Deep-sea fishing for chondrichthyan resources and sustainability concerns— a case study from southwest coast of India

Abstract

Elasmobranchs comprising sharks, skates and rays have traditionally formed an important fishery along the Indian coast. Since 2000, Indian shark fishermen are shifting their fishing operations to deeper/oceanic waters by conducting multi-day fishing trips, which has resulted in considerable changes in the species composition of the landings <i>vis- a-vis</i> those reported during the 1980’s and 1990’s. A case study at Cochin Fisheries Harbour (CFH), southwest coast of India during 2008-09 indicated that besides the existing gillnet–cum- hooks &amp; line and longline fishery for sharks, a targeted fishery at depths &gt;300-1000 m for gulper sharks (<i>Centrophorus </i>spp.) has emerged. In 2008, the chondrichthyan landings (excluding batoids) were mainly constituted by offshore and deep-sea species such as <i style="">Alopias superciliosus</i> (24.2%), <i style="">Carcharhinus limbatus </i>(21.1%), <i style="">Echinorhinus brucus</i> (8.2%), <i style="">Galeocerdo cuvier </i>(5.4%), <i style="">Centrophorus</i> spp. (7.3%) and <i style="">Neoharriotta pinnata</i> (4.2%) while the contribution by the coastal species<i style=""> </i>such as <i style="">Sphyrna lewini </i>(14.8%), <i style="">Carcharhinus sorrah</i> (1.4%) and other <i style="">Carcharhinus</i> spp. has reduced. Several deep-sea sharks previously not recorded in the landings at Cochin were also observed during 2008-09. It includes <i style="">Hexanchus griseus, Deania profundorum, Zameus squamulosus </i>and Pygmy false catshark<i style=""> </i>(undescribed)<i style=""> </i>which<i style=""> </i>have been<i style=""> </i>reported for the first time from Indian waters. Life history characteristics of the major fished species are discussed in relation to the fishery and its possible impacts on the resource.