The Introduced Species Survey (ISS) began in the fall of 2000 and continues to survey today to determine the presence and relative abundance of introduced aquatic species in California. The ISS study attempts to determine the effects introduced species have on entire ecosystems while most previous studies have focused on a single species or individual habitat. Introduced species do not strictly affect a single niche, rather they effect entire ecosystems; this study aims to show these interactions.
 
The ISS study has 3 objectives in addition to the primary goal of determining the presence and relative abundance of California’s introduced species. The first objective is to fill in gaps in the knowledge of the extent of invasions in California’s coastal waters and embayments. The second objective is to determine subsequent ecological adaptations.  The third objective is to determine trends in recruitment and succession caused by the invaders.
 
To fulfill the primary goal of the study, a master list of California’s aquatic introduced species was needed to refine the current known status of each species. This master list was compiled through an extensive literature review and contains information for over 4000 coastal species, including native, introduced, and cryptogenic species. The introduced species list contains information on species distribution, origins, the date of introduction, and the introduction vector, when known. Information about species presence and range was used as a baseline for the ISS study and can be used in future studies when assessing rates and modes of species introduction in California’s waters.
 
To determine the current presence and abundance of introduced species and to determine the effects these species have on an ecosystem, samples are taken from sites that the California Department of Fish and Game’s Office of Spill Prevention and Response (OSPR) has identified as areas of potential invasion. These locations include bays, harbors and major ports, prominent headlands near shipping lanes, locations where ballast water exchange is likely, and entrainment areas where there is potential for increased introduced larval settlement. Many of these sites include locations that overlap with historical datasets to allow change in species composition to be monitored over time. Field and laboratory studies are jointly conducted by OSPR and Moss Landing Marine Laboratories.