Peemoeller and Stevens: Age, size, and sexual maturity of Busycotypus canaliculatus in Buzzards Bay, Massachusetts 
277 
whelk may copulate with multiple males to increase 
fitness or because males do not excrete enough sperma- 
tozoa to fertilize an entire female brood. If male chan- 
neled whelk copulate with multiple females, then it is 
possible that males do not use all their spermatozoa on 
one female; this “sperm conservation” strategy of sperm 
competition is common among snow crab ( Cliionoece - 
tes opilio) when the ratio of females to males is high 
(Rondeau and Sainte-Marie, 2001; Sainte-Marie et ah, 
2002 ). 
Female maturity was determined mainly by the 
presence of VOs. We assumed a gonad with VOs that 
covered more than half the cross section could be capa- 
ble of reproduction, although fecundity could be lower 
in a female with such a gonad than in a fully 7 matured 
female. A LD-stage female contained VOs in less than 
half the cross section and most likely would not repro- 
duce until 1-2 years later. 
Staging of gonad development for male channeled 
whelk was more consistent than staging for females 
because there were a greater proportion of males at 
smaller SLs. Males accumulated at smaller size class- 
es (110-160 mm SL) because of a slower growth rate 
and a lower maximum size than the growth and size 
of females. In contrast, females grew rapidly past the 
shorter SL of males. Male and female channeled whelk 
classified as stage LD may not spawn until the follow- 
ing year because channeled whelk typically grow slow- 
ly and would have to overcome a large deficit in gonad- 
al development in just a few months to be considered 
mature. This large deficit in gonadal development is 
especially evident in females that probably invest more 
energy into reproduction than males. Females in stage 
R were not present at sizes >190 mm SL (Fig. 5A). 
It is not known if larger females (>190 mm SL) 
spawn every year, every other year, or multiple times 
per year. Bruce et al. 3 suggested that female knobbed 
whelk with gravid ovaries (comparable to a mature 
female) may stay in this state year-round and conse- 
quently, not spawn annually. In our study, smaller fe- 
male channeled whelk (<190 mm SL) classified in the 
R stage could have spawned earlier in the year or in 
the previous year. Large females also may not com- 
pletely deplete their ovaries when they spawn, as we 
observed in some smaller females, and, therefore, may 
have a shortened generation time. Large females also 
may have been ready to spawn after we sampled them 
in July and August. This circumstance may have been 
the reason why few females were classified as stage 
R. Reduced fecundity at older age or larger size, al- 
though unlikely, also could be a reason that no females 
in stage R were found at sizes >190 mm SL. 
Conclusions 
On the basis of the morphological and histological 
evidence collected in our study, we suggest that most 
channeled whelk do not change sex, although chan- 
neled whelk under some conditions may exhibit pro- 
tandric-like symptoms (as did the unusually large male 
in our study). We did not find any channeled whelk 
with both a penis and nidamental gland or both ovary 
and testes. All female whelk contained a nidamental 
gland and ovary. All male whelk contained a penis and 
testes, except for the large male that contained a pe- 
nis and an inactive gonad. Penis length increased with 
SL in males, indicating that channeled whelk are not 
protandric. Females reached a larger maximum size 
and age and had a quicker growth rate than males. 
With the current minimum size limit, this fishery cap- 
tures small females before they reach SM50 and males 
just after SM50. To prevent the occurrence of overfish- 
ing, fishery managers need to consider the sex-specific 
growth rates, SM50, and fecundity of channeled whelk. 
More information on population estimates are needed 
to understand if the channeled whelk population in 
Massachusetts is being overfished. The results from 
this study provide information necessary for managers 
to work with lawmakers to enact appropriate legisla- 
tion on size limits to secure the longevity of the Mas- 
sachusetts whelk fishery and to allow potential mature 
females to spawn. 
Acknowledgments 
This project was supported by the Saltonstall-Kennedy 
(S-K) Grant Program (grant no. NA10NMF4270007) 
and the Living Marine Resources Cooperative Science 
Center for salary of B. Stevens. We thank R. Bemis, 
S. Lawrentz, and K. Amagada for their help capturing 
and measuring channeled whelk and C. Conroy and S. 
Lawrentz for their contributions in aging opercula. S. 
Lawrentz also assisted greatly with histology. Special 
thanks go to the University of Massachusetts Dart- 
mouth for allowing us to use their Sea Water Labora- 
tory and to fisherman J. Drake for his assistance and 
experience in capturing channeled whelk. 
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