A study of the species composition and distribution of commercial penaeid prawns of Torres Strait

Abstract

Fishermen's logbook data were used to describe the distribution of fishing effort and the composition of the commercial catches in Torres Strait. Catches consist of tiger, endeavour and king prawns. Additional information on the distribution and abundance of the individual species was obtained from four trawl surveys carried out at 3-monthly intervals during 1985. Each survey extended over the entire area of the commercial prawn fishery in Torres Strait. The species composition of the trawl surveys (48% tiger, 44% endeavour and 8% king) differed noticeably from that of the commercial catch (60% tiger, 36% endeavour, 4% king). This difference was attributed to a combination of the commercial fishery's concentration on the higher-priced tiger prawns and the different spatial and temporal distributions of the species. The tiger prawn catch consisted of two species, Penaeus esculentus (99.6%) and P. semisulcatus (0.4%). The king prawn catch comprised P. longistylus (97.5%) and P. latisulcatus (2.5%). The endeavour prawn catch was represented by a single species, Metapenaeus endeavouri.

Spatial differences in the species distributions were found to be associated with the distribution of bottom sediments. Tiger prawns were most abundant on fine sediments with a mud content greater than 50%; P. semisulcatus was restricted to sediments with a mud content greater than 70%. The king prawns, unlike the tiger prawns, were most abundant on the coarse sediments with a mud content less than 20%. Endeavour prawns were the most widespread of all the species, being equally abundant on all sediment types.