Catch trends of bottom trawl fauna with an emphasis on prawns and stomatopods, off Goa, India

Abstract

Catch trends of bottom trawl fauna off Goa, India were investigated at fortnightly intervals from February 2006 – May 2008 with the exception of June – October months (monsoon). Inter-comparison of faunal abundance data obtained during February to April months of 2006, 2007 and 2008 indicated that abundance during 2006 and 2008 were significantly higher as compared to 2007. Available fish landing data for the region also corroborated this trend. The dominance of sub-adults among stomatopods during post-monsoon season (November – January), juveniles and sub-adults among prawns during pre-monsoon (February – May), indicated recruitment to the fishery. Comparison with 40-year-old published data indicated significant reduction in the overall yield (P = 0.043; α = 0.05). Additionally, yields of 12 out of 15 fish groups across the demersal trophic spectrum decreased significantly (P = 0.031; α = 0.05). However, catches of miscellaneous species increased 17 times, and were dominated by pufferfishes. The profusion of pufferfish is attributed to the perennial breeding habit of these fishes combined with increased removal of potential predators such as sharks and catfishes. Marine Trophic Index (MTI) and Fishing-in-Balance Index (FiB) decreased at rates of 0.017 and 0.016 per decade, respectively, implying sustained fishing pressure over the next few decades that could lead to potential trophic cascade and dominance of resilient opportunistic species such as puffers.