Population biology of the little gulper shark Centrophorus uyato in Lebanese waters.

Abstract

A total of 38 individuals of the heavily exploited little gulper shark Centrophorus uyato were collected from Lebanese coastal waters using bottom longlines and trammel nets of different meshes at depths ranging from 115 to 600 m between May 2013 and February 2014. Their total lengths were between 45 and 94 cm and their total mass was from 870 to 6700 g. The sex ratio was not significantly different from 1:1, with 20 males and 18 females, but bathymetric sexual segregation occurred. Catch per net setting (CNS) was used as a relative abundance index to detect spatial distribution; trammel nets showed largest CNS ranging from 4·9 to 5·45 kg per unit effort in the north and south, at depths from 120 to 200 m, during spring and summer. The mass-length relationships demonstrated negative allometric growth (b < 3) (males: MT = 0.3585LT2·071 , r2 = 0·94; females: MT = 0.0239LT2·735 , r2 = 0·64). The condition factor as well as the gonado-somatic and hepato-somatic indices of C. uyato in the study area were also calculated. The results are discussed in relation to the distribution, growth and reproduction as well as the management of C. uyato.