The Gulf Coast Vulnerability Assessment utilized expert opinion that was gathered through the Standardized Index of Vulnerability and Value (SIVVA) tool, which is an Excel-based vulnerability and prioritization tool that enables assessors to provide input in a relatively short time and allows for relatively seamless compilation of results. The vulnerability of each ecosystem and associated species was conducted by subregion, excluding those subregions where the species did not occur in significant numbers. Assessors were asked to evaluate species based on the habitats they use in a particular subregion. Because vulnerability can vary with life-stage for many species, assessors were asked to consider the most vulnerable life-stage of the species for each criterion scored.