Short-tailed Albatross (Phoebastria Albatrus)
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements and Literature Cited
- Biographical Summary of the Report Writer and Authorities Consulted
Limiting Factors and Threats
- Volcanic Eruptions
- Commercial Fishing
- Oil Pollution
- Plastics Ingestion
- Interspecific Competition
- Introduced Species
Approximately 85% of the Short-tailed Albatross population breeds on Torishima, an active volcano that erupted explosively in 1902 and 1939, destroying much of the original breeding colony sites. Submarine eruptions occurred in 1965 and 1975. Near the end of 2002 a small eruption occurred, and the volcano is currently ejecting gases (Hasegawa 2002, in litt.). Future eruptions are not predictable in time or magnitude and therefore represent a significant threat to the population. An eruption during the breeding season could kill many birds as well as destroy the breeding area (Hasegawa and DeGange 1982). Additionally, breeding habitat and nesting birds are threatened by frequent mud slides and erosion caused by monsoon rains that occur on the island (Federal Register 2000).
The potential impacts of the commercial fishing industry include direct injury or mortality from gear, as well as complications associated with discarded ship debris, such as entanglement. The former likely represents the greatest threat to the continued and increasing occurrence of the Short-tailed Albatross within Canadian waters.
In general, seabirds are vulnerable to becoming entangled in derelict fishing gear, although the magnitude of these impacts is unknown. Three to four Short-tailed Albatross come ashore entangled in fishing line per year on Torishima, some of which die as a result (Hasegawa 2001, in litt.). Lost or abandoned gear is a threat to the Short-tailed Albatross throughout its range.
The Short-tailed Albatross is known to co-occur with commercial fisheries off Alaska, at levels that vary both spatially and temporally (Gilroy et al. 2000). The species has been observed from fishing vessels off Alaska, and seven individuals were reported as incidental takes in the Alaskan fisheries from 1983 to 1998 (Cochrane and Starfield 1999). Additional unreported take has probably also occurred (Sherburne 1993, Balogh 2003, in litt.). The majority of takes were associated with groundfish (i.e. non-halibut) longline operations, and one in the Alaskan Pacific halibut (Hippoglossus stenolepis) fishery (Gilroy et al. 2000). All occurred in September.
To date the Department of Fisheries and Oceans has recorded no incidental take of the Short-tailed Albatross in Canadian waters (L. Yamanaka, pers. comm. 2003). The degree of overlap between the industry and the species is difficult to quantify as the effort for pelagic bird observations is too low and uneven. However the potential exists for the two to co-occur in space and time. As populations of Short-tailed Albatross increase, this potential is likely to increase correspondingly. The commercial fishing effort for halibut and rock-fish (Sebastes spp.) is concentrated along the continental shelf off the coast of British Columbia, with additional effort along the coast of Northern Vancouver Island and the east side of Queen Charlotte Sound (J. Smith pers. comm. 2003). Nine of the 10 sightings of the Short-tailed Albatross in British Columbian waters have occurred in these regions (Fig. 3). Black-footed Albatrosses are routinely killed in commercial halibut and rockfish longline fisheries in BC waters, despite the mandatory use of seabird avoidance devices as a condition of licensing (in the halibut fishery). Therefore, it is likely just a matter of time before a Short-tailed Albatross is taken in BC waters.
Sea-bird by-catch can also be age or sex biased, depending on the location and timing of albatross foraging in relation to local fishery concentrations (Cochrane and Starfield 1999). While there appears to be no evidence for a sex bias in Short-tailed Albatross mortality in general, there is some evidence of age-biased mortality associated with fisheries with six of the seven recorded takes in Alaska being immatures (Cochrane and Starfield 1999). The majority of Short-tailed Albatross sightings within Canadian waters have been of immatures (Table 1). The possibility therefore exists of a greater threat to these individuals where fishing effort overlaps with the species’ range in Canada. In long-lived species such as albatrosses, adult survival rate has the highest potential to influence the population growth rate. However, Cochrane and Starfield (1999) suggest that fishing-related mortality of immatures may have as strong an influence on trends as does adult survival for the Short-tailed Albatross.
No information is available on incidental take in foreign fisheries outside the United States and Canada. For the United States, at the current population level and growth rate, the level of recorded mortality resulting from longline fisheries, although significant, is not thought to represent a threat to the species’ survival (NMFS 2003), although it is likely slowing recovery. However, in the event of a major population decline resulting from a random stochastic event (e.g. volcanic eruption during the breeding season, or a major oil spill), the additional impact of longline fisheries on Short-tailed Albatrosses could be significant (Cochrane and Starfield 1999, Federal Register 2000).
Oil pollution could pose a threat to Short-tailed Albatrosses by causing physiological problems from petroleum toxicity and by interfering with the affected bird’s ability to thermoregulate. As mentioned, oil development has been considered in the past in the vicinity of the Senkaku Islands (Hasegawa and DeGange 1982, Federal Register 2000). Future development could impact the local marine environment used by the albatrosses during the breeding season by introducing the risk of spills or leaks related to oil extraction, transfer, and transportation.
Oil spills could also occur in many parts of the species’ marine range, including the United States and Canada. Fouling of the birds and their habitat could arise from the chronic illegal dumping of oily bilges, as well as from major oil spills should they occur. For Canada specifically, recent discussions concerning the lifting of the current moratorium on gas and oil exploration off the coast of British Columbia highlights this risk. Areas that might be affected by drilling include Queen Charlotte Sound, shallow areas within Hecate Strait and off the north and northwest coast of Vancouver Island (K. Morgan pers. comm. 2003). As previously mentioned, on the basis of Short-tailed Albatross distribution off the coast of British Columbia, the potential therefore exists for interactions between the species and the oil industry.
Albatrosses often consume plastics at sea, presumably mistaking them for food items. Plastics ingestion can lead to injury or mortality through internal injuries from sharp pieces of plastic, or through a reduction in ingested food volumes and dehydration (Sievert and Sileo 1993). Young birds may be particularly vulnerable to plastic ingestion prior to developing the ability to regurgitate (Sherburne 1993). Short-tailed Albatrosses on Torishima commonly regurgitate large amounts of plastics debris (Federal Register 2000), an observation that has become increasingly common in the last 10 years. However, the effects on survival and population growth are not known.
Black-footed Albatross also nest on Torishima. Historically this species nested on lower slopes; however, they are currently expanding their nesting area up into that of the Short-tailed Albatross (Hasegawa and DeGange 1982). However, Sherburne (1993) notes that Short-tailed Albatrosses arrive to establish and re-establish nests six weeks earlier than the Black-footed Albatross. It is therefore unknown if the observed encroachment represents actual competition for nesting habitat between the two species.
Ship rats (Rattus rattus) were introduced to Torishima at some point during human occupation, and now inhabit much of the island, including the albatrosses nesting slope. Although it is suspected they may prey on eggs or hatchling albatrosses, no direct evidence of rat depredation has been observed (Hasegawa 1984). Cats (Felis catus) were also present, most likely introduced during the feather hunting period. However, there has been no recent evidence of cats on the island, and it is thought that they no longer occur.
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