424 



Fishery Bulletin 93(2), 1995 



tion in condition, or the scatter about the length- 

 weight relationship, should be greatest at the devel- 

 opmental stage most vulnerable to food deprivation 

 (i.e. yolk absorption). However, the pattern of scat- 

 ter about the length-weight relationship shows little 

 evidence of a consistent pattern associated with that 

 stage of the early life history (Fig. 1). It is possible 

 that the majority of larvae undergo a degree of star- 

 vation associated with the period of yolk absorption 

 (e.g. Theilacker, 1986; Drolet et al., 1991; Marguiles, 

 1993), which would result in a uniform pattern in 

 the deviation from a general allometric length-weight 

 relationship. However, there is also evidence that 

 suggests that only a limited fraction of a larval fish 

 population suffers from substantial food deprivation 

 (O'Connell, 1981; Canino et al., 1991; McGurk et al., 

 1992). The consistent nonlinear pattern in the length- 

 weight relationship among a suite of species with 

 different life histories, which could result in substan- 

 tial differences in vulnerability to environmental fac- 

 tors (Miller et al., 1988; Pepin, 1991), suggests that 

 developmental processes in the early ontogeny of 

 fishes are important factors governing the form of 

 this relationship. The degree of curvature in the loga- 

 rithmic relationship (c": Eq. 4) is not significantly 

 correlated with size at hatch (r=0.45, P>0.05, n=14; 

 Fig. 2), which may be a measure of vulnerability to 



2 3 

 Length at hatch (mm) 



Figure 2 



The value of c" in relation to the size at hatch for 

 14 of the 16 species used in this study. The value 

 of c" provides a measure of the curvature in the 

 logarithmic length-weight relationship. Data on 

 size at hatch were obtained from general refer- 

 ence sources detailing fish life history character- 

 istics (Fahay, 1983; Scott and Scott, 1988). Data 

 were unavailable for Aspidophoroides mono- 

 pterygius and Lumpenus sp. 



starvation (Miller et al., 1988; but see Pepin, 1991). 

 In fact, the positive trend is opposite that expected 

 on the premise that species that produce small lar- 

 vae should be more vulnerable to starvation. 



Whether physiological processes rather than de- 

 velopmental constraints result in the nonlinear loga- 

 rithmic length-weight relationship described in this 

 study is uncertain. There are a number of approaches 

 that may be indicative of the physiological condition 

 of larval fish (e.g. Theilacker, 1986; Clemmensen, 

 1988; Fraser, 1989), but they may never the less be 

 highly correlated with morphometric indices of con- 

 dition (e.g. Theilacker, 1978; Harris et al., 1986; 

 Setzler-Hamilton et al., 1987). Furthermore, there 

 may remain considerable uncertainty about the in- 

 terpretation of variation in such condition indices of 

 larval fish (e.g. Bergeron and Boulhic, 1994). To in- 

 terpret variation in length-weight relationships cor- 

 rectly, it is essential that thorough studies be con- 

 ducted to establish the proper functional form and 

 how this may vary under different feeding conditions. 



Acknowledgments 



I thank D. Beales and T H. Shears for their techni- 

 cal assistance. Comments by E. Dalley, T Miller, W. 

 Warren, and two anonymous reviewers were helpful 

 in the development of this study. 



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