Friday, August 8, 2008 - 8:20 AM

COS 109-2: Designing marine reserve networks for species that move within a home range

Elizabeth A. Moffitt1, Louis W. Botsford1, David M. Kaplan2, and Michael R. O'Farrell3. (1) University of California, Davis, (2) Centre de Recherche Halieutique Mediterraneenne et Tropicale, (3) NOAA Southwest Fisheries Science Center

Background/Question/Methods

Marine reserves are increasingly being used as a tool in the management of ocean ecosystems. Models of marine reserves are useful for identifying general principles regarding population persistence and fishery yield and for comparing proposed reserve network designs. Moving regularly within a prescribed zone, known as a home range, is a common type of adult movement in marine species that has not previously been integrated into models of marine reserves. We incorporated home range into a spatially explicit marine reserve model to determine the effects on persistence and yield and to determine how results for species that move within a home range differ from those of sedentary species.

Results/Conclusions

Our results show that movement within a home range has the effect of introducing fishing mortality into reserves, which erodes buildup of egg production within them. Home range increases yield-per-recruit but decreases total larval supply, reflecting a trade-off between persistence and yield. Persistence of species within reserves is dependent on the exploitation rate outside reserves, the percentage of the coastline in reserves, spatial distribution of habitat, larval dispersal distance, and home range size. At high exploitation rates outside reserves, species with large larval dispersal distances can be protected with a network of small reserves, but species with large home ranges can only be protected with reserves of adequate size. A reserve network that protects sedentary species with larval dispersal of any length may not protect species that move within a home range. Adult movement within a home range can change persistence results significantly from those of sedentary adults and is an important consideration in reserve design. Results from the model have aided in the evaluation of proposed networks of marine protected areas along the north-central coast of California.