean daily sea temperatures exceeded this species’ thermal optimum of 19 °C, compared to 50.5% in AB. Food abundance (mean daily chlorophyll a concentration) in SB (7.8 mg m–3) was double that in AB (3.9 mg m–3) where, presumably to increase particle clearance rates in a relatively phytoplankton-poor environment, oysters had larger gill:palp surface area ratios. Plankton fatty acid profiles (indicators of food quality) differed between locations. In AB, instantaneous growth rates differed between cohorts, and trends varied seasonally. Within both locations, condition index was usually higher in Chilean oysters, whereas shell density was higher in Namibian oysters. In AB only, Chilean seed suffered substantially higher summer mortalities than Namibian seed, suggesting that the latter are more suited to temperatures in AB. AB should also be assessed for culture of the indigenous oyster species that occur there. 相似文献
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金枪鱼(Thunnus)延绳钓作业研究
——以印度洋东部中国船队为例 总被引:1,自引:0,他引:1
报道中国水产总公司金枪鱼船队1997年5月至1999年5月期间在印度洋东部海域进行延绳钓作业的有关情况。结果显示船均月产量,以尾数计在49~175尾之间波动,最高出现于1998年9月,最低出现于1997年5月,平均116尾/船 相似文献
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金枪鱼延绳钓不同位置钓钩渔获效率的研究 总被引:1,自引:1,他引:1
本文从金枪鱼延绳钓渔具的结构及渔获效果入手 ,分析了大眼金枪鱼 (Thunnus obesus)和黄鳍金枪鱼 (Thunnus albacares)的垂直分布及该延绳钓渔具不同位置钓钩的渔获效率 ,据以对钓具的性能做出初步评价 ,并提出了改进的建议 相似文献
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