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Front. Mar. Sci. | doi: 10.3389/fmars.2018.00443

Overfishing and climate drives changes in biology and recruitment of the Indian oil sardine Sardinella longiceps in southeastern Arabian Sea

 Vasant Kripa1, 2, 3,  Kolliyil S. Mohamed1, 2, 4*, KP S. Koya1, 2, 5,  R Jeyabaskaran1, 2, 3, D Prema1, 2, 3,  Shelton Padua1, 2, 3, Somy Kuriakose1, 2, P S. Anilkumar1, 2, 3, Preetha G. Nair1, 2, 3,  T V. Ambrose1, 2, 3, A M. Dhanya1, 2, 3, K S. Abhilash1, 2, 3,  John Bose1, 2, 3, N D. Divya1, 2, 3, A S. Shara1, 2, 3 and P G. Vishnu1, 2, 3
  • 1Central Marine Fisheries Research Institute (ICAR), India
  • 2Central Marine Fisheries Research Institute (ICAR), India
  • 3Fishery Environment Management Division, Central Marine Fisheries Research Institute (ICAR), India
  • 4Molluscan Fisheries Division, Division of Fishery Resources Assessment, Central Marine Fisheries Research Institute (ICAR), India
  • 5Pelagic Fisheries Division, Central Marine Fisheries Research Institute (ICAR), India

The recent fluctuations in abundance of the Indian oil sardine Sardinella longiceps, a tropical small pelagic clupeid fish, was investigated in the light of overfishing and variations in its habitat ecology in southeastern Arabian Sea. In 2012, its landings peaked to an all-time record making it the fifth largest sardine fishery in the world, and within 3 years the catches were reduced to nearly a tenth of that level. This study examined the fishery dependant factors such as effort, catch rates and expansion of fishing area; the biological variations in fish size, maturity and recruitment; and tried to relate this to the environmental variations in the sardine habitat and food availability. The 2012 mega harvest was a result of a 2-time increase in gear size and engine capacity of fishing crafts and a 3.7-time increase in fishing effort. The female maturation process was strongly influenced primarily by rainfall and then by upwelling and the resulting influx of cold nutrient-rich water in the habitat from April much before the start of the monsoon in June. After 2013, the weak monsoons and the 2015 El Nino Southern Oscillation resulted in a warmer (by an average of 1.1°C) period which negatively impacted the maturation process. The abundance of jellyfishes which are larval and young fish predators in the habitat negatively affected recruitment after 2013. The mismatch in timing of phytoplankton productivity and sardine larvae in the habitat also affected the recruitment success. These environmental divergences coupled with the excessive capture (beyond maximum sustainable yields) of spawning stock and juveniles from 2010 has resulted in this biological catastrophe which has affected the livelihood of thousands of small-scale fishers. A more responsive fisheries administration with timely restriction on fishing effort and protection of spawning stocks by way of fishery closure would have helped minimize the impacts.

Keywords: Indian oil sardine, Overfishing, climate variability, recruitment, Environmental drivers, Timing mismatch

Received: 08 Aug 2018; Accepted: 05 Nov 2018.

Edited by:

Nazli Demirel, Istanbul University, Turkey

Reviewed by:

M Cristina Mangano, Bangor University, United Kingdom
Athanassios C. Tsikliras, Aristotle University of Thessaloniki, Greece  

Copyright: © 2018 Kripa, Mohamed, Koya, Jeyabaskaran, Prema, Padua, Kuriakose, Anilkumar, Nair, Ambrose, Dhanya, Abhilash, Bose, Divya, Shara and Vishnu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Kolliyil S. Mohamed, Central Marine Fisheries Research Institute (ICAR), Kochi, Kerala, India, ksmohamed@gmail.com