辽东湾口虾蛄流刺网的渔获选择性研究

The Selectivity of Driftgill-net for Mantis Shrimp Oratosquilla oratoriain Liaodong Bay

为了提高近海渔业资源养护型捕捞与管理技术,促进《全国海洋捕捞渔具目录》的实施,2014年10—11月在辽东湾以口虾蛄为目标渔获,进行了网目尺寸为40、50、60mm的单片型刺网、双重型刺网、三重型刺网以及生产对照网的选择性对比试验,为确定渤海三重型刺网管理的过渡归属提供依据。结果显示,各试验网具的主要渔获种类基本相同,渔获优势种为口虾蛄和花鲈,随着网目尺寸的增大,各型刺网的口虾蛄相对重要性指数递减,而花鲈相对重要性指数则呈递增趋势。单片型刺网、双重型刺网和三重型刺网间的口虾蛄渔获量差异显著(P=0.04,P=0.66×10-6,P=0.029),口虾蛄渔获尾数占总渔获的比例呈现出按单片型刺网、双重型刺网、三重型刺网顺序增长的趋势。相同网目尺寸条件下,未达到可捕标准的口虾蛄渔获尾数呈现出按单片型刺网、双重型刺网、三重型刺网顺序递增的趋势,但其所占比例并无明显差别;相同型的刺网,随网目尺寸的增大未达到可捕标准口虾蛄的渔获比例递减。Gamma选择性模型曲线显示,当网目尺寸大于50mm时,单片型刺网、双重型刺网、三重型刺网的口虾蛄渔获优势体长均大于可捕标准,但是三重型刺网的渔获数量明显大于单片型刺网,且在渔业资源损害方面并无明显差别,因此,在目前渤海的口虾蛄渔业中,单片型刺网难以取代三重型刺网进行作业。

In order to improve the fishing and management technology of offshore fishery resources conservation,and to promote the implement of National Marine Fishing Gear Catalog,we performed a selective comparative experiment of Monolithic gillnet with mesh sizes of 40 mm,50mm,and 60 mm,Dual gillnet,Triple gillnet and Production control network for mantis shrimp Oratosquilla oratoriain Liaodong Bay in October and November,2014 to provide the basis for determing the adscription of managing Bohai Triple gillnet.Results showed that the main fishing species by various types of experimental nets were basically the same,with the dominant species of mantis shrimp and perch Lateolabrax japonicus.The larger each types of gillnets had the decreasing IRI value of mantis shrimp with increase in mesh size,while the IRI value of L.japonicus showed an increasing trend.The Monolithic gillnet,Dual gillnet and Triple gillnet had significant difference in mantis shrimp catch（P〈0.05）.The proportion of mantis shrimp catch in the total showed growth trend in order of Monolithic gillnet,Dual gillnet,and Triple gillnet.In the same mesh size,the mantis shrimp catches which come up to the standard showed growth trend in order of Monolithic gillnet,Dual gillnet,and Triple gillnet,without significant differences in the proportion in the total.For the same type of gillnets,with the increase in mesh size,the proportion of mantis shrimp catches did not rearch the standard declined gradually.Gamma selectivity curve displayed,when the mesh size was more than 50 mm,the mantis shrimp catches advantage length of the three types of gillnets was no less than that standard.However,the economic benefits of the triple gillnet was more than Monolithic gillnet obviously,and had no difference in terms of damage to fishery resources.Therefore,Monolithic gillnet is difficult to replace Triple gillnet which operates in current Bohai Fisheries of mantis shrimp.