California Sea Grant College Program

This study provides the first assessment of demographic and habitat information

for pinto abalone (Haliotis kamtschatkana) in San Diego, California, two decades after

the closure of all abalone fisheries in southern California. SCUBA surveys conducted

from June 2014 to December 2016 indicate that current low densities (0-0.03

individuals/m2) were far below critical thresholds identified for other abalone species

(0.15-0.30 abalone/m2) for successful spawning and recruitment. A broad range of sizes

were represented (13-146 mm), however, only 95 individuals were found. Some sites

showed significant aggregation of adult (> 50 mm) pinto abalone, 30% of adults had a

nearest-neighbor within a critical spawning distance of 2 m, and 65% had a neighbor

within 5 m, indicating that at least a small proportion of individuals may be capable of

reproducing successfully. Pinto abalone showed a significant preference for boulder

habitat at a lower relief (< 10 cm) relative to available habitat– a preference that may

influence aggregation around habitat features and enhance reproduction. The frequency,

timing, and broad spatial distribution of these surveys was not sufficient to measure

patterns in recruitment or changes in abundance, particularly over a strong El Niño event

that occurred during the study period. There is a critical need for consistent long-term

monitoring in southern California to better understand demographic and environmental

processes affecting recovery and persistence of populations, particularly at the southern

edge of the broad range of pinto abalone.