Tracey and Lyle: Age validation, growth modeling, and mortality estimates for Latns lineata 



179 



for striped trumpeter is largely restricted to depths of 

 greater than 50 m, and despite considerable hook-fish- 

 ing effort at shallower depths targeting other demersal 

 reef species, notably the wrasses Notolabrus fucicola 

 and N. tetricus, minimal catches of striped trumpeter 

 are taken and those that are caught tend to be small 

 in size (Lyle 2 ). Rather, size structuring by depth is 

 believed to reflect the movement of striped trumpeter 

 offshore into deeper water as they grow and mature. 



Seasonal growth was dramatic in young striped trum- 

 peter (Fig. 5 1. This phenomenon is common in temper- 

 ate species (Haddon, 2001; Jordan, 2001; McGarvey 

 and Fowler, 2002), and has been linked to fluctuations 

 in environmental factors, such as water temperature 

 and oceanographic conditions, as well as biotic factors, 

 such as seasonality in primary productivity (Harris et 

 al., 1991; Jordan, 2001). Our study supports a correla- 

 tion between water temperature and seasonal growth 

 (Fig. 6); maximum growth was observed to take place 

 consistently over a three-year period, approximately one 

 month after the peak sea-surface temperatures. 



Knowledge of growth and growth variability is es- 

 sential to the understanding of a stock's population 

 dynamics. To achieve an accurate assessment of these 

 characteristics, several issues need to be addressed. 

 Foremost, is a rigorous approach to the validation and 

 precision testing of age estimates (Campana, 2001). In 

 this study, a combination of age validation protocols 

 outlined by Fowler and Doherty (1992) and Campana 

 (2001) were subscribed to: 1) otoliths must display an 

 internal structure of increments, (Fig. 3); 2) otoliths 

 must grow throughout the lives of fish at a perceptible 

 rate, which was confirmed by the otolith weight-at-age 



regression (Table 2); 3) the age of first increment forma- 

 tion must be determined; and 4) increment periodicity 

 across the entire age range of interest must be veri- 



