Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Chinook salmon from the Lower Columbia River use these estuaries during the period when
carbaryl is applied based on their behaviors (Personal communication Eduardo Casillas NMFS
2/18/2009, Anne Shaffer WDFW 3/04/2009, and Thom Hooper NMFS, 2/12/2009).
Specifically, their use of dendritic channels to access inundated mud flats suggests juvenile
Chinook salmon will be exposed to peak carbaryl concentrations in the water column and also
from feeding on live and dead contaminated prey. Also, recent information (six years of
coastline surveys) shows that juvenile Columbia River Chinook salmon “bounce” north along the
Washington coastline and south along the Oregon coastline in the nearshore surf zones (Personal
communication Eduardo Casillas NMFS 2/18/2009 ) and have been found occupying nearshore
habitats as far North as the Strait of Juan de Fuca (Shaffer, Crain et al. submitted). In one study,
juvenile Chinook salmon captured along the coast Washington State were genetically analyzed to
determine natal river origins. Of the fish collected for genetic analysis, 45% of juvenile
Chinook salmon collected in Crescent Bay, 75% of those in Freshwater Bay, and 60% of those in
Pysht Bay were from ESA-listed stocks of the Columbia River (Shaffer, Crain et al. submitted).
DNA analysis revealed that adult salmonids harvested in Willapa Bay in July and August, when
carbaryl is typically applied, include several ESA-listed species: Lower Columbia River
Chinook salmon, California Coastal Chinook salmon, Puget Sound Chinook salmon, and Snake
River Fall-run Chinook salmon (Kassler and Marshall 2004). Given this information we also
expect these same species of Chinook salmon will be present in Grays Harbor as Grays Harbor is
located just north of Willapa Bay. Further, we expect adults of these stocks may be exposed to
carbaryl given that they occupy the estuary during the application periods and oyster plots occur
throughout the Bay. It is possible that chum salmon from the Columbia River also occur in the
Willipa Bay and Grays Harbor estuaries. However, we are unaware of documentation of their
occurrence at those locations, and unlike juvenile Chinook salmon from the Columbia River,
juvenile chum have not been found in recent sampling efforts of nearshore surf zones. We
therefore conclude that Columbia River ESA-listed chum are unlikely to be present in Willapa
Bay or Grays Harbor.
374