Diversity of flora and fauna in low-value bycatch from bottom trawls in Palk Bay, south-east coast of India

Species diversity of low-value bycatch

Abstract

Palk Bay is a highly stressed ecosystem due to intense trawling activities and standard operating procedures for trawlers along this coast are an immediate requirement. To support this, the diversity and biomass of low-value bycatch (LVB) from shrimp trawls operated on the Palk Bay coast of Tamil Nadu were studied. Following multistage stratified random sampling technique, samples were collected from Rameshwaram, Mandapam and Jagathapattinam landing centres. Palk Bay’s LVB contained  181 species from 142 genera, with 156 species recorded from Ramanathapuram, while Mandapam and Jagathapattinam recorded 77 and 129 species, respectively. Teleosts were the most abundant (45.9%), followed by crabs (16%) and shrimp (6%). Commercial landings peaked in January, while LVB landings peaked in June and July. The LVB/target group ratio ranged from 1.75 to 3.5, implying that the target group catch is increasing while LVB landings in Palk Bay are stable. An increase in LVB harvesting will cause ecological instability, depleting fisheries resources and unbalancing the functioning of the marine ecosystem. The findings of this study are important inputs for multi-species/multi-gear tropical fisheries management. There are attempts to certify the green tiger shrimp trawl fishery in Palk Bay and therefore, diversity studies will support formulation of strategies for ecosystem-based fisheries management.

Keywords: Ecosystem-Based Fisheries Management (EBFM), Fishery, Fisheries management, Marine ecosystem, Policy, Sustainable