California Sea Grant College Program
Movement Rates of Marine Fishes and the Implication of Dispersal for Population Persistence in Marine Reserves
- Author(s): Jorgensen, Salvador J.
- et al.
The abundance and distribution of organisms is of primary interest in population ecology. However, the dispersion of ocean fishes remains poorly understood. This dissertation addresses the spatial and temporal movement patterns of marine fishes in the adult phase, and also how patterns of larval dispersal affect population dynamics in the applied context of fixed boundary marine reserves.
Many fishes repeatedly move within the limits of a home range. The size of home ranges have been estimated for some fish species, however, the use of space and timing of activities within the home range has rarely been studied. We estimated the home range of blue rockfish (Sebastes mystinus) to be 8783m 2 ± 1137 (SE), and found that activity was highly concentrated in 1 to 3 core areas within each home range. Core areas measured 1350m2 ± 286 (mean ± SE), but accounted for -83% of activity. Individuals concentrated around rock pinnacles, however, temporal movement patterns were influenced by circadian light levels and oceanographic cycles. Limited movement in the adult phase may have important implications for spatial management.
Seamounts are considered "hotspots" of increased pelagic fish diversity in the open ocean, yet very little is known about the ecological processes that increase species richness and density there. We investigated the association of 17 fish species with the Espiritu Santo seamount. Different movement rates among species led to differences in the timing and duration of seamount residence and resulted in the formation of seasonally distinct species assemblages.
Marine reserves have been widely proposed for managing marine ecosystems with the goals of protecting biodiversity and preventing over-fishing. The movement rates of individuals, both in the planktonic larval phase and as adults, are likely to determine how reserves should best be designed. We developed a geographically referenced model to determine the spatial distribution of population persistence assuming sedentary adults and dispersing larvae.