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首页> 外文期刊>ICES Journal of Marine Science >Estimating gear efficiency in a combined acoustic and trawl survey, with reference to the spatial distribution of demersal fish
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Estimating gear efficiency in a combined acoustic and trawl survey, with reference to the spatial distribution of demersal fish

机译：结合水下鱼类的空间分布，在声学和拖网相结合的调查中估算渔具效率

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摘要

Few analyses have been 'performed to estimate the efficiency of trawls targeting demersal fish using the ratio of catches and acoustic densities. In summer 2006, acoustic and fishing data were collected simultaneously over 3 d by three fishing vessels equipped with identical pelagic trawls in the Bay of Biscay. Variography identified moderate spatial autocorrelation in the acoustic backscatter at a mean scale of 3 km, a scale slightly smaller than the mean haul length (3.5 km), indicating that fish horizontal availability did not influence trawl efficiency. Acoustic backscattering densities expressed as nautical area scattering coefficients (NASCs) recorded in the trawled layer were compared with equivalent NASC (ENASC) values calculated from the species composition in the trawl, fish-length structure, and available relationships between target strength and fish length. Estimates of trawl efficiency for hake-dominated trawls were computed as the slopes of the relationships ENASC = 0.008 NASC and ENASC = 0.18 NASC~(0.31) for trawls made by day and night, respectively. For the whole demersal community, the relationships were ENASC = 0.022 NASC and ENASC = 0.17 NASC~(0.33) for trawls made by day and night, respectively.
机译：很少有分析通过使用捕获量和声音密度之比来估算以海底鱼类为目标的拖网的效率。在2006年夏季，比斯开湾的三艘配备相同中上拖网的渔船在3天内同时收集了声音和捕鱼数据。变异函数法在声学反向散射中确定了中等的空间自相关，其平均尺度为3 km，该尺度略小于平均拖曳长度（3.5 km），表明鱼的水平可利用性不影响拖网效率。将以拖网层记录的航海区域散射系数（NASC）表示的声学反向散射密度与从拖网中物种组成，鱼长结构以及目标强度和鱼长之间的可用关系计算得出的等效NASC（ENASC）值进行比较。对于以鳕鱼为主的拖网，拖网效率的估算值是分别按白天和黑夜做出的拖网的关系ENASC = 0.008 NASC和ENASC = 0.18 NASC〜（0.31）的斜率计算的。对于整个水下社区，白天和黑夜拖网的关系分别为ENASC = 0.022 NASC和ENASC = 0.17 NASC〜（0.33）。

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