Shell shape as an indicator of phenotypic stocks of Tehuelche scallop in Northern Patagonia, Argentina

Abstract

The understanding of phenotypic plasticity in a heterogeneous environment is relevant at the ecological level, but also to the identification of discrete stocks that may be important for fisheries management. Tehuelche scallop, Aequipecten tehuelchus, is a commercially exploited species in Argentina that presents three morphotypes: tehuelchus, madrynensis and a non-common variant felipponei. The main goal of this study was to analyse the shell shape variation of Tehuelche scallop to differentiate and identify the phenotypic stocks. The shape differences of A. tehuelchus were assessed using geometric morphometrics in nine localities of the two main morphotypes. The shell shape presented variability at geographic scale, with the larger differentiation between morphotypes. Scallops from madrynensis morphotype presented circular shell discs with smaller auricles than those from tehuelchus morphotype. Morphometric differentiation was detected among localities of each morphotype, mainly related to the disc circularity and the symmetry of the auricles. The presence of morphological shell variations and the plastic nature of the species has relevance in the context of fishery management, especially if zoning and rotational strategies are implemented based on the differentiation of phenotypic stocks.