Northwest Fisheries Science Center

Hydrography, Zooplankton, and Ichthyoplankton

Much of the oceanographic data shown in this report came from sampling along the Newport Hydrographic Line (Figure HZI-01). We sample the coastal waters off Newport at biweekly intervals during the upwelling season in spring, summer, and fall. Sampling cruises are conducted monthly during stormy winter months. This program began in May 1996, but we also have data from these same stations from sampling conducted in 1973 (Peterson and Miller 1975), 1983 (Miller et al. 1985), and summer 1990-1992 (Fessenden 1995).

Map of Oregon and Northern California coast showing sampling transects used by NOAA Fisheries during ocean sampling cruises.  Figure HZI-01.  Transects and stations sampled during cruises by the NOAA Fisheries Service.

Cruises during May 1996-September 2001 were made only during daylight hours because our research vessel, the RV Sacajawea was only 37 ft in length, rendering it unsafe to work at night. With the acquisition of a new and larger research vessel ( The next link/button will exit from NWFSC web site RV Elakha; 54-ft.) in September 2000, we were able to sample at night. Thus in fall 2000, we began collecting data for an adult euphausiid time series.

This work included measurements of copepod and euphausiid egg production and molting rates.  We are also developing a long time–series of copepod and euphausiid production, which should prove useful in evaluating if in fact there are measurable differences in zooplankton production in association with changes in sign of the Pacific Decadal Oscillation.

From 1998 to 2003, we sampled a group of transects from Newport, Oregon down to Crescent City, California five times per year as part of the U.S. Global Ocean Ecosystem Dynamics ( The next link/button will exit from NWFSC web site GLOBEC) program. Since the GLOBEC project ended, we have continued to sample these same transect lines as frequently as possible. Thus far, we have been able to sample this region in 2004, 2006 and 2008-present, and have extended the Newport Line out to 200 miles from shore. Additionally, we also sample north of the Newport Line at least 3 times per year as part of the Juvenile Salmon sampling program. As a result, the Newport biweekly data are nested within larger scale semi-annual to quarterly surveys, an approach that is useful in helping us interpret locally derived data from the inner portions of the Newport Line.

At each station, a CTD profile (Conductivity, Temperature, and Depth; Seabird‡ SBE 19 CTD) is taken, and transparency of surface waters is measured (Secchi disc). A bucket of seawater is collected from the surface for analysis of chlorophyll-a and nutrients. A vertical plankton net fitted with a flowmeter is towed from near the sea floor to the surface (or from 100 m to the surface in deeper waters). The plankton net is 0.5 m in diameter with a mesh size of 202 µm. A double oblique tow is made for ichthyoplankton (0.6-m diameter bongo net with 333-µm mesh) over the upper 20 m. Since 2005, CTD casts have included fluorometry (WetLabs fluorometer) and oxygen (Seabird oxygen sensor).

Nutrients are analyzed using a Technicon Autoanalyzer.  Chlorophyll–a is extracted from glass–fiber filters in 90% acetone then analyzed using a Turner Designs Fluorometer.  Zooplankton samples are processed in the laboratory by subsampling with a Stempel pipette.  Species and developmental stage of copepods are enumerated with the aid of a dissecting microscope.  Counts are converted to number of individuals per m³ of water using appropriate conversion factors.  Biomass is estimated by multiplying the number of individuals per m³ by the dry weight of the taxa (using values from either literature or our own measurements).  Carbon content is calculated assuming carbon is 40% of dry weight. 

‡Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA.