Bottom Fish and Inverebrate

The objective of the bottom fish and invertebrate survey is to assess the health of organisms and the associated biological communities living on or just above the bottom of the seafloor (demersal) near the discharge. The demersal fishes and invertebrates are sampled by towing a net, called an otter trawl, over the seafloor. These trawls are also used to quantify and characterize marine debris along the Palos Verdes Peninsula. The Sanitation Districts conducts trawls at 16 stations on the Palos Verdes shelf and slope semi-annually. The trawls run along depth contours of 23, 61, 137, and 305 m. All organisms captured are identified and counted. Fish are size classed, and wet-weight biomass is measured for each species. Each individual captured is examined for external signs of disease or anomaly. Measurements of the type, quantity, and weight of trash and debris in each trawl are also made. The results of these monitoring efforts are discussed in the Invertebrate and Fish Trawls chapter of the JWPCP Biennial Receiving Water Monitoring Report.

Trawl Station Map