Discrimination ofTrisopterus luscusstocks in northern Portugal using otolith elemental fingerprints

Abstract

-The pout, Trisopterus luscus, is one of the most important gadoid fish captured by northern Portuguese traditional fisheries. In spite of a substantial decrease in fish catches, little data are available either on the population structure or on the management of the species. In this study, chemical analysis with inductively coupled plasma mass spectrometry of whole otoliths of 90 pouts (age group 2, total length: 17.9-25.0 cm) provided location-specific elemental signatures. Sampling took place in shallow waters along the coastline in three fishing grounds off the Portuguese north coast (Viana do Castelo, Matosinhos and Aveiro) between February and March 2010. Otolith fingerprint analysis detected the presence of several informative trace elements. Molar concentrations for each site were analysed through uni-and multivariate statistical tests. Strontium, barium, magnesium and lithium (Sr, Ba, Mg and Li) differed significantly among locations, while no significant differences were found for manganese (Mn) and nickel (Ni). Canonical analysis allowed us to discriminate the tested individuals with respect to their sampling origin with a mean classification accuracy of 69%. The observed site-specific elemental differences in pout otoliths suggest a high level of site-fidelity in relation to their growing/feeding areas. Pouts from these locations can be regarded as a single, although not necessary homogenous, stock. Furthermore, this study also suggests that the populations of juvenile fish mix partially and, therefore, cannot be assumed to be separate units for fisheries management purposes.

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

“…The incorporation of trace elements into otoliths is a complex and poorly understood process. For most elements, except Sr and Ba whose variation in otoliths has been clearly linked to variation in environmental availability, it is likely that a range of factors including ambient concentration, salinity, temperature, age, ontogeny, physiology, growth rate and metabolism may influence otolith elemental incorporation in complex and potentially interactive ways (Elsdon & Gillanders, 2003; Milton et al , 2008; Silva et al , 2011). Knowledge of the underlying causes of the variation observed in otolith elemental composition is not necessary for the use of this variation as an aid in understanding population structure (Thresher, 1999).…”

Identification of nurseries areas of juvenile Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) by scale and otolith morphometry and microchemistry

“…This test is appropriate for small samples and is robust to violations of the assumptions of normality and homogeneity of variance (Jørgensen & Rajeswaran, 2005;Avigliano & Volpedo, 2015;Avigliano et al, 2015d). A canonical discriminant analysis (DA) was performed using the morphometric variables in order to obtain the cross classification matrix and determine the capacity of these variables to identify the site of origin of the fish (Longmore et al, 2010;Silva et al, 2011). Multicollinearity between variables was analyzed, thus preventing a false outcome in the DA analysis and the use of redundant variables in the study (Graham, 2003).…”

Identifying Whitemouth Croaker (Micropogonias furnieri) Populations along the Rio de Janeiro Coast, Brazil, through Microsatellite and Otolith Analyses

“…A One-way Analysis of Variance (ANOVA) was performed to test each Element:Ca ratio separately to identify differences among locations, followed by a Tukey post-hoc test, if needed ( p < 0,05). Multivariate analysis of variance (MANOVA) and linear discriminant function analysis (LDFA) were used to explore the variation of multi-elemental signatures among locations [ 67 ]. For MANOVA, the Pillai statistic test was used.…”