While peer review is occurring presently for the scientific publication of our research papers, we also recognize the need for current scientific information on the question of what is leading to increased mortality rates in the southern orca population.
One of the main goals of the Orca Relief Citizens' Alliance is to further scientific knowledge regarding the recent decline of the Southern Resident pod of Orcas. To this end, we asked three independent researchers to find a cause for the orca decline.
Bain, David: A model linking energetic
effects of whale watching to Killer Whale (Orcinus orca) population
These three papers, we believe, extend the good work many of you have started in earlier years; most of the ideas are not too surprising (with a few exceptions), but the results certainly are. While I encourage you to read them in detail, I would like to take a moment to point out three results (one each) which I believe warrant real attention. The following comments are in my own words, although you will find matching statements in the papers themselves:
Although you will no doubt come to your own conclusions about what these findings all mean for the southern residents, we have constructed a sentence based upon your work, and this work, which we believe best represents what is known about what is killing these whales:
"In an environment of declining salmon, the presence of the whale watch fleet decreases sonar efficiency by 95-99%, while increasing food requirements; the resulting starvation forces the whales to draw down toxin-laden blubber, and they die."
Those of you most focused upon the role of toxins will notice that this explanation provides the first rationale explaining how the whales might be increasingly affected by PCBs, even as these have declined over decades in the marine environment.
We feel it is important to share these findings with the scientific community at this time in order to make this information known, and discuss and establish future policies regarding the southern resident killer whale population.
Study SummariesA MODEL LINKING ENERGETIC EFFECTS OF WHALE WATCHING TO KILLER WHALE(ORCINUS ORCA) POPULATION DYNAMICS
Dr. David Bain
The southern resident killer whale (Orcinus orca) population declined from 98 to 79 animals from 1995 through 2001. While reduced prey availability and exposure to toxic chemicals are widely accepted as potential contributing factors in the decline, the suggestion that whale watching traffic may also play a role is more controversial. We combined three analytical models with changes in behavior measured in northern residents and approximate levels of whale watching traffic experienced by southern residents to estimate population-scale effects. These effects would result from increased energy expenditure due to avoidance responses and reduced energy acquisition due to acoustic impairment of foraging efficiency. Our models indicate that population-level effects are negligible for killer whale populations well below carrying capacity (K). Thus population growth in the presence of disturbance cannot be used to conclude that disturbance will not affect the population at higher densities.
We demonstrate that missed prey due to noise is potentially a more important mechanism than excess energy expenditure. The high value of the shape parameter (z) of the killer whale population growth model suggests that the maximum net productivity level is over 80% of K, rather than the NMFS default of 50-60%. Similarly, the Potential Biological Removal level calculated with z=1.0 is too high. Southern residents are currently below their maximum net productivity level and should be considered a depleted stock. Any human-induced mortality or serious injury at levels exceeding one individual every 2-10 years needs to be reduced. The best estimate of the effect on carrying capacity of whale watching at current levels is about 3% due to excess energy expenditure, but insufficient data are available to reliably estimate the impact of noise.
Clearly, more data are needed to determine whether the actual impact of whale watching that our models predict exceeds “insignificant levels approaching zero.” However, the precautionary principle supports mitigating potential impacts until data become available to indicate that regulations or guidelines are unnecessary.
FROM 1986 TO 2001 IN THE SOUTHERN RESIDENT KILLER WHALE POPULATION,
This study provides a comparison of the physiological changes of the southern resident killer whale population from a period of very little boat traffic to an era of increased marine vessel commerce, and it clearly indicates that boat traffic has a negative effect on the whales. The regular physical activity of the southern whales has increased in recent years. Swimming velocities and respiration rates of the southern whales have shown statistically significant increases since the 1980’s. Increases in respiration rates indicate that the animals are stressed. It appears that the significant environmental change that may contribute to the change in energy expended is the increase in whale watch boat traffic.
The increase in swimming velocity is metabolically very costly. Avoidance behavior carries high energetic costs. Any increase in swimming velocity and respiration rate needs to be balanced by an increase in food consumption in order to pay metabolic debts. With the decrease in salmon stocks, this poses an additional threat to the orcas. If energetic demands cannot be met, females might not be able to satisfy high feeding demands of calves, adipose tissue is reduced, which concentrates the level of toxins in the blubber, and immune systems are weakened.
A decrease in foraging opportunity, increased energetic demands due to boat traffic and noise, a possible disruption of sleep patterns combined with a decrease in food availability and toxic contaminants all can lead to lowered immune functions, decreased fecundity, a decrease in survivorship, starvation, decreases in population size and possibly extinction.
EVALUATION OF FACTORS
INFLUENCING THE POPULATION DYNAMICS OF THE SOUTHERN RESIDENT POPULATION OF
KILLER WHALES (Orcinus orca[L.])
Survival rates in the southern resident orca (SRO) population were found to vary over time, with different age and gender classes showing different patterns of temporal variation. Survival rates declined most strongly for males and especially old males over the time course of the analysis (1974 through 1999). Survival rate also declined for old females. Calf survival was more variable than any other age or gender category. Despite the suggestion of declining calf survival in the data, however, variance over time was sufficiently high that the apparent temporal trend was not significant.
