UNDERWATER OBSERVATIONS ON SCALLOP (PLACOPECTEN MAGELLANICUS) BEHAVIOUR AND DRAG EFFICIENCY
UNDERWATER OBSERVATIONS ON SCALLOP (PLACOPECTEN MAGELLANICUS) BEHAVIOUR AND DRAG EFFICIENCY
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DOI：
10.1139/f68-189
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发表时间：
1968-01-01
期刊：
影响因子：
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通讯作者：
CADDY, JF
中科院分区：
文献类型：
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作者：
CADDY, JF
一个8英尺的扇贝阻力的效率是根据水肺潜水员测量的种群密度来估计的。由于扇贝的游泳活动，密度测量必须用封闭的样方进行。扇贝对接近的物体的反应是背对它们并游泳。通常在水平游泳之前会有一个陡峭的上升，平均高度为0.4米。记录到的点对点游泳距离高达4 m，对地速度超过67厘米/秒。 一些扇贝超过100毫米，可以诱导游泳。尽管水平的底部条件下，总的阻力效率很低（2.1%），但逐渐增加的大小范围内遇到的（20-150毫米）。 阻力函数的直接观察表明，游泳活动，而不是选择的阻力是负责低阻力效率捕获小于100 mm的扇贝。间接捕捞死亡率被埋的拖凹扇贝。 拖移导致死亡的贝壳移位到基板表面，和底栖捕食者聚集在拖移轨迹。
The efficiency of an 8-ft scallop drag was estimated from population density measurements by scuba divers. Density measurements had to be made with an enclosed quadrat because of scallop swimming activity. Scallops responded to approaching objects by facing away from them and swimming. A steep rise usually preceded level swimming at a mean height of 0.4 m from bottom. Point-to-point swimming distances of up to 4 m were recorded with ground speeds in excess of 67 cm/sec. Few scallops over 100 mm could be induced to swim.Despite level bottom conditions, overall drag efficiency was low (2.1%) but increased progressively over the size range encountered (20–150 mm). Direct observations of drag function showed that swimming activity rather than selection by the drag was responsible for the low drag efficiency for the capture of scallops smaller than 100 mm.An indirect fishing mortality was established for recessed scallops buried by the drag. Dragging resulted in dislodgement of dead shell to the substrate surface, and aggregation of benthic predators in the drag tracks.