Endangered White Abalone - the View from a Decade of Research

In 2001, white abalone (Haliotis sorenseni) became the first marine invertebrate to be listed as endangered under the Endangered Species Act (ESA).  Low densities from over harvest and recruitment failure due to population Allee effects were identified as being the major threats to the species’ existence.  The species also suffers from anthropogenic Allee effects because it became more valuable as the numbers dwindle.  Populations are far below minimum viable densities.  The vast majority (between 77 and 89%) of white abalone are observed alone, which suggests that the likelihood of reproductive success within this population remains very low. More ‘active’ rebuilding measures, such out-planting of captive-bred white abalone may be necessary to reverse the present downward trend toward extinction.  Continued illegal harvest also appears to be a threat to the rebuilding of this species.  Black abalone (Haliotis cracherodii) were listed as endangered in 2009 because of disease which lead to dramatic declines and extirpation in many areas.  The disease is accelerated by elevated temperatures and climate change is a threat.  However, some populations appear to be making a recovery.