Abstract
The blue jack mackerel Trachurus picturatus (Bowdich, 1825) specimens (N = 155) were collected during the MEDITS survey, done along the eastern side, precisely, of the Croatian fishing ground in July 2018. Biometrical analysis of ten morphometric and five meristic characters, as well as genetic analysis proved that the collected specimens were blue jack mackerel. The total length (TL) and weight (W) of all observed specimens ranged from 9.2 to 33.7 cm (12.15 ± 2.95 cm) and from 5.79 to 384.94 g (17.64 ± 39.42 g), respectively. All calculated length–length relationships were linear (r > 0.923). Sex was determined only on two larger specimens (28 cm < TL < 32.8 cm), which were females. In the length–weight relationship, positive allometry was established (b = 3.1789). Based on 37 partial cytochrome b sequences, the overall haplotype diversity (h) of 0.812 ± 0.048 and nucleotide diversity (π) of 0.0064 ± 0.0007 indicated high levels of haplotype and low nucleotide diversity. The obtained sequences were compared to previously published research within the Northeast Atlantic Ocean and the Mediterranean Sea, confirming the absence of genetic structure among these populations.
Highlights
Over the years, environmental variables have changed, mostly due to increasing globalisation processes [1]
The present paper provides phenotypic and genetic characteristics of this rare fish species in the Adriatic Sea, which might help us define this population that has obviously entered the Adriatic over the last decade
All collected specimens were mainly caught above the continental shelf of the open sea area of the middle eastern Adriatic, precisely from 50–200 m of the sea depth (Figure 1A.)
Summary
Environmental variables have changed, mostly due to increasing globalisation processes [1]. The modification of those variables directly influenced whole marine ecosystems. The blue jack mackerel Trachurus picturatus (Bowdich, 1825) is a benthopelagic fish species widely distributed and exploited in the area of East Atlantic (southern Bay of Biscay to south Morocco, including the Macaronesian archipelagos, Tristan de Cunha and Gough Islands). Within the distribution area of this species, its economic value is the lowest in the Mediterranean. As with other pelagic fish species, it forms schools and tends to migrate from open sea to coastal areas [4]. Only Bolognini et al [11]
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