EGG-PRODUCTION OF PACIFIC SARDINE (SARDINOPS-SAGAX) OFF OREGON IN 1994

Since the late 1970s, the Pacific sardine (Sardinops sagax) population off the west coast of the United States has been increasing. In 1994, an ichthyoplankton survey to assess anchovy biomass was conducted off the Oregon coast from the Columbia River to the Coquille River (just north of Cape Blanco) and out to 190 km offshore. Samples collected du ring the survey contained numerous Pacific sardine eggs and larvae, wh ich were used to estimate daily egg production (0.42 eggs/0.05 m(2)/da y) and egg mortality (0.13/day). The spawning biomass of Pacific sardi ne was calculated to be about 50,000 MT. There appears to be an associ ation between geographic distribution of sardine eggs and the 14 degre es C isotherm derived from the 1-m to 10-m depth zone. We hypothesize that the isotherm of 14 degrees C forms a distinct boundary for spawni ng sardine off Oregon and may prove useful for determining boundaries for future spawning surveys.