Estimation of density and abundance of the blue land crab, Cardisoma guanhumi Latreille, 1828, in the Imburana peninsula, northern Brazil

Abstract

The blue land crab (Cardisoma guanhumi Latreille, 1828) supports extensive small-scale artisanal fisheries in the tropical western Atlantic, including Brazil. Land surveys were conducted on a peninsula in a northeastern Brazilian estuary in 2014-2015 in order to evaluate density and abundance. The study area (26 700 m2) was dividied into three subareas with a total of 30 sampling points. In all, 529 burrows were registered of which 71.7% were open (indicating activity), 22.1% were closed (indicating moulting) and 6.2% were empty (fishermen catch). Burrow diameter ranged from 12 to 174 mm (mean: 62.05 ± 3.01 mm; 95% confidence interval). The highly significant correlation between mean burrow diameter and mean carapace length (n = 7; R2 = 0.8968, ) shows that one is a good proxy for the other. The estimated total population size in the study area was 10 362 individuals, with a mean density of 0.39 individuals/m2 (stock of 7347 kg).