2010年乌苏里江大麻哈鱼的群体结构及其变动

Population Structure and Changes in Chum Salmon Oncorhynchus keta in Ussuri River during 2010

2010年10月4日~21日,对乌苏里江大麻哈鱼（Oncorhynchus keta）洄游繁殖群体渔业资源及其种群结构变动进行了调查研究,共统计标本9160尾。初步结果显示,大麻哈鱼的日洄游数量受水温和溶解氧的影响较大,出现2次洄游高峰期,平均日单船捕捞量为64尾。体长为55~65cm的个体占群体中的74%,其中体长为55~60cm的雌（36.82%）、雄（36.58%）个体在群体中所占比例接近,在体长小于55cm的群体中,雄性（27.17%）个体在本群体中所占比例高于雌性（12.75%）,体长大于60cm的群体中,雌性（48.61%）在本群体中所占比例高于雄性（34.25%）。体质量为2 000~3 000g的个体占群体中的57%,体质量大于2 500g的群体中,雌性（61.73%）个体在本群体中所占比例高于雄性（46.06%）。雌、雄性比为1.09：1,其中体重大于2 500g的雌性在群体所占比例最高为36.06%,其次为小于2 500g的雄性,占28.8%。对比历史数据表明,该渔业产量为近15年的最高值,总体资源量呈增多趋势,群体中个体趋于小型化,雌性个体在群体中处于主导地位。

The resources of migratory spawning groups and changes in population structure were surveyed in a total of 9160 statistical samples of chum salmon Oncorhynchus keta collected in Ussuri River from October 4 to October 21 in 2010.The results showed that water temperature and dissolved oxygen have a great impact on the quantity of spawning chum salmon daily.Two peaks were observed with an average of 64 individuals in a daily single boat catch.The individuals with body length of 55~65 cm were found to account for 74% in the group,with very similar ratio of male（36.82%） to female（36.58%） for the individuals with body length of 55~60cm.For the individuals with body length of less than 55 cm,however,the male individuals（27.17%） had higher proportion than the females（12.75%） did.There was higher proportion in the female（48.61%） than in the males（34.25%） in the chum salmon with body length of over 60 cm.The individuals with body weight of 2 000~3 000 g comprised of 57% in the group surveyed,and for the individuals with body weight of over 2.500 g,there was higher proportion in the females（61.73%） than in the males（46.06%）,with the ratio of female to male = 1.09：1.In the group of the chum salmon with body weight of above 2 500 g the females were shown the maximal proportion（36.06%）,followed by in males（28.8%） with body weight of less than 2.500 g.The chum salmon production in this year was the maximum in the past 15 years compared with the past data,indicating that the overall amount of resources presents an increasing trend year by year,but that the fish become smaller in size,with predominant females.