First Successful Transport and Short-term Rearing of the Endangered Sardinella tawilis (Herre, 1927) in Ex Situ Captivity

Abstract

The Taal Lake endemic freshwater sardine Sardinella tawilis (Herre, 1927), an important fisheries species, has been recently placed in the Endangered category by the International Union for Conservation of Nature due to its high endemicity and population declines, coupled with potential threats from natural volcanic and geologic events. We examined the survivorship of S. tawilis in short-term ex situ captivity (~ 30 d) and determined water quality parameters that influence survival. Collection, transport, and ex situ captivity trials for a total of 333 S. tawilis individuals were conducted from February–May 2021. The survival rate ranged from 2.6–26.9% after 30 d across the four trials. Principal component analyses showed that salinity, conductivity, and dissolved oxygen (DO) influenced S. tawilis survival. Generalized linear mixed models revealed that the combination of conductivity and DO have a significant effect on survival. Manifestations of handling stress observed in captive individuals include scale loss, hemorrhaging at fin base, swelling of eyes, and possible fungal infections. This study documents the first attempt at rearing S. tawilis via ex situ captivity. The findings of this study will serve as a basis to improve the survival of S. tawilis in captivity and will open possibilities of captive breeding or larval rearing for this endemic freshwater sardine.