The Use of Derelict Vessels as Artificial Reefs

Defense Date

12-2002

Document Type

Capstone

Degree Name

M.S. Marine Biology

First Advisor

Richard Spieler

Second Advisor

David Gilliam

Abstract

The world's oceans have provided fisheries resources for food and other products for all of human history and prehistory. Until recently, the people of the world have been able to harvest the world's fisheries in a sustainable way. This was mainly due to the limited human population and primitive fisheries technology available. With an exponentially increasing population comes an increase in the demand for food. Presently, marine fishery resources all over the world are under intensive fishing pressure. The Food and Agriculture Organization of the United Nations (FAO) reported that the majority of fish stocks harvested from around the world may be classified as fully or overexploited (FAO 1997a,b). Botsford et al. (1997) suggests that this figure is close to 75% for commercial fisheries. There is a growing consensus that the reason for this reduction in sustainability is due to an increase in the fishing industry, as well as, a significant reduction in fish habitat.

Approximately 60% of the world's population lives within 60 km of a marine coast (Kennish 1998). The population density along the U.S. coast is four times the national average; also urban growth and development continues to expand into coastal areas. With this expansion comes increased coastal habitat degradation and pollution. Recently, technological advances have allowed fishermen to dramatically increase their catch per unit effort. Although catch rates have increased, fishermen have not yet become efficient at catching the targeted species. The FAO (1997a) has reported that one quarter of the total fisheries catch (approximately 29 million metric tons) is discarded as bycatch each year. The combined effects of wasteful fisheries harvests, habitat degradation and increased pollution have lead to the widespread recognition that marine fisheries have been greatly mismanaged and are in serious trouble in all parts of the world (Mace 1997, Schmitten 1999).

One management option currently being utilized to combat over fishing and habitat loss is the deployment of artificial reefs (ARs). Fisheries managers use ARs to: increase fishing opportunities, reduce fishing pressure on natural reefs, and produce new fish biomass. Concentrating fishery resources at AR sites can save time and fuel, reduce fishing effort, make locating fish more predictable, increase public access, and increase fish abundance at deployment sites (Bohnsack 1989). Although the primary goal of most AR projects is the enhancement of fisheries, managers are continually utilizing ARs for a variety of other reasons including: tourism, habitat restoration, natural resource management, recreational diving, and scientific research (Seamen and Jensen 2000). ARs provide additional habitat in barren unproductive areas, which can increase the environmental carrying capacity and eventually the abundance and biomass of fishes (Stone 1985). This may be due to 1) additional availability of food resources 2) increased feeding efficiency 3) -increased shelter from predation 4) additional habitat for recruits otherwise lost to the population and 5) movement of fishes from natural reefs to ARs (Bohnsack and Sutherland 1985, Grove and Sonu 1985, Bohnsack 1989).

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