BSc-MSc (Integrated)

The Arabian Sea is one of the most biologically productive oceanic provinces in the Indian Ocean and it lies between the Arabian Peninsula and the Indian subcontinent. Distinct peculiarities of the Arabian Sea compared to other low latitudinal oceanic regimes are the seasonal reversal of circulation pattern with respect to the seasonal reversal of prevailing wind. Seasonal occurrence of upwelling and downwelling over the sea describes its annual biological productivity. Eastern Arabian Sea has some pronounced economic importance as compared to the west. Seventy percent of annual fishery production belongs to the eastern Arabian Sea. India has a coastline of 8129 km and west coast of India is the principal eastern boundary of the Arabian Sea. In India, pelagic fishery contributes around fifty-two percentage of annual fishery production. Indian Oil Sardine and Indian Mackerel contributes a major part of pelagic fishery along the Indian coastline. Life history of small pelagic fishes (highly mobile, short lifespan, plankton-based food chain) makes it more responsive to environmental forcing. The catch statistics of Indian Oil Sardine and Indian Mackerel landings along the west coast of India (WCI) are highly fluctuating since 1985. Since this period, Indian Ocean faces many extreme climatic events. Considering the above-mentioned facts as baseline information, the proposed study is focused on the impact of coastal ocean dynamics and environmental forcing on Indian Oil Indian and Indian Mackerel fishery along the south-west coast of India. The present study adopted a Multi-Criteria Analysis (MCA) model to establish suitable links between upwelling and temperature to pelagic fishery along the south-west coast of India. Also, an attempt has been made to explaining the inter-annual variability of Indian Oil Sardine and Indian Mackerel fishery along the south-west coast of India from 1992 to 2015 based on the MCA. The research also reveals the impacts of climatic events such as El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on major small pelagic fishery along the south-west coast of India. The Standardized Catch per Unit Effort (SCPUE) along the south-west coast of India from 1985 to 2015 showed a declining trend in Indian Oil Sardine fishery during 1985 to 1999 and after that, an increasing trend was observed from 2000 to 2006. The SCPUE of Indian Oil Sardine was highly fluctuating after 2006 and the highest value was observed during 2013. The analysis of the inter-annual variability of Upwelling Index (Offshore Ekman transport), wind speed and Chlorophyll- a concentration along the shelf waters of the south west coast of India showed an increasing trend from 2000 to 2006 and it is well explained the increasing trend in Indian Oil Sardine fishery during this period. Analysis of Southern Oscillation Index (SOI) and Dipole Mode Index (DMI) revealed the specific influence of climatic events on Indian Oil Sardine fishery along the south-west coast of India especially during 1990 to 1999. During this decade, south-west coast of India was experienced by a declining phase in Indian Oil Sardine fishery and this decade was characterized by more number of climatic events. From 1990 to 2000 five IOD and five ENSO events were occurred and these years were noticeable with the co- occurrence of ENSO and IOD. The trend in SCPUE of Indian Mackerel showed an alternating pattern of abundance with Indian Oil Sardine and a collapse in Indian Mackerel fishery was observed from 2000 to 2006. The ranking of years made by the MCA well explained the inter-annual variability in Indian Oil Sardine fishery and it was not well correlated with Indian Mackerel because the Indian Mackerel showed an alternating pattern of abundance with Indian Oil Sardine. By looking towards the future, the research results and proposed Multi-Criteria Analysis (MCA) model can be further developed into a multi-variable model for fishery predictions with a perceptive of helping fisher folks.