Monthly Archives: October 2010

Chum salmon: orca prey around Puget Sound

As the southern residents are visiting Puget Sound today, I’m inspired to learn a bit more about chum and where to view the fall runs.

The Washington Department of Fish and Wildlife has some good background information in their section on Chum Salmon Stories.  Of particular import to the southern residents is the fact that Chum salmon are the most abundant salmon species in Washington State.  In “Respect” Jim Aimes writes points out that recent chum runs are about has good as they have ever been, in contrast to the declines experienced many Puget Sound chinook and coho populations:

If we consider only naturally produced fish, the most abundant salmon in Washington State are chum salmon. In case you missed that – chum salmon are the most abundant wild salmon in our state! This is probably the best kept “secret” in the salmon business. In the five-year period 1994-1998, over 6.5 million wild chum salmon returned to Washington waters. Of that total, approximately 6.2 million wild chum returned to Puget Sound and over 300,000 were destined for coastal streams. Given the very real problems faced by wild fish and the recent tales about the supposed imminent demise of all wild salmon, these chum returns are pretty remarkable.

Chum salmon are also very successful at a number of hatcheries, although they seldom receive the emphasis provided to chinook and coho salmon. The majority of hatchery chum programs are located in the Puget Sound region; producing fish from WDFW, tribal, and federal facilities. The return of hatchery-origin chum for the above 5 years (1994-1998) was nearly 2.6 million fish. Combine the wild and hatchery returns for those 5 years and the total is over 9 million fish, or an average annual return of more than 1.8 million chum.

For guidance on how to view these fantastic fish, here is a blurb from WDFW with a link to the Piper’s Creek (Carkeek Park) population:

Various chum salmon stocks spawn in Washington streams from August through March. The duration of spawning for individual streams, however, is typically much shorter; usually one to two months. The best time to view chum salmon in local streams is November and December, when the large runs of fall chum are spawning.

There are a number of visitor-friendly locations where chum salmon spawning (both wild and hatchery fish) can be observed. This page will identify a number of these locations, and will provide travel information and the best season for chum salmon viewing. The initial location will be the Kennedy Creek Salmon Trail in the Olympia area, with more locations to be added in the near future.

And here is a nice piece on the fall chum runs of the Kitsap Peninsula and Chico Creek in particular by Chris Dunagan.

Marine acoustics talks in Victoria (live blog)

This week the Canadian Acoustical Association is running a conference on marine and environmental sound (abstracts).  Below are notes from talks that relate to the southern resident killer whales, presented in near-real-time.

9:00 Keynote: The Marine Soundscape and the Effects of Noise on Aquatic Animals

Christine Erbe

Marine soundscapes include natural sounds (e.g. from rain), marine organisms, and human sources.  Christine played a wide variety of sounds from many of these sources, highlighting along the way the opportunity to listen live for southern residents in Washington State and British Columbia.  Most amazing were recordings of belugas, aptly known as “sea canaries,” and humpbacks singing over mid-frequency sonar.

Odontocetes generate sound within their nasal system, not the larynx.  Echolocation clicks include energy at frequencies as high as 180 kHz for some porpoises. Pile driving recorded near Australia has a power spectrum with a very broad peak centered near 200 Hz.

The effects of noise on aquatic animals can be graded from most severe to weak: damage, temporary threshold shifts, out to behavioral response.

Graded effects of noise on aquatic animals

There is little data on chronic effects of noise. We can model cumulative sound exposure, but measuring the exposure directly will be challenging. [Perhaps Marla's recent DTAG deployments on southern residents will help calibrate models made with regional ambient noise and ship traffic data?]

10:20 How deep do you call? Depth localization in Southern Resident killer whales using passive acoustics.

Jason Wood

We recorded 189 minutes of southern resident calls and clicks as they transited Admiralty Inlet where Snohomish Public Utility District is prospecting for tidal power.  We used a 4-element vertical array and localized the sound source by measuring the time of arrival differences (TOADs) between the different elements.  TOADs were computed using cross-correlation for calls and hand-picking of first arrivals for clicks.  The technique was validated using light bulbs as a synthetic source at known depths.

Of 510 calls and 145 independent clicks, about 80% of calls and clicks were made shallower than 30m, but some sounds (about 5%) were emitted at 60 m or deeper.  So killer whales are using the full depth of the prospective tidal turbine location.  Adjusting the source depths using the light bulb calibration (mean error of localization is 13 m deeper than actual bulb), our depth distribution compares well to the time-depth-recorder data from southern residents throughout their critical habitat (kindly shared with us by Robin Baird).

We also grouped our data by behavioral state of the pod during acoustic observations.  One surprise was that the depth of sounds made during social behavior were significantly deeper than other behavioral states.  Also, the mean depth of calls during foraging was the same as the mean depth of the clicks.

11:00 Assessing the effects of mid-frequency sonar on cetaceans in Southern California

Mariana Melcon

Looked for echolocation clicks of beaked whales (power at 30-60 kHz, depending on species) and periods of mid-frequency active sonar (MFA, 1-8 kHz) in HARP data (sampling at 200kHz).  Beaked whales click 30-50% less often during MFA exposures.  [Did southern residents click less during the Shoup incident?]

Transients harrassed near Shelton, WA

Interesting Kiro 7 video report regarding harassment of killer whales in Puget Sound during 2010.

And here’s a sighting report from Orca Network that is probably related:

Sighted 2 Orca for sure, when they came back east I thought at one point there were 3. They were in Hammersley Inlet at approximately N 047 12.360 – W 123 1.66, traveling west at 9 AM. East at 11AM. On the way west they were surfacing a lot. On the way east, they sounded right about the listed location and did not surface again in sight (I can see east to about 47 11.943). There was some construction noises going on at Skookum point – loud miter saw. The inlet is only 1/4 mile wide, and they were on the side opposite of me – much deeper water. I have noticed several harbor seals around in the morning lately – there must be food in the area. — Willard.

L pod was sighted that day in Haro Strait, so there are some indications these were transients who are listed as threatened under the ESA and also protected by the MMPA.  Fines could go even higher than $10k if the harassment was criminal, as opposed to civil.