2009/760 Development of vision and first feeding behaviour of Southern Bluefin Tuna and Yellowtail Kingfish

By Pollyanna Hilder

Southern Bluefin Tuna, Thunnus maccoyii and Yellowtail Kingfish, Seriola lalandi, are marine finfish species currently cultured in Australia. High early mortality and larval malformations have hindered the successful production of quality juveniles. This study describes the visual capacity of T. maccoyii and S. lalandi to feed under a variety of abiotic and biotic conditions and examined retinal morphology and physiology to identify species-specific adaptations to help explain the observed feeding behaviour.

The study found that T. maccoyii are photopically more sensitive and have a greater overall feeding performance compared to S. lalandi. The importance of low light intensity during larval culture of T. maccoyii was highlighted and the necessity to optimise culture conditions during the early-life history of S. lalandi to maximise their feeding success. The light environment is of paramount importance to larvae of both species, although they exhibit very different light requirements and visual capabilities. This has important culture implications. Southern Bluefin Tuna display morphometric and behavioural adaptations to life and feeding in low light environments. In contrast, Yellowtail Kingfish larvae display morphometric and behavioural adaptations to life in high light environments.