|Document Type:||Journal Article|
|Title:||Pacific sardine (Sardinops sagax) abundance, distribution and ecological relationships in the Pacific Northwest|
|Author:||Robert L. Emmett, Richard D. Brodeur, T. W. Miller, S. S. Pool, Paul J. Bentley, G. K. Krutzikowsky, J. McCrae|
|Journal:||California Cooperative Oceanic Fisheries Investigations Reports|
During the 1930s and 1940s, Pacific sardines (Sardinops sagax) supported an important fishery in Pacific Northwest waters, but after their population crashed in the mid–1950s, they were rarely observed in this region. Starting in the mid–1990s, sardines resumed migrating into Northwest waters to spawn and feed. Pacific sardines now support a relatively large purse seine fishery centered off the Columbia River. From 1994 to 1998, we identified the abundance and distribution of Pacific sardine eggs and larvae in Northwest waters. The highest egg densities were observed in June 1996. During all years, eggs were associated with surface temperatures between 14° and 15°C. From 1998 to 2004, surface–trawl surveys, primarily on the continental shelf, identified the temporal and spatial distribution and abundance patterns of juvenile and adult Pacific sardines. Adult sardines generally do not over–winter off the Northwest, but migrate north from California in the spring (MayJune) when surface temperatures exceed 12°C. However, juvenile sardines over–winter in nearshore coastal waters. During most years, few 0–age juveniles were captured, indicating relatively poor spawning success; however, high densities of 0–age sardines were observed in fall of 2003 and 2004, indicating successful spawning. During the summer, sardines are most abundant on the shelf in cool (<16°C) and high salinity (>30 S) coastal waters, with their highest densities occurring in northern Oregon/Washington waters. Sardines are non–selective planktonic filter feeders; prey include copepods, euphausiids, and phytoplankton. Sardines are important prey of Northwest fishes, such as sharks, salmon, Pacific hake (Merluccius productus), and jack mackerel (Trachurus symmetricus).