Biology Department, University of Crete, Heraklion, Greece.
Institute for Marine Biological Resources, Hellenic Centre for Marine Research, Heraklion, Greece.
J Fish Biol. 2021 Jan;98(1):277-286. doi: 10.1111/jfb.14578. Epub 2020 Oct 19.
Otolith structure is a useful tool in discrimination among fish populations as it is a permanent record of the influence of endogenous and exogenous factors. In the present study we examined otolith morphology and fluctuating asymmetry (FA) for differences between wild-caught (by bottom trawl) and reared specimens of Gilthead seabream (Sparus aurata). Based on the frequency of regenerated scales (degree of scale regeneration, SRD) on each specimen, a threshold of 30% SRD was used to assign wild-caught fish individuals as wild (≤30% SRD, LR group) or as possible aquaculture escapees (>30% SRD, HR group). Based on the analysis of elliptic Fourier descriptors, significant differences were found in otolith shape between reared (Rr) and the wild-caught groups (LR, HR). Reared fish had otoliths with significantly larger perimeter (O ) than wild-caught fish. Furthermore, FA was significantly higher in the Rr than the LR group for O and all except one shape descriptors (harmonics 2-7). The HR group exhibited intermediate levels of FA between the low and high FA levels observed in the LR and Rr groups. Results are discussed in terms of the value of combining otolith and scale morphology for the identification of escapees in wild Gilthead seabream stocks.
耳石结构是区分鱼类种群的有用工具，因为它是内源性和外源性因素影响的永久记录。本研究通过比较野生（底拖网捕捞）和养殖真鲷（Sparus aurata）的耳石形态和波动不对称（FA），研究了耳石形态和波动不对称（FA）。根据每个标本上再生鳞片的频率（鳞片再生程度，SRD），将 30%的 SRD 作为阈值，将野生捕捞鱼个体分为野生（≤30% SRD，LR 组）或可能的水产养殖逃逸者（>30% SRD，HR 组）。基于椭圆傅里叶描述符的分析，发现养殖（Rr）和野生捕捞组（LR、HR）的耳石形状存在显著差异。养殖鱼的耳石周长（O）明显大于野生鱼。此外，对于 O 和除一个形状描述符（谐波 2-7）之外，Rr 组的 FA 显著高于 LR 组。HR 组的 FA 水平介于 LR 和 Rr 组的低 FA 和高 FA 水平之间。结果从结合耳石和鳞片形态识别野生真鲷种群逃逸者的角度进行了讨论。
