Research Document - 2006/059

The intentional scuttling of surplus and derelict vessels: Some effects on marine biota and their habitats in British Columbia waters, 2002

By Smiley, B.D.

Abstract

Artificial reefs have been created in most world seas for a range of reasons including attempts to enhance marine productivity, and to attract recreational and commercial fish species and recreational divers. Many nations’ navies have a surplus of vessels requiring disposal. One cost-effective disposal method is to scuttle them in locations appropriate for the recreational use of scuba-equipped divers. Once in place the "vessel-reef" becomes colonized by epibenthic organisms, and attracts pelagic and demersal fishes, making it even more interesting to human divers. Habitat managers and ocean planners ask if the ecological benefits of scuttled vessels outweigh the ecological losses? This report reviews the Canadian and British Columbia regulatory information on the scuttling of vessels, the scientific information on artificial reefs, and collates the scattered information on the use of scuttled vessels as artificial reefs with emphasis on those in Canadian Pacific coast waters. A list of the 18 scuttled vessels-as-reefs in BC waters is provided along with the area of smothered sea floor per vessel (range from ~14-m² to ~2 330-m²); the estimated total for all scuttled vessels is ~10 500-m² (~1.1 ha). Where available, lists of macro-flora and -fauna (range from 25 to 96 species) either attached or closely associated (small to large epifaunal fishes and invertebrates) with each BC vessel-reef is provided along with descriptive narratives. Frequently observed fish include copper (Sebastes caurinus) and quillback (S. maliger) rockfish, lingcod (Ophiodun elongatus), kelp greenling (Hexogrammus decagrammus), shiner (Cymatogaster aggregata) and pile (Rhacochilus vacca) perch, and padded (Artedius fenestralis), grunt (Rhamphocottus richardsoni) and scalyhead (Artedius harringtoni) sculpins. Species richness becomes maximal in about two years. Detailed scientific studies surrounding scuttled vessels have not been carried out in BC waters, though workers elsewhere have shown that infaunal densities under a scuttled vessel hull were from 3 – 15 times less than one meter beyond the hull. Tagging studies show that artificial reefs both attract motile adult species from adjacent natural reefs, and add to the overall production of an area through the recruitment of juveniles that feed and grow in and around the reef. Other studies have shown that the production from an artificial reef far exceeds the production of the previous sand/mud ecosystem. A range of recommendations are provided including the discouragement of pyrotechnical shows during ship scuttlings, and that the location of vessel-reefs should be carefully selected with the site being >2 km from natural reefs.

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