Fish Survey - Zooplankton (CB) - San Francisco Estuary [ds630]

The purpose of the Zooplankton Study is to monitor the distribution and abundance of fish food resources in the upper San Francisco Estuary. Zooplankton are important food organisms for larval, juvenile, and small fish, such as delta smelt, longfin smelt, juvenile salmon, striped bass and splittail. The study also detects and monitors zooplankton recently introduced to the estuary and determines their effects on native species. Water Rights Decision 1379 first mandated the monitoring of Neomysis and zooplankton in Suisun Bay and the Sacramento- San Joaquin Delta. Decision 1485 reaffirmed the need to conduct ongoing and future monitoring surveys, as recommended by the California Department of Fish and Game and concurred by the State Water Resources Control Board, concerning food chain relationships and fisheries impacts as they are affected by Central Valley Project and State Water Project operations in the delta and Suisun Marsh. The data is used by various agencies and consultants for water quality evaluations and analysis.

<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>The Zooplankton Study has estimated the abundance of zooplankton taxa in the upper San Francisco Estuary, from eastern San Pablo Bay through the eastern Sacramento-San Joaquin Delta and Suisun Marsh, since 1968. From 1968-1971 the mysid Neomysis mercedis was identified and enumerated from macrozooplankton samples, in 1972 sampling gear was added to target smaller zooplankton. Since 1972 three gear types have been used for sampling: 1) a pump for sampling microzooplankton &lt;1.0 mm long, including rotifers, copepod nauplii, and adult copepods of the genus Limnoithona, 2) a modified Clarke-Bumpus (CB) net for sampling mesozooplankton 0.5-3.0 mm long, including cladocerans, copepodids (immature copepods), and adult copepods, and 3) a macrozooplankton net for sampling zooplankton 1-20 mm long, including mysid shrimp. Sampling is conducted once monthly, year round at both fixed stations and floating entrapment zone stations where electrical conductivity meets certain thresholds. The fixed sites were originally chosen to obtain samples from the entire salinity gradient in Suisun Bay, to sample the large Suisun Marsh sloughs, and to provide good spatial coverage of the delta. In 1994, when the sampling effort was reduced, a subset of stations was chosen based on the ability of stations to replicate the long-term trends seen in the complete station set. The floating stations were chosen to provide coverage of the entrapment zone. Seasonal abundance indices are calculated from 1974 through present from 16 core stations that have been sampled consistently since 1974. Winter abundance indices (December, January, and February) are not calculated, since sampling was not historically conducted in winter. The annual seasonal indices are the average catch-per-unit-effort at all core stations during spring (March-May), summer (June-August), and fall (September-November). Catch-per-unit-effort (CPUE) is calculated for each species at each station by dividing the total catch by the volume of water sampled. Various water quality parameters such as temperature, electrical conductivity, turbidity, and chlorophyll-a are measured at each station, allowing CPUE data to be analyzed with respect to these environmental conditions. ------------------------------------------------------------ Three tables were included along with the Zooplankton study dataset. These tables include: 1. 2002-2007 CB Presence Absence Data 2. 2002-2007 Mysid Presence Absence Data 3. 2002-2007 Pump Presence Absence Data This Zooplankton study dataset contains data from the 2002-2007 CB Presence Absence Data table.</SPAN></P></DIV></DIV></DIV>

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