As part of PISCO’s kelp forest monitoring program, led by PISCO/UCSC principal investigator Mark Carr and PISCO/UCSB science coordinator Jenn Caselle, divers count young rockfish and kelp bass each year at sites from Monterey Bay to the Channel Islands. These summer surveys of ecologically and economically important species provide scientists and managers with a large-scale, long-term perspective on the distribution and year-to-year changes in population replenishment.
Conducted since 1999, the surveys reveal interesting geographic patterns and changes over time (see figure, below). Kelp forests located near each other, such as the Hopkins and MacAbee sites in Monterey Bay, tended to have similar trends in their numbers of young rockfish (red and pink lines on graphs). More distant sites, such as Sandhill Bluff (purple lines), had different trends.
On a regional scale, kelp forests located at, above, and below Point Conception displayed distinct trends in fish population replenishment. For example, young kelp bass occurred only at southern sites, but these sites had few young rockfish. Conversely, sites north of Point Conception had greater number of young rockfish, but young kelp bass have not been encountered during surveys at these sites.
These findings suggest that coastal currents strongly influence patterns of reef fish population replenishment. To understand these local- and regional-scale linkages, PISCO is conducting ongoing studies using oceanographic instruments and devices that collect young fish. Information from this research informs the design and evaluation of marine reserves and other management efforts.