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Download Inter-annual variability in Sardinella longiceps in response to ENSO
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Inter-annual variability in Sardinella longiceps in response to ENSO event in the coastal waters of India Grinson George1, Muhammad Shafeeque1, Nandini Menon2, Shubha Sathyendranath3 and Trevor Platt3 1 Central Marine Fisheries Research Institute, Kochi, India. E-mail: [email protected] Nansen Environmental Research Centre (India), Kochi, India 3 Plymouth Marine Laboratory, Plymouth, UK 2 Abstract Sardinella longiceps (sardine) is a small pelagic fish dominating in the marine landings of India. An analysis of the effort involved for catching sardine showed a decreasing trend in catch per unit effort in recent years. The inter-annual variability in sardine landings is not completely driven by variability in effort. There are a lot of seasonal and inter-annual environmental changes in the coastal waters of India where the fish are abundant. The environmental factors are major drivers for large-scale variation in fish abundance. Here, we try to analyse remotely-sensed chlorophyll-a concentration and Sea Surface Temperature (SST) data to explore the possible causative factors which affect fish abundance. The maximum sardine catch reported in India was 0.72 million tonnes in 2012, with a decreasing trend afterwards. We assume that the sardine catch per unit effort reflects its abundance. Sardine gets recruited into fishery the same year it spawns and sufficient crafts are available to harvest the abundant fish. The monthly SST anomaly after 2012 showed an increasing trend. There is a major change of nearly 2-2.5 OC in the SST anomaly during 2015- 2016 which coincide with El Niño-Southern Oscillation (ENSO) event. An alteration in the Walker circulation pattern during ENSO event results in a net heat gain during summer months in the coastal waters of India. Breeding of sardines also occurs during summer monsoon. Therefore, it appears that the inter-annual variability in sardine is due to unfavourable environmental conditions resulting from ENSO-associated temperature variations.
