Spatial Conservation Assessment for Balancing Avoidance of Impacts of Tilapia Introduction on Imperiled Fish Biodiversity with Economic Impacts to the Aquaculture Industry
Monica E. McGarrity
Abstract—Introduction of invasive species, whether deliberate or inadvertent, poses a significant, human-mediated threat to biodiversity that has the potential to exacerbate other anthropogenic impacts and contribute to declines in fish biodiversity. In general, invasive species share life history traits that contribute to their success, such as prolific reproduction and the ability to thrive in highly disturbed habitats. These traits inherently pose difficulties in managing these species. Prevention is widely recognized as the most effective—and often only—management strategy. From a regulatory perspective, prevention often takes the form of a blacklist of prohibited species based on risk assessments, and both the list and associated regulations are developed with input from key stakeholder groups. In the case of prohibited tilapia in Texas, a long-standing regulatory exception allowing possession of Mozambique Tilapia Oreochromis mossambicus for pond stocking is believed to have resulted in frequent, unlawful escapes into public waters that may pose a threat to fish species of greatest conservation need and jeopardize the success of conservation initiatives. Spatial conservation prioritization is a method gaining popularity for identifying areas where conservation actions may have the greatest positive benefit, yet the “knowing-doing gap” between science and implementation is commonly recognized as a hurdle that must be overcome. There is a need to develop science to better inform regulatory approaches to prevention and management of invasive species. This is a unique, and successful, case study that demonstrates potential for development and implementation of systematic conservation planning approaches to conservation action that addresses this need. Spatial conservation assessment using Zonation software was a component of the planning framework that facilitated identification of science-based, regulatory zones that consider potential economic impacts to commercial stakeholders. Feedback from these stakeholders, decision makers, and those tasked with enforcement was obtained and incorporated into development of a realistic, balanced regulatory approach to mitigating impacts of invasive tilapia escape on imperiled fishes in Texas.