Fishery Bulletin 93(1), 1995 



Why ages derived from whole and sectioned 

 otoliths were significantly different remains unclear. 

 The differences in ring counts increased with the size 

 of the fish, and the slope of the regression (whole vs. 

 sectioned ring count) was steepest for the fastest- 

 growing species, L. erythropterus. The otoliths were 

 large (up to 30 mm long, and weighing 3 g), so the 

 daily rings during periods of reduced or variable 

 growth of younger fish were still relatively widely 

 spaced. Thus, what would appear as a diffuse, single 

 hyaline zone in a whole otolith examined against 

 reflected light may have appeared in section as a 

 group of hyaline and opaque zones. These problems 



in otolith interpretation were most marked in L. 

 erythropterus and led to the greatest discrepancy in 

 ring counts. 



Studies of the age and growth of Lutjanus mala- 

 baricus from northern Australia and the South China 

 Sea used ring counts in vertebrae (Lai and Liu, 1974, 

 1979; Edwards, 1985), sectioned otoliths (Chen et al., 

 1984), and whole otoliths (McPherson and Squire, 

 1992). Their estimates were similar to the estimates 

 we obtained from whole-otolith ageing, although L. 

 malabaricus from the Great Barrier Reef appear to 

 grow much faster and live at least one year less than 

 those found in other areas (McPherson and Squire, 

 1992). However, the previous studies and our study 

 provide different estimates of the von Bertalanffy 

 growth parameters L x and K (Table 5). These differ- 

 ences may have major impacts on age-structured fish- 

 ery models (e.g. yield per recruit) that use these pa- 

 rameters to estimate optimal yield. 



Lutjanus erythropterus and L. sebae from the Gulf 

 of Carpentaria grew at similar rates to those reported 

 from other parts of northern Australia (Ju et al., 1988; 

 McPherson and Squire, 1992) and elsewhere within 

 their range (Druzhinin and Filatova 1980; Yeh et al., 

 1986; McPherson and Squire, 1992). However, the 

 growth of L. sebae in the Gulf of Carpentaria did not 

 decline as they approached the maximum age ob- 

 served. This may have been caused by an error in 

 the ring count in otoliths of older fish or because the 

 older age classes were not caught in the trawls. The 

 maximum size of L. sebae in Australian waters has 

 been reported to be between 1.0 and 1.4 m (Allen, 



