Carcinus maenas (Linnaeus, 1758) in two New Hampshire estuaries. Part 2: assessment of average intermolt period

Abstract

Green crabs, Carcinus maenas (Linnaeus, 1758), were sampled from two New Hampshire estuaries, Hampton-Seabrook Estuary (HSE) and Great Bay Estuary (GBE), over the course of a one year field season (Nov. 2009-Oct. 2010) in order to determine the timing of molt cycles and egg-bearing periods expressed by both populations. Average timing of population molt was assessed by length of average intermolt period, which was estimated based on the color of the ventral side of the crab using the Munsell paint color charts, 40 hue edn. Crabs in both estuaries appeared to be on a simultaneous molting schedule centered around the month of June. Females experienced a single population-wide molt beginning in June and completed by November. Males experienced two population-wide molts starting in April and November that were both completed by June. Regressions between color variables and crab size or distance from the mouth of the estuary ( α = 0 . 05 ) revealed no statistically significant correlations. Photoperiod (day-length) appeared to be the most important environmental cue for green crab molting and reproduction. Berried females were captured from January until November, with peak catch occurring in May. These results suggest that green crabs in both estuaries experience a single summer breeding season between June and November, which coincides with a period of relatively lower foraging activity as compared to the spring and fall months.