Spawning aggregations of reef fishes on the Great Barrier Reef: implications for management

Abstract

Many species of tropical fish associated with coral reefs aggregate at specific times and locations to spawn. Spawning aggregations of fishes are influenced by season, lunar phase and temperature and commonly form at traditional spawning sites. These traditional spawning sites, known as fish spawning aggregation sites (FSAS), typically occur at locations with several key characteristics, including water movements that transport eggs and larvae offshore or into the water column to facilitate the open-water phase of development. In recent years spawning aggregations of 49 species of fish have been reported in the Great Barrier Reef Marine Park. An additional 84 species of fish that occur on the Great Barrier Reef have been reported to aggregate to spawn elsewhere within their geographical range. The increased abundance of fish in localised areas at predictable times makes spawning aggregations particularly vulnerable to overexploitation. The Great Barrier Reef Marine Park Authority is concerned that fishing, tourism and, to a lesser extent, research activities are impacting on FSAS and the fishes when they aggregate to spawn at these sites. There is concern that fishers are targeting spawning aggregations of coral trout, Plectropomus spp. and other predatory fishes on the Great Barrier Reef; that tourism facilities and activities occur at or near FSAS; and that some research activities directly impact spawning fishes. The importance of developing policy and management strategies to protect fish spawning aggregations in the Great Barrier Reef Marine Park has been recognised. This report provides an overview of the status and vulnerability of spawning aggregations of reef fishes in a global context. It uses this background as a basis for developing management strategies to protect aggregating fishes from anthropogenic impacts in the Great Barrier Reef Marine Park.