POPULATION BIOLOGY OF RED ABALONES, HALIOTIS RUFESCENS, 



IN SOUTHERN CALIFORNIA AND MANAGEMENT OF THE RED AND 



PINK, H. CORRUGATA, ABALONE FISHERIES 



Mia J. Tegner,' Paul A. Breen,^ and Cleridy E. Lennert' 



ABSTRACT 



Population dynamics of red abalones, Haliotis rufescens Swainson, were studied at Johnsons Lee, Santa 

 Rosa Island, California from 1978 through 1982 and in 1984. Tagging studies were used to calculate 

 the von Bertalanffy growth parameters. Size-frequency distributions were used to assess settlement rate 

 and fishable stock, and to estimate the natural mortality rate. These results were employed in yield-per- 

 recruit and egg-per-recruit analyses; similar calculations were made for pink abalones, H. corrugata Gray, 

 using values from the literature. Our analyses suggest that present sport and commercial minimum legal 

 sizes allow for adequate egg production to maintain stock sizes; simple recruitment overfishing is not 

 a satisfactory explanation for the sharp and continuing decline in landings of both species. We consider 

 other factors which may be responsible and argue that prudent abalone management should maintain 

 egg-per-recruit at the cost of some potential yield. 



The red abalone, Haliotis rufescens Swainson, is the 

 largest member of its genus and historically the 

 most important species in the California abalone 

 fishery. Ranging from Coos Bay, OR to Bahia Tor- 

 tugas, Baja California (Cox 1962), red abalones are 

 found along the entire coast of California but almost 

 all of the commercial harvest comes from Point Con- 

 ception south (Fig. 1). The recovery of the sea otter, 

 Enhydra lutris, population has precluded the com- 

 mercial fishery within its central California range 

 (Miller and Geibel 1973; Hardy et al, 1982; Estes 

 and Van Blaricom 1985) and the north coast has 

 been reserved for the recreational fishery since 1945 

 (Cicin-Sain et al, 1977). Today the major commer- 

 cial red abalone fishing grounds are in southern 

 California— the northern Channel Islands, Santa 

 Cruz, San Miguel, San Nicolas, and Santa Rosa 

 Islands— and mainland sites where upwelling pro- 

 duces cooler temperatiu-es which are north and west 

 of Santa Barbara and near San Diego. Red abalones 

 are also found on the Palos Verdes Peninsula within 

 the coastal area closed to all abalone fishing. The 

 present size limits are 178 mm for the recreational 

 fishery and 197 mm for commercial harvest. 



The pink abalone, H. corrugata Gray, is found 

 from Point Conception, CA (Cox 1962) to Punta 

 Abreojos, Baja California (Doi et al, 1977). From 

 1949 to 1970, pink abalones supported a fishery 



'Scripps Institution of Oceanography, University of California. 

 San Diego, A-OOl, La Jolla, CA 92093. 



^Ministry of Agriculture and Fisheries, Fisheries Research 

 Center, Greta Point, P.O. Box 297, Wellington, New Zealand. 



Manuscript accepted February 1989. 

 Fishery BuUetin. U.S. 87:313-339. 



equal in importance to the red abalone fishery. In 

 1970, an increase in the minimum legal commercial 

 size from 152 to 159 mm caused a sharp decrease 

 in landings (Tegner 1989). The present size limits 

 are 152 mm for sport and 159 mm for commercial 

 harvesters. 



Despite the high landed value and the recreational 

 importance of the abalone fishery in California, no 

 stock assessments are available. Management has 

 been based on the assumption that an appropriate 

 size limit will protect the stocks. An appropriate size 

 limit is considered to be one large enough to allow 

 sublegal abalones to spawn several times before 

 being recruited to the fishery, yet small enough that 

 the size is attained within a reasonable number of 

 years after settlement (Burge et al. 1975), A strong 

 dependence on a minimum size limit is consistent 

 with abalone fishery management elsewhere. In 

 his review of world abalone fisheries, Harrison 

 (1986, p, 21) suggested that "an appropriate set of 

 effectively policed minimum size regulations is the 

 cornerstone of managing these fisheries." Despite 

 the importance of the size limit in managing Califor- 

 nia abalone fisheries, no analysis of its effect on 

 population dynamics or fisheries yield has been 

 published. 



After many years of relative stability, the red and 

 pink abalone harvests began a marked decline in the 

 late 1960s (Burge et al. 1975; Cicin-Sain et al. 1977). 

 Despite limitation of entry to the commercial fish- 

 ery and tighter restrictions on the recreational fish- 

 ery in the mid-1970s, the decline in landings has con- 



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