52 



Fishery Bulletin 92(1), 1994 



WSSAWSSAW 



Tag No AUG 90 



 Fluorescent 

 | Translucent 

 ^ Opaque 



YY Winter § Summer 



^ Spnng /\ Autumn 



Figure 5 



Diagrammatic representation of otoliths of mark- 

 released-recaptured coral trout, P. leopardus, 

 treated with tetracycline showing relative positions 

 of the fluorescent bands, otolith margin, translucent 

 and opaque zones. Bars represent only the distal 

 part of the radius of the otolith section, measured 

 from the nucleus to the proximal surface of the 

 sagitta along the ventral margin of the sulcus 

 acousticus. The dates on the top of the bars indi- 

 cate time of tetracycline treatment and the dates on 

 the end of the bars indicate time of recapture. 



ment (Boehlert, 1985; Maceina and Betsill, 1987), 

 others have suggested that reading whole otoliths 

 underestimates true age and that this problem be- 

 comes worse with fish age (Boehlert, 1985; Hoyer et 

 al., 1985). This is mainly due to the fact that in 

 many species, sagittae growth is asymmetrical (Irie, 

 1960). Growth appears to be linear only up to a cer- 

 tain age or size, after which additions occur mainly 

 on the interior proximal surface, along the sulcus 

 region (Boehlert, 1985; Brothers, 1987; Beamish and 

 McFarlane, 1987). That seems to be the case for the 

 coral trout, as comparison of results of whole and 

 sectioned otoliths indicated that lateral views did 

 not reveal many of the annual growth zones in older 

 individuals. However, whole otoliths require much 

 less time for analysis than sectioned ones and seem 

 to provide more precise readings. Therefore, it is use- 

 ful to know the limit of reliability of whole readings 

 and to define the conditions appropriate for its use. 



Like the inshore coral trout Plectropomus 

 macula tits (Ferreira and Russ, 1992), the common 

 coral trout P. leopardus is a relatively long-lived, 

 slow-growing species. The results on growth and 



longevity obtained here differ somewhat from those 

 of previous studies. Goeden (1978), using the 

 Petersen method, identified age cohorts up to age 

 5+ for P. leopardus. However, the limitations of the 

 use of length-frequency data to estimate age of long- 

 lived fish are well known (Manooch, 1987; Ferreira 

 and Vooren, 1991). Mcpherson et al. (1988), using 

 counts of annuli in whole otoliths, were able to age 

 fish up to seven years old. Longevity was probably 

 underestimated in their study as counts were per- 

 formed only on whole otoliths. More recently. Brown 

 et al. (1992) 3 analyzed whole and sectioned otoliths 

 of coral trout from the same area as Mcpherson et 

 al. (1988) and were able to count up to 14 rings. 

 Loubens ( 1980) counted annuli from burnt and bro- 

 ken otoliths and estimated a maximum longevity for 



3 Brown, I. W., L. C. Squire, and L. Mikula. 1992. Effect of zon- 

 ing changes on the fish populations of unexploited reefs. Stage 

 1: pre-opening assessment. Draft interim report to the Great Bar- 

 rier Reef Marine Park Authority, Townsville, Australia, 27 p. 



SAWSSAWSS 



age = 2 



| Fluorescent 

 | Translucent 

 ^] Opaque 



yry Winter ^ Sumrr 



^ Spnng J\ Auturr 



Figure 6 



Diagrammatic representation of otoliths of young- 

 of-the year coral trout, P. leopardus, kept in captiv- 

 ity, showing relative positions of the fluorescent 

 bands, otolith margin, translucent, and opaque 

 zones. Bars represent the whole radius of the otolith 

 section, measured from the nucleus to the proximal 

 surface of the sagitta along the ventral margin of 

 the sulcus acousticus. The dates on the top of the 

 bars indicate time of tetracycline treatment or cap- 

 ture and the dates on the end of the bars indicate 

 time of death. 



