Interagency Ecological Program San Francisco Estuary Spring Kodiak Trawl Survey 2002 - 2021

The Interagency Ecological Program San Francisco Estuary Spring Kodiak Trawl Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2002 to improve the detection rate of pre-spawning and mature Delta Smelt (hypomesus transpacificus). The survey began as the Spring Midwater Trawl Survey, an extension of the Fall Midwater Trawl Survey, in 1991 to assist with water management and export decisions in relation to the distribution of pre-spawning Delta Smelt. Net evaluations studies compared the relative catch efficiency of 3 types of nets and found that the Kodiak net was most effective for Sampling adult Delta Smelt. Objectives of SKT are to improve the ability to detect Delta Smelt, obtain maturity status for adult Delta Smelt, and provide results to scientist and managers on a near real-time basis to ais in resource management. SKT operates 6 monthly surveys December through May each lasting 4-5 days in length. Each survey, 40 fix sample locations are sampled using a standard 10 minute Kodiak trawl with a total length of 65 feet and a fully expanded mouth opening of 25 feet by 6 feet. The volume of water sampled is estimated using a General Oceanics flowmeter placed over the side of the boat. The net is constructed of green or black variable mesh ranging in dimension from 2 inches knoteted stretched mesh at the mouth and decreasing by ½ inch through a series of 5 panels to ¼ inch knotless stretched mesh at the cod-end. All fish sampled are identified to species and enumeration, Delta Smelt are staged in the field. At each station, environmental and water quality data are also collected, and include: temperature, electrical conductivity (normalized @ 25°C), water clarity, and tidal condition.