174 



Fishery Bulletin 103(1) 





B 







Figure 2 



Photomicrograph of transverse otolith sections of striped trumpeter (Latris 

 lineata) from (A) a 5-year-old male (515 mm, FL), and (B) a 15-year-old 

 female (724 mm, FL), using transmitted light. Scale bar = 1 mm. 



otolith matrix. Viewed under transmitted light the zones 

 showed as dark (opaque) and light (translucent) (Fig. 

 2). A robust linear relationship existed between otolith 

 mass and individual age (Table 2). 



The core area of each section consisted of an opaque 

 region. Immediately adjacent to this was a faint thin 

 translucent zone followed by the first broad opaque an- 

 nual increment. In some cases the transition from core 

 to the first expected increment could not be discerned 

 because of a continuation of the opaque region (the 

 expected thin translucent zone was too faint to see). 

 In such cases, increment measurements were required 

 to ensure that the annulus was not overlooked. Mean 

 increment radius (±SD) from the primordia to the first 

 annulus was 491 ±63 f<m (/!=122); and the deposition 

 of the second annulus occurred at a mean radius of 

 733 ±55 jim (n=122). The next four opaque and trans- 

 lucent zone pairs were relatively broad compared with 

 subsequent zones that consistently narrowed as they 

 approached the growing edge (Fig. 2). 



To validate the first increment we compared somatic 

 and otolith growth of wild individuals with that of indi- 

 viduals cultured under ambient conditions. Larval-rear- 

 ing trials of striped trumpeter juveniles have produced 

 mean lengths of 190 mm at 14 months and 261 mm at 

 24 months. The smallest individuals recorded from the 

 wild in our study were 190-220 mm and were captured 

 in January 1995. From the rearing trials it seemed 



reasonable to assume that the wild-caught individuals 

 of this size were between 1 and 2 years of age. If a 

 birth date of 1 October is assumed, these individuals 

 would have been about 16 months old and therefore 

 were spawned in 1993. Viewing the sectioned otoliths 

 of these small wild-caught individuals revealed only one 

 increment within the margin, analogous to the incre- 

 ment composition of cultured individuals at a similar 

 length. 



To test for comparable growth between wild and cul- 

 tured individuals as a means to facilitate confident vali- 

 dation of the first increment deposition, von Bertalanffy 

 growth curves were fitted to length-at-age data of both 

 wild (based on otoliths) and cultured individuals (of 

 known age) to age four. A likelihood ratio test indicated 

 that wild-caught individuals increased in length slightly 

 faster than those cultured to the same age (x~ = 5.3 df=6 

 P=0.51); however, this trend was not significant (F=4.4 

 df=23 P=0.04). 



Tracking length-frequency distributions (Fig. 3) from 

 1995 through 1997, from inshore gillnet samples, re- 

 vealed progression of a strong cohort. Based on its size 

 structure, the spawning year for this cohort was as- 

 sumed to be 1993. A second cohort was evident in the 

 last quarter of 1996, assumed to have been spawned in 

 1994. The progression of the cohort spawned in 1993 

 was clearly evident in the age structure of the samples 

 over the period 1995-2001, proving useful in the valida- 



