Population characteristics unravel occurrence of distinct stocks of yellowfin tuna (Thunnus albacares) population in the Indian seas

Abstract

Fishery and biological observations of yellowfin tuna caught from seas surrounding the
Indian mainland and its island territories have indicated the presence of biologically distinct
stocks in the region. Those caught around the submerged mounts of Chagos-Laccadive
Ridge in the Lakshadweep Sea, off Kerala-Karnataka coast exhibit early maturity, small size
at maturity, short lifespan and a close association with sea mounts. In contrast, those caught
off other coasts of the mainland, including Andaman waters, exhibit late maturity and larger
sizes at maturity indicating a fishery dominated by larger-sized individuals. These findings
suggest that the yellowfin tuna associated with the Lakshadweep Sea mounts constitutes
a distinct stock, highlighting the necessity for comprehensive genetic, morphometric and
population investigations to confirm their stock status.

Keywords:
Chagos-Laccadive Ridge, Indian mainland,
Lakshadweep Sea, Maturity, Stock, Sea mounts,
Yellowfin tuna