Understanding production and attraction on artificial reefs to improve the science of mitigation

THIS IS DRAFT TEXT TAKEN FROM AN LOI When artificial reefs are implemented for mitigation, ideally they are monitored and assessed to see if they achieve mitigation targets, such as a certain amount of fish biomass or production. It is well documented that artificial reefs attract fish, however, it is less clear how much they boost production of fish biomass (i.e., is there a net increase in fish populations, or do fish simply abandon natural habitats to aggregate on artificial reefs?). Addressing this hotly debated question requires long-term monitoring data from before and after artificial reef creation at nearby natural reefs in addition to the artificial reef, as well as size-structured data; often such data are not available. This issue is the focus of our project, which will use Wheeler North Reef, an artificial reef in Southern California, as a case study. Despite the fact this reef has a monitoring plan and extensive monitoring data, these data have not been used to address the attraction-production question, nor is that part of the monitoring plan. Leveraging this extensive data set will allow a rigorous examination of several questions that will inform management. This would be impossible to achieve on the other less-studied artificial reefs in California within the time and budget scope of this RFP. INVESTIGATORY QUESTIONS: Our project addresses the following questions: 1. What have been the relative contributions of attraction and production of fish biomass at an artificial reef in Southern California through time? 2. Does attraction impact the ability of artificial reefs to meet mitigation performance standards of fish density and biomass? 3. Which elements of reef design shift the attraction-production equation towards production? 4. Which species of fish are more likely to be attracted than produced on artificial reefs? 5. How does the spatial context (e.g., proximity to natural reefs) influence an artificial reef?s ability to produce vs. attract new fish biomass? 6. How does oceanographic context (e.g., warm-water events) influence the extent to which artificial reefs produce vs. attract fish biomass? We will apply new modeling techniques to conduct a retrospective analysis of production and attraction using an existing 20-year data set of fish biomass, abundance, and size at the Wheeler North artificial reef and two nearby natural reefs in Southern California. We will assess how attraction, production, and reef expansion impact the ability of artificial reefs to meet mitigation performance standards. These issues are critical to the design and management of artificial reefs in the State of California. By addressing these issues, we hope to evaluate the potential for artificial reefs as mitigation tools, an issue very relevant to people living along impacted coastlines that depend on ocean resources.