Determination of some bioecological characteristics of crab species Liocarcinus vemalis and pachygrapsus marmoratus of Trabzon coasts

SUMMARY In this study, which was carried out on Trabzon coast-line from October 1995 to November 1996, some bioecological characteristics of crab species Liocarcinus vemalis (Risso, 1816) and Pachygrapsus marmoratus (Fabricius, 1787) were studied. During the study period, 672 L. vemalis and 475 P. marmoratus specimens were sampled. The sexual distribution of L. vemalis was as 86 % male and 14 % female, while 56 % of P. marmoratus specimes male and 44 % were females. In both species, carapace width (CW) - carapace length (CL) and carapace width (CW) - weight (W) relationships were determined. The relationships are CL = 1.54 + 0.78CW (r = 0.98), W = 0.00034CW292 (r = 0.97); for L. vemalis and CL = 0.50 + 0.90 CW (r = 0.98), W = 0.00083CW2 83 (r = 0.97) for P. marmoratus, respectively. It appears that the spawning season for both species begins in April and lasts until the end of August. Mean egg diameter and the number of egg were estimated as 0.27 ±0.018 mm, 26000 number/individual for L. vemalis and 0.34 ± 0.022 mm, 43700 number/individual for P. marmoratus, respectively. Key words : Crabs, Black Sea, Liocarcinus vemalis, Pachygrapsus marmoratus, growth, morphology, reproduction. VI