【摘要】 为定量阐明电捕作业方式损害渔业资源的科学依据，通过2019年7月1—7日在东海北部近海进行的平行拖网同步试验，分析比较电脉冲虾拖网(电捕网)和对照虾拖网(对照网)渔获组成及捕捞效率差异。结果表明，渔获组成和渔获率随不同渔具和昼夜均呈显著性差异。电捕网渔获种类73种，对照网渔获种类80种，两种渔具共有种类58种；两种渔具主要渔获种类均为三疣梭子蟹(Portunus trituberculatus)和绿鳍鱼(Chelidonichthys spinosus);鹰爪虾(Trachypenaeus curvirostris)等6种虾类所占渔获量比例仅为2.8%～3.2%;电捕网和对照网渔获的种类组成平均相异性为43.85%,主要相异性分歧种有三疣梭子蟹、绿鳍鱼、角木叶鲽(Pleuronichthys cornutus)等；电捕网和对照网昼夜渔获种类组成平均相异性分别为44.60%和40.73%。相比对照网，电捕网渔获率提高了81.9%,主要渔获物中绿鳍鱼、三疣梭子蟹和鹰爪虾渔获率有显著提高；电捕网和对照网夜间渔获率较日间分别提高了54.4%和31.4%。研究结果表明，电捕作业可有效提高捕捞效率(尤其在夜间),但渔获物仍以底层鱼类和蟹类为主，而主要目标物种虾类比例很低，目标选择性较差。更多还原

【Abstract】 Shrimp beam trawl has started since the 1980 s in the East China Sea, and electric pulse trawl was used in early 1990 s because of its increased catch and reduced fuel cost. The principle of electric pulse trawl is to energize by a pulse generator, which generates a pulse electric filed at the net mouth, then the shrimp buried is electrically stimulated and becomes susceptible for capture. At the end of 1990 s, the heavy use of pulse trawling caused subsequent overfishing and further biomass depletion of the fisheries resources, and then was banned in 2001. However, its considerable economic returns led to the frequent illegal use of electrofishing. To assess the harmful effects of electrofishing and to quantify its damage on fishery resources, paired samplings of beam trawl and multivariate statistical software PRIMER were applied. Pulse trawl（electrofishing） and beam trawl（control trawl） hauled parallelly at a distance of 0.15-0.2 n mile with 2-3 kn towing speed from July 1 st to 7 th, 2019, off the East China Sea（32°00′-32°12′N、122°30′-123°18′E） were studied. Then the catch effectiveness and composition between electrofishing and control trawl were compared. Analysis of similarity（ANOSIM） test of the composition dissimilarity between fishing gears and similarity percentage analysis（SIMPER） estimated the contribution of main species to each group. Nonparametric（Mann-Whitney U test） test determined differences in catch rate between day and night and between fishing gears. Results showed significant differences in composition and catch rate between gears and diel period. Electrofishing produced lower species richness（73 species, including 46 fishes, 16 crustaceans, 11 cephalopod） than control trawl（80 species, including 49 fishes, 21 crustaceans, 10 cephalopod） with 58 sharing species. The catch of electrofishing was mainly composed of fishes（49.7%） and crustaceans（47.3%） while control trawl with fishes（58.9%）. The species Chelidonichthys spinosus and Portunus trituberculatus dominated（> 75% by weight） in both of the two fishing gears, while the six shrimps（Trachypenaeus curvirostris and Parapenaeopsis hardwickii etc.）only occupied 2.8%-3.2% of the total catch. The result of SIMPER indicated that the dissimilarity of catch composition between electrofishing and control trawl was 43.85%（P= 0.001）, and species P. trituberculatus, C. spinosus, Octopus ocellatus, Pleuronichthys cornutus, Paraplagusia japonica, Johnius grypotus and Argyrosomus argentatus showed relatively high dissimilarity contributions（>4%）. For diel catch composition comparison, ANOSIM showed that significant differences were obtained by both electrofishing（P=0.001） and control trawl（P=0.001）. Electrofishing captured more species at night（60） than at day（57） with 40 sharing species, while control trawl captured the same species（66） at day and night with 51 sharing species. The diel dissimilarity of catch composition was 44.60% by electrofishing and 40.73% by control trawl, and species P. trituberculatus, C. spinosus, J. grypotus, P. cornutus, O. ocellatus and A. argentatus showed high dissimilarity contributions（>4%） with different degrees of contribution to each group. Catch rate was 45 386 g ·h^-1 by electrofishing and 24 945 g ·h^-1 by control trawl. Electrofishing showed 81.9% catch rate increment, indicating more effective catch than control trawl（Mann-Whitney U test, P<0.001）. Catch rate in fishes, crustacean and cephalopod was 22 547 g ·h^-1,21 476 g ·h^-1,1 363 g ·h^-1, respectively by electrofishing and 14 692 g ·h^-1,9 318 g ·h^-1,934 g ·h^-1, respectively by control fishing, showing significant differences in fishes（53.5% increment） and crustacean（130.5% increment）（Mann-Whitney U test, P<0.001）. The remarkable change of catch rate by electrofishing was observed in species C. spinosus, P. trituberculatus, P. cornutus and T. curvirostris. Catch rate of C. spinosus was 16 899 g ·h^-1 and 10 746 g ·h^-1,respectively by electrofishing and control trawl, showing 57.3% increment（P<0.001）. Catch rate of P. trituberculatus was 19 496 g ·h^-1 and 8 026 g ·h^-1,respectively by electrofishing and control trawl, showing 142.9% increment（P<0.001）. And the species P. cornutus showed significant increment of catch rate（P<0.05）, while species T. curvirostris displayed significant decrement of catch rate by electrofishing（P<0.05）. Diel comparison of catch rate revealed significant differences for both electrofishing and control trawl. Night time catch rate(55 085 g ·h^-1) was more efficient than daytime(35 688 g ·h^-1), with 54.4% increment by electrofishing（P<0.001）. For control trawl, nighttime catch rate(28 330 g ·h^-1) was more efficient that daytime(21 560 g ·h^-1) with 31.4% increment（P<0.05）. The catch rate of fishes was 14 540 g ·h^-1 at day and 30 555 g ·h^-1 at night by electrofishing, while it was 11 666 g ·h^-1 at day and 17 719 g ·h^-1 at night by control trawl. There was a significant diel increment of catch rate by both electrofishing（110.1%） and control trawl（51.9%）（P<0.001）. The diel variation of catch rate showed that there were significant differences in species C. spinosus, J. grypotus, T. curvirostris and P. hardwickii. Compared with daytime, nighttime fishing efficiency of the four species increased by 154.1%,494.9%,61.1%,134.2%, respectively for electrofishing（P<0.05）, and 60.3%,565.2%,138.5%,39.7%, respectively for control trawl（P<0.05）. From the results, it concluded that electrofishing showed more efficientcy in catch, especially at night. Differences in species richness, species composition and catch rate may be determined by the combined effect of differences in electric（electrofishing） and mechanical（control trawl） stimulations. It was also probably due to the differences in diel period, species, behavior and physiological condition of species. Though high efficiency by electrofishing, the percentages of shrimp catches were still very low, which indicated that the catch structure was not improved at all. Electrofishing, in fact, has no significant selectivity for target species（shrimp）, but displays more harmful destruction to the demersal fishes and crab in the East China Sea.更多还原