Studies Using Square Mesh Panel in Trawl Codends Along Cochin Coast of Kerala.

Abstract- Bycatch is an important issue in fisheries and trawling is often implicated, due to the generation of large quantities of bycatch compared to any other fishing method. A large number of studies are being carried out to address the issue of bycatch in Indian Fisheries. Though soft and hard bycatch reduction devices and square mesh codends were widely field tested, works on square mesh panel in trawls is limited in the Indian scenario. This study reports the results of design development and field testing of a square mesh panel fitted 24.7 m off bottom trawlnet along the coastal waters off Cochin. As a corollary to the main study, commercial trawl bycatch was also analyzed to derive the length frequencies of species. The major species that was encountered among the incidental catches from commercial trawling was Thryssa hamiltonii with a mean of 13.73%. Relationship between the girth and length of the commercially important species shows that only four species (P. argenteus, N. maculata. T. lepturus and Parastromateus niger) have significantly different values for the G3 (maximum girth of the body). SIMPER analysis showed that the average similarity for assemblages in codend group was 39.85 and the value for the panel cover was 38.42. P. argenteus and U. duvauceli, with contribution of 25.6% and 15.54% respectively, were the main species responsible for similarity within the codend group, while Stolephorus indicus (25.32%), Ambassis gymnocephalus (14.23%) and Alepes klenii (12.95%) contributed the to similarity in panel cover. Generalized linear mixed model anlaysis was used for catch comparison studies and the results showed that A. klenii of TL more than 8.25 cm were caught mostly in the trawlnet installed with 40 mm SMP, while length at separation in case of A. gymnocephalus was around 5.7 cm. The implications of the results are discussed and it is concluded that SMP can be an effective BRD for improving the selectivity of trawl nets.