Edible Crabs “Go West”: Migrations and Incubation Cycle of Cancer pagurus Revealed by Electronic Tags

Abstract

Crustaceans are key components of marine ecosystems which, like other exploited marine taxa, show seasonable patterns of distribution and activity, with consequences for their availability to capture by targeted fisheries. Despite concerns over the sustainability of crab fisheries worldwide, difficulties in observing crabs’ behaviour over their annual cycles, and the timings and durations of reproduction, remain poorly understood. From the release of 128 mature female edible crabs tagged with electronic data storage tags (DSTs), we demonstrate predominantly westward migration in the English Channel. Eastern Channel crabs migrated further than western Channel crabs, while crabs released outside the Channel showed little or no migration. Individual migrations were punctuated by a 7-month hiatus, when crabs remained stationary, coincident with the main period of crab spawning and egg incubation. Incubation commenced earlier in the west, from late October onwards, and brooding locations, determined using tidal geolocation, occurred throughout the species range. With an overall return rate of 34%, our results demonstrate that previous reluctance to tag crabs with relatively high-cost DSTs for fear of loss following moulting is unfounded, and that DSTs can generate precise information with regards life-history metrics that would be unachievable using other conventional means.

Some observations of Cancer pagurus Linnaeus, 1758 (Decapoda, Brachyura) in deep water

“…Assuming they where predominantly females, these individuals could be migrating to suitable spawning grounds. Such migrations have been documented in several studies (Williamson, 1904;Meek, 1914;Bennett & Brown, 1983;Le Foll, 1986;Ungfors et al, 2007;Hunter et al, 2013). Tagging experiments of C. pagurus conducted by the Institute of Marine Science in the 1960's at Kjeldosen, just 40 km south of the location of our study, 8 demonstrated a primarily southward directional movement of mature female crabs in the area (Gundersen, 1977(Gundersen, , 1979.…”

Thermal behaviour and the prospect spread of an invasive benthic top predator onto the Euro‐Arctic shelves

“…Laboratory tests should be supplemented by field campaigns using biotelemetry and DSTs to document realised habitats by free-ranging animals (e.g. Hunter et al, 2013).…”

Ecology of the brown crab (Cancer pagurus) : and production potential for passive fisheries in Dutch offshore wind farms

“…In the North Sea, berried females migrate offshore to release larvae and then move back inshore to feed (Nichols et al, 1982). The time at which the crabs cease most activity is used as the onset of brooding and occurs from mid-November through to early January (Hunter et al, 2013). In the North Sea, egg development has been observed to cease in late November, at which point the eggs entered a period of diapause (Naylor et al, 1997).…”

“…Spawning and larval development in C. pagurus are both dependent upon temperature and neither are triggered below 7 or 8ᵒC (Lindley, 1987). The pelagic larval stage lasts for approximately 3 months (Eaton et al, 2003, Hunter et al, 2013, Weiss et al, 2009 or at least for 60 days at temperatures of 15-20 ᵒC (Nichols et al, 1982). Larvae are detected in coastal waters from May until September.…”

“…From the release of mature female edible crabs tagged with electronic data storage tags (DSTs) from 4 locations in UK waters, a predominantly westward migration in the English Channel was demonstrated (Hunter et al, 2013). Eastern Channel crabs migrated further than western Channel crabs, while crabs released outside the Channel showed little or no migration.…”