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Fishery Bulletin 91(1). 1993 



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B 



Figure 5 



(A) Accessory growth centers on sagitta of metamorphosing 

 winter flounder Pleuronectes amerieanus. (B) Symmetrical 

 otolith from 73 d-old winter flounder that had not yet under- 

 gone metamorphosis, showing continuing lack of accessory 

 growth centers. 



est dimension) and fish length was nonlinear for pre- 

 metamorphic larvae raised under laboratory conditions 

 (Fig. 6). The best fit equation was exponential, 



Y = 7.8e 03 * (r 2 =0.87), 



where x is standard length and Y is otolith length. 

 Because larger larvae had an average shrinkage of 

 8.69? as compared with 4.2% for smaller larvae, the 



parameter estimates in the above equation may not be 

 bias-free. By the end of the first year, however, the 

 relationship was linear (Fig. 7). Covariate analysis in- 

 dicated that the regression lines for laboratory-reared 

 and wild YOY winter flounders were not significantly 

 different, so data pairs were pooled. The resulting re- 

 gression line for YOY flounders (about 3 mo or older) 

 using the same variables as above was 



Y = 0.10+0.29x (r 2 =0.95). 



Both linear and allometric relationships between oto- 

 lith size and larval fish length have been reported in 

 the literature (Taubert & Coble 1977, Brothers & 

 McFarland 1981, Methot 1981, Radtke & Dean 1981). 

 Although this relationship has been reported for starry 

 flounder (Campana 1984c), it has not been previously 

 reported for larval winter flounder. It is not surpris- 

 ing, however, that otolith growth exceeds growth in 

 body length. Addition to body depth is enhanced as the 

 body form alters towards the adult shape. This feature 

 may compensate for the decline in growth in length at 

 this time (Pearcy 1962, Laurence 1975). Investigating 

 the relationships between length, depth, otolith dimen- 

 sion, otolith mass, and fish mass may in future studies 

 elucidate the relationship between larval flounder so- 

 matic growth and otolith growth. 



Wild vs. laboratory-reared fish Otoliths from wild 

 juvenile samples showed the same diameter/fish length 

 relationship as otoliths from our laboratory-reared fish. 

 Otoliths from wild fish exhibited a more regular and 

 somewhat sharper depositional pattern of increments. 

 Therefore, these were used more frequently for SEM 

 analysis. The superior clarity and regularity of otolith 

 incremental patterns from wild fish over laboratory- 

 reared fish have been discussed in the literature 

 (Blaxter 1975, Uchiyama & Struhsaker 1981, Radtke 

 & Dean 1982, Radtke & Scherer 1982) and is discussed 

 in detail by Campana & Neilson (1985). 



Early larvae: Hatch to 40 d Under a temperature 

 regime of 5-7°C, larvae hatched 14-18 d after being 

 spawned. Hatching was accompanied by intermittent 

 writhing and vibrating motions of the embryos. Hatch- 

 lings sank to the tray bottom when not in motion. 



Swimming began immediately after hatching. Lar- 

 vae swam with rapid lateral tail-whips and could con- 

 trol direction. All swam away from disturbances caused 

 by a pipette tip. Swimming became stronger and more 

 sustained over the first 10 d posthatch. On the third 

 day after hatching, a series of brief (l-8s) upward 

 swims, followed by a 20 s to lmin passive period re- 

 sulting in head-down sinkings, were first noted. This 

 intermittent swimming behavior may be adaptive in 



