Monster Jam, Brad Hanson, 07/04/05
Diet of southern resident killer whales
Inferences from prey samples and sensors deployed on killer whales
Time-depth-recorder deployments in southern residents
- Baird and Hansen+? (2005) J Canadian Zoology
- 40 deployments from 1993-2002
- ~10.5 minutes median record duration
- L87 Haro Strait example record: 2 dives to 100m with velocity spikes near deepest point; 2 dives to 20m with velocity spikes (~4m/s peak)
- overall bimodal distribution with most dives to 25m or 100-150m…
- compare with fisheries data: Quinn says sockeye usually at 16m, Chinook ~70m; Horne says larger echosounder targets are common at 100m (trawl there gave dogfish and juvenile salmon)
2002 crittercam on J25 (1.5 hr data total) example from S Lopez
- Blows bubbles before surfacing
- Blow hole puckers during vocalization
Foraging behavior (samples/behavior metric) is more often defined by low energy behavior (slow convergence) than high
Molecular Genetic analysis
(scales and tissue ~77 samples; about 150 if you include fecal, mucous, regurgitations)
Most samples collected N/S of false bay, SJI
Primary seasonal prey species:
- Chinook (primarily in June-Aug)
- Little data from Sept/oct
- Chum in Oct/Nov/Dec
- NO sockeye or pinks
- ==> are seals and orcas partitioning resources?
From which river systems did the ingested chinook come? (L. Weitkamp, unpublished)
base on (genetic sampling) via coded wire tag program?
- May: southern puget sound fish! (only one Fraser)
- June-Sept:
- Predominance of Fraser
- upper fraser first in mid Jun-aug; then South Thompson; then mixed in Sept
- One central valley ca
- Some N sound, but minimal S sound
Fecal data from sep and oct and nov include evidence of dover sole and lingcod
Planned collections in 2007: June and Sept
Desire for May and Oct collections