An Analysis of 1974 Striped Bass spawning success in the Potomac Estuary.

ABSTRACT: The Potomac River Fisheries Program is concerned with the longterm effects of power plant ichthyoplankton entrainment on striped bass(hforone smatilis) recruitment. Since striped bass population fluctuations are determined strongly by environmental conditions during spawning and early development, assessment of power plant-induced ichthyoplankton mortalities must consider the mechanisms controlling spawning success. Ichthyoplankton distributions for 1974, spawning population abundance and fecundity, and environmental conditions were considered for analysis. Loss of the early part of the spawn (including the peak) accounted for the highest mortalities among ichthyoplankton. This was due to the proximity of these distributions to the salt wedge where transport into regions un!ivorable to survival seems to have occurred. The later, successful portion of the spawn occurred further upstream, in fresh tidal portions of the river. The sequence of events Ieading to an assessment of factors affecting ichthyoplankton surnnl are evaluated. Due to high early mortalities in ichthyoplankton, 1974 spawning success was low, and a poor yearclass is projected.

Ecologic and hydrographic studies of Elkhorn Slough, Moss Landing Harbor and near coastal waters, July 1974 to June 1976

In July 1974, we began a two-year baseline study of the Moss Landing Elkhorn Slough marine environment for Pacific Gas and Electric Company as mandated by the Coastal Commission. The original proposal included strong recommendations for more complete oceanographic studies and a third year of data collection. These further studies were not funded. This report is divided into three sections: oceanography, benthic invertebrate ecology and fish and zooplankton ecology. (PDF contains 480 pages)