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Recovery Strategy for the Sea Otter (Enhydra lutris) in Canada



2. Recovery

The sea otter recovery strategy recommends a non-intrusive approach to recovery that recognizes sea otters’ ability to rebound, but also considers that threats could limit or even reverse the current population trend if not addressed. The approach focuses on identifying and reducing threats that might impede continued recovery.

2.1 Recovery Goal

The recovery goal for sea otters is to see that the sea otter population in BC is sufficiently large and adequately distributed so that threats, including events catastrophic to the species, such as oil spills, would be unlikely to cause extirpation or diminish the population such that recovery to pre-event numbers would be very slow.

2.2  Recovery Feasibility

Sea otter recovery is feasible. Sea otters have the capacity to rebound from a small founding population, as illustrated by the growth of several translocated populations, including the population in BC, and remnant populations. Food is generally viewed as the main factor that limits population growth. Much of the BC coast remains unoccupied by sea otters and, for this reason, population recovery is unlikely to be limited by food or habitat at least in the near future. Among successfully translocated populations, early growth rates have been very high (between 17 and 20% per year) at a rate near the physiological maximum (rmax ) of the species (Estes 1990). These high rates are likely attributable to unlimited food and habitat resources in the areas of reintroduction (Bodkin 2003). Growth rates have, however, been more variable and lower (Bodkin et al. 1999), including periods of decline, among remnant populations. The reasons for these differences are not clear, although it is likely that continued illegal harvest following protection in 1911, as well as incidental mortality related to fisheries in the later part of the 20th century, were some of the contributing factors (Bodkin 2003).  

One of the largest threats to sea otters is an oil spill. Such an event could occur at any time and could cause significant mortality. Furthermore, recovery of sea otter populations in an area contaminated by oil can be slow (Bodkin et al. 2002). Concerns about the reduction of socially and economically valuable invertebrate resources by sea otters may also prove to be a challenge to gaining support for sea otter recovery. Finally, sea otter population growth can reverse dramatically and rapidly. Entanglement in fishing gear, disease, large scale ecosystem shifts and oil spills have been demonstrated to cause or contribute to declines in California, Southwestern Alaska and Prince William Sound, Alaska.

2.3 Population and Distribution Objectives

Sea otter distribution and abundance are highly inter-related. Unoccupied habitat is sequentially occupied as the number of otters in an area approaches carrying capacity. Given the relationship between range size and population abundance, coupled with the localized movements of individuals, it follows that increasing the geographic range to reduce the risk from human-induced mortality will also result in an increased abundance of sea otters.

The objectives for at least the next five years that will be used as a measure of progress towards reaching the recovery goal are:

  1. To observe that the geographic range of sea otters in coastal BC continues to expand naturally beyond the 2004 continuous range (see Section 1.3 Populations and Distribution) in order to be able to survive events catastrophic to the species, such as an oil spill, and be able to rebound within a relatively short period of time to pre-catastrophe numbers.
  2. To observe that the number of sea otters (compared to 2004) correspondingly continues to increase in order for the geographic range to expand.

2.4 Recovery Objective

Identify and, where possible, mitigate threats to sea otters and their habitat to provide for recovery of the population.

2.5  Approaches Recommended to Meet Objectives

The following activities are broadly grouped into four approaches that are recommended for recovery: Threat Clarification Research, Population Assessment, Protection, and Communication. The approaches are ordered in relation to the objectives, and within each approach, the activities are ordered from highest to lowest priority. The approaches refer only to the sea otter population in Canada, unless otherwise stated.

2.5.1 Threat Clarification Research

In order to protect sea otters from threats to their survival, research is needed to identify and clarify the significance of threats and factors that may limit sea otter population growth and range expansion. These include threats not only to sea otters but also to their habitat.

  • Assess the potential for oil spills to impact sea otters by modeling oil spill trajectories and sea otter habitat, using sea otter distribution, rafting and foraging area data and identify areas where sea otters are most susceptible to oil spills. 
  •  Identify options to reduce risk to the population from oil spills. 
  • Assess the genetic diversity of the sea otter population and monitor population measures that are indicative of fitness and of vulnerability to stochastic events.
  • Develop a sea otter health-monitoring program. Include assessment of body condition, disease exposure and contaminant burdens in live-captured sea otters and perform necropsies of fresh carcasses when the opportunity arises. Develop a set of standard morphometric measurements.
  • Assess the occurrence and significance of sea otter entanglement in fishing gear and collisions with vessels.
  • Assess the occurrence and significance of illegal killing and disturbance of sea otters.
  • Assess sources and the significance of natural predation.
  •  Incorporate relevant research from other jurisdictions (e.g. Washington, Alaska), First Nations and coastal communities.

