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Recovery Strategy for the Grey Whale (Eschrichtius robustus), Atlantic Population, in Canada

Recovery Feasibility

 

The only possible approach to recover this extirpated population would be the reintroduction of a viable population from another area.  The recovery of the grey whale (Atlantic population) is not considered feasible at this time, based on examination of a series of issues in the following sections.

 

Availability of individuals for re-establishment

Recovery would require that individuals be available to support re-establishment of a viable population. There are no more Atlantic grey whales, but the eastern Pacific population of grey whales could potentially serve as a donor population.  The most recent agreed estimate of abundance for the eastern Pacific population was 26,300 individuals in 1997/98 (International Whaling Commission 2006a).  Allowable removals from this population are 620 individuals in the period 2003-2007 with a maximum of 140 in any given year, and there are currently no harvests of this population (International Whaling Commission 2006b).  Accordingly, this number of individuals is potentially available to support a reintroduction program.

 

Habitat availability

For recovery to be feasible, sufficient habitat must be available to support the species or must be made available through habitat management or restoration.  Several different habitats would be needed over a wide geographic range and in both Canada and the United States of America (USA) to ensure the re-establishment of a viable population.  Some of the necessary habitats are currently impacted in ways which would probably make them unsuitable for grey whale life history stages.  The shallow coastal lagoons and bays in southeastern and south-central Florida, the presumed breeding and calving area, are heavily impacted by the urban development of the Florida coastal area and associated industrial and recreational activities.  The Southeast Florida Metropolitan Statistical Area, including Palm Beach, Broward and Miami-Dade counties, is the sixth largest in the USA and had a 2002 population of over 5 million (Broward County Planning Services Division 2004).  As a result, coastal and nearshore marine habitats are heavily degraded and actions to reduce land-based pollution, improve water quality, and minimize impacts of dredging, filling and coastal construction are required (Florida Department of Environmental Protection 2004).  Coastal and nearshore habitats are heavily used by recreational boaters.  In Broward County alone there are 43,000 registered recreational vessels and over 100 marinas and boatyards (Florida Sea Grant n.d.).  Overall there would be considerable doubt as to whether these coastal habitats could be made suitable for grey whale breeding and calving, which require quiet conditions of good environmental quality (Reeves and Mitchell 1987).  In some areas, the coastal habitats required for migration in the eastern USA and Canada are also highly impacted by transport and industrial activities, particularly in the northeastern USA.

 

Potential to mitigate threats to individuals and habitat

The potential to mitigate or avoid significant threats to the species or its habitat must also be considered in assessing recovery feasibility.  For Atlantic grey whales, threats could possibly be mitigated, but it is doubtful that threats could be removed effectively enough to allow the increase of a small re-introduced population.  Key threats to other large cetaceans in the northwest Atlantic include entanglement in fishing gear, vessel strikes, chemical accumulation and acoustic pollution.  Entanglement in fishing gear and vessel strikes are documented causes of mortality for eastern Pacific grey whales (Reeves and Mitchell 1987).  Reduction of mortality from vessel strikes and fishing gear entanglement is a central theme of recovery efforts for the endangered North Atlantic right whale which migrates between the southeastern US and eastern Canada.  Some success in reducing the impact of these threats has been achieved, but this population is showing no signs of recovery from a low population level (ca 300 individuals) in the current threat environment, which is assumed to be generally similar to that which would be faced by re-introduced grey whales.  Such threats do not seem to be having a significant impact on the eastern Pacific grey whale population, but that population is currently abundant.  Even low removals due to these threats could have a significant impact on a small re-established Atlantic grey whale population.

Health risks associated with translocating marine mammals have been recognized as a potential threat to the conservation of species at risk and some best practices have been recommended (Measures 2004). Any reintroduction would require a risk assessment of the threat of translocating grey whale pathogen and parasites from a donor population to the Atlantic and what these ‘novel and exotic’ pathogens may mean for resident species, particularly those already at risk such as the endangered northern right whale. 

With respect to habitat threats, it is not certain that threats to key habitats, particularly subtropical coastal and lagoon habitats needed for calving, could be mitigated to allow grey whales to use them successfully.  As noted above, these environments are currently subject to very intense recreational use and are impacted by explosive urban development, such that conditions would be practically impossible for calving and rearing of young cetaceans.  The environmental problems of these areas have been recognized for many years, and efforts are under way to restore degraded coastal and nearshore environments in this area.  Substantial efforts will, however, still be required over many years (Florida Department of Environmental Protection 2004).  Further, restoration of these essential habitats is under the jurisdiction of authorities in the USA and could not be mandated under SARA.

Existence of effective recovery techniques

Recovery techniques which have been proven effective must exist if this population is to be re-established.  The reintroduction of a population of large whales to an area from which they have been extirpated, and the associated re-establishment of their migratory routes (with related ‘ecological learning’ issues) has never been attempted or completed successfully, and appears unlikely to be feasible.

The introduction of well over 100 mature individuals would probably be necessary to lay the basis for the re-establishment of a viable population of grey whales in the Atlantic.  Populations of less than 250 mature individuals are considered “endangered” under the risk assessment criteria used by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and the International Union for the Conservation of Nature and Natural Resources (IUCN) (COSEWIC 2004a).  The western Pacific population of grey whales is apparently not recovering from a reduced population size of around 100 individuals, while the North Atlantic right whale is showing no signs of recovery from a population of some 300 individuals. 

The transport of small whales in limited numbers (e.g. killer whales) is possible, and there is a documented report of live capture, holding and subsequent release to the wild of a newborn grey whale (Reeves and Mitchell 1987), but the transport of large whales, of breeding size, has not been successfully attempted.  This transportation would probably be feasible on an individual basis, but enormous (essentially infeasible) efforts would be required to transport the number of individuals necessary to establish a breeding population.  

Even if the transportation of many whales were possible, it is extremely doubtful that re-introduced individuals could re-establish the complex and lengthy seasonal migration pattern which appears to be essential for the species in the eastern Pacific.  Migration from subtropical to northern areas is typical of many large whales (e.g. right whales, humpback whales), but the eastern Pacific grey whale has the longest migration route of any mammal and the migratory pathway would have to link much more specific habitats for successful completion of their life cycle than for other large whale species.

Recovery feasibility conclusion

In summary, recovery of the grey whale (Atlantic population) appears neither biologically nor technically feasible at the present time.  Biologically, the ability of individuals from a different area to learn the complex migratory pathway which appears essential to successful completion of the life cycle of this species seems highly questionable.  Recent experience has shown that the recovery of populations of large whales from very depleted states (several hundred individuals) is biologically difficult.  The technical feasibility of transporting the large numbers of whales needed to support the re-establishment of a viable population has not been demonstrated.  The technical feasibility of restoration of the coastal habitats necessary for calving, breeding, and the north-south migration has also not been demonstrated, and in any case, jurisdiction for restoration of the essential calving and rearing habitats is outside Canada.