Rs. Burton et Mj. Tegner, Enhancement of red abalone Haliotis rufescens stocks at San Miguel Island:reassessing a success story, MAR ECOL-PR, 202, 2000, pp. 303-308
Outplanting of hatchery-reared juvenile abalone has received much attention
as a strategy for enhancement of depleted natural stocks. Most outplants a
ttempted to date appear to have been unsuccessful. However, based on geneti
c analyses of a population sample taken in 1992, it has recently been sugge
sted that a 1979 outplanting of red abalone Haliotis rufescens, on the sout
h side of San Miguel Island (California, USA), was successful and probably
sustained the fishery there through the 1980s. We resampled the San Miguel
population in 1999 and found no genetic signature of the outplants. Allelic
frequencies in our 1999 sample closely resemble those observed in a pre-ou
tplant 1979 southern California sample and two 1999 northern California pop
ulations. All genotypic frequencies were in Hardy-Weinberg expected proport
ions. We also assessed mtDNA diversity at San Miguel and found it not to di
ffer from that of 2 robust northern California populations of H. rufescens.
Our results suggest that either the composition of the San Miguel abalone
population changed rapidly between 1992 and 1999, or the genetic anomalies
attributed to hatchery source for the 1992 sample were due to sample degrad
ation or other laboratory artifacts. Since we lack samples from the 1992 co
llections, we cannot directly test which explanation is valid. However, sev
eral lines of reasoning call into question the earlier conclusion of outpla
nt success.