2.5.2 Population Assessment

Population assessment will involve surveys to assess population distribution, relative abundance and trends in growth to monitor progress towards recovery.

  • Undertake regular surveys of the sea otter population, to monitor population size, growth and distribution. 
  • Develop models to help define a geographic distribution that is better able to withstand catastrophic events, particularly oil spills.
  • Develop or refine a sea otter carrying capacity model for the BC coast that could be used to assess recovery compared to a theoretical maximum population size that the habitat could support.

2.5.3 Protection

Approaches to protection should include the following activities.  With further research (See Section 2.5.1), additional efforts may be needed.

  • Respond to oil spills. Oil spills remain the single biggest threat to sea otters.  An oil spill response plan working document specifically for sea otters has been developed (SORT 2004). Greater readiness to implement the response plan in the event of a spill is needed.
  • Protect important habitat for sea otters from identified threats. This might be achieved in part by improving habitat protection in existing protected areas and closures from activities that are likely to result in destruction or harm to important habitat. Protection measures may be developed through coastal planning initiatives. It may also require investigating options for moving oil transport corridors, an approach that has been used in Washington and California. It may also require input to discussions on oil and gas exploration and drilling in BC marine waters.
  • Provide for an adequate level of protection and enforcement of regulations to reduce the threats.

2.5.4 Communication

Communication to the public and others is important to garner support and understanding for the need to protect sea otters and their habitat. Sea otters were absent from Canada’s fauna for almost a hundred years. With their return, there is a need to raise the level of understanding of the role of sea otters in structuring nearshore ecosystems and of the threats to sea otters and their habitat. This approach should include, but is not limited to the following:

  • Establish and maintain collaboration and information exchange with First Nations (traditional knowledge), coastal communities and others about protection of sea otters and their habitat.
  • Produce public communications materials such as school curricula, booklets, brochures, films, local newsletters, and websites to inform the public of the status of sea otters, and threats to their recovery.
  • Promote sea otter watching guidelines for eco-tour operators and the general public. Human disturbance of sea otters from vessels and people are not yet considered to be significant threats, but as the sea otter population expands it may require additional considerations.

 2.6 Performance Measures

Within five years [1] and in every subsequent five-year period until the objectives have been achieved or the species recovery is no longer feasible, a report on the implementation of the recovery strategy and the progress towards meeting its objectives will be undertaken.

The objective-based performance measures that will be used to monitor progress are:

  • Did the geographic range of sea otters continue to expand naturally beyond the 2004 continuous range?
  • Did the number of sea otters increase (compared to the 2004 estimate) to correspond to the range expansion?
  • Were threats better identified or clarified? Were threats to sea otters and their habitat mitigated to provide for continued recovery?

2.7 Critical Habitat

2.7.1 Identification of the species’ critical habitat

The seaward extent of sea otter habitat is largely limited by sea otters’ ability to dive to the sea floor for food. Most foraging dives occur in depths of 40m or less, although sea otters are capable of diving to 100m. Thus, their habitat is typically within 1 to 2km of shore unless areas of extensive shallows extend further. When present, kelp beds are often used habitually as rafting sites. Kelp beds are also used for foraging and are important, though not essential, habitat components. Sea otters prey upon a wide variety of invertebrate species and both rocky and soft bottom communities provide foraging habitat.

In BC, sea otters occupy exposed coastal areas with extensive rocky reefs and associated shallow depths along the west coast of Vancouver Island and the central BC coast. As the range expands, the characteristics of the habitat used by sea otters are likely to become more diverse. Habitat is not limiting for this population at this time but further study is needed to assess the components that could identify critical habitat as defined by SARA

Winter is thought to be the season of highest natural mortality for sea otters and is also the time when oil spills are most likely to occur and are most difficult to respond to because of sea conditions. The spatial and temporal distribution of the sea otter population in winter may indicate the areas most critical to its survival and recovery.  

