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Title: April 2008 Krill Mortality
Author: HCDOP IAM; Newton and Hannafious
Category: Fish kills
Data Source: HCDOP
File Size: 2 mb
File Type: Image (JPG or GIF)
Date Catalogued: Monday, April 21, 2008
Comments:

Several reports of dead krill in Hood Canal were received over the period 7-16 April, 2008. Krill are zooplankton, tiny small shrimp-like marine invertebrate crustaceans; the scientific name for krill is euphausiids. Samples of the dead organisms from a beach were examined by Dr. Julie Keister, University of Washington, who identified them as Thysanoessa rachii, a euphausiid species known to occur in Dabob Bay, Hood Canal. The spatial extent within Hood Canal appears extensive, but cause of the event is still not known. Oxygen concentrations are seasonally high at this time, and the concentrations measured in the area are very unlikely to have caused mortality. Similar mortality events have been reported elsewhere, and are sometimes associated with post-spawning. One of the recent Hood Canal observations noted very high concentrations of living euphausiids, and it is possible that some of the very plentiful organisms were carried ashore by wind or waves. Samples have been obtained for examination of health, parasites, or other abnormalities. A chronology of this event is provided below.

On 7 April, the Department of Fish and Wildlife received a report from a Hood Canal citizen that a mortality event of “krill” had occurred over the weekend and was still evident. The resident, who lives near Musqueti Point (southern Hood Canal), described the event as a “huge kill” of shrimp or krill in a two foot swath of shoreline that had extended an unknown distance in either direction. By the time of the report, the mortality appeared to have ceased and no samples had been taken for identification. The extent of the kill was undetermined at that point.

The report was forwarded to the Department of Ecology per the Hood Canal event response routine and HCDOP was notified. As part of the response mechanism, the Skokomish Tribe was contacted and they responded by boat to investigate the report, but found no dead organisms in the area.

On 10 April, several Pt Gamble S’Klallam Tribal natural resource personnel reported a large mortality of krill while water sampling from the Hood Canal bridge. Tribal staff found large numbers of dead animals on the beach at Salsbury Pt and collected a few, which were later frozen.

On 11 April, personnel from the Hood Canal Salmon Enhancement Group (HCSEG) collected samples of krill that were evident on the beach north of the Hood Canal bridge. The preserved samples were sent to the UW where Dr. Julie Keister, University of Washington, identified them as Thysanoessa rachii, a euphausiid species known to occur in Dabob Bay, Hood Canal.

On 16 April, the Washington Department of Fish and Wildlife relayed another message from a resident in southern Hood Canal about a large number of dead shrimp-like animals washing ashore east of Union. The animals had been on the beach for several days and there appeared to be no sign new mortality. No other types of organisms were associated with the mortality. HCSEG personnel investigated several beaches in the vicinity and collected some specimens from the high tide line of four beaches. The specimens appeared different than the krill identified previously and have been sent to the UW for identification.

On 16 April, Jake Gregg of the United States Geological Survey collected several thousand live euphasiids from near the Hood Canal bridge. They had been caught between the sections of the bridge and according to bridge personnel represented just a remnant of the animals observed the previous week, when the water was "red" with the organisms. The animals will be screened for disease and parasites and a portion of these samples have been sent to UW for taxonomic identification.

Dr. Bill Peterson (NOAA, Newport Oregon) shared that a massive die off of krill-like organisms was also reported 10 April on the beaches just inshore of Coos Bay, Oregon.