Journal of Environment and Sociobiology

N. A. Talwar ¹, B. Hanumanthappa ²

Affiliations
1 Department of Fishery Engg, West Bengal University of Animal and Fishery Sciences, Kolkata-94, IN
2 College of Fisheries (KVAFSU), Mangalore–575 002, Karnataka state, IN

Abstract

Studies on selectivity of penaeids were carried out by comparing the catches of the conventional two-seam overhang trawl with that of experimental two-seam overhang trawl having square mesh panels of 45 mm mesh size in the forward part of upper belly and 28 mm mesh size in the cod end. Alternate trawling technique was used by maintaining similarity in towing direction, towing duration, speed and depth of operation to minimize possible errors between the trawls. The results revealed that the experimental trawl caught less quantity of juvenile penaeids than that of conventional trawl having diamond mesh webbing in the body and the cod end. The by-catch was also reduced considerably indicating that the new gear would be helpful for the better management of penaeids resources.

Keywords

Selectivity, Shrimps, Trawls, Diamond Mesh and Square Mesh.

Full Text

     

N. A. Talwar ¹, D. S. Sheshappa ², B. Hanumanthappa ²

Affiliations
1 Dept. of Fishery Engineering, (W.B.U.A.FS) Kolkata-94., IN
2 Dept. of Fishery Engineering College of Fisheries (UAS), Mangalore-575002, IN

Abstract

Reduction of by-catch in two-seam overhang trawl was studied by using a square mesh panels in forward part of upper belly and codend and comparison made with thai of the conventional two-seam overhang trawl. Fishing cruises were carried out randomly at depths of between 24 m and 34 m isobaths in the inshore waters of Mangalore coast. Alternative hauling technique was followed for maintaining similarity in towing direction, duration, speed and depth of operation to minimize the possible errors between the trawls. The results showed that the average by-catch was about 5.5 times lesser in two-seam overhang trawl using a square mesh panels in forward part of upper belly and codend than conventional twoseam hang trawl. However, the difference m reduction of by-catch in both conventional as well as experimental trawls was not found to be statistically significant.

Keywords

Two-seam Overhang Trawl, Square Mesh Panels, By-Catch.

Full Text

     

N. A. Talwar ¹, B. Hanumanthappa ²

Affiliations
1 Department of Fishery Engineering, West Bengal University of Animal and Fishery Sciences, Kolkata 700 094, IN
2 College of Fisheries (UAS), Mangalore-575002, IN

Abstract

Investigations were carried out to study the comparative impact of 28 mm square mcslies and diamond mesiies in codends of High Opening Bottom Trawl (HOBT) on different sizes of dominant fin fishes. The fishing trials were carried out through the M.F.V.Dopihin, a 13.26 m OAL wooden stern trawler, fitted with Ruston engine developing 102 BHP at 1800 r.p.m. of College of fisheries (UAS), Mangalore. Atlemative haul techniques were followed under identical condition to provide the equal chance for both the trawls. The results shown that the 50% of retention lengths of Mackerels, Pomfrets, Soles and Ribbon fishes (Trichinrus spp.) were comparatively found better in high opening bottom trawl (HOBT) with 28 mm mesh size square mesh codend and for clupeids (Sardinella spp.) and Silver bellies (Leiognaihiis spp.) were same in both the codends of square mesh and diamond mesh of same mesh size in high opening bottom trawl (HOBT).

Keywords

High Opening Bottom Trawl (HOBT), Square Mesh, Diamond Mesh, Finfishes and 50% of Retention Length.

Full Text