Effect of angling intensity on feeding behaviour and community structure of subtropical reef-associated fishes

Baited hooks used in angling may influence foraging behaviour and trophic interactions among reef fishes, which may be reinforced over successive generations. In contrast to other scavenging opportunities involving pulsed resources (e.g. food falls), there is an asymmetric susceptibility to becoming hooked for species and size classes. The resulting effect may provoke behavioural changes in reef fishes through cognitive or phenotypic selective processes. We investigated the effects of angling pressure on the feeding behaviour and community structure of reef-associated fishes using a novel underwater video approach. Fish community and behavioural responses to simulated angling baits were assessed at paired sites of contrasting angling pressure at Amity Point and Ballina, on the east coast of Australia from late 2013 to 2014. Bait introduction differentially influenced trophic interactions of reef-associated communities according to angling intensity regime. Locations with higher angling pressure correlated with increased feeding hesitation among potentially capture-susceptible species, most notably Acanthopagrus australis. The feeding hierarchy of less dominant feeders and their interactions also differed compared with those exhibited under lower angling intensity regimes. Specifically, smaller opportunistic feeders (e.g. Microcanthus strigatus) that could utilise angling bait for dietary supplementation without risk of being hooked were able to maintain higher feeding ranks in areas subject to high angling pressure due to reduced interference competition from larger species, e.g. A. australis. We discuss the potential for complex ecological effects to follow from high-intensity angling activities and highlight the potentially confounding effects of using bait as a focus for fish assemblage monitoring.