环境与摄食对山东省近海鱼礁区不同体长许氏平鲉分布的影响

为研究环境与摄食因素对人工鱼礁区不同体长许氏平鲉分布的影响,采用2017—2018年山东省近岸3处鱼礁区环境和渔业资源的调查数据,利用变异系数CV均值将样本的体长分为10组,每组体长间隔为33 mm,并使用Bray-Curtis相似性指数比较不同海域许氏平鲉体长组成的相似性;运用去趋势对应分析(DCA)、典范对应分析(CCA)分析各环境要素对不同体长组许氏平鲉分布的影响;运用胃含物分析法分析许氏平鲉的食物组成。结果显示,西霞口与长岛鱼礁区样本体长组成相似性指数为70.66%,前三岛鱼礁区与西霞口鱼礁区、长岛鱼礁区的相似性指数较低,分别为54.94%和59.46%;大体长(299～365mm)许氏平鲉的分布与水深、水质指数(WQI)和化学需氧量(COD)相关性较大,喜好水深较深、营养丰富的水域;小体长(35～200 mm)许氏平鲉喜好水深较浅,水质好的水域。大体长(200～365 mm),高龄(2～3龄)的个体主要摄食鱼类、虾类和蟹类,优势饵料为鱼类(IRI为65.94%);小体长(35～200 mm),低龄(0～1龄)的个体主要摄食虾类和蟹类,优势饵料为虾类(IRI为45.69%)。研究表明,在浅水区域投放幼鱼保护型鱼礁,为幼鱼提供庇护所;将捕捞作业集中在深水区,减少对许氏平鲉小体长个体的兼捕,可以达到针对性增殖、保护许氏平鲉资源的目的。

Effects of environment and feeding factors on the distribution of different body lengths of Sebastes schlegelii in the reef areas of Shandong Province

In order to study the impact of environmental and feeding factors on the distribution of rockfish (Sebastes schlegelii) in artificial reef areas, this study used environmental and fishery data of three reef areas in Shandong Province from 2017 to 2018. Fish body length was divided into 10 groups by using the mean of the coefficient of variation, and the interval was 33 mm. Using Bray-Curtis similarity index to compare the similarity of the body length composition of rockfish in different regions, detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to describe the effects of environmental factors on the S. schlegelii distribution of different body length groups; the composition of the food of S. schlegelii was detected by using the stomach contents analyses. The results showed that the body length composition similarity index of Xixiakou and Changdao artificial reef areas was 70.66%. Compared with Xixiakou and Changdao, the Qiansandao artificial reef area has a low similarity index with them, which is 54.94% and 59.46% respectively. The distribution of S. schlegelii with larger body type (299-365 mm) is more correlated with depth, WQI and chemical oxygen demand (COD), and it prefers to live in a deep, nutrient-rich environment. Small body type (35-200 mm) S. schlegelii prefers environment with shallow sea areas and good water quality. The older (2-3 years old) large body length (200-365 mm) S. schlegelii mainly consumes fish, shrimp and crabs, and the dominant bait is fish (IRI, %=65.94). Younger (0-1 year old) small body length (35-200 mm) individuals mainly feed on shrimp and crab, the dominant bait is shrimps (IRI, %=45.69). Consequently, the application of juvenile-fish-protection artificial reefs in shallow water can provide shelter for juvenile S. schlegelii; concentration on fishing in deep water can reduce the bycatch of juvenile S. schlegelii, and then their resources can be proliferated and protected.