Stephenson and Hall: Timing of otolith ring formation in marine teleosts from northwestern Australia 



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Figure 2 



Index of completion at time<,(c„ t), for L. sp. 3 for growth-ring categories 2,3,4,5,6, 7,8, and 9-11 sampled 

 between the months 1 October 1993 {t=0} to 31 March 1995 it=\8). The sohd circles (•) represent those (c,, 

 t) most likely represented by c^ and lying closest to the function Fj and the solid triangles (A) are those 

 most likely represented by c,, and lying closest to the function Fj. The logistic function, P,, indicates the 

 probability that points (c,, t) are most likely represented by function F,. 



the marginal increment to the width of the previous band, 

 would be expected to be constant at the same time of year 

 for a particular species, regardless of the ring count. 

 Thus, during the maximization of the objective function 



n 



the rate of increase parameter b is assumed constant for 

 all ring counts for a species, but the other parameters (dj , 

 d^, R, and S) are estimated for each number of rings for 

 each species. 



Figure 2 shows the pattern of changes in the index 

 of completion for L. sp. 3 for otoliths with two to eleven 



growth rings from 1 October 1993 («=0) to 31 March 1995 

 (<=18). The data were pooled for the older age classes (nine 

 or more growth rings) because of the small numbers of old 

 fish in the samples. The points indicating the values of in- 

 dex of completion, c^, are represented with different symbols 

 according to whether they are most likely to be represented 

 by Cj (lying closest to the function Fj) or most likely to be 

 represented by c^ dj^ng closest to the lower line F^). The 

 function P, represents the probability of points being repre- 

 sented by line Fj. The time where P,=0.5 is the most likely 

 time of detection of the formation of a new growth ring. 



In the other three species, L. vitta, N. furcosus, and L. 

 sebae, the points representing index of completion, (c,, t) 

 and functions, F^, Fj, and P, are illustrated in Figures 3, 4, 



