赤道海域茎柔鱼角质颚形态及生长特征分析

Morphological and growth characteristics of Dosidicus gigas beak in the equatorial waters

茎柔鱼(Dosidicus gigas)资源丰富,约占我国远洋鱿钓总产量的50%以上,角质颚形态稳定,在头足类的种类、种群划分中有着重要意义。根据2017年2-4月调查期间赤道海域采集到的茎柔鱼角质颚样本,观测分析其角质颚形态特征、茎柔鱼个体生长对角质颚形态的影响。结果表明:雌、雄个体间角质颚的各形态参数具有显著性差异(P<0.05),且雌性个体的角质颚大于雄性个体;主成分分析结果表明可以选用上脊突长(upper crest length,UCL)代表赤道茎柔鱼角质颚的形态特征,并且可以做为茎柔鱼个体大小的估算;对不同胴长和性腺成熟度与角质颚上脊突长(UCL)的生长关系进行分析,显示随着胴长的增大和性腺的发育,茎柔鱼雌、雄个体角质颚上脊突长(UCL)也逐渐增加,角质颚逐渐增大。因此,根据角质颚上脊突长(UCL)的长度对茎柔鱼的胴长及生长情况进行判定是可行的。

The jumbo flying squid（ Dosidicus gigas） has abundant resources,accounting for more than 50%of the annual total yield of Chinese squid jigging. Researches on its＇ fishery biology can provide a lot of information for scientific management and protection. Squid＇s beak is characterized by stable morphology and can be used for cephalopod stock identification. Scholars had done studies of beak for the jumbo flying squid living in the coastal waters of the South America. However,study on this species in the equatorial waters is still scarce. Therefore,based on the beaks of jumbo flying squid collected in the equatorial waters（ 0°19＇N-1°9＇S,109°23＇-116°36＇W） from February to April in 2017,we analyzed the morphological characteristics of beaks,upper hood length（ UHL）,upper crest length（ UCL）,upper rostrum length（ URL）,upper rostrum width（ URW）,upper lateral wall length（ ULWL）,upper wing length（ UWL）,lower hood length（ LHL）,lower crest length（ LCL）,lower rostrum length（ LRL）,lower rostrum width（ LRW）,lower lateral wall length（ LLWL）,lower wing length（ LWL）,and their relationship with individual growth. We firstly combined Student＇s t test to get the differences of beak morphological parameters between the male and the female. Then principal component analysis（ PCA） was used to find a beak morphological parameter that could represent the jumbo flying squid ＇s beaks morphological characteristics most. In addition,the first principle component score（ C1） of PCA＇s results was applied to the individual size（ mantle length,ML） estimation. Results showed that the beak morphological parameters had significant differences（ P 0. 05） between male and female. In detail,all females＇ beak morphological parameters were significantly higher than those of males＇.The PCA revealed that the UCL could represent beak morphological characteristics and the first principle component score（ C1） was useful for the estimation of individual size. The relationship between the jumbo flying squid ML and C1 could be shown as ML = 7. 45 × C1＋ 353. 2（ R2= 0. 85）. Based on the PCA＇s result,the relationship between the mantle length or gonad maturity stage and UCL＇s growth was analyzed combining the analysis of variance（ ANOVA） and multiple comparisons（ LSD method）. Our studies indicated that both males and females had nearly the same situation that with the mantle length increasing and gonad becoming maturity,the UCL was also increasing（ P 0. 05）. Therefore,it is practicable to use the UCL as an indicator to determine the jumbo flying squid＇s mantle length and its growth condition. Our studies give a basic support for the research of the biology jumbo flying squid. We suggest that the UCL could be used for the of stock identification of jumbo flying squid between the coastal waters of the South America and the equatorial waters.