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