Subject: Info: Paper on Ocra Rescue, Barnes Lake, AK
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From: Michael Williamson <WHE_WILLIAM@FLO.ORG>
Subject: Info: Paper on Ocra Rescue, Barnes Lake, AK
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Subj: Nine page summary of Barnes Lake, AK, killer whale rescue
Date: Tue, 28 Feb 1995 16:24:10 -0800
Reply-To: Marine Mammals Research and Conservation Discussion
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From: David Bain <dbain@u.washington.edu>
Subject: Nine page summary of Barnes Lake, AK, killer whale rescue
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The following is a preliminary report on the entrapment and
intervention to aid killer whales in Barnes Lake, Alaska, in
1994. A formal report to be submitted for publication is planned
when data analysis has been completed.
KILLER WHALES (ORCINUS ORCA) IN BARNES LAKE, ALASKA: A
PRELIMINARY REPORT
David E. Bain
Marine World Foundation
Vallejo, CA 94589
February 28, 1994
INTRODUCTION
I received a report that a group of killer whales (Orcinus orca)
was in Barnes Lake, Alaska, from Russ Cameron of Peregrine
Productions of Beaverton, OR. His report raised two bases for
concern. First, the lake contained significant amounts of fresh
water, which might be harmful to killer whales after long-term
exposure. Second, due to the small size of the lake, the food
supply might be limiting. Mitigating these concerns were the
addition to the lake of approximately one-third its volume of sea
water at each high tide, and salmon migrating into Sweetwater
Lake just upstream of Barnes Lake. The whales had apparently
entered the lake on their own, and hence should have been able to
exit the lake on their own. However, killer whales can be
confined by psychological barriers, such as nets or low walls,
which they are physically able to cross.
These concerns raised the possibility that human intervention in
the situation could promote the welfare of the whales. To help
determine whether intervention would promote their welfare, and
what kind of intervention might be appropriate, NMML granted my
request to become a designated agent under its marine mammal
permit, No. 791. Whether intervention was the appropriate action
versus allowing nature to take its course is beyond the scope of
this report.
Prior to my departure for Barnes Lake, I made a number of phone
calls to assess the situation. Descriptions of the group ranged
from seven individuals including one bull, to ten individuals
including 4 bulls. Reported dates of entry into the lake ranged
from mid-July to mid-August. Salmon runs typically persist into
the middle of September, although the runs apparently ended early
this year, with only small numbers of fish entering Barnes Lake
after the 23rd of August. Although U. S. Coast Pilot reports
that there is sufficient depth for killer whales to exit the lake
at high tide, people living in the area indicated current was a
limiting factor, and that there was a short time window around
high slack that they felt safe entering and leaving the lake.
There were also reports that harbor seals had used the lake in
significant numbers prior to the whales' arrival, but had been
scarce since. There was one report of the whales actively
chasing fish during the first half of September.
One fishing guide indicated he had used the lake for nine years
and that this was the first time he had seen killer whales there.
Outside the lake, NMML has been conducting surveys and has
sighted killer whales fairly regularly. Local residents also
reported sightings of killer whales outside the lake, with whales
feeding on fish on some occasions and marine mammals on others.
Although whales had been sighted outside the lake subsequent to
reported dates of entry, there were no reports of killer whales
not being in the lake once it became common knowledge that whales
had been sighted there.
The Barnes Lake area may be used by killer whales described as
members of the Northern Resident Community, Offshore Community,
Transient Community, and other whales previously sighted in
Alaskan waters.
With these thoughts in mind, I departed for the area.
OBSERVATIONS
I flew over Barnes Lake on Sunday, October 2, 1994. One whale
was dead-stranded on a small island. Other whales were still
swimming in the lake. The altitude of the observation (>2000')
did not allow assessment of the condition of the live animals.
On Monday, October 3, I entered the lake in a small boat.
Lighting was poor, and the whales did not allow close approaches.
However, the observations reported below indicated the remaining
whales were in poor to fair condition.
On Tuesday, October 4, no effort was made to enter the lake due
to a tsunami warning.
On Wednesday, October 5, I was joined by Linda Shaw of NMFS, and
Jim Antrim and Bill Winhall of Sea World to aid in assessment of
the situation and to gather information important to the
consideration of options for intervention. Lighting was better
on this day allowing a more thorough assessment of the condition
of the whales.
GROUP COMPOSITION
The original group appeared to consist of nine whales: one adult
male, one adolescent male, four adult female sized animals, one
large juvenile (est. age = 6-8 yr), one small juvenile (est. age
= 2-4 yr) and one calf (est. age = 0-2 yr). By the time I
arrived, one adult female had died. The subadult male was only
seen alive on October 3, and was found dead on Friday, October 7.
