Publications
Prepared by
Biodiversity Group Environment Australia in consultation with the Threat Abatement Team
Environment Australia, 1998
ISBN 0 642 21420 4
Albatrosses are the most threatened and vulnerable of all groups of marine birds and the best available evidence indicates that longline fishing is both the most recent and the most serious threat facing albatrosses today (Birdlife International 1995; Croxall and Gales in press; Gales in press). Other processes do, however, also impact on albatrosses and the nature and extent of these threatening processes have been reviewed by Gales (1993; in press), Birdlife International (1995), Alexander et al. (1997) and Croxall (in press). The direct and chronic persecution of albatrosses on land which peaked in the 19th Century has largely ceased but lesser threatening processes, other than longline fishing, continue to impact on albatrosses both in their marine and terrestrial domains. Some of these are briefly described below. The summary refers to threats to albatrosses globally.
Large-scale driftnet fisheries operated from the late 1980s until the end of 1992 when a global moratorium was declared due to concerns regarding the level of by-catch. During 1990 an estimated 500 000 seabirds were killed in the North Pacific driftnet fisheries, including 17 548 Laysan albatrosses and 4 246 Black-footed albatrosses (Johnston et al. 1993). These rates of mortality (2.5 and 1.5% of world populations) were sufficient to cause the decline of populations. An unknown level of illegal High Seas driftnetting persists. Similar rates of seabird mortality to those incurred in driftnet operations are suspected for the North Pacific longline fisheries which have flourished since the cessation of drift netting (Ludwig et al. in press).
Pelagic gillnet fishing in the North Pacific has also killed many thousands of seabirds, including albatrosses (King 1984). The extent of mortality of albatrosses in this fishery, however, is not well known for either the North Pacific region or for any other oceanic sectors (Croxall in press).
Seabirds are attracted to trawling operations as a result of the availability of discarded by-catch and offal dumped during processing at-sea. The changes in seabird foraging ranges and dynamics which result from discarding at sea (e.g Ryan and Molony 1988; Adams 1992; Acros and Oro 1996; Weimerskirch in press) are not acceptable outcomes of trawl fishing practices and the excessive and wasteful practices of ad lib dumping should be redressed (Birdlife International 1995).
Seabirds are also killed during trawling operations as a result of collisions with trawl gear. In the New Zealand squid trawl fishery, 2300 Shy Albatrosses were killed by collision with net-sonde monitor cables in 1990 alone (Bartle 1991). The same source of mortality has been described for Black-browed albatrosses during trawl operations off Kerguelen Island (Duhamel 1991). Since these observations, the use of net-sonde monitor cables has been prohibited in the New Zealand Exclusive Economic Zone and also in the CCAMLR Convention Area. These prohibitions have reduced trawler related albatross deaths in these areas (although casualties still persist, albeit in low numbers; see Williams and Capdeville 1996) but casualties persist in other areas as a result of albatrosses becoming caught and drowned in the nets (e.g. in the hake fishery off South America, Stagi et al. 1995) and collisions with other trawl warps (e.g during demersal trawling operations off South Africa, Adams 1992, D. Pemberton, pers. obs.). Collisions between albatrosses and trawl warps have more recently been observed during demersal trawl operations off Macquarie Island but the degrees of injuries and fate of the birds is unknown (T. Reid pers. obs).
Whilst the problem of mortality of seabirds resulting from trawl operations, at least in areas where net sonde cables are not used is minor compared to the problem of deaths on longlines, localised problems may occur where trawl operations are concentrated in regions close to the breeding sites of small populations of vulnerable species.
The major forms of marine debris observed with albatrosses are the ingestion of plastics and more recently, fishing hooks.
Albatrosses have been known to ingest plastics since the 1960s, with Laysan albatrosses exhibiting the greatest incidence and volumes of plastic ingest for any seabird. The direct effects on adult albatrosses do not appear to be severe but when the plastics are transferred to chicks via regurgitation the sub-lethal effects of impaction and ulceration are likely to lower post-fledging survival (Sileo et al. 1990). Plastic ingestion is not confined to Pacific species, a high incidence of plastics has recently been observed at the nesting sites of Royal albatrosses at Campbell Island (J. Scott pers. comm). As recommended by Adams (1992) and Croxall (in press), the incidence of plastic ingestion by albatrosses across their range should be monitored
The incidence of longline hooks being regurgitated at the nest sites of wandering and black-browed albatrosses has increased six-fold in recent years (Cooper 1995, Huin and Croxall in press). An estimated 20% of albatross chicks at South Georgia ingest regurgitated hooks which are swallowed by the adults scavenging discarded fish heads during longline fishing operations.
