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Recovery Strategy for Blue, Fin, and Sei Whales in Pacific Canadian Waters [Proposed]

9. Recovery

The blue, fin, and sei whales that occur in Pacific Canadian waters are presumed to belong to populations that range over the entire eastern North Pacific. These populations move seasonally between international, Canadian, U.S., and possibly Mexican territorial waters. Thus the recovery of these populations is unlikely to be accomplished by Canadian efforts alone. The need for multi-lateral and international cooperation is therefore considered essential to the successful recovery of these species.

The Recovery Strategy must consider the long time scales associated with the longevity of these species and the relatively slow response of their associated life history parameters. However, it must also address imminent threats and immediate conservation issues impacting the species.

It must also recognize that marine habitats are dynamic, at both short and long time scales, and that the physical oceanographic processes that contribute to the creation of habitat are largely beyond human control. The Recovery Strategy should therefore focus on human actions and activities that can be directly managed.

9.1. Recovery Feasibility

Recovery of the blue and fin whale populations that use Pacific Canadian waters is considered feasible. The precautionary approach requires the presumption that recovery of sei whales that use Pacific Canadian waters is also feasible, until it is shown otherwise.

Given their apparently low abundance and considerable longevity, none of these whale populations can be expected to recover to historic levels in the near future. For example, while the eastern North Pacific blue whale population now appears stable and may be increasing (Carretta et al. 2003), this has taken over 30 years since the cessation of commercial whaling. Expectations for recovery should therefore reflect these long time scales.

Despite being depleted by commercial whaling, blue whales continue to make use of Canadian waters, and fin whales are regularly sighted in both shelf-break and on-shelf habitats. Thus, available evidence clearly implies that these species have the opportunity to recover in Pacific Canadian waters.

While apparently less abundant now in the eastern North Pacific than fin or blue whales, sei whales likely continue to use Canada’s offshore Pacific waters. The recovery of the species in the eastern North Pacific should be facilitated by its more diverse diet.

Fin and blue whales in the eastern North Pacific are sufficiently abundant (see Sections 2.3 and 3.3 Population size) to have the reproductive potential needed for increased population growth rates. This may also be the case for sei whales, despite recent estimates of just 56 animals for this region (Section 4.3). Sei whale populations are known to be highly mobile, preferring offshore habitats and rarely frequenting coastal areas. A longer time series of observations is therefore required before recovery feasibility is disproved.

The physical processes responsible for concentrating prey species have changed little over time. Thus, sufficient potential habitat for these species, defined as the availability of prey concentrations, is likely available in Pacific Canadian waters.

The threats identified to both individuals and populations could be mitigated through management actions, and a number of techniques have been demonstrated as effective. For example, in the western Atlantic, shipping lanes on the continental shelf have been moved and an early warning system has been implemented to reduce the likelihood of ship strikes on right whales; and gear modifications on both Atlantic and Pacific coasts have been effective at reducing entanglements of humpback whales and smaller cetaceans. Mitigation strategies have also been developed in a number of jurisdictions to reduce the impact of seismic surveys and military-related sonar use.

9.2. Recovery Goals

Blue, fin and sei whales are long-lived species with life spans between 50 and 100 years. Long-term goals must span several generations, and therefore have a horizon of 150-300 years. The recovery goals for these species are:

  1. To attain a long-term viable population of blue whales that use Pacific Canadian waters.
  2. To attain a long-term viable population of fin whales that use Pacific Canadian waters.
  3. To attain a long-term viable population of sei whales that occasionally use Pacific Canadian waters.

9.3. Recovery Objectives

Blue, fin, and sei whales that occur in Pacific Canadian waters are presumed to belong to eastern North Pacific populations. These populations move seasonally between Canadian, U.S., international, and possibly Mexican territorial waters. These objectives refer only to the portion of these populations that occur in Canadian waters and provide a short-term measure of progress towards reaching the recovery goals.

  1. By 2011, determine the identity of the population of blue and fin whales that occur in Pacific Canadian waters.
  2. Maintain or increase the relative proportions of blue and fin whales in Pacific Canadian waters compared to the whole population through to 2016.
  3. By 2011, confirm the presence of sei whale(s) in Pacific Canadian waters. If confirmed, maintain or increase the relative proportion of sei whales that occur in Pacific Canadian waters compared to the whole population through to 2016.
  4. See that the threats as they are identified do not significantly reduce the potential habitat or distribution in Pacific Canadian waters for blue, fin, and sei whales through to 2016 (by comparison to when identified as a threat).

9.4. Strategies to address threats & effect recovery

As sightings of balaenopterids are rare (particularly of blue and sei whales), recovery efforts will need to follow an adaptive approach. The development of mitigation strategies, for example, will have to be tailored to the understanding of threats to individuals and the identification of critical habitat.

