Relative Growth and Size Structure of Achelous spinicarpus Stimpson, 1871 Associated with Shrimp Trawling in the State of Veracruz

Abstract

The objective was to analyse the relative growth and size structure of Achelous spinicarpus associated with trawling in Veracruz. The organisms came from shrimp trawls carried out in July 2013. There were 45 trawls organized in two depth intervals (B: 22 to 46 m and C: >46 m) and 14 fishing quadrants. Abundance, mean and standard deviation, by sex and depth interval, and sex ratio were determined. An ANOVA was applied to compare CW means, depth intervals and fishing quadrants. The CW-weight relationship was obtained, and growth type was also determined. Length-frequency analyses were carried out. A total of 2377 crabs were collected, 1164 males and 713 females. The overall average CW was 3.65 ± 0.7677 cm, the minimum value was 1.50 cm, and the maximum was 6.00 cm. For males, the average CW was 3.65 ± 0.8242 cm, with1.50 cm minimum value and 6.00 cm maximum value. The average CW of females was 3.64 ± 0.6164 cm, with 1.60 cm minimum value and 5.90 cm maximum value. There were no statistically significant differences in CW between males and females. However, there were significant differences between depth intervals (B and C) for the total and sex CW data. The sex ratio was 2.94:1 and 2.05:1 for depth intervals B and C, and 2.33:1 for the total data set. Growth type was allometric negative for both sexes and overall, with significant differences in slopes between sexes. There was a unimodal pattern for the two fishing depth intervals and for each sex; crabs were between 2.40 and 4.00 cm (77.64%) and between 2.56 and 5.12 (91.12%) for the B and C intervals, respectively. In males, 88.46% were between 2.40 and 4.80 cm, and 90.46% of females were between 2.72 and 4.64 cm. Achelous spinicarpus is an essential species in the structure of the brachyuran assemblage and in benthic communities, as well as a food resource for various species of demersal fish. Thus, the present study provides information on the population subjected to the impact of fishing activity in the area, allowing comparisons between different populations in the species’ area of distribution.