Biomass Assessments of Spawning Aggregations

Combining passive- and active-acoustic sampling to assess the effects of boat noise and fishing activities on the distribution, abundance, and behavior of spawning croakers

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The proposed project will be conducted in coordination with NOAA Fisheries Southwest Fisheries Science Center to contribute to NOAA’s long-term mission goal of establishing Healthy Oceans by developing new acoustic techniques to assess spawning stocks and the impacts of acoustic disturbances on fish populations in order to promote sustainable fish populations. The project will use passive and active acoustic instrumentation to evaluate the relationship between fish sound production and metrics of fish abundance (e.g. density, biomass) and the potentially deleterious effects of engine noise on spawning behavior at the spawning grounds of Gulf Corvina (Cynoscion othonopterus) and Totoaba (Totoaba macdonaldi) in the Colorado River Delta. During Spring 2016, passive acoustic (hydrophone) and active acoustic (split beam and multi-beam sonar units) surveys will be conducted simultaneously to measure fish sound production, fish abundance and density, and fish behavior in order yield a quantifiable relationship from which fish abundance and stock size can be predicted from future acoustic recordings. Changes in fish densities, distributions, behaviors, and sound production near vessels as engines are ignited and engaged will be examined to assess possible effects of anthropogenic noise on spawning activities. The results may be directly applicable to croaker stocks elsewhere (e.g., Cynoscion nebulosus in the Gulf of Mexico and C. regalis in the Atlantic) that occur in similar habitats, produce similar types of sounds for spawning, and experience similar types of noise disturbances during spawning. This project will enhance NOAA’s ability to be versatile in their approaches to monitor and develop sustainable fisheries and progress to the goal of ensuring a healthy ocean for present and future generations.