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Recovery Strategy for the Transient Killer Whale [Proposed]
- Executive Summary
- Background (Description and population distribution)
- Background (Habitat and Biological Requirements, Ecological Role and Limiting Factors)
- Background (Threats)
- Background(Actions Already Completed or Underway and Knowledges Gap)
- Recovery ( Goals and Feasibility)
- Recovery (Approaches, Effect and Performance)
- Appendix A: Reference
- Appendix B: Glossary
- Appendix C: Threat Classification table
- Appendix D: Record of Cooperation and Consultation
1.6 Actions Already Completed or Underway
Since the early 1970s, there have been intensive field studies of both resident and transient killer whales in British Columbia undertaken by researchers with DFO, the Vancouver Aquarium, and universities. Annual photo-identification of individual killer whales over this time has provided the foundation upon which studies of killer whale life history, acoustics, genetics and dietary specialization have been built. This, coupled with transboundary collaboration with researchers in Washington, California and Alaska, has been invaluable in providing insight into the life history and ecology of the wide-ranging West Coast transient population. A summary of current research is listed below.
Life history data are collected by photo-documenting individuals on an annual basis whenever possible. The ability to identify and track individuals over time is critical to estimating longevity, birth rates, survivorship, etc., as well as to provide overall abundance estimates for the population. It also forms the basis for analysis for other data, such as acoustic and contaminant analyses. Insight into the foraging behaviour and dietary preferences of killer whales is being provided through direct observations and prey fragment sampling, as well as through the use of acoustic data loggers and time-depth recorders.
Biopsy samples of killer whales are being analyzed for chemical contaminants. These analyses provide information on the contaminant burdens that upper trophic level predators, including humans, are carrying, and to date have revealed that killer whales are among the most contaminated marine mammals in the world. Contaminants in the prey species of killer whales, particularly harbour seals, are also being analyzed. These samples also reflect the contaminant burden of upper trophic level predators, are easier to collect (based on age and sex) than killer whale samples, and provide a means of evaluating the quality of transient killer whale diet (e.g. ‘dietary exposure’ measurement). Environment Canada’s regulatory review of chemicals and non-government programs such as the Green Boater Program and Pesticide Free Lawns, along with the implementation of the Georgia Basin Action Plan (Environment Canada, 2003) are ongoing initiatives that are effective in reducing contaminant inputs to the environment.
Information on the population structure and mating patterns of transient killer whales is being collected through the genetic analyses of biopsy samples. To date these studies have revealed that transient, resident and offshore killer whales are genetically distinct, suggesting a lack of interbreeding. (Barrett-Lennard 2000).
The underwater vocalizations of transient killer whales are being monitored directly during encounters using hydrophones, and also by remotely placed hydrophones. These remote hydrophones can be useful in monitoring habitat use during times of the year when researchers are not able to work in the field.
Killer whales are being monitored for infections, diseases and general health condition through necropsy sampling, and more recently, through assays of exhalations and/or fecal samples obtained from animals in the wild.
Bioenergetic models for killer whales combined with information on the historic abundance of Steller sea lions and harbour seals in British Columbia are being used to estimate the maximum transient killer whale population size that could have been supported by pinnipeds.
DFO is currently undertaking a Recovery Potential Assessment (RPA) to investigate life history parameters for transients, including the ability of the population to grow and recover. This work will inform both the determination of population recovery and assist in the establishment of future population objectives.
The Killer Whale Ecological Survey Team (KWEST), comprised of researchers from California through Alaska who are examining range-wide issues relevant to killer whales, has proposed a broad scale joint Canada/US multi-year killer whale research program across the North Pacific to investigate the ecological role of transient killer whales and their effects on endangered marine mammal species.
1.6.3 Management and Stewardship
Stewardship-based whale watching monitoring and education programs continue to promote safe boating behaviour around transient killer whales. At present these programs are based in Johnstone Strait and in the transboundary waters of Georgia Strait, Juan de Fuca Strait, and connecting passes and channels. The ‘Be Whale Wise’ guidelines, which suggest appropriate behaviours for boaters in the vicinity of whales, have recently been revised by DFO.
Sightings and encounters with killer whales by the public are documented in one of two ways. If a sighting or an encounter is made of live animals, this information is forwarded to the BC Cetacean Sightings Network (http://www.wildwhales.org/stewardship/sightings.intro.html). DFO collects information on incidents in which an animal is injured or dead, or interacts with humans in an unusual way or a possible violation has occurred. A 24-hour hotline is available at 1-800-465-4336 for the reporting of all incidents. Necropsies are performed whenever possible, and can provide information on the diet, cause of death, contaminant loads and other aspects of biological interest relevant to killer whales.
Environment Canada is revising their proposed Risk Management Strategy for Polybrominated Diphenyl Ethers, under the Canadian Environmental Protection Act (CEPA). This strategy supports the ban of several (but not all) of the forms of PBDEs that are known to bioaccumulate in killer whales.
The Department of National Defence (DND) has established protocols to protect marine mammals from disturbance and/or harm from the use of military active sonar. Maritime Command Order 46-13, for marine mammal mitigation, is to avoid transmission of sonar any time a marine mammal is observed within the defined mitigation avoidance zone, which is established specific to each type of sonar. Ship’s personnel receive training in marine mammal identification and detection.
