NOTE Beckmann et at: Reproductive biology, growth, and natural mortality of Sebastes emphaeus 
355 
Although egg size was variable, the ma- 
jority of the eggs within an individual fe- 
male were about the same size and at the 
same developmental stage. The time span 
between the capture of the first fertilized 
female and the first spent female yields a 
rough estimate of 30 days for the gesta- 
tion period. 
Discussion 
Puget Sound rockfish show high fecundity 
per gram, early age at maturation, small 
body size, and a relatively short life ex- 
pectancy compared with other rockfish of 
the genus. No other rockfish studied to 
date has a higher fecundity per gram at 
L 05 (Haldorson and Love, 1991). A high 
natural mortality would be expected to ac- 
company these life history characteristics, 
and the estimated M of 0.44 is high compared 
with that of other rockfish . 
Puget Sound rockfish have a GSI (0.10) 
close to that of other early maturing rock- 
fish (e.g. shortbelly rockfish, GSI=0.07, 
M=0.26, maturation age=2 years; Gunderson, 
1997). However, a comparison of the catch- 
curve estimate of M with empirically derived 
estimates suggests some possibility that the 
catch curve is based on an unrepresentative 
sample and has been overestimated. The 
maximum age observed in our study (13 
years) corresponds to an M of 0.32 with 
Hoenig’s (1983) empirical estimation tech- 
nique, whereas the GSI (0.10) gives an esti- 
mate of M = 0.18 with Gunderson’s (1997) 
estimator. 
A constant recruitment is assumed if the 
catch curve is used, yet the data in Figure 2 
suggest that the 1988 year class (age 6 in 
1994) appears to have recruited at significantly lower 
levels than the others. Our catch-curve estimate of 
M should probably be regarded as provisional, and 
additional collections of age-composition data or tag- 
ging studies should be undertaken to validate it. 
The fecundity of 3,300-57,800 eggs observed for 
Puget Sound rockfish is in the range of fecundities 
of similar-size rockfish. Shortbelly rockfish ( 18-31 cm 
TL) has a fecundity from 7,000 to 50,000 (Hart 1973). 
Our fecundity estimates for Puget Sound rockfish are 
comparable to those obtained by Moulton (1975). 
The estimated gestation period for Puget Sound 
rockfish is similar to the 29-day gestation period re- 
ported for yellowtail rockfish (S. flavidus), a species 
which has been shown to be lecithotrophic, provid- 
ing only a negligible amount of maternal energy dur- 
ing gestation (Hopkins et al. 1995). The high fecun- 
dity per gram and relatively brief gestation period 
suggest that parental care is limited in comparison 
to other rockfish. 
Acknowledgments 
This project was supported by stipends provided to 
the senior author by University of Washington’s Fri- 
day Harbor Laboratories. The paper is based in part 
on a diploma thesis submitted to Bochum Univer- 
