We developed a biological algorithm to study the general behaviour and dispersal of Acanthopagrus butcheri larvae. Dispersal models are useful for testing hypotheses about the relative influence of environmental and behavioural factors on the dispersal of fish eggs and larvae.
This behavioural model was created using results from laboratory experiments conducted by Eleanor Gee at the University of Melbourne. Preliminary experiments were necessary as the current information on the development of environmental preferences and swimming abilities in A. Butcheri larvae was insufficient to inform a dispersal model of early life stages of the specie. Developmental changes were assessed in critical swimming speed, halocline response and depth response of A. butcheri larvae using swimming flumes, salinity stratified cylinders and pressure tanks.
The larva model is fully coupled with a 3 dimension stratified temperature and salinity hydrodynamic model of Gippsland Lakes, Australia’s largest estuarine system. The model simulates the dispersal and behaviour of A. butcheri as a function of age and environmental factors such as current velocities, depth, salinity, temperature and presence of halocline/thermocline. Vertical and horizontal swimming velocity of larvae is limited to an age dependant maximum swimming velocity. The larval “particles” can follow behaviour such as:
- swim against current or maintain position
- swim toward a preferred depth
- swim toward a preferred salinity or temperature
- swim above or below halocline or thermocline