Abundance, bathymetric distribution and diversity of deep sea demersal finfish resources along the south-west coast of India

Abstract

Abundance, bathymetric distribution and diversity of deep sea demersal finfish resources along the south-west coast of India were studied. A total catch of 4255 kg (96.7 kg h-1) was recorded by sampling in the depths ranging from 100 to 1100 m. The major constituents were finfishes i.e., teleost fishes (67%) followed by elasmobranchs (14%), crustaceans (13%), cephalopods (2%) and others (4%). Maximum abundance (113.81 kg h-1) of finfishes was observed in the depth zone of 100-300 m, followed by 500-700 m (86.91 kg h-1), 700-900 m (67.71 kg h-1) and 900-1100 m (7.58 kg h-1). Nettastoma sp. (12.13 kg h-1), Lamprogrammus exutus (5.22 kg h-1), Chlorophthalmus bicornis (4.19 kg h-1), Bembrops caudimaculata (5 kg h-1) and Uranoscopus sp. (4.95 kg h-1) were the dominant fish species. The bathymetric distribution of the fishes which occurred more than one time were analysed using measures of the centre of gravity (COG) and the habitat width (HW). The analysis revealed that most of the species exhibited a wide distribution range, although a few were restricted to the greatest depths. Species richness index was maximum (8.25) at 500-700 m depth zone and minimum (3.20) at 900-1100 m depth zone. Species diversity did increase up to the depth of 900 m and declined beyond this depth, whereas, the species evenness increased with depth.