Evidence for recovery The ability of coral trout populations to recover from disturbances is influenced by key life history traits, such as growing rapidly in the first few years of life, maturing relatively early, variable timing of the change from female to male, having high annual fecundity, and spreading reproductive effort over space and time. In addition, some fisheries management measures are well matched to coral trout, for example conservative size limits for most coral trout species allow individuals to spawn for at least one season before they reach legal harvestable size.
Coral trout can recover quickly when disturbance is reduced.
When disturbance from fishing is reduced, coral trout numbers have recovered reasonably quickly, as demonstrated by the two-fold increase in their biomass in zones closed to fishing within two years of implementation of revised zoning arrangements in 2004.106 Further work has confirmed this recovery has been maintained with coral trout generally found in greater abundance in no-take zones than fished zones (see Figure 2.10).96 The zoning arrangements provide critical support to the potential for coral trout recovery and their overall resilience throughout the Region. For example, coral trout are generally larger in protected zones.103 Size is especially important because larger fish produce disproportionately more larvae, improving overall reproduction within the population.102,110,111 Increased reproduction within no-take zones appears to also benefit zones open to fishing. While many coral trout larvae in the Keppel Islands remain on their original reef, many others are dispersed, both to other no-take reefs and to reefs open to fishing.112 An estimated 60 per cent of larvae on reefs open to fishing in the Keppel Islands area originated from reefs in protected zones.112 Importantly, spatial analyses have shown that the design of the Great Barrier Reef zoning means that most reefs, open to fishing and no-take, are within range of dispersal from a no-take reef.102,113,114 Thus, by maintaining connectivity between reefs, zoning has ensured they operate as a network, rather than in isolation — networks are recognised as more resilient than isolated components2. In 2009 cyclone Hamish damaged a large number of coral reefs within the Region, including many used by commercial fishers.115 In 2011 cyclone Yasi also damaged reefs. In both instances one of the early hypotheses for the decline in commercial catch rates was that the cyclone increased mortality of coral trout. However, later work showed that adult fish were still present; it was their catchability that had been negatively affected.104,115
Coral trout larvae from no-take areas disperse into other areas.
8.3.5 Loggerhead turtles