2.7.2 Schedule of studies to identify critical habitat

Table 4.  Schedule of Studies
Recovery ActivityOutcome/RationaleTimeline

Identify rafting and foraging areas and seasonal variation in their use

  • Survey summer rafting and foraging locations
  • Survey winter raft locations
  • Compile incidental reports of sightings of rafts of sea otters, especially in winter, from First Nations, fishermen and coastal communities
  • Use physical attributes of observed winter distribution to characterize habitat use in winter

Model physical attributes of observed winter distribution to predict probable winter habitat in other areas, including areas not occupied by sea otters

Determine the winter distribution of sea otters.  Summer rafting areas can be identified in conjunction with population survey work but winter rafting areas are likely different. 2007-2012
Study movement and home range of sea otters (e.g.,  telemetry)Determine the size of home ranges and habitat use2012+

2.8 Existing and Recommended Approaches to Habitat Protection

In Canada, the Fisheries Act has provisions to protect sea otter habitat. A list of existing Marine Protected Areas is summarized in Jamieson and Lessard (2000), and includes the Checleset Bay Ecological Reserve established in 1981 for the protection of sea otter habitat. Marine Protected Areas may also be established under the Oceans Act

Under the Canada National Marine Conservation Areas Act, Parks Canada is responsible for the creation of National Marine Conservation Areas (NMCAs) which will be managed for sustainable use, and protected from industrial activities such as marine dumping, mining, and oil and gas exploration and development. A NMCA is proposed in the southern Queen Charlotte Islands that would extend 10 km offshore from Gwaii Haanas National Park Reserve. As such, it would encompass habitat to which sea otters may in future be expected to recover. Pacific Rim National Park Reserve (PRNPR) along the west coast of Vancouver Island has special provisions under the Canada National Parks Act. The PRNPR encompasses the nearshore waters adjacent to it and the Broken Group Islands. The sea otter population’s range can be expected to extend in to the PRNPR as the population recovers.  

Works or developments on, in and under the water that may affect sea otter habitat may be subject to review under the Navigable Waters Protection Act and the Canadian Environmental Assessment Act.

2.9 Effects on Other Species

See Section 1.4.2 Ecological Role.

2.10 Recommended Approach for Recovery Implementation

The single-species approach for recovery was chosen largely for expediency as it allows a focused consideration of the approaches needed to recover sea otters, independently from other species of conservation concern. There are, however, compelling arguments in support of a multi-species approach for species such as the sea otter, but the effort to integrate multiple species conservation issues would have been significant and development of such a recovery strategy could not have been completed within the required timelines. Sea otters are keystone predators and contribute to the structure of nearshore ecosystems (see Section 1.4.2 Ecological Role), with both direct and indirect effects on other species at risk and their associated habitats. For example, sea otters prey on the northern abalone (listed under SARA as Threatened), and will reduce abalone abundance and size significantly from present levels. However, by preying on sea urchins, sea otters enhance kelp growth. As kelp increases, there is ample evidence that fish abundance, including juvenile rockfish (e.g. the boccacio, designated under COSEWIC as Threatened), increases, and species that feed in kelp forests (e.g. the marbled murrelet, listed under SARA as threatened) should benefit. Furthermore, the major threat to sea otters is oil spills, which would also affect cetaceans, sea birds, fish and invertebrates. Efforts to reduce the threat of chronic or catastrophic oil spills will effectively lessen the threat of oil to many other species.

2.11 Statement on Action Plans

One or more sea otter action plans will be completed within six years of approval of the sea otter recovery strategy. However, in the event sea otters are listed under SARA as a species of special concern based on the reassessment by COSEWIC, a management plan outlining measures for the conservation of the speciesmust be prepared within three years of listing, replacing the recovery strategy and the requirement for the development of one or more action plans. 

2.12 Permitted activities under the Species at Risk Act

As set out in subsection 83(4) of the Species at Risk Act, a person can engage in an otherwise prohibited activity if the activity is permitted by a recovery strategy and the person is authorized under an Act of Parliament to engage in that activity. Presently, there is scientific confidence that a limited harvest of sea otters by Aboriginal groups for food, social and ceremonial purposes will not jeopardize the survival or recovery of sea otters. Accordingly, pursuant to subsection 83(4) of SARA, and in accordance with this recovery strategy, Fisheries and Oceans Canada may, following a request, permit the taking of a limited number of sea otters by aboriginal people for food, social and ceremonial purposes (e.g., for use in ceremonial regalia). The activity of engaging in a First Nation's food, social and ceremonial fishery of the sea otter must be authorized under a communal licence issued by the Minister of Fisheries and Oceans pursuant to the AboriginalCommunal Fishing LicencesRegulations made under the Fisheries Act . The Minister may specify in the communal licence any terms and conditions governing the activity that the Minister considers necessary for protecting the species. Such conditions would be expected to include harvest limits in specified areas and geographic distribution so as to minimize impact to the population and provide for further recovery (i.e. range expansion).

Scientific research and activities beneficial to sea otter recovery or that are incidental to the carrying out of the activity may also be conducted through a permit issued under Section 73 of SARA.


[1] of posting to the SARA Public Registry