Population structure of the black seabream Spondyliosoma cantharus along the south‐west Portuguese coast inferred from otolith chemistry

Abstract

The chemistry of black seabream Spondyliosoma cantharus otoliths from three main fishery grounds (Olhão, Sagres and Sesimbra) located along c. 400 km of the Portuguese south and west coasts was examined. Element:Ca ratios were determined in whole otoliths and otolith cores of young adult specimens of 2-3 years of age. Using the data from whole otoliths, it was possible to discriminate among S. cantharus from the three fishing grounds with an average accuracy of 91%. Differences among fishing grounds were significant for all element:Ca ratios, and otoliths from Sagres had significantly higher levels of all ratios compared to the other fishing grounds. In contrast, the chemical composition of the otolith core, representative of the larval stage, showed limited variation among the fishing grounds, with an average discrimination accuracy of only 44%, although the Mg:Ca ratio of the otolith cores was also significantly higher for the Sagres samples. The data suggest that larval stages experienced a homogenous environment consistent with an offshore oceanic spawning. Juveniles appeared to display local residency on the inshore fishing grounds, areas probably characterized by greater environmental heterogeneity. Spondyliosoma cantharus population structure is consistent with distinct local population units that share a spawning ground providing recruits to different coastal fishery areas.

Stock Evaluation of the Euryhaline Cichlid, Etroplus suratensis (Bloch, 1790), from Significant Brackish and Freshwater Regions of India

“…It should be high for the model ftted to be good. In the present study, the estimated coefcients of determination (R 2 ) were within the range of (0.85-1.0), which shows better predictive power and smaller dispersion of LWRs data [32,33]. Generally, variations in LWR parameters of each fsh species occur mainly due to abiotic factors such as seasons, habitats, and biological parameters like size range, sex, maturity stages, and feeding habits [34][35][36].…”

Taxonomic and geographic influences on fish otolith microchemistry

“…As the number of new papers increases (e.g. Correia et al 2012;Hamer et al 2012;Mercier et al 2012;Tanner et al 2012) with more data on species and areas reported with increasing detail, it should be possible to accomplish more rigorous comparisons of the patterns of elemental distributions in time and space across species. The potential for mapping otolith geochemical patterns is improving and will complement ecological studies of fish populations.…”

Deep phylogeographic structure may indicate cryptic species within the Sparid genus Spondyliosoma

“…The gap between the ranges of the two species corresponds with the location of the Benguela Upwelling System (BUS), an established biographic boundary for a number of taxa (Grant & Bowen, 1998;Henriques et al, 2012Henriques et al, , 2014Henriques et al, , 2015. Throughout their respective ranges both species represent important fisheries resources and there are indications that stocks may be overfished (Correia et al, 2012).…”