Spawning biomass of Pacific sardine (Sardinops sagax), from 1994-2004 off California

The daily egg production method (DEPM) has been used to estimate the spawning biomass of Pacific sardine (Sardinops sagax) since 1986. In this paper, we document the current DEPM procedure using is an example the 2004 survey which incorporates the new procedures adopted since 1997. An adaptive allocation survey design used for sardine eggs has been successfully implemented. Yet, other issues associated with estimating spawning biomass of Pacific sardines remain. We also examine the time series of DEPM spawning biomass estimates and associated parameters from 1994 to 2004 and compare them to the spawning stock biomass (SSB) estimates derived from stock assessment models. The spawning biomass estimates off California increased from less than 10,000 Fur in 1986 to 118,000 mt in 1994, to nearly 300,000 nit in 2004 and have fluctuated during the recent years. The spatial distribution of Pacific sardine eggs varied with sea surface temperature. The average fish weight doubled in the last 10 years, as has the reproductive rate.