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

Abstract

In this study, we quantified the three key biological processes, growth, recruitment, and dispersal pattern, which are necessary for a better understanding of the population dynamics of the blue and red shrimp Aristeus antennatus. This marine exploited crustacean shows sex-related distribution along the water column, being females predominate in the middle slope. The present study attempts to fill the existing gap in the females’ genetic demography, as scarce knowledge is available despite being the most abundant sex in catches. We analyzed morphometric data and genotyped 12 microsatellite loci in 665 A. antennatus females collected in two consecutive seasons, winter and summer 2016, at the main Mediterranean fishing ground as a model. Almost every female in summer was inseminated. Five modal groups were observed in both seasons, from 0+ to 4+ in winter and from 1+ to 5+ in summer. Commercial-sized sorting based on fishermen’s experience resulted in a moderate-to-high assertive method concerning cohort determination. Genetic data pointed out females’ horizontal movement between neighboring fishing grounds, explaining the low genetic divergence detected among western Mediterranean grounds. Our results could represent critical information for the future implementation of management measures to ensure long-time conservation of the A. antennatus populations.

Keywords: deep-sea shrimp; genetic demography; horizontal movement; microsatellite loci; recruitment.

Figure 1

Sampling locations of A. antennatus. Relief map: Sémhur/Wikimedia Commons.

Figure 2

Comparison of the mean carapace length (CL) of A. antennatus females based on commercial categories (a) and the groups derived from the modal progression analysis (b) in winter (filled circles) and summer (empty circles) for each group present in both campaigns. p < 0.05 obtained from one-way ANOVA and Post-hoc Scheffe test are indicated with an asterisk (*).

Figure 3

Size frequency distributions (carapace length, CL) of A. antennatus female groups in winter (a) and in summer (b) coupled with commercial size composition of each group derived from the modal progression analysis (MPA) in winter (c) and summer (d). Arrows indicate the CL mean computed for each age group by the MPA.

Figure 4

Carapace length (CL) of A. antennatus female groups based on commercial categories (white boxes) and the modal progression analysis components (MPA, grey boxes) in winter (a) and summer (b). The line that cuts through the box indicates the median value.

Figure 5

Distribution of the proportion (%) of assignment to other sources of the simulated offspring sets and the 2016 A. antennatus female groups. Continuous lines indicate the median value of each group and dashed lines represent the quartiles. Letters (a, b) indicate groups identified by the post-hoc Scheffe test. F, females; S, spermatophores; M, males.

Figure 6

Assignment distribution (%) of A. antennatus female commercial categories collected during the summer at Palamós fishing ground.

Figure 7

Assignment distribution (%) of A. antennatus female summer groups up to 3+ derived from the modal progression analysis (MPA) to their closest winter baselines: summer 1+ (a), summer 2+ (b) and summer 3+ (c).