Abstract
A 2 km2 area off the southwest coast of the Isle of Man (Irish Sea) has been closed to commercial fishing with mobile gear since March 1989. This area was heavily fished for Pecten maximus (Linnaeus, 1758) prior to closure, and the seabed immediately surrounding the closed area is still one of the most heavily dredged in the Irish Sea. Two methods have been used to study the effect of scallop dredging on the benthos in this closed area and adjacent fished areas. Firstly, twice-yearly grab sampling of experimental plots inside and outside the closed area since 1995 has enabled comparisons of the benthic infauna and epifauna of experimentally dredged plots, undredged control plots and plots exposed to commercial dredging. Secondly, divers have carried out visual transect surveys of P. maximus numbers regularly since closure. Communities of experimentally disturbed plots have become less similar to adjacent undisturbed control areas and more similar to commercially dredged areas. At each sampling date, similarity between dredged samples was greater than between undredged samples. Since 1989, there have been increases in the mean numbers of P. maximus in the closed area. The age structure of the closed area P. maximus population is also different to that outside, with a higher mean age due to the presence of large, old individuals.
These results present strong evidence that scallop dredging alters benthic communities and suggest that the closure of areas to commercial dredging may allow the development of more heterogeneous communities and permit the populations of some species to increase. A common problem with studying fishing disturbance is the lack of good control sites and this work also demonstrates the value of closed areas to scientific studies of demersal fishing.
Similar content being viewed by others
References
Ansell, A. D., J. C. Dao & J. Mason, 1991. Three European scallops: Pecten maximus, Chlamys (Aequipecten) opercularis and C. (Chlamys) varia. In Shumway, S. E. (ed.), Scallops: Biology, Ecology and Aquaculture. Developments in Aquaculture and Fisheries Science, vol 21. Elsevier, Amsterdam: 715–751.
Auster, P. J., R. J. Malatesta, R. W. Langton, L. Watling, P. C. Valentine, C. L. S. Donaldson, E. W. Langton, A. N. Shepard & I. G. Babb, 1996. The impacts of mobile fishing gear on seafloor habitats in the Gulf of Maine (Northwest Atlantic): Implications for conservation of fish populations. Rev. Fish. Sci. 4: 185–202.
Bradshaw, C., L. O. Veale, A. S. Hill & A. R. Brand, 2000. The effects of scallop dredging on gravelly sea-bed communities. In Kaiser, M. J. & S. J. De Groot (eds), Effects of Fishing on Non-Target Species and Habitats. Gray Publishing, Tunbridge Wells: 83–104.
Brand, A. R. & B. Beukers–Stewart, 2000. Shellfish Research Report to the Isle of Man Government, Department of Agriculture, Fisheries and Forestry: 22 pp.
Brand, A. R., U. A. W. Wilson, S. J. Hawkins, E. H. Allison & N. A. Duggan, 1991. Pectinid fisheries, spat collection, and the potential for stock enhancement in the Isle of Man. ICES mar. Sci. Symp. 192: 79–86.
Bridger, J. P., 1970. Some effects of the passage of a beam trawl over the seabed. ICES Gear and Behaviour Committee Report C. M. 1970/B: 10
Caddy, J. F., 1973. Underwater observations on the tracks of dredges and trawls and some effects of dredging on a scallop ground. J. Fish Res. Bd Can. 30: 173–180.
Carr, M. H. & D. C. Reed, 1993. Conceptual issues relevant to marine harvest refuges: examples from temperate reef fishes. Can. J. Fish. aquat. Sci. 50: 2019–2028.
Caswell, H. & J. E. Cohen, 1991. Communities in patchy environments: a model of disturbance, competition and heterogeneity. In Kolasa, J. & S. T. A. Pickett (eds), Ecological Heterogeneity. Springer-Verlag, New York: 97–122.
Clarke, B. M., 1998. No Take Zones (NTZ's). A Realistic Tool for Fisheries Management? Marine Conservation Society, Ross-on-Wye: 52 pp.
