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首页> 外文期刊>ICES Journal of Marine Science >Discarding Norway lobster (Nephrops norvegicus L.) through low salinity layers ― mortality and damage seen in simulation experiments
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Discarding Norway lobster (Nephrops norvegicus L.) through low salinity layers ― mortality and damage seen in simulation experiments

机译：通过低盐度层丢弃挪威龙虾（Nephrops norvegicus L.）-在模拟实验中看到的死亡率和破坏力

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The Kattegat/Skagerrak Nephrops fishery is unusual in that animals normally live in high salinities (33―34 psu) but are raised through a low salinity surface layer and, if discarded, descend back through it to the sea bed. In other open-sea Nephrops fisheries, such low salinity exposure is rare. Physiologically the species is described as being marine stenohaline, i.e. intolerant of reduced salinities, and a lower salinity limit of 29―30 for its distribution has been suggested. Using CTD data from the Anholt E hydrographic station, near to known Nephrops grounds, a knowledge of hauling times (including washing the cod-end with surface water) and of the sinking rate of Nephrops, we simulated conditions experienced by the catch in this fishery. We also included a period of emersion (air exposure) on deck during sorting or reshooting the trawl. Blood electrolytes, body mass changes and simple behavioural responses were examined before and after the simulation over a 5-day period. "Discarded" Nephrops experienced significant haemodilution and gained mass rapidly. Animals showed slow rates of "tail-flipping", or absence of responses to stimulation, in the period immediately following return to salinity 33 seawater, although many showed recovery later. Delayed effects included abdominal stiffness, swelling and further mortalities (25―42% overall). Controls (exposed to 33 psu seawater only) showed good survival and vigorous responses, even with a period of emersion. The effects of salinity exposure, which are additional to the stresses of being trawled, on the fitness of discarded animals were evaluated. Our results suggest that Nephrops discard mortality in this fishery is significantly higher than past estimates and is due to the stress of this brief exposure to low salinity surface water.
机译：Kattegat / Skagerrak Nephrops渔业是不寻常的，因为动物通常生活在高盐度（33-34 psu）中，但通过低盐度表层饲养，如果丢弃，则通过其下降回到海床。在其他远洋海螯虾渔业中，如此低的盐度暴露是罕见的。从生理学上讲，该物种被认为是海洋碱no鱼，即不耐盐度降低，并建议其分布的盐度下限为29-30。利用靠近已知Nephrops地的Anholt E水文站的CTD数据，运输时间（包括用地表水冲洗鳕鱼端）和Nephrops的下沉率的知识，我们模拟了该渔业中渔获物所经历的条件。在对拖网进行分类或重新拍摄时，我们还在甲板上出现了一段时间的暴露（空气暴露）。在5天的模拟前后，检查了血液电解质，体重变化和简单的行为反应。 “丢弃”的肾单位经历了严重的血液稀释，并迅速增重。在恢复到咸度为33的海水后的一段时间内，动物表现出缓慢的“尾巴翻转”或对刺激无反应的速度，尽管许多动物后来恢复。延迟的影响包括腹部僵硬，肿胀和进一步的死亡（总体占25％至42％）。对照组（仅暴露于33 psu的海水中）显示出良好的存活率和强烈的反应，甚至出现了一段时间。评估了盐分暴露对拖网动物适应性的影响。我们的研究结果表明，在该渔业中，海肾丢弃物的死亡率显着高于过去的估计，这是由于短暂暴露于低盐度地表水中造成的压力。

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