Natural History and Conservation of the Greenland Whale, or Bowhead, in the Northwest Atlantic

Abstract

ABSTRACT. One of the longest-living mammals, the Greenland whale or bowhead (Balaena mysticetus) is specialized to filter small crustaceans, especially Calanus copepods, from barren Arctic seas. Brought to near extinction by commercial whaling, the North Atlantic 'meta-population' remains at less than 5% of its former abundance, and none of its three constituent stocks has shown demonstrable recovery during the last century. Two of these stocks, the Baffin Bay and Hudson Bay populations, occur in coastal waters of the Eastern Canadian Arctic during summer. Each of these two stocks numbers in the low hundreds and exists in isolated groups segregated by age and sex, showing strong fidelity to essential habitats. A skewed age distribution, predation by killer whales (Orcinus orca), hunting, net entanglement, tourism, climate change, habitat loss, and inbreeding suppression are some of the factors that may affect the bowhead's recovery. We need local and historical knowledge to understand the bowhead's natural history. Together with scientific data, such knowledge is also useful in evaluating the status of the species and prescribing a management plan. A recovery plan must employ the precautionary principle, both within the international 'meta-population' context and at the sub-population level; it must take a historical view and seek to protect abandoned habitats. Canada has conducted whaling activities that violate international agreements and diminish the effectiveness of the International Whaling Commission.Key words: Greenland whale, bowhead whale, Balaena mysticetus, biology, conservation, management, traditional knowledge RÉSUMÉ. La baleine boréale ou baleine franche (Balaena mysticetus), l'un des mammifères qui vit le plus longtemps, est spécialisée pour filtrer les petits crustacés, des copépodes Calanus pour la plupart, vivant dans les mers arctiques peu peuplées. Amenée au bord de l'extinction par la chasse commerciale à la baleine, la «métapopulation» de l'Atlantique Nord se maintient à moins de 5 p. cent de son abondance passée, et aucun des trois stocks qui la composent n'a montré un rétablissement ferme au cours du siècle dernier. Deux de ces stocks, la population de la baie de Baffin et celle de la baie d'Hudson, se trouvent en été dans les eaux côtières de l'Arctique canadien oriental. Chacun d'eux comprend quelques centaines d'individus, répartis en groupes isolés selon l'âge et le sexe, qui démontrent une fidélité marquée pour les habitats essentiels à leur survie. Une asymétrie de la distribution par âge, la prédation par les épaulards (Orcinus orca), la chasse, l'enchevêtrement dans les filets, le tourisme, le changement climatique, la perte d'habitat et la dépression consanguine sont au nombre des facteurs qui pourraient influencer le rétablissement de l'espèce. Le savoir local et le savoir historique sont tous deux nécessaires pour comprendre l'évolution naturelle de la baleine boréale. Couplés aux données scientifiques, ces savoirs sont en outre utiles dans l'évaluation de l'état de l'espèce ...

Bowhead whale Balaena mysticetus seasonal selection of sea ice

“…Larger whales may forgo ice cover in favour of areas that concentrate zooplankton at depth. Such feeding behaviour is well documented at Isabella Bay, eastern Baffin Island, where adolescent and adult bowhead whales aggregate in autumn to feed on concentrations of copepods in deepwater troughs (Finley 2001). Although the east Baffin Bay segment of the EC-WG population may not be represented by this analysis, the Cumberland Sound segment of the population that was tagged in west Baffin Bay displayed movement behaviour that could be attributable to whales that generally use Baffin Bay, both east and west, during late spring and summer.…”

“…Bowhead whales have sizeable energetic needs in support of their large body mass and therefore colocate with abundant food resources located at high densities during specific periods of the year. Thus, bowhead whales may select sea ice areas for foraging opportunities (Finley 2001). Between the open water and permanent ice cover, the marginal ice zone is the most productive area in the Arctic Ocean (Gosselin et al 1997).…”

“…The Foxe Basin nursery area (Cosens & Blouw 2003) is characterized by shallow waters and spring ice cover, providing safe and relatively calm waters with predictable oceanographic processes suitable for nursing, in contrast to other segments of the population that tend to occupy coastal areas around Baffin Bay during spring (Finley 2001). As sea ice melts, whales are likely exposed to increased vulnerability to predation as killer whales enter the area (Dueck & Ferguson 2009).…”

“…Bowhead whales feed primarily in late summer-fall on pelagic and epibenthic zooplankton (e.g. Finley 2001, Lowry et al 2004 in areas that may be critical to their annual cycle of fat deposition and catabolism; however, reports of intensive feeding during late winter-early spring have been reported (Lee et al 2005). In fall, whales move south along the east coast of Baffin Island or cross over to the West Greenland coast (Reeves et al 1983), whereas whales in Foxe Basin are thought to move south to east and winter in Hudson Strait (Reeves & Mitchell 1990).…”

Current state and trends in Canadian Arctic marine ecosystems: II. Heterotrophic food web, pelagic-benthic coupling, and biodiversity

“…Bowhead whales are assumed to feed on pelagic and epibenthic zooplankton in late summer and fall (Finley 2001;Lowry et al 2004;Pomerleau et al 2011b), and on pre-ascending diapausing calanoid copepods in late winter and early spring, based on data from Disko Bay, Greenland (Heide- Jørgensen et al 2012;Laidre et al 2007). The proportional contribution of various food sources (zooplankton) to the diet of bowhead whales was determined using a Bayesian stable isotope mixing model (SIAR; Parnell et al 2008).…”