Benthic community response to a scallop dredging closure within a dynamic seabed habitat

Abstract

Fishing with bottom towed gear is widely considered an invasive form of fishing in terms of its impacts upon seabed habitats and fauna. Fishery closures or marine protected areas provide baseline conditions against which to assess the response to the removal of fishing disturbance and thus shed light on their use as fisheries management tools. We conducted repeat underwater camera surveys inside a recently established area that is permanently closed to scallop fishing and a seasonally fished area in Cardigan Bay, UK, to test for differences in scallop abundance and epibenthic community structure and to examine recovery processes over a 23 mo study period. Changes in scallop density and epifaunal diversity and community composition were primarily driven by seasonal fluctuations; no differences were found between the permanently closed area and the seasonally fished area. Temporal changes in epibenthic community inside the permanently closed area were not related to recovery processes associated with the cessation of scallop dredging. Sediment composition and bedforms shifted between surveys, suggesting that this community is exposed to a dynamic environment. It is likely that scallop dredging at the present levels of fishing may be insufficient to induce changes large enough to be detected in the presence of strong natural disturbance. We highlight the importance of considering the physical nature and dynamics of the environment and the nature of the species concerned throughout the process of designating closed areas, to avoid negative impacts on fisheries and limited conservation benefits.

Recovery linked to life history of sessile epifauna following exclusion of towed mobile fishing gear

“…Shorter‐lived species such as scallops and dead men's fingers had much shorter recovery times of 2.5–6 year. Although neither predictive relationship was significant in the formal analysis for the latter two species, these recovery times are similar to other studies (Lambert et al., ; Sciberras et al., ). We set out to be precautionary and avoid Type II errors by setting α = 0.1 as our level of significance (Thrush et al., ), but in the majority of cases the effects of fishing had probabilities ≪0.05.…”

Mediation of nitrogen by post-disturbance shelf communities experiencing organic matter enrichment

“…Tillin et al 2006;van Denderen et al 2015), it is surprising that we found a higher ratio of suspension to deposit feeders in sand communities that experienced a higher frequency of chronic fishing. However, a clear trend that emerges from previous studies is that the degree of natural disturbance in which a community develops determines the degree to which it is affected by bottom fishing (Kaiser and Spencer 1996;Hiddink et al 2006;Sciberras et al 2013). The macro-invertebrate communities at our sandy study sites are adapted to living in physically dynamic areas that are characterized by relatively high near-bed current flows (Hiddink et al 2009) and infrequent fishing activity (1.63 times year -1 ), so community recruitment and growth is unlikely to be significantly affected by fishing.…”

Intertidal invertebrate harvesting: a meta-analysis of impacts and recovery in an important waterbird prey resource

“…Extensive research has demonstrated the effectiveness of marine reserves or no-take areas in subtidal ecosystems in conserving ecosystem function and productivity (Sciberras et al 2013); the limited work carried out in intertidal habitats suggests the benefits may be comparable (Byers 2005, Griffiths et al 2006.…”

“…Study-level variances may be calculated using r = 1 (assuming complete correlation) or r = 0 (assuming full independence). The former is likely to overestimate the variance and underestimate the precision, while the latter is likely to underestimate the variance and overestimate the precision (Sciberras et al 2013). In order to avoid the consequences of working with these extreme assumptions, r = 0.5 was used when combining effects.…”