BASSETT, D.K.*; MONTGOMERY, J.C.; Univ. of Auckland, New Zealand; Univ. of Auckland, New Zealand: Ecological implications of different search strategies in nocturnal teleost predators

Underwater diver transects and baited underwater video determined that the Dwarf Scorpionfish, Scorpaena papillosus, and the Southern Bastard Cod,Pseudophycis barbata, were the two dominant nocturnal teleost reef predators along the northeast coast of New Zealand. Laboratory based behavioural experiments investigated the search strategy of both species in response to live and dead prey. The Southern Bastard Cod is in constant motion when searching for prey and utilises more than one sensory system. It detects the respiratory currents of live crabs using its lateral line and detects dead crabs through the use of its barbels. In contrast, the Dwarf Scorpionfish exhibits a saltatory search strategy and detects the respiratory currents with its lateral line while motionless. Remaining motionless when searching for prey would eliminate any self generated noise and may explain the larger reactive distances for this species for hydrodynamic detection of prey. Non-visual predators that adopt a cruise search strategy would search a larger area than those species adopting a saltatory search strategy. However a saltatory searcher would search an area more thoroughly detecting both cryptic and conspicuous prey rather than only conspicuous prey as in the cruise searcher. This is reflected in the habitats that are utilised by these two species with the Dwarf Scorpionfish spending more time foraging in broken heterogenous parts of the reef while the Southern Bastard Cod spending more time in the uniform flat parts of the reef.