Collie, J. S., G. A. Escanero & P. C. Valentine, 1997. Effects of bottom fishing on the benthic megafauna of Georges Bank. Mar. Ecol. Prog. Ser. 155: 159–172.
Currie, D. R. & G. D. Parry, 1996. Effects of scallop dredging on a soft-sediment community: a large-scale experimental study. Mar. Ecol. Prog. Ser. 134: 131–150.
Dayton, P. K., S. F. Thrush, M. Tundi Agardy & R. J. Hofman, 1995. Environmental effects of marine fishing. Aquat. Conserv. 5: 205–232.
Dial, R. & J. Roughgarden, 1998. Theory of marine communities: the intermediate disturbance hypothesis. Ecology 79: 1412–1424.
Dugan. J. E. & G. E. Davis, 1993. Applications of marine refugia to coastal fisheries management. Can. J. Fish. aquat. Sci. 50: 2029–2042.
Eleftheriou A. & M. R. Robertson, 1992. The effects of experimental scallop dredging on the fauna and physical environment of a shallow sandy community. Neth. J. Sea Res. 30: 289–299.
Hall, S. J., 1994. Physical disturbance and marine benthic communities life in unconsolidated sediments. Oceanogr. mar biol. Ann. Rev. 32: 179–239.
Hall, S. J., D. J. Raffaelli, D. J. Basford & M. R. Robertson, 1990. The importance of flatfish predation and disturbance on marine benthos: an experiment with dab Limanda limanda (L.). J. exp. mar. Biol. Ecol. 136: 65–76.
Hall-Spencer, J. M. & P. G. Moore, 2000a. Impacts of scallop dredging on maerl grounds. In Kaiser, M. J. & S. J. De Groot (eds), Effects of Fishing on Non-Target Species and Habitats. Gray Publishing, Tunbridge Wells: 105–117.
Hall-Spencer, J. M. & P. G. Moore, 2000b. Scallop dredging has profound, long-term impacts on maerl habitats. ICES J. mar. Sci. 57: 1407–1415.
Hatcher, B. G., R. E. Scheibling, M. A. Barbeau, A W. Hennigar, L. H. Taylor & A. J. Windust, 1996. Dispersion and mortality of a population of sea scallop (Placopecten magellanicus) seeded in a tidal channel. Can. J. Fish. aquat. Sci. 53: 38–54.
Hill, A. S., A. R. Brand, L. O. Veale & S. J. Hawkins, 1997. Assessment of the effects scallop dredging on benthic communities. Report to MAFF, University of Liverpool: 112 pp.
Horwood, J. W., 2000. No-take zones: a management context. In Kaiser, M. J. & S. J. De Groot (eds), Effects of Fishing on Non-Target Species and Habitat. Gray Publishing, Tunbridge Wells: 302–311.
Ito, H., 1991. Japan. In Shumway, S. E. (ed.). Scallops: Biology, Ecology and Aquaculture. Developments in aquaculture and fisheries science, vol 21. Elsevier, Amsterdam: 1017–1056.
Jennings, S. & M. J. Kaiser, 1998. The effects of fishing on marine ecosystems. Adv. mar. Biol 34: 201–351.
Jones, J. B., 1992. Environmental impact of trawling on the seabed: a review. N.Z. J. mar. Freshwat. Res. 26: 59–67.
Kaiser, M. J., 1998. Significance of bottom-fishing disturbance. Conserv. Biol. 12: 1230–1235.
Kaiser, M. J. & B. E. Spencer, 1996. The effects of beam-trawl disturbance on infaunal communities in different habitats. J. anim. Ecol. 65: 348–358.
Kaiser, M. J., A. S. Hill, K. Ramsay, B. E. Spencer, A. R. Brand, L. O. Veale, K. Prudden, E. I. S. Rees, B. W. Munday, B. Ball & S. J. Hawkins, 1996. Benthic disturbance by fishing gear in the Irish Sea: a comparison of beam trawling and scallop dredging. Aquat. Conserv. 6: 269–285.
