313 



Abstract. ^The recent age valida- 

 tion of the tropical snappers L. adetii 

 and L. quinquelineatus has facilitated 

 the comparison of growth, mortality, 

 and age structures for both these spe- 

 cies at the spatial scale of individual 

 reefs. The age structure of both species 

 among reefs within the Great Barrier 

 Reef Marine Park was based on counts 

 of annuli from sectioned otoliths. There 

 was significant variability in growth, 

 mortality, and age structures. Signifi- 

 cant differences in mean length, age, 

 and weight (independent of the sex of 

 the fish ) were observed for both species 

 among reefs. Peaks in abundance of 

 year classes were variable from reef to 

 reef. Comparisons of the von Berta- 

 lanffy growth curves indicated that the 

 pattern of growth in individuals of L. 

 quinquelineatus was significantly dif- 

 ferent among reefs, whereas the pat- 

 tern of growth in L. adetii was not. 

 However, there were no significant dif- 

 ferences in the mean length of the early 

 age classes of either species among 

 reefs. The mortality rates and hence 

 survivorship of both L. adetii and L. 

 quinquelineatus among reefs were 

 highly variable. It is hypothesized that 

 the varying age structures and mortal- 

 ity rates of both of these species at the 

 spatial scale of individual coral reefs 

 are determined by the nonequilibrial 

 balance of variable recruitment inter- 

 acting with density-independent mor- 

 tality. Hence the effect of good recruit- 

 ment years may persist in the age 

 structure of populations over time. 



Variability in the population structure 

 of Lutjanus adetii (Castelnau, 1 873) 

 and L quinquelineatus (Bloch, 1 790) 

 among reefs in the central Great 

 Barrier Reef, Australia* 



Stephen J. Newman 



Australian Institute of Marine Science. PMB No 3 

 Townsville. M C . Queensland, 48 1 0, Australia 



and 



Department of Marine Biology, James Cook University 



Townsville, 48 1 1 . Australia 



Present address Western Australia Marine Research Laboratories 



Fisheries Department of Western Australia, PO Box 20 

 North Beach, 6020, Western Australia 



David McB. Williams 



Australian Institute of Marine Science. PM B No 3 

 Townsville, M C , Queensland, 4810, Australia 



Garry R. Russ 



Department of Marine Biology, James Cook University 

 Townsville, 48 II, Australia 



Manuscript accepted 28 September, 1995. 

 Fishery Bulletin 94:313-329 1 19961. 



Spatial comparisons of life history 

 parameters of species of the family 

 Lutjanidae have been undertaken 

 only among broad geographic areas 

 (e.g. Nelson and Manooch, 1982). 

 Likewise, the majority of life history 

 studies of species of the Lutjanidae 

 have been based on widespread col- 

 lections of individuals from broad 

 geographic areas (e.g. Druzhinin 

 and Filatova, 1980; Loubens, 1980; 

 Liu and Yeh, 1991; Davis and West, 

 1992; Sanders et al. 1 ; Mees 2 ) and 

 not on an individual reef scale. On 

 the Great Barrier Reef in Austra- 

 lia, the fishing industry and other 

 resource users (e.g. tourists, rec- 

 reationalists, etc.) are managed 

 under a system which protects ma- 

 rine areas of which individual coral 

 reefs are the primary management 

 unit. 3 To date, a comparison of age 

 and growth parameters of lutjanids 



among individual reefs within a 

 single geographic area has not been 

 undertaken. 



Comparisons of the age structure 

 of lutjanids among a number of 



Contribution 757 of the Australian Insti- 

 tute of Marine Science, Townville, Queens- 

 land, Australia. 



1 Sanders, M. J.. 

 Hegasy. 1984. 



S. M. Kedidi, and M. R. 



Stock assessment for the 

 bigeye snapper (Lutjanus lineolatus) 

 caught by trawl in the Gulf of Suez. Food 

 and Agriculture Organization of the United 

 Nations Project for the Development of Fish- 

 eries in Areas of the Red Sea and Gulf of 

 Aden, FAO/UNDP RAB/83/023/08, 40 p. 



2 Mees, C. C. 1992. Seychelles demersal 

 fishery: an analysis of data relating to four 

 key demersal species. Technical Report 

 019, Seychelles FishingAuthority, Victoria, 

 Seychelles, 143 p. 



3 Great Barrier Reef Marine Park Autho- 

 rity. 1985. Zoning the central section. 

 Townsville, Australia. 



