Otolith phenotypic variability of the blue jack mackerel, Trachurus picturatus, from the Canary Islands (NE Atlantic): Implications in its population dynamic

Abstract

33Studies have described the presence of different population units of blue jack mackerel, 34Trachurus picturatus, in the NE Atlantic region. However, the hypothesis of several 35 populations has been subtly questioned due to the high similarity in the otolith shape among 36 some regions. It suggests the possibility of migrations processes connecting them, especially 37 between Madeira, the Canary Islands and the African coast, being the Canary Islands the region 38 with higher potential of mixing due to the oceanographic conditions. In order to explore this 39 hypothesis, we quantified the phenotypic variability in the otolith contour of the blue jack 40 mackerel from Canary Islands using wavelets as mathematical descriptor. Our findings revealed 41 the presence of three otolith phenotypes (M1, M2 and M3) in similar proportions. They were 42 not linked to sex, age and size, but showed temporal variations associated with spawning, 43 recruitment and feeding seasons. The best model to explain the population structure of T. 44 picturatus in the Canary waters was based on local migration triangles and the 'contingent 45 theory', where migrants and residents compose the population. In addition, we estimated 46 different somatic growth parameters linked to these phenotypes. These results suggest a 47 complex population structure in the region with possibility of connectivity with the closest 48 populations inhabiting the Madeira archipelago and the African coast. However, future studies 49 are necessary including the whole Atlantic distribution of the species, with special attention to 50 the seasonal variations in the frequency of these phenotypes to clarify the intraspecific 51 polymorphism and the migratory processes. 52 53 54 55 56 57 58 59 60 61 62

Fish size effect on sagittal otolith outer shape variability in round goby Neogobius melanostomus (Pallas 1814)

“…Tuset et al . (2019) noted three morphotypes in Trachurus picturatus ; nonetheless, they were not linked to size, age or sex but to temporal variations associated with spawning, recruitment and feeding seasons.…”

Application of Shape Analyses to Recording Structures of Marine Organisms for Stock Discrimination and Taxonomic Purposes

“…Mathematically speaking, WT is based on expanding a signal into a family of functions obtained as the dilations and translations of a unique function known as a mother wavelet (Mallat, 1991;Parisi-Baradad et al, 2005;Sadighzadeh et al, 2012). Studying the variability of coefficients at a given angle of an outline is not possible with Fourier methods, which do not provide information on localized differences but on the overall shape (Libungan and Pálsson, 2015;Tuset et al, 2019).…”

“…It is currently recognized that otolith shape is under dual regulation with overall shape regulated genetically (Gauldie and Nelson, 1990;Reichenbacher et al, 2009;Vignon and Morat, 2010), and a wide range of exogenous factors altering the rate of otolith growth, which in turn modifies otolith shape (Gauldie and Nelson, 1990;Smith, 1992;Begg and Brown, 2000;Cardinale et al, 2004;Vignon and Morat, 2010). This produces variation among conspecifics that have experienced contrasting life histories (Vignon, 2012;Tuset et al, 2019). In some cases, genetically regulated shape change has only been found to affect shape change in certain areas of the otolith.…”

Spatiotemporal variability in the occurrence of juvenile Japanese jack mackerel Trachurus japonicus along coastal areas of the Kuroshio Current

“…Based on a phenotypic analysis of the otolith of T . picturatus off the Canary Islands, Tuset et al, (2019) suggested the contingent theory to explain its population structure. The main spawning the Chilean jack mackerel T .…”