Sex differences in growth of channeled whelks from buzzards bay, Massachusetts, during one or two years at liberty

Abstract

With the southern New England lobster fishery in distress, lobster fishers have focused more effort toward harvesting channeled whelks Busycotypus canaliculatus. Melongenid whelks generally grow slowly and mature late in life—characteristics that can make them vulnerable to overfishing as exploitation increases. However, minimal research has been conducted on the life history and growth rates of channeled whelks. We captured, marked, and released more than 8,700 whelks in Buzzards Bay, Massachusetts, during 2010 and 2011; 314 of the marked individuals were recovered after 1 or 2 years at liberty. Whelks that were recaptured in 2011 were measured and rereleased without determining sex, whereas whelks that were recovered in 2012 were dissected for sex determination. The unsexed animals were later classified by linear discriminant analysis using growth and morphometric variables. For both male and female whelks, growth increments decreased significantly with increasing size. Size-specific growth rates were significantly greater for females than for males, and females reached larger maximum sizes than males. Furthermore, rates of growth in shell length declined significantly with increasing time at liberty, whereas growth in shell width did not; this result may have been due to differential rates of shell damage versus repair. Increased fishing pressure on whelks—combined with their slow growth rates and inability to reproduce before being harvested—can easily constrain the long-term viability of the channeled whelk fishery in Massachusetts. Therefore, current whelk fishery management practices should be revised.