Of covariates evaluated, boat activity was most strongly correlated with the trends in survival described above, followed by salmon abundance, except that the apparent trend in calf survival was sensitive to the specific model used. Sea surface temperature, a proxy for a number of important environmental processes, did not correlate well with survival trend. Contaminant effects could not be evaluated as a covariate because of the absence of a time series of data. Finally, a simulation analysis indicated that demographic stochasticity alone could explain observed trends in the SRO population at least through 2000. Our analysis suggests the possibility of a combination of anthropogenic factors and random demographic variation are contributors to declines in the SRO population.
Dr. Birgit Kriete, Ph.D. brings nearly 20 years of whale research experience in Europe and North America to her position as Executive Director at the Orca Relief Citizens' Alliance (ORCA). ORCA is a non-profit effort to study and reduce Orca mortality rates.
Kriete obtained her Ph.D. as a whale researcher through the University of British Columbia in Vancouver, B.C. in 1995. Her dissertation was "Bioenergetics in the killer whale, Orcinus orca". She has been an independent researcher since then.
Her many years of studying whales includes serving as research and education director at The Whale Museum in Friday Harbor, Washington as well as work as a research intern and assistant at the Center for Coastal Studies in Provincetown, MA, where her work included research on right, humpback, finback whales, focusing on prey items of the endangered North Atlantic Right Whale. Kriete also conducted research on the "Killer Whale Population Assessment in Sweden and Norway" through Memorial University, St. Johns, Newfoundland.
Kriete currently resides in Friday Harbor, Washington.
Carlos Alvarez-Flores is a Doctoral Candidate at the School of Aquatic and Fisheries Sciences of the University of Washington. He works under the supervision of Glenn VanBlaricom Assistant Unit Leader (Wildlife) of the Washington Cooperative Fish and Wildlife Research Unit. He is also under the supervision of Douglas DeMaster currently Science and Research Director of the Alaska Fisheries Science Center of the National Marine Fisheries Service.
Carlos is a citizen of Mexico where he got his MS degree in Science (Biology). His research interests are directed towards applications for the management of activities that affect marine mammal populations and wildlife in general. He initiated in Mexico many of the now successful cetacean photo - identification efforts. He has also worked as a private consultant for the governments of Mexico, the USA and Greenland. He has also conducted private consulting research for the private sector and for international organizations of different nature such as Greenpeace and the North Atlantic Marine Mammal Commission.
Carlos is expecting to defend in July his dissertation on the incorporation of uncertainty in the management of activities that affect marine mammals utilizing as a case study the problem of dolphin mortality in the tuna fishery of the eastern tropical Pacific Ocean.
Glenn R. VanBlaricom
Glenn R. VanBlaricom is an Associate Professor at the School of Aquatic and Fishery Sciences, University of Washington (UW), and is the Assistant Unit Leader (Wildlife) of the Washington Cooperative Fish and Wildlife Research Unit. He has a research group of nine currently enrolled graduate students (7 PhD, 2 MS). Five doctoral and five MS students have graduated from the UW Program since it was established in 1993. VanBlaricom has 41 publications in the technical literature and has made 122 formal research presentations, including 49 invited presentations, at professional conferences and university seminars. He has published two books (one technical, one non-technical) on sea otters. He has served two stints (eight years total) on the Board of Governors of the Society for Marine Mammalogy (SMM), is currently a candidate for the office of SMM President-elect, and he is a former member of the Board of Editorial Advisors and Referees of the international research journal Marine Ecology Progress Series.
VanBlaricom received Bachelor of Science degrees in Zoology and Oceanography in 1972 from the University of Washington, and a PhD in Oceanography from the Scripps Institution of Oceanography, University of California, San Diego, in 1978.
The VanBlaricom research group is interested in the conservation biology and trophic and community ecology of marine mammal populations, with particular emphasis on coastal species of the North Pacific Rim and the Arctic region. Among current activities are: studies of predation by harbor seals on depleted salmon populations in Puget Sound and southern coastal British Columbia; studies of beluga whale population dynamics and habitat utilization in Cook Inlet; studies of habitat utilization by belugas and narwhals along the Arctic coast of Canada; population dynamics of killer whales in the Bering Sea, northern Gulf of Alaska, southern British Columbia, and Puget Sound; population dynamics of gray whales in the Russian Far East; interactions of the tuna purse-seine fishery with pelagic dolphin populations in the eastern tropical Pacific; population estimation for minke whales in wintering grounds off Brazil; migratory corridors of humpback whales in the southwest Atlantic; and the community ecology of sea otter populations in Washington. The VanBlaricom group is also involved in coastal benthic ecological studies, including the population biology and conservation genetics of black abalones in California, the effects of disturbance by geoduck fisheries on benthic ecosystems in Puget Sound, and habitat and ecosystem associations of deepwater benthic rockfish populations off the Washington coast.
ORCA RELIEF CITIZENS' ALLIANCE
© 2011 Orca Relief Citizen's Alliance