中西太平洋人工集鱼装置下鲣鱼的碳氮稳定同位素组成初步分析

The preliminary analysis of carbon and nitrogen stable isotope composition of skipjack(Katsuwonus pelamis) gathering around fish aggregation devices in the Western and Central Pacific Ocean

为了解中西太平洋人工集鱼装置下鲣鱼的稳定同位素特征,根据2013年2月至3月金枪鱼围网采集的鲣鱼样本,对其碳、氮稳定同位素组成（δ13C和δ15N）及碳氮比（C∶N）随叉长的分布进行了初步研究。结果显示,鲣鱼叉长范围为31.0-65.0 cm,平均值为（44.30±7.85）cm,优势叉长组为40.1-50.0 cm,占总体样本的45.12%。δ13C的平均值为（-15.94±0.59）‰,叉长对δ13C有显著性影响（F=10.92,P〈0.05）,各叉长组的δ13C均值相差较小,说明所有样本的初始饵料来源相似。δ15N的平均值为（17.50±1.81）‰,叉长对δ15N有显著性影响（F=16.72,P〈0.05）,且小型鲣鱼的δ15N明显大于大型同类,说明小型鲣鱼的营养位比大型同类高。C∶N的平均值为（3.06±0.05）‰,叉长对C∶N值均有显著性影响（F=4.21,P〈0.05）,各叉长组C∶N均值随叉长的增加而减小,说明鲣鱼的营养状况随叉长的增加而降低。

The distribution of stable carbon and nitrogen isotope composition（ δ13C and δ15N） and ratios of carbon to nitrogen（ C∶ N） with fork length were studied to investigate the characteristics of stable isotope of skipjack,Katsuwonus pelamis,collected from Fish Aggregating Devices（ FAD）,based on the survey data of purse-seine fishery in the Western and Central Pacific Ocean from February to March 2013. The results showed that the mean value of fork length was（ 44. 30 ± 7. 85） cm,ranged from 31. 0 to 65. 0 cm in fork length,with the dominant fork length of 40. 1 to 50. 0 cm accounting for 45. 12% of the total samples. The mean value of δ13C was（- 15. 94 ± 0. 59） ‰,and it was significantly influenced by fork length（ F =10. 92,P 0. 05）. The differences among the mean values of δ13C from each fork length class were very small and it indicated that the sources of initial diets were similar for all samples. The δ15N was significantly influenced by fork length（ F = 16. 72,P 0. 05）. The mean value of δ15N was（ 17. 50 ± 1. 81） ‰ and it was greater in small skipjacks,which indicted that the trophic position of skipjack is higher in small scale than in larger scale. The mean value of C∶ N ratios was（ 3. 06 ± 0. 05） ‰,and it was significantly influenced by fork length（ F = 4. 21,P 0. 05）. The mean value of C∶ N ratios decreases with the increase of the fork length,which indicated that nutritional status of skipjack reduced by fork length class.