Australian Whale Sightings & Entanglement:

Southern Right Whale Eubalaena australis

Sightings on the Australian coast and the increasing potential for entanglement

SIMON ALLEN¹ and LARS BEJDER²

¹Marine Mammal Research Group, Graduate School of the Environment, Macquarie University, New South Wales 2109, Australia, sallen@els.mq.edu.au
²Biology Department, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada

Southern Right Whales Eubalaena australis are an endangered species that have been recovering from unsustainable whaling practices and, despite being reported along the east and west coasts of Australia, they have not been duly accounted for in recent risk assessments for marine development.

This review of the last decade of sightings highlights northerly movements into temperate and sub-tropical waters, indicates that fatal entanglement has occurred and points toward an increasing likelihood of interactions between migrating whales and inshore marine development. Given that entanglements and vessel strike are preventing the recovery of North Atlantic Right Whales Eubalaena glacialis, we recommend a precautionary approach to risk assessment around Australia and the formation of a national animal entanglement committee with both a pre-emptive role in assessing coastal development applications and a reactive role in the event of entanglement.

Key Words: Aquaculture, Entanglement, Eubalaena australis, Recovery, Risk assessment, Sightings, Southern Right Whale.

INTRODUCTION

The precise migratory paths of Southern Right Whales Eubalaena australis to presumed summer feeding grounds in the sub-Antarctic (55-65°S) remain unresolved, but the coastal nature of their movements to winter calving grounds are more conspicuous and better documented (Bannister et al. 1999; Bannister 2001; Best et al. 1993; Brownell et al. 1986; Burnell and Bryden 1997). Individuals are known to range as far north as 20°S off the east and west coasts of South America, and they have been found beyond the Tropic of Capricorn (23°26.5´S) off the east and west coasts of Africa (Brownell et al. 1986; Carwardine 1995). Southern Australian coastal waters form a critically important component in Southern Right Whale distribution. However, they have only recently begun appearing north of ~34°S (Botany Bay) on the east coast and they were rarely recorded north of ~29°S (around the Houtman Abrolhos) off the west coast prior to the mid-1980s (Bannister 1986; Kemper et al. 1997).

In the mid- to late-1990s, increasingly frequent seasonal sightings of Southern Right Whales ('right whales' here-after) along the east and west coasts of Australia have been reported (Australian Broadcasting Commission 1999; Bannister 2001; Brigden 2001; Chilvers 2000; Courier Mail 1999; Noad 2000). Detailed knowledge also exists of right whale behaviour around the south coast during the Austral winter. For example, they aggregate inshore, travel between coastal locations and show a tendency for strong site fidelity during calving (Burnell and Bryden 1997). Right whales have also become entangled in lines and nets and are considered less amenable to disentanglement efforts than Humpback Whales Megaptera novaeangliae (Costello and Coughran 2002; D. Coughran pers. comm.; N. Gales pers. comm.).

Due to their proximity to human activity, the right whale's inshore coastal haunts represent those habitats most 'manageable' or, at least, open to intervention measures to reduce the risk of possible ship strike, entanglement or displacement - each of these being identified as current threats in The Action Plan for Australian Cetaceans (Bannister et al. 1996). A recent Environmental Impact Statement for a proposed finfish sea cage project in Moreton Bay, Queensland, makes no reference to right whales despite several documented sightings in recent years. The statement suggests that whales have adapted to human activity since they have been seen to move close to marine farms in Tasmania. Moreover, the statement dismisses concerns over the potential impacts of multiple sea cages on various endangered marine animals (including mammals, turtles and sharks) by stating "no changes in distribution and abundance are expected" (WBM 2003).

Similarly, an Environmental Impact Statement for a pearl oyster aquaculture operation in Port Stephens, New South Wales, suggests that all migrating whales travel parallel to the land and offers "parallel orientation of the long-lines to the shore" so that whales would pass "between the long-lines as opposed to across the long-lines" as a mitigatory solution against potential entanglement (Umwelt 2001). This proposal was socially and ecologically contentious enough to warrant a Commission of Inquiry, at which New South Wales Fisheries scientists and a biologist with expertise in baleen whale movements made formal submissions for evaluation. Statements there-in included: "there is no record of significant entanglement", "the likelihood of whale entanglement can be calculated as one per 1388 years", and, the implication that numerous pearl farms (situated at around 32°42´S) are unlikely to affect right whales since the area represents the northern limit of their range (Commission of Inquiry 2002).

