274 
Fishery Bulletin 111(3) 
Maturity 
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 
Female shell length (mm) 
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 
Male shell length (mm) 
6 7 8 9 10 11 12 
Female age (years) 
13 14 
7 8 9 10 11 
Male age (years) 
Figure 5 
Proportions of channeled whelk (Busycotypus canaliculatus ) 
classified at different stages of gonad development in our study 
of this species in Buzzards Bay, Massachusetts, in August 2010 
and July 2011, shown by varying shell lengths (for (A] females 
and [B] males) and by varying ages (for [C] females and [D] 
males). The maturity stages used in our study and presented 
here are immature (I), early developing (ED), late developing 
(LD), mature (M), and recovering (R). For gonad analysis, we 
used 115 females and 112 males. 
whelk also reach 50% maturity before females do, at 
an age of 3 years versus 4 years (Heude-Bertherlin et 
al., 2011). Sustainability of the channeled whelk popu- 
lation is of concern for this fishery because effort and 
incentives are biased toward catch of larger 
whelk, which are almost entirely female. 
The highest growth rate for males and fe- 
males occurred in the first few years of life. 
Growth rate progressively decreased as chan- 
neled whelk aged (Fig. 4D). There was a wide 
range of SL at each age for this species (Fig. 
4, A and B). This variation also was evident 
in knobbed whelk in Delaware Bay (Bruce 
et al. 3 ) and Buccinum isaotakii (llano et al., 
2004), both of which were aged by examining 
opercula. 
Harding (2011) reported an average size of 
3.8 mm SL at hatching for channeled whelk 
cultured from hatch in the laboratory. At 171 
days after hatching, the average SL was 48.4 
mm; a linear growth model for age-at-lengfh 
resulted in a growth rate of 0.21 mm/day 
(Harding, 2011). In our study of wild channeled 
whelk, the von Bertalanffy growth model pre- 
dicted that an average SL of 48.4 mm would 
not be achieved until the age of 3 years, indi- 
cating a much slower growth rate for whelks 
in our study than the one found by Harding 
(2011). Although we did not capture channeled 
whelk younger than 4 years old, the von Berta- 
lanffy growth model predicted that 3-year-old 
males and females would be only 41.3 mm SL 
and 43.5 mm SL, respectively (Fig. 4C; Table 
5). The discrepancy in growth rates between 
channeled whelk in our study and the whelk 
in the Harding (2011) study possibly reflects 
individual variation, although food availability, 
predator abundance, and habitat may affect 
shell growth as well. 
Channeled whelk held in laboratory tanks 
may be more protected from shell damage than 
channeled whelk in their natural environment. 
Channeled whelk have thin shells and can eas- 
ily chip their shells (or siphons) while they 
feed or move around on the ocean floor. In ad- 
dition, channeled whelk in a laboratory may 
be exposed to more food than they would be 
if they were in the ocean. Bourdeau (2010) re- 
ported that the frilled dogwinkle ( Nucella lam- 
ellosa), a marine snail, had thicker shells and 
reduced shell growth when in the presence of 
red rock crab ( Cancer productus). Food-limited 
snails did not significantly differ from snails 
exposed to crab, indicating food consumption, 
instead of a physiological response from pre- 
dation, ultimately affected growth (Bourdeau, 
2010). These factors that affect SL growth may 
partially explain the quicker growth rates in 
Harding (2011) compared with the rates found 
in our study. 
Although knobbed whelk are in a different genus 
and have thicker shells than channeled whelk (Mag- 
alhaes, 1948), both whelks share similar growth pat- 
