阿根廷滑柔鱼两个群体间耳石和角质颚的形态差异

Abstract

头足类硬组织具有稳定的形态特征、良好的信息储存以及抗腐蚀性等特点。根据2007年2-5月和2010年1-3月我国鱿钓船采集的阿根廷滑柔鱼样品,提取出625对耳石和787对角质颚,测量耳石10个形态数据和角质颚12个形态数据,通过除以胴长(Mantle Length, ML)校正后,对南巴塔哥尼亚群体(South Patagonic Stock, SPS)和布宜诺斯艾利斯-巴塔哥尼亚群体(Bonaerensis-Northpatagonic Stock, BNS)形态差异进行分析,并建立不同群体的判别函数。结果表明,BNS群体耳石和角质颚外形参数雌性大于雄性,而SPS群体则为雄性大于雌性。均数差异性检验认为,同一群体不同性别的耳石总长(Total Statolith Length, TSL)、最大宽度(Maximum Width, MW)、侧区长(Lateral Dome Length, LDL)、翼区长(Wing Length, WL)、翼区宽(Wing Width, WW)存在显著差异(<em>P</em><0.05),同性别不同群体的MW、背侧区长(Dorsal Lateral Length, DLL)、吻侧区长(Rostrum Lateral Length, RLL)和WW存在显著差异(<em>P</em><0.05)。而同一群体不同性别间角质颚的上头盖长(Upper Hood length,UHL)、上脊突长(Upper Crest length,UCL)、上喙长(Upper Rostrum length,URL)、上喙宽(Upper rostrum width,URW)、上侧壁长(Upper Lateral wall length,ULWL)、下喙长(Lower Rostrum length, LRL)存在显著差异(<em>P</em><0.01),同一性别不同群体角质颚的下头盖长(Lower Hood length, LHL)、下脊突长(Lower crest length, LCL)、LRL、下喙宽(Lower Rostrum width,LRW)、下侧壁长(Lower Lateral wall length,LLWL)、下翼长(Lower Wing length, LWL)存在显著差异(<em>P</em><0.01)。耳石形态参数经主成分分析,认为BNS群体雌雄的主成分因子主要集中在TSL/ML、DLL/ML、RW/ML和MW/ML,SPS群体主要集中于TSL/ML、RW/ML、WW/ML和DDL/ML;角质颚形态参数经主成分分析,认为BNS群体主成分因子主要集中在UHL/ML、UCL/ML、ULWL/ML和 LRW/ML,SPS群体主要集中在UHL/ML、UCL/ML、ULWL/ML、URL/ML、LWL/ML和LRL/ML。利用角质颚和耳石对两群体样本分性别建立了判别函数,判别正确率均高于60%,所划分群体在部分形态指标上差异明显,具有一定的可信度。今后应加强样本采集个体大小和时间跨度,以更好的分析其群体变化规律。;The Argentinean short-finned squid,<em> Illex argenginus</em>, is a common neritic specie with a wide distribution from approximately 22°S to 54°S along the continental shelf and slope waters and around the Falkland/Malvinas Islands in the Southwest Atlantic Ocean. It is a cepholopod species of great commercial importance targeted by international fishing fleets consisting of both jigging fleets from Asian countries and trawelers from European countries. This species also plays a crucial role in its marine ecosystem in the southwest Atlantic Ocean. The Argentinean short-finned squid had a complicated intrapopulation structrue. At least five major intraspecific stocks are defined based on length at maturity, spawning, hatching time and distribution of animals in early life history stages. Its hard structures, including beaks and statoliths, have stable morphological characteristics, and are resistance to corrosion to a certain extent and suitable for life history information storage. They are often used separately in previous studies, and few studies have used both hard structures in studying squid life history. In this study, using specimens of Argentinean short-finned squid collected by the Chinese squid Jigging fishery fleet during February to May in 2007 and from January to March in 2010, we extracted 625 pairs of statolith from statocysts and 787 pairs of beaks from buccal masses.Ten morphological variables were measured for statoliths and 12 morphological variables were measured for beaks. These morphological variable measurements were standardized using mantle length (ML), which were then used to compare differences among the stocks (i.e., South Patagonic Stock, SPS; and Bonaerensis-Northpatagonic Stock, BNS)and between the sexes. This study showed that the morphological variables of statolith and beak for BNS females were larger than those of males. However, for the SPS cohort, male morphological variables tended to be larger than those of females. A Student's t-test showed that for a given stock the statoliths had significant differences between the sexes in the following morphological variables: Total Statolith Length (TSL), Maximum Width (MW), Lateral Dome Length (LDL), Wing Length (WL), and Wing Width (WW) (<em>P</em><0.05). For a given sex, significant differences between the two stocks were found in MW, Dorsal Lateral Length (DLL), Rostrum Lateral Length (RLL), and Wing Width (WW) <em>(P</em><0.05). Student's t- test also showed that for a given stock beaks had significant differences between the sexes in Upper Hood length (UHL), Upper Crest length (UCL), Upper Rostrum length (URL), Upper rostrum width (URW), Upper Lateral Wall Length (ULWL), Lower Rostrum length (LRL) (<em>P</em><0.01).For a given sex, significant differences were found in Lower Hood length (LHL), Lower crest length (LCL), LRL, Lower Rostrum width (LRW), Lower Lateral Wall Length (LLWL), Lower Wing Length (LWL) between the two stocks (<em>P</em><0.01). The majority of data variability in principal component analysis of statolith could be explained by TSL/ML, DLL/ML, RW/ML, MW/ML for the BNS and by TSL/ML, RW/ML, WW/ML, DDL/ML for the SPS. The majority of data variability in principal component analysis of beaks could be explained by UHL/ML, UCL/ML, ULWL/ML and LRW/ML for the BNS and by UHL/ML,UCL/ML, ULWL/ML, URL/ML, LWL/ML, LRL/ML for the SPS. When statolith and beaks were used to establish the discrimination function, accuracy rates in distinguishing the two cohorts were above 60%. These findings suggested that the cohorts of <em>Illex argentinus</em> in the Southwest Atlantic Ocean could be morphologically indentified. However, more samples and longer time series of data may be needed for further validation of this approach and evaluation of uncertainty associated with the results.