A preliminary review of photographs indicates that the whales are
part of the "offshore" community. One has been tentatively
identified as AP1, a female sighted in Icy Strait in 1989 by Dena
Matkin. A second was tentatively identified as O55, sighted in
1992 off Langara Pt. in the Queen Charlotte Islands (G. Ellis,
Pacific Biological Station, pers. comm.).
BEHAVIOR
The whales moved very slowly, generally singly, though
occasionally in pairs, and rarely as a three-some. Saddles were
not raised out of the water, except by the young juveniles. At
least one whale listed slightly to the side on some surfacings.
On some occasions, the dorsal fin was not completely submerged
between breaths. Respiratory intervals tended to be long and
relatively uniform. Breathing sounded slightly less forceful and
crisp than normal. Echolocation clicks were heard, but calls
were not (though the time spent monitoring acoustic behavior was
short). No observations of successful or presumed prey capture
were made. The orcas showed no interest in a harbor seal that
inhabited the lake.
These abnormalities cannot be attributed to the limited size of
the lake. Killer whales in aquaria of comparable depth and
smaller surface area exhibit behavior much more similar to that
of free ranging killer whales than that observed in Barnes Lake.
In contrast to the observed behavior, groups of three or four are
common, and it would not be uncommon for all animals to travel
together. Saddles are normally raised out of the water on most
breaths. Dorsal fins are normally kept vertical, except during
play and foraging. Partial submergence of the dorsal fin is only
normal during deep rest for males, and other whales during active
foraging. Respiratory intervals are normally bi-modal, with a
series of short intervals followed by a long interval.
PHYSICAL CONDITION
The skin of some whales showed large areas of gray discoloration.
The skin had a "matte" finish, rather than the normal glossy
appearance. Observations of the dead male indicated the gray
areas were due to sloughing of large patches of skin, in contrast
to the small flakes that are normally sloughed. The matte
appearance was apparently due to the failure to slough skin.
Slight depressions were observed behind the blowholes of some
whales (most were not approached closely enough to make this
determination). The dead whale appeared thin along the back, and
the outline of the rib cage was visible. Such observations would
not have been possible with the live whales as they did not raise
their backs or ribs out of the water, and the dark color of the
water (perhaps due to dissolved organic matter) prevented
underwater observation.
The dorsal fins were erect, except for small bends which were
well within the range of healthy animals.
POTENTIAL FOR UNASSISTED DEPARTURE
The orcas remained in the deep portion of the lake. They did not
explore the channels leading to open water, or use the shallow
fringes of the lake. Strong currents (estimated at 8 knots 2
hours prior to high tide) flowing into the lake during the rising
tide lent support to the idea that current contributed to the
whales unwillingness or inability to leave lake even when there
was sufficient depth. Thus it seemed unlikely that they would
leave the lake on their own.
POPULATION DENSITY
Barnes Lake has a surface area of approximately 2.5 sq. km. Thus
the population density ranged from about 3.6 / sq. km to 2.8 /
sq. km. For comparison, the smallest day range I have observed
in over 500 days of observation wild killer whales is
approximately 25 sq. km (for daylight periods up to two
consecutive days). The highest population density I have
observed is about 0.4 whale per sq. km of day range. These
observations were in core areas at times believed to correspond
to periods of peak food availability. Observations during times
of limited food availability indicate day ranges may exceed 500
sq. km, with population densities of .01 whales / sq. km of day
range.
INTERPRETATION
I interpreted the observations as follows. The whales showed
subtle signs of being in poor condition. The population density
was far in excess of what was sustainable. The lake was not part
of normal killer whale habitat. The orcas were unlikely to leave
the lake on their own, even if their physical condition
deteriorated. In the absence of subsequent observations to the
contrary, it likely would be in the interest of the whales to be
relocated to open water. Given that one whale had died and that
the condition of the others was likely to deteriorate rather than
improve, intervention as soon as possible was likely to be more
helpful than waiting for obvious signs of distress. With this
interpretation in hand, my authority under the NMML permit was
rescinded, and control of the situation was placed clearly in the
hands of the Alaska Region's stranding coordinator, Linda Shaw.
INTERVENTION
A decision was made to intervene with the following concerns.