DFO had developed the draft Statement of Canadian Practice on the Mitigation of Seismic Noise in the Marine Environment (DFO, 2005a), to address concerns regarding the potential impact of seismic use on marine mammals and other marine life. A process for the revision and further consultation of the draft Statement is underway. In the Pacific Region, each proposed seismic survey is reviewed by DFO marine mammal experts and mitigation measures are developed based on the species of concern in the area of the survey for each project. Further evaluation is necessary to determine the nature and extent of this threat and the effectiveness of these mitigation measures.
A revised COSEWIC status report for killer whales is currently being prepared. This will provide updated information on the population status of transient killer whales, as well as a review of the threats that the population currently faces.
1.7 Knowledge Gaps
1.7.1 Gaps in Transient Population Data
- There are numerous difficulties associated with accurately estimating the total population of West Coast transients and this is a pressing concern. Achieving consensus among researchers to establish criteria to define and enumerate the population is a priority.
- The life history parameters specific to the transient population are not yet known, primarily because a significant proportion of the population is not reliably sighted each year. Mortality rates are particularly difficult to determine with precision because of long gaps between resightings of many animals in the population. More intensive efforts to encounter transients specifically would help to alleviate this, as well as to acquire acoustic, genetic, distribution and behavioural data that would fill many of the other knowledge gaps for this population. Statistical methods, such as mark-recapture (or sight-resight) techniques, are currently being employed to estimate abundance.
- The historical abundance of transient killer whales is not known. Better estimates of their historical abundance will help to establish meaningful targets for population recovery.
- The population-level consequences of a low population size, and its effects on the sustainability and viability of the transient killer whale population are not well understood. Better insight into the genetic relationships within and between transient populations will help determine the population size needed to maintain the cultural and genetic diversity of West Coast transient killer whales.
- The effects of environmental catastrophes on the abundance of transient killer whales and their prey, as well as their habitat, are not well understood. Similarly, the effects of climate or environmental change on transient killer whales, their prey and their habitat are not well understood.
1.7.2 Knowledge Gaps Regarding Distribution
- Members of the West Coast transient population range widely, and their spatial and temporal distribution is not well understood. The preferred areas or home ranges of some individuals have been estimated for a small proportion of the population only.
- Critical and important habitat for transient killer whales has not been identified.
1.7.3 Dietary Knowledge Gaps
- Although it is well known that transients prey on marine mammals, there are many questions regarding their year-round diet and energetic requirements. The extent to which killer whales rely on specific prey species is not well known. It is also not known how readily, or why, they shift from one prey species to another. The foraging strategies that transients use to detect and successfully hunt their prey are also not well understood.
- Information on the consequences of changes in prey populations is lacking. This is of particular concern given the decline of prey populations in western Alaska and the apparent shifting/switching of key prey species by Gulf of Alaska transients. There is very little known about the distribution and abundance of small cetaceans in British Columbia, thus it is difficult to know their role in the year-round diet of transient killer whales.
- Fatty acid and contaminant profiles that could provide additional information on the full range of prey for West Coast transients have yet to be developed.
- The health indicators for prey populations in the wild are not well developed. Information is generally collected only for stranded small cetaceans and pinnipeds.
1.7.4 Knowledge Gaps Regarding Contaminants
- There is a distinct lack of information on the wide range of anthropogenic environmental contaminants to which transient killer whales and their prey are exposed.
- There is a lack of baseline information on contaminant levels in killer whale males, females and young, and trends over time.
- The effects of contaminants on killer whales, both at the individual and the population level, as well as on their prey and their habitat are not well understood. Similarly, the effects of contaminants passed on to offspring from reproducing females are not well known.
- There are very few baseline data on contaminant levels, including hydrocarbons, in the British Columbia coastal environment (West Coast transient killer whale habitat), rendering mitigation of possible sources challenging.
- There are insufficient means available to measure the health of killer whales in the wild (e.g., biomarkers using biopsy samples).
- The virulence of pathogens in killer whales is not well understood.
1.7.5 Knowledge Gaps Regarding Social Behaviour
- The association patterns of West Coast transients are not well understood, nor are the factors that influence their dispersal.
- The extent to which competition exists within or between groups of transients, and whether this is a factor in individuals dispersing (either temporarily or permanently), is not known.
- The breeding system of transients is not well understood. The mechanisms that transients use to avoid inbreeding are unknown, particularly because all members of the West Coast population share acoustic calls.
- The social relationship between residents and transients is not well understood. The relationships between West Coast transients and other transient populations are unknown.
1.7.6 Gaps in Knowledge Regarding Disturbance
- The long- and short-term effects of physical disturbance (e.g. shipping, whale-watching) on transient killer whales are not well understood.
- The long and short-term effects of acoustic disturbance (chronic as well as acute) on transient killer whales and their prey are not well understood.
- There are very few data on ambient noise levels throughout the range of West Coast transients. These data would provide an important frame of reference to use to assess the effects of acoustic disturbance.
- The effects of stress associated with chronic disturbance of transient killer whales are not known.
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