Northwest Fisheries Science Center

Newportal Blog

A gateway to oceanographic adventures from the Newport Line and beyond

Blog on ocean conditions along the Newport Line and the northern CA Current.

On the Columbia River transect

By Curtis Roegner
June 27, 2016

The crew just deployed the plankton camera sled ISIIS, which we are towing in a sawtooth pattern shoreward. The ship is presently steaming outside the Columbia River plume in “tuna water” (Sal = 31.9; Temp = 15.5oC); unfortunately no bites yet. It will be interesting to see images of plankton from the ISIIS cameras as we transit through the Columbia River frontal region, probably near Station 3. Transit time is ~ 6 hours.

The CTD at sunset.

The primary cruise plan of 10 cross-shelf transects is winding up. The weather has been remarkably calm save for a brief blow on the 18th and we have lost no samples (or cod ends!) due to adverse conditions. Unprecedented! The oceanography across all transects has been very similar except for the varying presence of the Columbia River plume. Salinity gradients indicate weak upwelling at the coast. All nearshore stations had elevated chlorophyll ranging from 4.2 to 25.0 mg/m3 (mean +/- sd = 14.9 +/- 7.2) and bottom DO saturation ranging from 21 to 50%.  Offshore, temperatures ranged (north to south) from 12 to >15 oC.  We encountered plume-influenced salinities at offshore stations on the Newport and Lincoln City lines, and a strong narrow plume (S=28) on the Tillamook Line between stations 7 and 1.  In all, these calm conditions have generated a highly stratified water column in the upper 10 -20 meters that has persisted throughout the cruise. Rather uneventful!  

Neuston net action shot.

We deployed 76 neuston tows targeting crab megalopae, larval fish, and Velella (by-the-wind sailor). Interest in the hydrozoan is due to the huge abundances observed on past cruises and its propensity to feed on fish eggs. This year megalopae and Velella have been scarce and numbers only picked up in the northern transects. Quite a contrast from previous years, but zeros are numbers too.  For the megalopae, comparatively low numbers may be a combination of increased advection due to El Niño and the late June sampling period (later than previous cruises and near the end of the primary crab settlement period). Not sure what explains the low Velella numbers; plenty were reported washed up on Washington beaches in May. Perhaps all the “right-handed” sailors beached and the “left handed” sails advected offshore…. In contrast, larval fish (primarily Pacific saury but at least 4 other species including rockfishes) have been found throughout the sampling. Catches of copepods and krill are also low, but Pleurobrachia comb jellies and salps are unfortunately all too abundant. All in all, a definite contrast to the cruise last year during Warm Blob conditions and a more normal year in 2014.

Food has been superb and I expect all of us will need extra time on the treadmill back on shore.

Tagged: Prerecruit

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