Perceptions of Change in Puget Sound: Reconstructing Historical Trends in Marine Species Abundance from Local Ecological Knowledge

Historical records of marine populations are important for establishing biological reference points, stock rebuilding measures, and conservation strategies for harvested species.  Lacking these data, scientists and resource managers are often confronted with a loss of collective memory that may lead to misconceptions about the sustainability of fisheries.  In Puget Sound, Washington, many fish and invertebrate species have declined from past abundances; however, the magnitude of these changes is difficult to quantify because of limited historical data.  This study was designed to develop a historical record of marine species over the last 70 years from knowledge of fishers, divers, and researchers in Puget Sound.  A total of 101 individuals were interviewed about their fishing, diving, and/or research practices and observations of relative species abundances by decade.  Interview respondents ranged in age from 24 to 90 years, with a median age of 60.  Respondents demonstrated a wide range of expertise, including commercial and recreational fishing, charter operation, commercial and recreational diving, research, and other professional experience; 84% of respondents indicated that they had experience in two or more of these categories.  A fuzzy logic system was used to quantify information from interviews and derive decadal scale trends in the abundance of 23 species from 1940 to the present.  On average, individuals observed greatest declines in the relative abundance of gadids and rockfishes.  In contrast, respondents reported relatively flat trends in the abundance of flatfishes and macroinvertebrates (e.g., Dungeness crab, jellyfish).  A dramatic increase in harbor seals was observed after the 1960s, showing concordance with contemporary data collected in scientific surveys.  To inform interpretation of species trends derived from interviews, respondents were given color photos of marine mammals, fishes, and invertebrates and asked to group and name the organisms according to their own criteria.  Our analyses revealed that the way in which people classified marine species varied among individuals and was related to their primary type of experience in the marine environment.  Continuing work will focus on determining whether individuals with shared classification systems also have common perceptions of species abundance changes over time.