A quantitative analysis of fishing impacts on shelf‐sea benthos

Abstract

Summary1. The eects of towed bottom-®shing gear on benthic communities is the subject of heated debate, but the generality of trawl eects with respect to gear and habitat types is poorly understood. To address this de®ciency we undertook a meta-analysis of 39 published ®shing impact studies. 2. Our analysis shows that inter-tidal dredging and scallop dredging have the greatest initial eects on benthic biota, while trawling has less eect. Fauna in stable gravel, mud and biogenic habitats are more adversely aected than those in less consolidated coarse sediments. 3. Recovery rate appears most rapid in these less physically stable habitats, which are generally inhabited by more opportunistic species. However, de®ned areas that are ®shed in excess of three times per year (as occurs in parts of the North Sea and Georges Bank) are likely to be maintained in a permanently altered state. 4. We conclude that intuition about how ®shing ought to aect benthic communities is generally supported, but that there are substantial gaps in the available data, which urgently need to be ®lled. In particular, data on impacts and recovery of epifaunal structure-forming benthic communities are badly needed.

Mediation of macronutrients and carbon by post-disturbance shelf sea sediment communities

“…As per capita effects on sediment-water nutrient fluxes are disproportionately greater for larger polychaetes (Bosch et al 2015), there is less capacity for most of the resident infauna to influence biogeochemical processes. A similar effect is also true for non-cohesive sediments which, due to their inherent mobility, host a high proportion of opportunistic species (Collie et al 2000), but these communities also harbour large deep-burrowing fauna (e.g. decapod crustaceans, spatangoid urchins) that can form extensive galleries (Lohrer et al 2004) and disproportionately augment oxygen uptake (Volkenborn et al 2012) and the flux of dissolved substances across the water-sediment interface (Osinga et al 1995;Bird et al 1999;D'Andrea and DeWitt 2009).…”

“…Alterations in community biomass associated with fishing pressure, as observed here, are known to decrease the strength of interspecific interactions and minimise the effects of biodiversity on ecosystem processes (Caliman et al 2012), yet the lowest species abundances documented here were not in communities that had experienced the greatest frequency of fishing. This apparently anomalous finding can be explained, however, because the areas under study likely represent a permanently disrupted state (Collie et al 2000;Kaiser et al 2000;Pommer et al 2016), with recovery times measured in years (Kaiser et al 2006). In such environments there tends to be a predominance of small species with opportunistic reproductive modes that are able to respond quickly post-disturbance and can reach high abundances, but these species are more likely to have a low bioturbation potential (Solan et al 2004a;Queirós et al 2013).…”

Characterizing the marine Natura 2000 network for the Atlantic region

“…Clearly real protected area networks are likely to lie somewhere between these extremes. Extensive habitat modification may increase the relative importance of protected areas if this reduces suitable habitat outside a network (it is possible that trawling may produce such widespread modification; Collie et al, 2000). Interspecific variation in the relative importance of protected and non-protected areas as sources of recruits has conservation planning implications as it affects the degree of consideration that should be given to unmanaged (or less intensively managed) areas of habitat.…”

Clam dredging effects and subsequent recovery of benthic communities at different depth ranges

“…Dolmer and Frandsen, 2002;Carbines et al, 2004). According to the studies undertaken in subtidal grounds the magnitude of the impacts caused by such fisheries depends on several factors, namely gear type, habitat, depth, benthic communities and scale of disturbance (Collie et al, 2000). Therefore, the magnitude of the impacts can range from no detrimental post-fishing effects (e.g.…”