[Assessment of enhancement release of Oncorhynchus keta in Suifen River, Northeast China]. / 绥芬河大麻哈鱼增殖放流效果评估.

ABSTRACT

To evaluate the effects of enhancement release of Chum salmon (Oncorhynchus keta) in Suifen River, the homing Chum salmon was monitored in Dongning section of Suifen River from 2012 to 2017. A total of 462 samples were collected, 41 samples out of which were tagged indivi-duals which were cut off adipose fin before they were released. The recapture rate and the effects of Chum salmon enhancement release were analyzed and evaluated based on the releasing information. The results showed that the entire recapture rate of Chum salmon from 2010 to 2012 was 0.295%, and the input-output ratio of enhancement release was 12.87. Both the tagged and non-tagged groups were composed of 1+ to 5+ age individuals, with the average age being 3.93 and 3.63 years, respectively. The fork length at 50% individuals reached sexual maturity (L50) was estimated using a logistic moderating function, which was 53.13 cm and 49.89 cm for tagged and non-tagged groups, respectively. Results from ARSS analysis showed that there was no significant difference in fork length growth between tagged and non-tagged groups, but a significant difference in sexual maturity ratio. Our results confirmed the positive effects of enhancement release on recovery of Chum salmon resource and provided suggestions for the enhancement release efforts.