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Measuring abalone (Haliotis Spp.) recruitment in California to examine recruitment overfishing and recovery criteria


Abalone populations in southern California have declined dramatically since the 1950s when they supported a multispecies, commercial, and recreational fishery producing more than 3,000 t per year. Today the commercial fishery is closed statewide and the recreational fishery is closed south of San Francisco. In contrast, red abalone, Haliotis rufescens (Swainson, 1822), populations in northern California continue to sustain a 1,100 1 per year free-diving recreational fishery. We used standardized Abalone Recruitment Modules (ARMs) made of half cinder blocks (area = 2.6 m(2)) to compare the recruitment of juvenile abalone in northern California. where stocks are abundant, with southern California where stocks have declined. We compared the abundance of abalone inside ARMs (n = 12) in Van Damme State Park (VDSP). northern California with abalone inside ARMs (n - 82) in the Channel Islands National Park from 2001 to 2003. Abalone densities on the reefs Surrounding the ARMs at VDSP, averaged 8300/ha compared with abalone densities of 30/ha on reefs in three of the northern Channel Islands. Red, flat abalone, H. walallensis and pinto abalone. H. kamstchatkana kamstchatkana were found in the northern ARMs, whereas in the south red, pink, H. corrugata, threaded, H. kamtchatkana assimilis, and the endangered white abalone, H. sorenseni, were rare in the southern ARMs. Abalone were 30 times more abundant inside the ARMs in the north (5.30/ARM) compared with the south (0.18/ARM). Similar numbers of abalone were found in all 3 years in the ARMs in northern (69, 69, and 53 abalone) and southern California (14, 11, and 20 abalone). The majority of abalone in both the north and the south were less then 100 mm in shell length. Ironically, the rare flat abalone was more abundant in the north, than pink abalone were in the south, a species which once supported a major fishery. Clearly. abalone stocks in southern California are so low that recruitment is failing, despite their potential high fecundity and the fishery closure. These results demonstrate that ARMs call be used to monitor recruitment in the northern fishery, as well as establish quantitative recovery criteria to assess abalone restoration efforts that are desperately needed in the south.

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