Combined methods of otolith shape analysis improve identification of spawning areas of Atlantic cod

Abstract

2006. Combined methods of otolith shape analysis improve identification of spawning areas of Atlantic cod. e ICES Journal of Marine Science, 63: 1710e1717.The effectiveness of otolith shape for identifying Atlantic cod (Gadus morhua) spawning populations in the northern North Sea and west coast of Scotland was investigated. Otolith shape was described using Cartesian Fourier analysis of the otolith outline and morphometric variable rectangularity. Pairwise randomization analysis of Fourier descriptors, and discriminant analysis of rectangularity and Fourier descriptors were used to identify differences between spawning stocks. Significant differences and a high classification success (>70%) in otolith shape indicated that spawning groups from Viking Bank and Moray Firth had different shapes from those of cod in other spawning areas. Significant differences in otolith shape of age 2 cod suggested that otoliths from the South Minch and Irish Sea were different from those from the Moray Firth and the Clyde. These results appear consistent with genetic evidence for a low gene flow, and tag-recapture evidence of resident populations. The results of pairwise randomization analysis and discriminant analysis differed slightly, indicating that use of a combination of methods increases the potential to identify spawning groups on the basis of otolith shape.

Use of otolith strontium:calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

“…An analysis of covariance (ANCOVA) was then used to determine the effect of fish length on the study variables within each age group. Variables that were significantly correlated to fish length were corrected using the common within-group slope (b) for the variable on fish length (e.g., Reist, 1985;Begg et al, 2001;Cardinale et al, 2004;Galley et al, 2006;Burke et al, 2008). Subsequently, the otolith Sr:Ca and Zn:Ca ratios were compared among the three sampling sites and age groups using the KruskalWallis non-parametric analysis of variance (Sokal & Rholf, 1995).…”

Otolith shape and size: The importance of age when determining indices for fish-stock separation

“…In some cases these measurements are supplemented with, or normalised by, measures such as fish length or weight (DeVries et al 2002;Stransky 2005;Mérigot et al 2007). Otolith boundaries are also extracted and represented, or encoded in different ways (transformed) prior to analysis with methods such as Fourier transforms (Begg and Brown 2000;Galley et al 2006;Bani et al 2013); and Elliptical Fourier transforms (Campana and Casselman 1993;Duarte-Neto et al 2008). Other methods of otolith boundary representation include Wavelets (Parisi-Baradad et al 2005), Curvature-Scale-Space (Begg et al 2005;Parisi-Baradad et al 2005) and the more recent Shapelet transform method (Lines et al 2012;Mapp et al 2013;Hills et al 2014).…”

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

“…Previously, normality and homogeneity of variance were tested (Shapiro-Wilk test, p>0.05 and Shapiro-Wilk test, p>0.05, respectively). Moreover, we tested for relationships between elemental concentration and fish size (otolith weight) with analysis of covariance (ANCOVA, otolith weight as co-variate) (Campana et al, 2000;Galley et al, 2006;Burke et al, 2008;Longmore et al, 2010;Kerr & Campana, 2013;Avigliano et al, 2015d, f). Element:Ca ratios were not significantly correlated with otolith mass.…”