Marine Reserves as a Tool for Ecosystem-Based Management: The Potential Importance of Megafauna

T state of the global oceans is rapidly deteriorating, with dire consequences for marine species (Jackson et al. 2001). Historically,most conservation efforts have focused on terrestrial systems, but it is becoming increasingly apparent that conservation efforts are urgently required for the oceans as well (Myers et al. 1997, Casey and Myers 1998). Recently, significant attention has been given to the establishment of marine reserves (Boersma and Parrish 1999, Mangel 2000), with most of the focus of research directed at economically valuable (i.e., mid–trophic level) species (Rowley 1994). Some of the lessons learned from these reserves have now been widely accepted (e.g., bigger is better, and dispersal matters; NCEAS 2001). However, one of the most interesting questions to emerge from the initial exploration of marine reserve design theory is the significance of life-history characteristics. Here we review issues concerning the ecology of higher predators and their relevance for the design and selection of marine reserves. The grouping of higher marine predators describes ocean megafauna, including a variety of taxa: cetaceans, pinnipeds, sea otters, polar bears, seabirds, sharks, cephalopods, and predatory fish. Our primary expertise is in marine mammal ecology,and so most of our review focuses on the ecology and conservation of this group. Nevertheless, many aspects of these species’ ecology, life history, and demography apply to other marine predators as well, allowing us to propose certain generalities that apply to all marine predators. There is currently a trend toward the advocation and establishment of marine sanctuaries based on their marine megafauna, and particularly their mammal or bird fauna (table 1). However, systematic theory on how to select, design, and monitor these reserves is lacking, and their efficacy in protecting marine predators is not clear. We discuss two issues here: (1) the potential for marine reserves to protect marine predators, and (2) the question of whether these species can serve as ecological indicators, demonstrating where and how to target and design marine reserves. This article is loosely based on