Project 4.8.3

Management implications of the life history characteristics of serranid fish species on the Great Barrier Reef

Project Leader: Dr Colin Simpfendorfer, JCU

Sustainable management of fisheries requires sound scientific understanding of the biology and ecology of targeted species. This MTSRF-funded project addressed key gaps in our knowledge of important life history parameters such as growth, length and age at sex change, and longevity for 18 species within five different genera of serranid fishes (groupers) on the Great Barrier Reef. Wide variations in these parameters were observed across all species, precluding any attempt to manage them effectively as a single group. Three species (Epinephelus fuscoguttatus, E. polyphekadion and Cephalopholis cyanostigma) had maximum ages greater than 40 years, some of the oldest epinepheline serranids aged to date. The peak spawning period for a number of species appeared to be in the austral spring and summer, from October to January. Some species were monandric protogynous hermaphrodites (in which individuals are first female, with some mature females later changing sex to function as males), with large overlaps in the size and age of males and females suggesting that the cue for sex change in these species is not based solely on an endogenous developmental schedule - exogenous mechanisms such as the maintenance of a threshold sex ratio within the population could influence the timing of sex change. E. fuscoguttatus and E. polyphekadion changed sex very late in life (age at 50% sex change greater than the 90th percentile in age) and at very large size (846 mm and 550 mm respectively). However, whilst evidence indicates monandric protogyny for E. fuscoguttatus, E. polyphekadion males may develop via two pathways (diandry), from immature and mature females. The current management arrangements for these two species on the Great Barrier Reef include both minimum (500 mm) and maximum (700 mm) size limits, affording some protection to the larger E. fuscoguttatus, but none at all to large female and male E. polyphekadion. While none of the eighteen species reviewed in this project are specifically targeted by fishers on the Great Barrier Reef, there are many instances in which existing regulations and gear selectivity lead to the exclusive harvest of older large males and large mature females, which may not be a desirable management outcome. The results generated by this study are the first available information for some species, and are already helping to improve the sustainability of management of coral reef fisheries, both in the Great Barrier Reef and other parts of the Indo-Pacific.





Project 4.8.3 JCU Currey, L. et al. (2010) Comparative biology of key inter-reefal labrid species on the Great Barrier Reef

This project progress report describes the biology of labrids collected from fishery surveys on the Great Barrier Reef, providing results of length and weight relationships, length frequencies, spawning seasonality, length at sex change and sex ratios where data is available. The resilience of the wrasses to fishing in the Great Barrier Reef World Heritage Area will be assessed from this data and the existing literature.


Project 4.8.3 JCU Currey, L. et al. (2010) Resilience of reef fish species on the Great Barrier Reef and in Torres Strait

This project report uses reef fish species life history data, collected by the decade-long Effects of Line Fishing Project to (1) identify reef fish species with biological characteristics that make them most vulnerable to over-exploitation and other disturbances, and (2) evaluate the effectiveness of size-based regulations and gear characteristics in achieving sustainability of commonly caught species from three of the most important reef fish families of the Australian east coast.


Report Series No. 38 - Cappo, M., De'ath, G., Stowar, M., Johansson, C. and Doherty, P. (2009) The influence of zoning (closure to fishing) on fish communities of the deep shoals and reef bases of the southern Great Barrier Reef Marine Park. Part 2 - Development of protocols to improve accuracy in baited video techniques used to detect effects of zoning


Project 4.8.3 JCU Heupel, M. et al. (2009) The Comparative Biology of Lutjanid Species on the Great Barrier Reef

Project Milestone Report. The Lutjanidae family comprises a wide array of species of varying size and body form, and with 103 species, this family is one of the largest and most diverse families of fish. Project 4.8.3 research was designed to examine and compare the biology of several lutjanid species occurring in mid and outer shelf reefs of the Great Barrier Reef. Comparisons between biological parameters were completed where possible to define differences between species, examine their resilience to fishing pressure and determine whether current management measures are appropriate.


Project 4.8.3 JCU Mapleston, A. (2009) Comparative biology of key inter-reefal serranid species on the Great Barrier Reef

This project progress report examines biological samples collected as part of the CRC Reef-funded Effects of Line Fishing Experiment to provide information on the ecological resilience and vulnerability of key inter-reef fish species. Commonly referred to as groupers, the sub-family Epinepheline (Family: Serranidae) is the focus of this study due to concern about the status of a large number of grouper species being caught in tropical and temperate fisheries.


Project 4.8.3 JCU Currey, L. et al. (2008) Comparative biology of key inter-reefal lethrinid species on the Great Barrier Reef

This project progress report describes the biology of four lethrinid species that occur on the Great Barrier Reef: Lethrinus nebulosus (spangled emperor), L. atkinsoni (yellow-tailed emperor), L. olivaceus (long-nosed emperor) and L. lentjan (pink-eared emperor). Biological characteristics investigated included size, age, growth, mortality and reproduction. The biological characteristics were compared between species and the implications of differences considered in relation to the resilience of populations to fishing.


Project 4.8.3 JCU Simpfendorfer, C. (2008) Harvest patterns of the 'Other Species' quota group in the Coral Reef Fin Fish Fishery Updated June 2008

Report by researchers of the Fishing and Fisheries Team, James Cook University. This report documents the harvest patterns of the 'other species' component of the Coral Reef Fin Fish Fishery, a multi-sector line fishery that operates in the waters of the Great Barrier Reef World Heritage Area. Updated June 2008.