Kaiser, M. J., K. Cheney, F. E. Spence, D. B. Edwards & K. Radford, 1999. Fishing effects in northeast Atlantic shelf seas: patterns in fishing effort, diversity and community structure VII. The effects of trawling disturbance on the fauna associated with the tubeheads of serpulid worms. Fish. Res. 40: 195–205.
M. J., F. E. Spence & P. J. B. Hart, 2000. Fishing gear restrictions and conservation of benthic habitat complexity. Conserv. Biol. 15(4).
Lindeboom, H. J., 2000. The need for closed areas as conservation tools. In Kaiser, M. J. & S. J. De Groot (eds), Effects of Fishing on Non-Target Species and Habitats. Gray Publishing, Tunbridge Wells: 290–301.
Lindeboom, H. J. & S. J. E. De Groot, 1998. IMPACT II The Effects of Different Types of Fisheries on the North Sea and Irish Sea Benthic Ecosystems. Netherlands Institute for Sea Research (NIOZ), Den Burg, Texel, Netherlands: 404 pp.
Murawski, S. R. Brown, H.-L. Lai, P. J. Rago & L. Hendrickson, 2000. Large-scale closed areas as a fishery-management tool in temperate marine systems: the Georges Bank experience. Bull. mar. Sci. 66: 775–798.
Ramsay, K. & M. J. Kaiser, 1998. Demersal fishing disturbance increases predation risk for whelks (Buccinum undatum L.). J. Sea Res. 39: 299–304.
Reise, K., 1982. Long-term changes in the macrobenthic invertebrate fauna of theWadden Sea: are polychaetes about to take over? Neth. J. Sea Res. 16: 29–36.
Reise, K. & A. Schubert, 1987. Macrobenthic turnover in the subtidal Wadden Sea: the Norderaue revisited after 60 years. Helgoländer wiss. Meeresunters. 41: 69–82.
Riesen, W. & K. Reise, 1982. Macrobenthos of the subtidal Wadden Sea: revisited after 55 years Helgoländer wiss. Meeresunters 35:409–423.
Rice, M. A., C. Hickox & I. Zehra, 1989. Effects of intensive fishing effort on the population structure of quahogs, Mercenaria mercenaria (Linnaeus 1758), in Narragansett Bay. J. Shellfish Res. 8: 345–354.
Roberts, C. M. & N. V. C. Polunin, 1991. Are marine reserves effective in the management of reef fisheries? Rev. Fish Biol. Fish. 1: 65–91.
Shepard, A. N. & P. J. Auster, 1991. Incidental (non-capture) damage to scallops caused by dragging on rock and sand substrates. In Shumway, S. E. & P. A. Sandifer (eds), An International Compendium of Scallop Biology and Culture. World Aquaculture Society, Baton Rouge: 219–230.
Smith, F. & J. D. Witman, 1999. Species diversity in subtidal landscapes: Maintenance by physical processes and larval recruitment. Ecology 80: 51–69.
Tang, S. F., 1941. The breeding of the scallop (Pecten maximus (L.)) with a note on growth rate. Proc. Liverpool biol. Soc. 54: 9–28.
Thrush, S. F., J. E. Hewitt, V. J. Cummings & P. K Dayton, 1995. The impact of habitat disturbance by scallop dredging on marine benthic communities: what can be predicted from the results of experiments? Mar. Ecol. Prog. Ser. 129: 141–150.
Van Dolah, R. F., P. H. Wendt & N. Nicholson, 1987. Effects of a research trawl on a hard-bottom assemblage of sponges and corals. Fish. Res. 5: 39–54.
Warwick, R. M. & K. R. Clarke, 1993. Increased variability as a symptom of stress in marine communities. Changes In Marine Communities 172: 215–226.
Watling, L. & E. A. Norse, 1998. Disturbance of the seabed by mobile fishing gear: a comparison to forest clearcutting. Conserv. Biol. 12: 1180–1197.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bradshaw, C., Veale, L., Hill, A. et al. The effect of scallop dredging on Irish Sea benthos: experiments using a closed area. Hydrobiologia 465, 129–138 (2001). https://doi.org/10.1023/A:1014573731609
Issue Date:
DOI: https://doi.org/10.1023/A:1014573731609