ESR prepress abstract  -  doi: 10.3354/esr00804

Evaluating factors affecting restoration of an endangered marine broadcast-spawning invertebrate using an individual-based model of white abalone

Yan Li*, Laura Rogers-Bennett

*Email: yxl73@psu.edu

ABSTRACT: Restoration and modeling of endangered species is challenging when the available data are sparse and the environmental conditions are stochastic. White abalone (Haliotis sorenseni) is a critically endangered marine broadcast spawner with spatially patchy remnant populations in southern California. Using white abalone as an example, we developed an individual-based model that describes density-, temperature- and habitat-dependent biological processes. Using the model, we evaluated hypothetical stocking strategies including spatial distribution of stocked abalone, initial density of resident abalone and size of stocked abalone. Our results show that stocking strategies for the modeled white abalone populations benefited most when stocking locations had resident abalone and when stocked abalone were large in size. We also examined the potential influence of the spatial structure of the habitat (i.e., the percentage of suitable habitat and the spatial distribution of habitat cells – random or clustered), ocean warming and illegal take (poaching) on restoration outcomes. We found that the percentage of suitable habitat greatly affected the population dynamics white abalone, with more suitable habitat resulting in a slower decline in population growth and recruitment, as well as a higher and more stable proportion of intermediate-size abalone. The spatial distribution of habitat cells (random or clustered) and the spatial distribution of stocked abalones (random or clustered) had less of an impact on model outcomes. Elevated temperature and poaching both had strong negative impacts on population growth of white abalone in the model. Considering the spatial structure of the habitat and population, ocean warming and poaching are critical factors in the development of restoration strategies for endangered broadcast spawners.