270 
Fishery Bulletin 111(3) 
knowledge, there is no other published infor- 
mation about temperatures during the spawn- 
ing season of channeled whelk, but our data do 
not allow inferences to be made about temper- 
ature effects on spawning because we sampled 
only during 1 month in each of 2 years and 
did not sample throughout the entire spawn- 
ing season. 
Histological examination showed that male 
channeled whelk classified as stage I of gonad 
development had small circular tubules that 
contained no spermatozoa and few spermato- 
gonia, spermatocytes, and spermatids (Fig. 
3A). The cross section contained connective tis- 
sue and empty space. Males assigned to stage 
ED had <25% of tubules with spermatozoa 
(Fig. 3B). There were few spermatogonia, sper- 
matocytes, and spermatids present, and some 
empty space was still visible in the cross sec- 
tion. Males in stage LD had 25-50% of tubules 
with spermatozoa; more spermatogonia, sper- 
matocytes, and spermatids were present and 
tubules were more elongate than they were in 
males in earlier stages (Fig. 30. Males classi- 
fied as stage M had >50% of tubules with sper- 
matozoa; tubules were elongate and contained 
many spermatogonia, spermatocytes, and sper- 
matids (Fig. 3D). 
Female channeled whelk classified in de- 
velopment stage I had gonads with minimal 
previtellogenic oocytes (PVOs), no nuclei pres- 
ent, and empty space in the cross section; con- 
nective tissue was more prevalent than it was 
in later stages, as seen in males classified as 
stage I (Fig. 3E). Females in stage ED had 
more developed PVOs that contained round 
nuclei and visible nucleoli than did females in 
the earlier stage (Fig. 3F). Females identified 
as LD generally had <50% of the cross section 
with VOs (Fig. 3G). The VOs were larger and 
more elongate than the PVOs, although some 
PVOs still were present in the gonad. Females 
classified as M had >50% of the cross section 
with VOs, which were elongate and full of 
large yolk granules (Fig. 3H). Females in stage 
R had some elongate oocytes and some small 
oocytes that were empty or had minimal PVOs 
or VOs (Fig. 3D. 
Morphological relationships 
The ratio of females to males in our sample 
of dissected channeled whelk was near unity 
at the size range of 90-110 mm SL (Table 1) 
and ages of 4—6 years (Table 2). The smallest 
size intervals (70-90 mm SL) were male domi- 
nated, although not many individuals in that 
range were caught (Table 1). Male whelk had 
a lower maximum size and age than female 
Figure 3 
Histological photographs of the stages of gonad development 
for (A-D) male and (E-I) female channeled whelk ( Busycotypus 
canaliculatus ) used in our study to classify whelk collected in 
Buzzards Bay, Massachusetts, in July 2010 and August 2011. Ob- 
served male gonad stages: (A) immature; (B) early developing; 
(C) late developing; and (D) mature, with arrow pointing to sper- 
matozoa. Observed female gonad stages: (E) immature; (F) early 
developing, with arrow pointing to a nucleus (also containing a 
nucleolus) from a previtellogenic oocyte; (G) late developing; (H) 
mature female with vitellogenic oocytes full of large yolk gran- 
ules; and (I) recovering. Scale bars are set at 100 pm for panels 
A-F and 200 pm for panels G-I. 
