Abundance and spatial distribution of brown crab (Cancer pagurus) from fishery-independent dredge and trawl surveys in the North Sea

Abstract

Brown crab (Cancer pagurus) is a widely distributed crustacean that occurs around the British coastline supporting important commercial fisheries. The habitat preferences of brown crab around Scotland are poorly documented and for the purposes of stock assessment, the species is considered data-poor. Based on an analysis of dredge and trawl surveys taking place in the North Sea (2008–2018), we describe the spatial distribution of brown crab and for the first time, develop abundance and recruitment indices for the species. We make use of geostatistical methods and apply generalized additive models to model catch rates in relation to a number of explanatory variables (depth, distance to the coast, sediment type and year). The dredge and trawl abundance indices were correlated showing a similar trend of increasing catch rates in the early years of the time series up to 2016 and a subsequent reduction. The recruitment index showed a gradual increase in captured juvenile crabs up to 2014 followed by a steep decrease with 2018 being the lowest value estimated. The derivation of robust indicators of stock abundance will contribute to the stock assessment of this species and enable the provision of improved fisheries management advice for brown crab around Scotland.

Quantifying use of kelp forest habitat by commercially important crustaceans in the United Kingdom

“…Moreover, as kelp-associated assemblages of macroalgae and invertebrates are generally rich and abundant at these sites (Teagle et al ., 2017; Bué et al ., 2020; Smale et al ., 2020 a ; King et al ., 2021), and the supply of detrital kelp and associated organisms is substantial (Smale et al ., 2021), food availability for crustacean populations is likely to be high. Our study aligns with previous studies conducted in other regions (Öndes et al ., 2017; Mesquita et al ., 2020), which also found a prevalence of smaller juvenile crabs in shallow coastal habitats, and suggests that the complex habitat formed by kelps provides shelter and resources.…”

“…The size distributions of the individuals sampled suggested these crustaceans were predominantly juveniles and sub-adults and therefore likely utilizing kelp forests as nursery grounds, perhaps before migrating offshore or to other habitats at a more mature life stage (Bennett & Brown, 2009; Mesquita et al ., 2020). Interestingly, the median carapace width of C. pagurus would suggest that the majority of individuals within these populations are not sexually mature (Haig et al ., 2016), whereas the median carapace width of N. puber is indicative of a relatively older and more mature population (González-Gurriarán & Freire, 1994).…”

Bayesian occupancy modelling of benthic Crustacea and the recovery of the European spiny lobster, Palinurus elephas

“…There are, of course, numerous good reasons why patterns in landings may not match those in records from divers. Shellfish landed may have been caught in other areas, landings or effort may be mis-reported, shellfish landed may have come from depths not accessible to divers, standardization of catch-rates can be difficult (Mesquita et al ., 2020) and regulations in the EU Common Fisheries Policy governing landings also make it difficult to determine trends in underlying stocks (Thurstan et al ., 2010; Catchpole et al ., 2017).…”

“…There is an increasing demand from fisheries managers and stakeholders to obtain information on stock status of exploited marine species (Mesquita et al ., 2020). Organizations with a vested interest in the crawfish fishery and its management met to discuss the situation at a workshop in April 2019.…”

“…Two other Crustacea of economic value, similar size and with overlapping distributions are Cancer pagurus (edible or brown crab) and Homarus gammarus (European lobster). In England, stocks of these species are reported on biennially and, although there may be concerns about the fisheries and their management (Mesquita et al, 2020), these have not shown the same catastrophic declines (CEFAS, 2020a(CEFAS, , 2020b. On a much more positive note, however, there is good anecdotal evidence that crawfish have been undergoing a resurgence since 2014 (Bolton, 2018a;Hiscock, 2019).…”