In the immediate future, recovery objectives will be predominantly research-focused until basic information on habitat, abundance, and distribution is gathered. The collection of this basic information is led by CRP-DFO (see Section 7 for Actions Completed or Underway) and is needed to assist in the identification of critical habitat and to provide the baseline information necessary to monitor threats and measure progress towards recovery.

Once critical habitat is identified and the abundance and distribution of these species is better understood, further action to address threats to their survival may be required. A number of mitigation measures to address threats to large whales have been demonstrated as effective in other jurisdictions (see examples in Section 9.1) and may be  adapted in consultation with industry and possibly other jurisdictions to protect balaenopterids in Pacific Canadian waters. Specific activities to address threats will be further prioritized in the action plan.

9.4.1.  Schedule of studies to identify critical habitat

Priority: High

Threats addressed: All

Objective addressed: 2, 3, and 4

The following schedule (Table 1) identifies the activities required over the next 5 years (2006-2011) to identify, to the extent possible, critical habitat for blue, fin, and sei whales. The activities identified in this schedule are recommendations that are subject to priorities and budgetary constraints of the participating jurisdictions and organizations.

The study of balaenopterid critical habitat has been divided into studies of potential and realized habitat. From an ecological perspective, potential habitat represents areas where suitable habitat exists, while realized habitat describes where species actually occur. In theory, realized habitat should be a small portion of the potential habitat, particularly for severely depleted species. The distinction makes it possible to distinguish between unsuitable habitat and suitable habitat that is merely unoccupied. Additionally, given the lack of baseline data on species distributions, identification of potential habitat helps prioritize scarce survey effort.

The potential habitat studies outlined in Table 1 focus on identifying oceanographic regions that could provide appropriate prey at suitable densities for blue, fin, and sei whales. The realized habitat studies focus on how balaenopterids occupy the potential habitats. Critical habitat can then be defined as the realized and potential habitats needed for survival and recovery.

Table 1: Recommended studies and associated timelines for the identification of critical habitat for blue, fin and sei whales by 2011.
Schedule of Studies to Identify Critical HabitatDate
Identify potential habitat 
Relate historic distributions of balaenopterids to long-term oceanographic conditions to predict potential habitats 2006-2008
Develop and test methods to predict the distribution of prey species2006-2008
Identify realized habitat 
Determine relative seasonal distribution of eastern North Pacific balaenopterids in Pacific Canadian waters2006-2010
Identify factors (e.g., prey, ocean currents, upwellings) contributing to species’ distributions2006-2010
Relate the identified factors to the seasonal distributions and predict how species may occupy potential habitats (not all potential habitats will be occupied)2006-2010
Define critical habitat 
Establish collaborations with researchers in other jurisdictions to identify frequently used habitat and prioritize areas for critical habitat selection 2006-2010
Define critical habitat for blue, fin, and sei whales based on the amount of potential habitat needed for survival and recovery 2008-2011

 

9.4.2.  Species abundance and distribution

Priority: High

Threats addressed: All

Objective addressed: All

  1. Estimate number of blue and fin whales using Pacific Canadian waters;
  2. Establish presence of sei whales in Pacific Canadian waters;
  3. Determine the extent of migrations and identify the populations to which blue, fin and sei whales using Pacific Canadian waters belong;
  4. Determine relative seasonal distribution in Pacific Canadian waters of blue, fin and sei whales through surveys, photo-identification, and/or acoustic detection;
  5. Establish collaborations and data sharing with researchers in other jurisdictions to develop estimates of abundance and range-wide distribution and habitat use.

9.4.3.  Threat mitigation

Priority: High

Threats addressed: All

Objectives addressed: 2, 3, 4

  1. Determine the spatial distribution of commercial shipping traffic and relate to the critical habitat of blue, fin and sei whales;
  2. Determine likely locations and timing of seismic surveys and low frequency sonar use and relate to critical habitat of blue, fin and sei whales;
  3. Determine source locations and background noise levels from industrial activities and other anthropogenic sources and relate to critical habitat of blue, fin and sei whales;
  4. With the information gathered in (a) through (c), develop options to protect critical habitat and implement as necessary;
  5. Investigate methods to obtain information on the frequency of ship strikes and fishing gear entanglements and, if necessary, develop options to reduce their occurrence;
  6. Include the presence of balaenopterids in oil spill response plan(s) to prevent individuals from being oiled in the event of an oil spill;
  7. Confirm that there is little threat to balaenopterids in Pacific Canadian waters from chronic and acute sources of pollution;
  8. Confirm that seismic mitigation strategies and low frequency sonar use policies protect individuals from injury or mortality and, if necessary develop options to improve protection;
  9. Promote marine mammal viewing guidelines and enforce compliance with regulations against disturbance.