Monthly Archives: March 2009

Gregg Schorr for Brad, dive behavior

• Is dive depth related to prey preference?
• Do dive rates vary between pods, day/night, years?
• Is frequency of max dive depth constant over time?

Prey field mapping in Sept, 2004 (after sockeye, during fall Chinook run): big targets are near middle of water column (>100m); prey assemblages different in Haro Strait?

Wild Salmon Center identified rivers with multiple runs and little development that could be wild salmon “strongholds” or refuges during an age of global warming.

40 deployments 93-2000, 419 hours data, median duration of deployment 10.5hrs.  Velocity spikes are often associated with deepest portion of dive (and some shallow dives).

What are accelerations in shallow dives?  (Tried critter cam)

All individuals old/young and across pods have similar dive profiles and all swam slower at night, but males dive deeper than female adults (but only during day).  There is also an inexplicable change in depth of dives over the years.

Focal follows show they don’t go to the bottom (e.g. 150m dive in 300m water).  This summer we’ll use new tags with a hydrophone and body orientation sensors.  Also planned are satellite tagging efforts.

Rich Osborne, long-term patterns in SRKW residency

43,000 sightings in the OrcaMaster database 1980-2008 (biased towards summer initially, but in last 2 decades it’s become more balanced).  Puget Sound is Admiralty Inlet and Deception Pass south.

After L pod members spent ~a month in Dyes Inlet, they extended their stay in inland waters ever since.  They didn’t often do that before.  This suggests they can adapt to different prey (e.g. Chilco Creek Chum) when stressed (there was only chum to eat in Dye’s Inlet).

NW Straits and Puget Sound seem to be getting more attention in last decade compared with previous 2 decades.  We should be spending all PS salmon restoration  money for those wild rivers.

Pete for Steve Rafferty, epidemiological and pathologic findings

Only 10/81 confirmed SR deaths and 4/142 of NR were beach cast and available for post-mortem examination.  Infectious pneumonia is most common reported cause of mortality (60% of those necropsied).  We now have a standardized protocol for doing necropsies (available at http://seadocsociety.org)  Since 2002, Steve and Joe Gaydos have been trying to determine if bacterial infection was the primary cause of death.

Pete Schroeder, microbial assessment of orca breath and marine microlayer

Used 4 petri dishes swept through blow of adult males.  Each dish has a different medium.  Sampled in 06-08, mostly in late summer/fall.

Partial results:

• L74: Salmonella heidelberg (resistant to 2 antibiotics)
• J1: Vibrio alginolyticus (resistant to 1 antibiotic)
• L41: Pseudomonas fluorescens (resistant to 4 antibiotics)
• >50 bacteria and fungi in local microlayer, similar to biodiversity in Hawaiian waters

Q: Has there been any attempt to correlate the bacteria in the microlayer you sample with local sources of contamination?  Sewer water is a likely source of antibiotics and endocrine disruptors.

Kathrine Ayres, physiological monitoring of SRKW

Looked at two compounds and two sources of change:

• Glucocorticoids (GC, stress hormone) and thyroid (T3, nutrition)
• Nutritional deficit (lowers GC, raises T3), stress from boat interactions (raises GC, doesn’t affect T3)

Prey levels (DFO test catch fishery, Chinook CPUE) and boat density time series increase in May, peak mid-summer, and tail off in the fall.  Samples taken with pool net or 2-liter bottle examined per gram of dry weight.

Results:

• GC falling from May, lowest in July/August, rising towards winter (supports Prey+Boats hypothesis — whales experience times of nutritional stress and disturbance by boats.
• T3 levels in 2008 significantly lower than in 2007 (bad salmon year in 2008)

John Durban, Size and body condition of SRKWs

Southern residents are food limited and culturally specialized to Chinook prey.  Used laser pointers for morphometrics (of commonly visible body parts).  Pitmann, 2007 used size of type C killer whales in Antarctica.  10 filights in September 2008 (elevation >750′ according to permit), 12,000 photos, differential GPS gave accuracy of 2-3m (altitude).  Measured length, girth, and head width, calibrated with boat photos.

We were able to estimate boat lengths well.  We can see growth curves and hope to be able to resolve changes in growth rate.  We can use the head width to estimate body condition.  Dependent young tend to have fattest head, and their mothers are often the thinnest.