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.