Diel movement patterns of ocean sunfish Mola mola off southern California
Diel movement patterns of ocean sunfish Mola mola off southern California
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DOI：
10.3354/meps266245
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发表时间：
2004-01-01
影响因子：
2.5
通讯作者：
Lowe, CG
中科院分区：
文献类型：
--
作者：
Cartamil, DP;Lowe, CG
海洋太阳鱼翻车鱼是南加州水域季节性常见的居民，是加州旗鱼漂流刺网渔业中最大的副渔获物(占总渔获量的29%)。我们使用温度和深度传感声波发射器来量化加州圣卡塔利纳岛附近海洋太阳鱼的精细运动模式。对8条海洋太阳鱼进行了24~72h的连续跟踪，每隔2 h收集一次海洋学数据，分析被跟踪鱼的地理位置和深度与海洋数据和一天中的时间的关系。海洋太阳鱼的平均活动距离为26.8+/-5.2(+/-SD)Kmd(-1)。水平运动的特点是夜间前6h的运动速率(ROM值=0.76 kmh(-1))(SD=0.31)明显低于夜间剩余时段(ROM值=1.00krnh(-1))(SD=0.39)，而白天的ROM值(中位数ROM值=1.22kmh(-1))(SD=0.58)明显高于任何一个夜间时段。水平运动是高度定向的，在整个轨道的持续时间内，角集中值(R)高达0.765。夜间的垂直运动仅限于表层混合层和温跃层，而白天的垂直运动往往以反复潜入温跃层以下为特征。发现最大潜水深度与潜水后在混合层中停留的时间之间存在显著的关系，这表明海洋太阳鱼可能在白天潜水较深的两次潜水之间进行体温调节。观察到的海洋太阳鱼的深度分布模式表明，降低水柱中刺网的深度可以显著减少加州流刺网渔业中这一物种的副渔获量。
Ocean sunfish Mola mola are a seasonally common inhabitant of southern Californian waters, and comprise the largest bycatch component (29% of total catch) of the California drift gillnet fishery for swordfish. We used temperature and depth-sensing acoustic transmitters to quantify the fine-scale movement patterns of ocean sunfish near Santa Catalina Island, California. Eight ocean sunfish were tracked continuously over 24 to 72 h periods, during which oceanographic data were collected every 2 h. Geographical position and depth of tracked fish were analyzed in relation to oceanographic data and time of day. Ocean sunfish traveled a mean distance of 26.8 +/- 5.2 (+/-SD) km d(-1). Horizontal movements were characterized by a significant decrease in rate of movement (ROM) during the first 6 h of night (median ROM = 0.76 km h(-1)) (SD = 0.31) as compared to the remaining night-time period (median ROM = 1.00 krn h(-1)) (SD = 0.39), whereas daytime ROM (median ROM = 1.22 km h(-1)) (SD = 0.58) was significantly higher than either nighttime period. Horizontal movements were highly directional, with angular concentration values (r) as high as 0.765 over the duration of entire tracks. Nocturnal vertical movements were confined to the surface mixed layer and thermocline, while diurnal vertical movements were often characterized by repeated dives below the thermocline. A significant relationship was found between maximum dive depth and the post-dive period spent in the mixed layer, suggesting that ocean sunfish may behaviorally thermoregulate between deeper daytime dives. The observed depth-distribution patterns of ocean sunfish indicate that lowering the depth of gillnets in the water column could significantly reduce bycatch of this species in the California drift gillnet fishery.