Assessment of the Impacts of selected extreme Climatic events on the Marine fisheries along Kerala and Tamil Nadu Coast

Abstract

Globally, one of the most severe impacts of climate change has been identified as the increase in the number of extreme events. The impact of two extreme events, the South India Flood 2015 in Tamil Nadu (TN) and tropical cyclone Ockhi which hit the Kerala and south TN coast in 2017 on the marine fisheries was studied. Analysis of impact on 13 craft-gear combinations in the five flood affected districts of TN indicated that the impact on catch, effort and catch per unit effort (CPUE) varied between districts and gears. Overall, the impact on catch and effort was highly negative in out-board motorised sectors with 64 to 97% reduction. Reduction / absence in pelagic fishes like sardine, Indian mackerel, Stolephorus, and Thryssa was evident and indicating the impact of flood waters in near-shore fishing grounds. Increase in catch of penaeid prawns, lobsters and crabs were observed in some areas indicating disturbance in benthic regions which was beneficial for Mechanized trawlers. The impact of tropical cyclone Ockhi was very high with more than 90% reduction on the marine fisheries of Thiruvananthapuram (TVM), Kollam, Alappuzha and Ernakulam districts. Along TN coast, Kanyakumari, Tuticorin and Thirunelveli were affected and the most impacted was Kanyakumari with more than 85% decline in catch for almost all major gears. The SIMPER test revealed that the species constituting a community were almost the same, but with either low abundance or complete absence. During Ockhi chlorophyll concentration increased by 27% (0.42 to 0.54 mg m-3), the velocity of the surface current increased (0.08 to 0.25 ms-1), SST reduced, there was change in current direction along the Kerala coast. In Kerala, total economic loss from loss in fishing days due to cyclone Ockhi was estimated as ₹107.29 crores with maximum loss at Kollam (₹22.98 crores) followed by TVM (₹16.84 crores). In TN coast, estimated economic loss was 12.5 crores. The study clearly indicated the increased vulnerability of marine fishers and the communities to climate change especially extreme events. The loss in human lives, fishing craft and gear due to Ockhi which was an unexpected event had a deep impact on the coastal communities making the recovery time from impact longer and stressful. The study points out that though the ecological system based changes were low due to tropical cyclone, the socio-economic impact was high and there is a need to develop early warning and vessel tracking systems to increase the preparedness of fishers to unexpected extreme events. Targeted research programs to assess the impact of environmental variations of extreme events on eggs, larvae and juveniles would help to identify the reasons for fishery fluctuations if any and help in fishery predictions