Article Title

Recruitment, Growth, and Survivorship of Black Abalone on Santa Cruz Island following Mass Mortality





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Populations of black abalone experienced major declines in abundance throughout the California Channel Islands in the late 1980's. The focus of this research was to monitor the potential recovery of populations on Santa Cruz Island in 1990-1993 following mass mortality in 1987-1989. Abalone continued to decline in abundance between 1990-1993. These declines were associated with low survivorship and low relative weights, indicating that individuals were con- tinuing to die from the withering syndrome (WS) which was associated with the principal mass mortality. Recruitment, and the movement of small abalone from their cryptic juvenile habitat unto open surge channels, was an important process maintaining adult abundance. However, major declines in the density of juvenile abalone occurred between 1991-1993. Small abalone (length) exhib- ited the greatest effects of WS and these effects decreased with increasing size. Temperature was indicated to be the single most important factor influencing population recovery. Oceanographic factors that result in elevated seawater tem- peratures, such as El Niiio, will have a strong negative impact on the recovery of black abalone populations in southern California.