• behaviour;
  • elasmobranchs;
  • habitat selection;
  • predation;
  • thermal physiology

The relatively complex pattern of temperature selection exhibited by juvenile lemon sharks Negaprion brevirostris in the North Sound differed markedly from many previously described responses of fish preferenda. Thermal data demonstrated that juvenile N. brevirostris did not attempt to behaviourally maintain a constant eccritic temperature. Rather, juveniles selected progressively warmer temperatures throughout the day until reaching the highest temperatures available, and then moved to cooler temperatures during late evening and early morning hours. It is possible that by exploiting habitat thermal heterogeneity juvenile N. brevirostris prolong activities such as feeding or digestion well into the cooler parts of the evening. The complex pattern of temperature occupation by juvenile N. brevirostris within the thermally heterogeneous North Sound nursery is probably linked to key daily activities such as prey capture, predator avoidance and digestive efficiency.