...to January 2004. Sites were similar in fish density, species richness and biomass of the entire fish assemblage. However, the adult densities of two important fishery species, California sheephead (Semicossyphus pulcher; 7.6 [+ or -] 0.5 and 5.5 [+ or -] 0.4/100 [m.sup.2] inside versus outside) and kelp bass (Paralabrax clathratus, 3.6 [+ or -] 0.4 and 2.9 [+ or -] 0.4 inside versus outside), were significantly higher within the reserve. The reserve appears to be effective in increasing density and biomass of two impacted species that were readily observed and surveyed on SCUBA.

Introduction

Fully protected marine reserves are a powerful tool for conservation and management prompted by declining fish stocks (Botsford 1997; Halpern and Warner 2002). Marine reserves have various functions, one of which is to prevent fishing and the removal of any living or nonliving marine resource (Lubchenco et al. 2003). Benefits of marine reserves for fish and invertebrate populations have been demonstrated previously in many studies, largely in tropical regions (Bell 1983; Alcala 1988; Bennett and Attwood 1991; Buxton and Smale 1989; Russ and Alcala 1989; McClanahan and Shafir 1990; Polunin and Roberts 1993; Grigg 1994; Jennings et al. 1994; McClanahan 1994; Watson and Ormand 1994; McClanahan and Kaunda-Arara 1996; Stoner and Ray 1996). The interest in no-take refuges has emerged, in part, because of the collapse of many fisheries worldwide and the failure of traditional fisheries management techniques to protect them. Marine reserves may influence ecosystems in many ways (Russ 2002). Theoretically, inside a marine reserve, I) fishing mortality is reduced significantly, 2) densities of target species increase, 3) mean size/age and biomass of target species may increase significantly and 4) higher production of propagules of target species occur per unit area. Areas outside of the marine reserve may benefit both from the density-dependent spillover of adults into fished areas and in the net export of eggs/larvae from the marine reserve (Russ and Alcala 1996). The latter can lead to an enhanced supply of recruits to fished areas (Russ 2002). Despite the fact that marine reserve research has focused on tropical habitats (e.g., Craik 1981; Russ 1985; Russ and Alcala 1996), marine reserves are becoming increasingly popular as management tools in California in response to declining fish stocks (Paddack and Estes 2000, Craig et al. 2004, Parnell et al. 2005, Parnell in press. However, relatively few studies have described the effects of marine reserves in California. This may be due, in part, to the fact that these reserves are few in number (Paddack and Estes 2000) and generally small in size (Lowe 2003; Parnell et al. 2005). Despite this lack of knowledge, there has been considerable interest in expanding marine reserves throughout California in an effort to enhance stocks of impacted species (Paddack and Estes 2000). The Marine Life Protection Act of 1999 mandates the establishment of a marine reserve network in California to promote the sustainability of marine resources and is currently being developed by the Department of California Fish and Game. Therefore, it is both ecologically and economically critical that we understand the role of marine reserves in structuring fish assemblages in southern California so that effective marine reserves can be developed to maximize fish production and minimize restricted habitat. In this study we examined some of these hypotheses in a temperate, island ecosystem in southern California.

It is perhaps most important to evaluate the effect of marine reserves on species that are most intensively targeted. In southern California, the kelp bass (Paralabrax clathratus) and the California sheephead (Semicossyphus pulcher) are prominent members of the southern California rocky reef fish assemblage and support substantial fisheries. Fishing pressure on kelp bass has increased over the last 50 years and has resulted in a decrease in landings in California (Rodgers-Bennett 1991, Allen & Hovey 2001). California sheephead are a protogynous hermaphrodite that have been historically targeted by recreational fishermen, both hook and line and using spear. However, since 1988 this species has also been targeted by the live-fin fishery and has accounted for nearly 90% of all target species landed by this fishery since its inception in southern California (Palmer-Zwahlen et al. 1993). Kelp bass and California sheephead may serve as good indicators of the potential of marine reserves to enhance or restore fish stocks in California. Parnell et al. (2005) reported a significant increase in the proportion of large California sheephead males between the San Diego-La Jolla Ecological Reserve and comparable nearby habitats outside the protected area. Paddack and Estes (2000) studied three reserves in central California and found increased fish abundance and increased size of the heavily exploited rockfishes (Scorpaenidae) within two of the three reserves.

The fish stock enhancement potential of coastal reserves in California is promising. However, it is critical to enhance our understanding of this tool in the offshore California islands. The southern California islands consist largely of rocky shorelines while only 10-15% of the southern California mainland shoreline contains rocky substrate, effectively doubling the amount of hard bottom shoreline in California (Stephens et al. 2006). The southern California islands are likely less affected by anthropogenic influences including pollution and coastal runoff, although many are utilized intensively for recreational marine activities. These islands have also been the focus of a proposed reserve network to enhance fish stocks. The purpose of the present investigation was to...

NOTE: All illustrations and photos have been removed from this article.



Looking for additional articles?
Search our database of over 3 million articles.

Looking for more in-depth information on this industry?
Search our complete database of Industry & Market reports by text, subject, publication name or publication date.

About Goliath
Whether you're looking for sales prospects, competitive information, company analysis or best practices in managing your organization, Goliath can help you meet your business needs.

Our extensive business information databases empower business professionals with both the breadth and depth of credible, authoritative information they need to support their business goals. Whether it be strategic planning, sales prospecting, company research or defining management best practices - Goliath is your leading source for accurate information.