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Abstract
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Article Information:
Environmental Preferences of Yellowfin Tuna in the North East Indian Ocean: An Application of Satellite Data to Longline Catches
J.K. Rajapaksha, L. Samarakoon and A.A.J.K. Gunathilaka
Corresponding Author: J.K. Rajapaksha
Submitted: August 01, 2013
Accepted: August 16, 2013
Published: November 20, 2013 |
Abstract:
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Development of state-of-the-art methodologies to minimise search time and to increase the fishing efficiency of high seas fishery are vital for fishing success. It, minimise the operational cost as well as fishing duration that save the fish quality. Understanding of the ocean environment and their preferences of Yellowfin Tuna (YFT) are important aspect to addresses the fishing uncertainty thereby ensuring the expected catch during a short period of time. Environmental parameters such as temperature, chlorophyll and dynamic height of the sea surface were obtained from remote sensing satellites and a YFT catch dataset was obtained from Sri Lankan longliners. The results of the data analyses have shown that the relationships between oceanographic parameters and YFT catch rates were found significant. These relations are capable of predicting fishable aggregations of YFT using near-real time satellite observations. High frequencies of YFT catches were found in the areas where Sea Surface Temperature (SST) varied primarily between 28-30C. The corresponding Sea Surface Heights (SSH) ranged from 205-215 cm and Sea Surface Clorophyll_a (SSC) concentration ranged from 0.1-0.4 mg/m3. The relationships between catch rates and the three environmental variables have been tested with the Empirical Cumulative Distribution Function (ECDF). The degrees of differences between the ECDF and catch-weighted cumulative distributions of the three variables are statistically significant (p<0.01). The strongest association showed between catch rates and SSC while SSH showed the lowest. The results obtained from a Generalized Additive Model (GAM) have shown that the space-time factor is well above the ocean environmental factors and the oceanographic factors are also in significant levels (p<0.05). Therefore, the migratory pathway is an essential factor in predicting YFT inhabitants in the northeast Indian Ocean.
Key words: ECDF, fishing ground forecast, GAM, GLM, Indian Ocean, satellite data, Thunnus albacores
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Cite this Reference:
J.K. Rajapaksha, L. Samarakoon and A.A.J.K. Gunathilaka, . Environmental Preferences of Yellowfin Tuna in the North East Indian Ocean: An Application of Satellite Data to Longline Catches. International Journal of Fisheries and Aquatic Sciences, (4): 72-80.
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ISSN (Online): 2049-842X
ISSN (Print): 2049-8411 |
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