It has been suggested that albatrosses be used as global indicators of contamination of oceanic systems because they are characteristically long lived and because of their wholly pelagic feeding habit (Croxall in press; Ludwig et al. in press). Cadmium has been shown to accumulate with age in Wandering and Royal albatrosses (Hindell et al. 1995), but the implications of this is not clear. North Pacific Albatrosses are potentially at the greatest risk from organochlorine contaminants and such contamination has been ascribed to reduced reproductive success in Black-footed albatrosses (Ludwig et al. in press). In the populations of Black-footed albatrosses nearest to Honolulu, contaminants were believed to cause about 9% of the excessive human-caused mortalities in the population, the remaining 91% being ascribed to longline fishing by-catch (Ludwig et al. in press). Recent evidence of egg shell thinning and chick deformities in Royal albatrosses breeding at the Chatham Islands may be related to increases in contamination in more southern foodchains; these observations reinforce the need for the initiation of baseline monitoring programs (Robertson in press).
An issue of concern has recently been highlighted by Croxall (in press) which focuses on the progressive degradation of albatross marine habitat, particularly in terms of the potential consequences of the global over-exploitation of components of the food webs to which albatrosses belong. The major fisheries for bait fish and fish meal in some areas target fish species which form major components of the "natural" diets of albatrosses (eg: Jack mackerel fishery off Tasmania). Croxall (in press) maintains that the chronic deterioration of marine habitats may have long-term effects on the status of albatrosses as serious as the more direct and acute effects which currently command our attention.
Habitat erosion of nesting areas due to the introduction of stock and rabbits has contributed to breeding failures in a number of albatross species including Laysan, Black-footed, Waved, Amsterdam, Grey-headed and Black-browed albatrosses (see Gales 1993). Habitat changes resulting from fire, as well as the direct threats of fire through breeding colonies, have been realised by Yellow-nosed and Amsterdam Albatrosses. Climatically induced changes in nesting habitat (resulting from storm and elevated temperatures causing drying of soils) are expected to have a significant effect on Royal albatrosses at the Chatham Islands due to lack of suitable nesting materials and substrates (Robertson in press).
The vulnerability of the Endangered Short-tailed albatross is exacerbated by Torishima (the major breeding site) being an active volcano and the resultant instability of the ash slopes where the birds breed. Efforts to attract the birds to breed in more stable areas however have recently been successful (Hasegawa pers. comm., in Gales in press).
Predation of eggs and chicks by introduced rats has been recorded for Laysan albatrosses and Black-footed albatrosses and rats are also implicated in the deaths of eggs and newly hatch chicks of Short-tailed, Yellow-nosed and Sooty Albatrosses (Moors and Atkinson 1984, Hasegawa 1984, Weimerskirch pers. comm)
Cats have been responsible for the death of albatross chicks at both Marion and Amsterdam islands (Weimerskirch pers. comm) and they are suspected as contributing to the death of Light-mantled Sooty Albatross chicks at Macquarie Island (Gales 1993). Dogs and pigs are responsible for the deaths of eggs, chicks and adult Laysan albatrosses (Moors and Atkinson 1984, Harrison 1990).
Human depredation of albatross eggs and chicks has largely ceased with possible sporadic occurrences persisting at the Chatham Islands and Tristan da Cunha (C.J.R. Robertson pers. comm and J. Cooper pers. comm in Gales 1993).
Mosquitoes have been implicated as vectors of an avian pox virus to Black-footed albatrosses (Harrison 1990), whereas ticks and fleas transfer avian pox virus in other albatross species, including Black-browed, Shy, Grey-headed Albatrosses (Gales 1993 and references therein; C.J.R. Robertson pers. comm). In Shy Albatrosses repeated infection of the virus causes death as a result of liver and kidney failure, breeding success being reduced to 20% in some years (N. Brothers in Gales 1993).