Ovary development of walleye pollock (Gadus chalcogrammus) in the western Bering Sea summer

Abstract:

Based on ovarian samples randomly collected from June to September 2017 and August to September 2018 in the western Bering Sea (60°28'N -61°57'N, 179°11'E -177°57'W), histological analysis was used to describe the development stages of the oocytes and ovaries of walleye pollock.The results showed that oocytes in different phases occurred in the ovary of Walleye Pollock in the western Bering Sea. The oocytes of Walleye Pollock were divided into 9 developmental phases, and the ovary was divided into 5 developmental stages.There were no statistically significant correlations between ovarian development and fork length, net mass, ovarian mass and gonadosomatic index, respectively.The gonadosomatic index can not be considered as a good index for predicting the maturity of Walleye Pollock in the western Bering Sea.Most of sampled Walleye Pollock did not spawn during summer, the mature individuals did not ovulate frequently, and few individuals in the second and last stages of development were found in the samples.The present study provided biological information for the stock assessment and sustainable exploitation of Walleye Pollock resources in the western Bering Sea.