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

8 Knowledge Gaps

Lack of information on population trends and human caused mortality are the basis of continued listing of large whale species in the U.S. (Waring et al. 2001). No current abundance estimates or population trends exist for eastern North Pacific blue, fin, or sei whales in Canadian waters. There is an urgent need for information on their abundance and distribution, their habitat, and the threats they face.

8.1 Abundance and distribution

Uncertainties about population structure, distribution and abundance will make mitigation of threats more difficult. A clear understanding of the populations that use Pacific Canadian waters, and how these populations are distributed in other jurisdictions within the species’ range (Alaska, California/Washington/Oregon, Mexico) is needed in order to address threats to recovery and to monitor whether recovery objectives are being met.

8.2 Critical habitat

Critical habitat(s) have not been definitively identified for any baleen whale species in Pacific Canadian waters. This lack of delineation makes habitat protection and potential threat assessment difficult. Basic abundance and distribution data is required in order to identify critical habitat.

8.3 Threats

How human activities affect the mortality, foraging, reproductive success, and critical habitat of blue, fin and sei whales requires investigation in order to be effectively mitigated.

The intensity and distribution of acoustic activities needs to be characterized in relation to foraging areas and critical habitat. An improved understanding of the species’ sensitivity and resilience to anthropogenic sounds needs to be assessed in order to determine whether noise is, or will become, a significant hindrance to recovery. The frequency of ship strikes and fishing gear interactions needs to be quantified to ensure that these potential sources of mortality are not responsible for the lack of recovery. Understanding how ocean climate contributes to the formation of critical habitat will facilitate the development of hypotheses describing how a changing climate may reduce or displace balaenopterid habitats. While the effect of chemical pollution on balaenopterid whales is thought to be minimal because of their trophic position, this has not been determined definitively. The effects of oil spills, both chronic and acute, and other forms of marine pollution (i.e., plastics and other flotsam) are also poorly understood and should be investigated to the extent possible.