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.

Keywords: Aristeus antennatus; deep-sea species; fishing grounds; male recruitment; microsatellite loci.

Figure 1

Sampling scheme to collect large and small specimens of A. antennatus.

Figure 2

Carapace length (CL) of male Aristeus antennatus groups captured at Palamós fishing ground, Spain. (a) Box and whisker plot, the median is shown by the line that cuts through the box, the mean is represented by a cross, P values were obtained from Post-hoc Scheffe test; (b) Size-frequency distributions.

Figure 3

Distribution of the proportion (%) of assignment to other sources of the simulated offspring sets (F × S and F × M, see text) and the 2016 samples. Letters (a, b, c, d and e) indicate groups identified by post-hoc Scheffe test.