Juvenile abundance and post-larval incursion of mud crabs (<i style="mso-bidi-font-style:normal">Scylla </i>spp.) in Chilika lagoon

Abstract

834-840was carried out on the juvenile abundance and post-larval incursion of two species of Scylla into the lagoon for period of two years from August, 2005-July, 2007.<span style="color:black;mso-bidi-font-weight: bold;mso-bidi-font-style:italic"> Occurrence of juvenile, <span style="color:black;mso-bidi-font-weight: bold">S. serrata<span style="color:black;mso-bidi-font-weight:bold; mso-bidi-font-style:italic"> were throughout the year, while in <span style="color:black; mso-bidi-font-weight:bold">S. tranquebarica<span style="color:black; mso-bidi-font-weight:bold;mso-bidi-font-style:italic">, juveniles were not encountered during December-February. December-May register higher median CPUE values with peak in March for S. serrata. In <span style="color:black;mso-bidi-font-weight: bold">S. tranquebarica<span style="color:black;mso-bidi-font-weight: bold;mso-bidi-font-style:italic">, the peak juvenile abundance period was restricted to June-September with peak in July. The CPUE values for juveniles indicted that the recruitment was intense for S. serrata during post-winter (January-April) and for <i style="mso-bidi-font-style: normal">S. tranquebarica during monsoon (June-September). The crab seeds were available throughout the year which gave a clear evidence for the year round recruitment with the peak during the months of November-March for Scylla species from the Bay of Bengal to the Chilika lagoon. During the study period, the megalopa and first crab instar recruitment per net-hour collection was significantly higher during spring tides than neap tide phase (p&lt; 0.05) and also higher incursion was observed in the night hours than day hours (p&lt; 0.05).<span style="mso-bidi-font-weight:bold;mso-bidi-font-style: italic"> Significantly higher night collections of mud crab juveniles (mixed population of both species) from net box traps (khandas) were obtained during new moon phases (t=3.88; d.f.=11; P&lt; 0.01). </span