Intervention would not promote the welfare of the animals if it
resulted in: A) movement into Sweetwater Lake, B) stranding on a
beach, or C) separation of the two youngest animals from the bulk
of the group. Intervention was to take the form of small boats
driving the orcas through Indian Creek towards open water by
their occupants banging on hollow, metal pipes. To prevent
outcome (A), two boats were stationed at the entrance to
Sweetwater Lake. To reduce the probability of outcome (B), the
drive began with boats far away from the whales, and behavior was
continuously monitored for signs of panic that might lead to
stranding. To mitigate outcome (B) if it occurred, personnel
with experience handling killer whales and stranded marine
mammals were recruited from Marine World / Africa USA, Sea World,
and the California Marine Mammal Center. To prevent outcome (C),
the whales were continuously monitored.
We were also concerned about the safety of the human
participants. The U.S. Coast Guard was notified that the drive
would take place. The Forest Service was notified, and
arrangements were made to use their cabin in case people were
unable to leave the lake (due to tidal conditions or engine
failure). Potential threat displays from the orcas were
discussed, and appropriate responses determined.
A goal was set of having ten boats participate, which would
result in a maximum spacing of ten boats per mile. In the event,
13 boats were recruited. Ten of these boats were assigned
routes, while the remaining three were positioned as necessary.
One boat not banging pipes was used to try to finely adjust the
movement of the whales.
In addition to the three major concerns, some minor problems were
anticipated. First, there was uncertainty in the time the drive
would take. (Timing was critical because human access to the
lake was limited to a few hours, and the time at which the exit
was likely to be passable for the orcas was believed to be much
shorter.) The drive was scheduled as early as possible (based on
tidal limitations to access to the lake), but that might have
resulted in the whales reaching the rapids while they were
impassable. Thus a holding area was identified that had a
relatively narrow opening back into the lake, but provided the
orcas space to remain a comfortable distance from the banging
pipes. This narrow opening was also designated a position for a
safety line in case the whales evaded the main drive line. In
the event, the holding area was used while waiting for the
current to slacken, but the safety line was unnecessary. Another
anticipated problem was that the orcas would enter coves on the
side rather than following the main stream. A boat with just its
engine running was designated to guard the coves. In one case,
the whales went under a boat into a cove. A boat with a banging
pipe was able to return the whales to the main stream. No other
problems, either anticipated or unanticipated were encountered.
Following completion of a final planning meeting, placement of
the boats began at 12:30 P.M. on Thursday, October 6. Once all
boats were positioned, the orcas were located about 2.5 km from
open water.
A boat not banging pipes was used to move the whales farther from
the entrance to Sweetwater Lake. At this point, the orcas were
milling in a tight "ball" in contrast to the wide spacing
observed prior to the entrance of the boats into the lake. Once
we felt the whales were a safe distance from Sweetwater Lake,
people began banging pipes. The whales showed no additional
reaction to this initially. After a few minutes, they began
moving slowly towards Indian Creek, the intended exit.
Two peninsulas form the boundary between Barnes Lake and Indian
Creek. The orcas stopped for quite a while before entering
Indian Creek. Thus these peninsulas appeared to form the first
psychological barrier to leaving the lake.
Once in Indian Creek, the whales proceeded until the first
island. This island caused a significant narrowing in the
channel. The section between the peninsulas and the island had
been designated a "holding area". I checked on the condition of
the rapids and concluded that it would be better to wait for the
current to slacken. The whales milled against the island for a
while, and then moved a short distance back towards the boats,
which held positions between the peninsulas. Thus the island
appeared to form a second psychological barrier. After the
current slackened, the drive continued.
The orcas moved past the island, and proceeded to a kelp bed.
They milled in front of the kelp bed, then moved out of the
mainstream into a cove. A boat with banging pipes was able to
move the whales out of the cove and back to the edge of the kelp
bed. The drive line reached its closest point to the whales, but
the orcas continued to mill next to the kelp. The drive was
paused, because prior observation indicated that increased
outbound current would cause the kelp to lie down, giving the
whales better access to the channel. After a few more minutes,
the orcas went through the kelp bed. Thus the kelp bed appeared
to be the third and most significant psychological barrier.
The whales proceeded to the island which formed the narrowest
portion of Indian Creek. The orcas had passed over the "rapids"
(which were simply a shallow ledge at that time due to the
slackness of the current) without any difficulty. The whales
milled briefly at the island, and chose the narrow channel rather
than the wider dead end bay. The "rapids" would have constituted
a physical barrier at other tidal states, but did not appear to
be even a psychological barrier at high slack. The combination
of the rapids and the island would have constituted a fourth
barrier if the orcas had tried to leave the lake on their own at
any other tidal state.
