Male Deep-Sea Shrimps Aristeus antennatus at Fishing Grounds: Growth and First Evaluation of Recruitment by Multilocus Genotyping

Abstract

The population biology of the deep-sea shrimp Aristeus antennatus, as with other exploited demersal species, is usually studied using data from fishery statistics. Such statistical analyses have shown female-biased sex ratios during the spawning season in this species. Because the abundance of males increases at greater depths that are not exploited by fisheries (virgin grounds), knowledge on their recruitment is limited. Here, the growth and recruitment of A. antennatus males at fishing grounds was evaluated. This was achieved by integrating information on previously identified breeding behaviours and by tracing the young-of-year cohort through genotyping at 10 microsatellite loci. Using a codend and a codend cover with distinct meshed windows, four groups of males were collected in winter and in a subsequent spawning summer season. Summer collections were mostly composed of pre-adult males, reaching sizes that are to be expected from the growth of winter juveniles; however, many specimens also originated from nearby grounds. This result indicates the horizontal dispersal of male juveniles via intermediate and deep oceanographic currents. Such dispersal complements passive larval dispersal in surface waters, and contributes to the weak genetic divergence among regional fishing grounds. These features could be shared by other deep-sea crustacean and fish species, and should be considered for the sustainable exploitation of demersal fisheries.

Genetic Demography of the Blue and Red Shrimp, Aristeus antennatus: A Female-Based Case Study Integrating Multilocus Genotyping and Morphometric Data

“…(iv) The size of the catches is larger in females, indicating the size dimorphism of the species [25,56], which is consistent with both the present study and the previous one focused on males carried out during the same sampling campaigns [20]. Small females were bigger (mean CL = 25.26 ± 3.39 mm) than males in the same sampling (mean CL = 21.92 ± 2.83 mm) [20] (t-test p < 0.001). (v) Females have greater age diversity and size composition [55].…”

“…Even so, more than 50% of the females in this group were correctly assigned to their baseline. As previously observed in males [20], the recruitment from other grounds was confirmed by the high proportion of individuals assigned to Roses, Blanes, and other sources, reaching 35% of the total assignments in summer small females. Small summer females showed an assignment pattern significantly different from winter juveniles (p = 0.02) and winter small (p < 0.0001) but more related to winter juveniles (44% of individuals assigned to this baseline) (Figure 6).…”

“…Otherwise, in both sexes, the level of contribution from adjacent fishing grounds is high. More than 40% of males in summer groups originated from outside the Palamós ground [20], whereas the percentage of contribution from neighboring grounds to summer small females rose to 35% (present study) (Figure 6). Our results corroborate the connectivity between nearby fishing grounds of A. antennatus in the north-western Mediterranean Sea, which likely occurs through the dispersal of different stages of the life-cycle of A. antennatus, i.e., larvae, juveniles, and adults of both sexes [16,17,20,40].…”

“…Genetic relatedness analyses showed that spermatophores attached to females collected at 400–700 m depth during the reproductive period came only partially from males captured simultaneously with the females, whereas a large proportion of spermatophores belonged to unsampled and less related males, likely from other spawning grounds [ 19 ]. Using genetic assignment analyses, Abras et al [ 20 ] recently reported the horizontal dispersal of juvenile males. On the other hand, females’ horizontal displacements have only been proposed by a single tagging study [ 21 ] and, despite their relevant contribution to the fisheries of this species, there are no genetic studies inferring the demography and dispersal of A. antennatus females.…”

Evolutionary and Conservation Genetics

“…), not only (and not anymore) for the mere appreciation of biodiversity, but also to provide a support for the management and conservation of endangered species or species deemed potentially dangerous to the human health. Therefore, this Special Issue aimed to combine the contributions of researchers working globally in the field of evolutionary genetics/biology, population genetics, molecular taxonomy, and conservation genetics, in order to obtain a bulk of papers that underscore the importance of studying genetic variability in organisms for safeguarding biodiversity, in all ways it can be understood [4][5][6][7][8][9][10][11].…”