The Interagency Ecological Program San Francisco Estuary Smelt Larva Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2009 to monitor the distribution and abundance of newly-hatched Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary. Surveys are conducted bi-weekly and sampling begins early January and continues through March. The surveys sample at fixed locations, stations, from Carquinez Strait through Suisun Bay and into the Sacramento-San Joaquin River Delta. Napa River stations were added in 2014. Each survey consists of 44 stations. At each station, one 10 minute stepped-oblique (bottom to top) tow is made following a prescribed tow schedule. The net is a conical 505 microm mesh lashed to a D shaped frame mounted on skis. Larval fish samples are preserved in the field in 10% Formalin and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. Several types of data are collected at each station, in addition to the larval fish sample, including the volume of water sampled by the net, surface water temperature, surface and bottom specific conductance (EC normalized at 25 degreeC), Secchi disk depth, tow duration, tidal condition, and surface water turbidity.

The Interagency Ecological Program San Francisco Estuary Smelt Larva Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2009 to monitor the distribution and abundance of newly-hatched Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary. Surveys are conducted bi-weekly and sampling begins early January and continues through March. The surveys sample at fixed locations, stations, from Carquinez Strait through Suisun Bay and into the Sacramento-San Joaquin River Delta. Napa River stations were added in 2014. Each survey consists of 44 stations. At each station, one 10 minute stepped-oblique (bottom to top) tow is made following a prescribed tow schedule. The net is a conical 505 microm mesh lashed to a D shaped frame mounted on skis. Larval fish samples are preserved in the field in 10% Formalin and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. Several types of data are collected at each station, in addition to the larval fish sample, including the volume of water sampled by the net, surface water temperature, surface and bottom specific conductance (EC normalized at 25 degreeC), Secchi disk depth, tow duration, tidal condition, and surface water turbidity.

The Interagency Ecological Program San Francisco Estuary Smelt Larva Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2009 to monitor the distribution and abundance of newly-hatched Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary. Surveys are conducted bi-weekly and sampling begins early January and continues through March. The surveys sample at fixed locations, stations, from Carquinez Strait through Suisun Bay and into the Sacramento-San Joaquin River Delta. Napa River stations were added in 2014. Each survey consists of 44 stations. At each station, one 10 minute stepped-oblique (bottom to top) tow is made following a prescribed tow schedule. The net is a conical 505 microm mesh lashed to a D shaped frame mounted on skis. Larval fish samples are preserved in the field in 10% Formalin and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. Several types of data are collected at each station, in addition to the larval fish sample, including the volume of water sampled by the net, surface water temperature, surface and bottom specific conductance (EC normalized at 25˚C), Secchi disk depth, tow duration, tidal condition, and surface water turbidity.

The Interagency Ecological Program San Francisco Estuary 20-mm Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 1995 to monitor the distribution and abundance of post-larval and juvenile Delta Smelt (Hypomesus transpacificus). Delta Smelt are considered to be an annual fish endemic to the upper San Francisco Estuary that spawn in early spring and rear through the summer and fall in fresh to brackish water. Young of the Year (YOY) Delta Smelt are considered juveniles at sizes greater than or equal to 20-mm, and this survey targets those Delta Smelt. The 20-mm Survey currently samples 47 stations at fixed locations from San Pablo Bay through Suisun Bay and into the Sacramento-San Joaquin River Delta every other week from March to July. During high outflow years, 5 additional stations are sampled in San Pablo Bay to provide greater spatial coverage of potential Delta Smelt habitat. The survey has historically sampled between 41 and 55 stations. At each station, three 10-minute stepped oblique tows are conducted for fish. Each stepped oblique tow follows a tow schedule to sample the entire water column, and the volume of water sampled is estimated using a General Oceanics flowmeter. The net is a cone shaped plankton net composed of 1600μm mesh and measuring 5.5 meters in length with a mouth area of 1.51m2 lashed onto a rigid D-frame with skis. Post-larval and juvenile fish samples are preserved in the field in 10% Formalin dyed with Rose Bengal and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. At each station, environmental and water quality data are also collected, and include: top temperature, top and bottom electrical conductivity (normalized at 25degreeC), water clarity, and tidal condition.

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.