The drive was completed about 3:15 P.M. The whales were followed
for an additional hour to ascertain whether they were headed for
open water, or into dead-end coves or bays. After exiting the
creek, the orcas headed towards a flock of birds which appeared
to be feeding near shore. After traveling under the birds, they
headed for mid-channel. They continued out to Whale Passage.
They then headed towards Clarence Strait, rather than towards
Whale Pass, which is at the end of an inlet. After leaving the
flock of birds, the whales exhibited normal grouping patterns of
seven abreast or subgroups of 3 and 4 individuals, normal
surfacing postures, and normal respiratory intervals. They
paused about 3 km outside the lake. It is unclear whether they
paused to try to determine their location, or they were just
resting. After this pause, they continued toward open water.
OPTIONS REJECTED
A number of possible interventions were considered and rejected.
First, handling the orcas for medical exams prior to attempting
to coax them from the lake was considered. However, observation
of the surviving whales the day before the drive indicated that
they were likely to be in good enough condition to take care of
themselves. Providing food supplements to the whales until they
figured out for themselves how to get out of the lake was
considered. However, the skittish behavior of the orcas around
boats suggested they would be difficult to feed directly unless
their condition worsened and they stranded on a beach.
Supplementing the lake population of fish was considered
impractical due to the large quantity of fish needed to feed that
particular group of whales. The use of nets rather than noise to
herd the orcas was rejected due to difficulties anticipated from
bottom topography, complications due to kelp beds, and the risk
of entanglement. The use of explosives such as seal bombs was
deemed unlikely to be necessary. The use of a single sound
source was rejected due to the difficulty in directing movement
in a particular direction, and the consequent risk of stranding.
The play-back of killer whale calls was rejected because the
population affiliation of the whales was unknown, and hence their
response to a play-back would be totally unpredictable.
TIMING OF THE INTERVENTION
On October 3, the first day of close observation, it was
determined that some form of intervention was likely to be
appropriate, and preparation for the drive option began
immediately. Personnel and equipment began moving to the area on
October 4 (due to the remoteness of the area, it was not possible
for all of the key people to reach the area in one day).
Intervention was not attempted on October 5 because local
resources were committed to an earthquake preparedness drill, and
more information about the lake itself and the conditions of the
whales were needed to plan for a safe intervention. Intervention
took place on October 6, the day with the best tidal conditions
and suitable weather. October 7 would not have been possible
because bad weather would have precluded the use of the small
boats. Tidal conditions progressively worsened after October 7.
DISCUSSION
The decision to intervene was based primarily on the situation
(population density and food availability considerations) and
subtle abnormalities in behavior and appearance. Thus it is
possible that the decision to intervene was premature. However,
the four points during the drive where the orcas stopped
supported my impression that it would be unlikely for the whales
to leave the lake on their own. The death of the second whale,
which was not confirmed until after the drive, supported the
impression that the whales would remain in the lake until death
rather than leave when their condition became poor. The marked
change in behavior upon leaving the lake suggested their welfare
had been improved, whether or not intervention was necessary to
save their lives. The lack of significant adverse reactions to
the drive (changes in individual spacing, direction of movement,
and an occasional fluke slap were all that was observed, and
these are not uncommon responses to recreational whale watching)
indicated that the intervention was humane and probably caused
the least possible disturbance. Presumably, early intervention
as selected here was more beneficial to the orcas than delayed
intervention would have been. In the latter case the whales
would have been in worse condition and less able to take care of
themselves when they did leave the lake.
ACKNOWLEDGMENTS
I would like to thank Russ Cameron and Peregrine Productions for
organizing the logistics for this work, his assistance with data
collection, and financial support. Louisiana Pacific, Ketchikan
Air, The Marine World Foundation and Sea World provided financial
support. I would like to give special thanks to Nani Fannemel
and Geno Namaau of Whales Resort for providing logistical support
to the field team. Gene Hering, Victor Ives, and Mike McKenzie
also provided assistance in the field. I would like to thank
many people from NMFS (both in Seattle and Juneau) and the U.S.
Forest Service for helpful information and advice. I would like
to give special thanks to Laurie Gage of Marine World for her
advice and assistance with coordinating the intervention. I also
give special thanks to Mike Demetrios of Marine World / Africa
USA for encouraging me and Dr. Gage to participate, his behind
the scenes work on logistics, and his usual advice to "do what's
best for the whales." Mike Farley played a key role in
organizing local responses from Whale Pass and Coffman Cove. I
thank him and the people of those communities for their excellent
work. The California Marine Mammal Center provided the poles
used in the drive and staff support. Finally, I would like to
thank NMFS for responding promptly to all requests for permission
to take actions to benefit the welfare of the killer whales in
Barnes Lake.