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7212596 
Journal Article 
Decline of the abalone fishery at La Natividad, Mexico: Overfishing or climate change? 
Shepherd, SA; Turrubiates-Morales, , JR; Hall, K; , 
1998 
NATL SHELLFISHERIES ASSOC 
GROTON 
839-846 
WOS:000078250300042 
Abalone have been exploited commercially at La Natividad Island Baja California since about 1956. The fishery for Haliolis sorenseni collapsed after about 7 years, and those for Haliotis corrugata and Haliotis fulgens in 1984. Subsequently, the fishery recovered somewhat before the recent decline in 1994 to 1997. Egg-per-recruit (EPR) analyses for the two major species were carried out with information on growth rate, fishing mortality rate, and size at sexual maturity and other data obtained mostly during the 1990s. Egg production conserved before the 1984 collapse was probably somewhat low for H. corrugata at similar to 30-40% of the maximum possible in unfished conditions, and certainly low for H. fulgens at similar to 20%. After the collapse with better control of the fishery, the egg production improved slightly for H. corrugata to similar to 30-50%, and for H. fulgens to similar to 25-40%, but from 1995 has declined again as fishing mortality increased. The periodic El Ninos cause elevated sea temperatures and loss of Macrocystis in the region. The total abalone catch from 1965 to 1996 was correlated with mean sea surface temperature anomalies with a lag of 8 years, which is the average period from larval settlement until recruitment into the fishery. This implies that sea temperature anomalies have a positive effect on recruitment. On the other hand, there is also slight evidence of recruitment failure during severe El Ninos. Although environmental variables and recruitment overfishing can each cause reductions in catch, the presence of both makes a decline practically inevitable. Quota managed fisheries must take into account environmental effects on recruitment if they wish to avert declines. 
3rd International Symposium of Abalone Biology, Fisheries, and Culture 
MONTEREY, CA