Using life history characteristics to determine optimum placement of marine reserves
The purpose of this study is to use rockfish life history and reproductive dynamics to determine marine reserve locations to protect the species that demonstrate age-related differences in parturition timing or quality of larvae produced. These long-lived species are extremely vulnerable to overfishing because of their slow population growth rates and late ages at reproduction. Several species of California rockfish are currently in overfished status. Previous research by the principal investigator has demonstrated that in a number of nearshore rockfish species, older females spawn earlier in the season and produce larvae with characteristics that are more likely to survive (Berkeley et al. 2004). Evidence of similar age-related patterns in spawning seasonality and progeny quality has been observed in a diverse range of teleost species. Because even moderate rates of fishing rapidly eliminate older fish from the population, the burden of reproduction is shifted to younger and younger fish. Elimination of older age classes would effectively shorten the parturition season and eliminate reproductive output from the early part of the spawning season. As a consequence, the likelihood of larval production matching peak plankton production will be reduced (the match-mismatch hypothesis; Cushing 1969, 1990). Fish species that display these “maternal age effects” are most likely to benefit from the protection offered by marine reserves, where no fishing is allowed and the population ages naturally, creating a higher percentage of older individuals.