Here, we provide evidence to the contrary and contend that such an approach to risk assessment pays little heed to New South Wales Coastal Policy, the Draft Recovery Plan for Southern Right Whales in Australian Waters, The Action Plan for Australian Cetaceans, and to media and scientific publications on right whale status around Australia (Bannister 2001; Bannister et al. 1996; New South Wales Government 1997). This approach also promotes aquaculture as ecologically sustainable development without adequate or objective assessment of threats to a number of species on the IUCN Red List of Threatened Species (including, but not limited to, Southern Right Whales, Humpback Whales and Dugongs Dugong dugon - International Union for the Conservation of Nature 2002).

While we cannot predict the effects of anti-shark meshing, fishing operations and the variety of aquaculture operations proposed for the Australian coastline on migrating whales with absolute certainty, we: submit this account of Southern Right Whale sightings to facilitate wider acknowledgment of their ranging behaviour; appeal for acceptance of the uncertainties of animal movements and recommend a more precautionary approach to threatened species risk assessment in the light of increasing whale populations; and, recommend the formation of a national marine animal entanglement committee to oversee minimising risk of - and coordinating response to - potential entanglements.

METHODS

We reviewed accounts of Southern Right Whale catches and the results of recent surveys off southern Australia. Records of right whale sightings off eastern and western Australia in the last decade are mapped, followed by a brief account of entanglement numbers. The implications of recent sightings and potential mortalities associated with increasing northerly movements by right whales are discussed. Information was collated from published literature, Government agencies and personnel, non-government organizations, personal observations and personal communications with marine mammal scientists and tour operators.

RESULTS

Whaling in previous centuries decimated the southwestern Pacific stocks of right whales, like most other stocks. While original population numbers are unknown, Dawbin (1986) reported that over 26,000 right whales were caught in southeastern Australian and New Zealand waters from 1822. Numbers were severely depleted by the mid-1800s, with most individuals landed after that period being incidental to the main targets of Sperm Physeter macrocephalus and Humpback Whales (Bannister 1986; Dawbin 1986). Whaling stations at Twofold Bay on the southern New South Wales coastline (37°05´S) caught only three right whales in the early 1900s before ceasing operations in 1930 (Bannister 1986). A single individual was seen in Queensland waters (27°S) in the mid-1950s (reported in Noad, 2000).

Both coastal and pelagic whaling of right whales off Western Australia commenced later than that of southeastern Australia, peaking in the late 1830s and being carried with such intensity that the industry was all but devoid of yield by the mid-1860s (Bannister 1986; reviewed in Bannister 2001). A century passed before numerous right whale sightings from southwestern Australia prompted aerial survey work to begin in 1976 (Bannister 2001). The protracted period between protection from hunting by international agreement in 1935 and evidence of recovery in the 1980s is likely to be explained by the continued exploitation of right whales by the former Soviet Union from 1950-1970 (Yablokov 1994; Tormosov 1998). Results of longitudinal survey work along the southern Australian coastline suggested a minimum population size of ca 700 for 1995-1997 and population increase rates of ca 7-13% since 1983 (Bannister 2001).

Using a combination of aerial surveys and anecdotal information, Kemper et al. (1997) found that right whales were rarely sighted in southeastern Australian waters until the 1980s, and that they have seldom ventured further north than the waters off Sydney (33°50´S). Several authors rightly note the relative importance of the Western Australian and western South Australian coastline to right whales (Bannister 2001; Burnell and Bryden 1997; Kemper et al. 1997). However, during the last decade there have been frequent sightings on the east coast (Table 1).

Table 1: Southern Right Whale sightings on the east coast of Australia from 1993 to 2002.

*All observers have had at least 10 years experience observing whales in the field and/or formal training in the natural sciences.
**Locales where observers reported cow-calf pairs.

On the west coast of Australia, a dolphin research team observed a lone right whale on consecutive days in September 2002 at Shark Bay (25°44´S, 113°44´E; pers. obs.). The individual was also observed by marine mammal tourism operators and is the second to be seen by researchers in Shark Bay in recent years (M. Krützen pers. comm.). Right whales were also seen in Shark Bay during aerial surveys for Humpback Whales in 1999 and are now being sighted around Perth (~32°S) annually (J. Bannister pers. comm.; D. Coughran pers. comm.). Sightings at Hervey Bay (25°S) on the east coast and at Exmouth (22°S; reported in Bannister 2001) and Shark Bay (25°S) on the west coast are, to the best of our knowledge, the most northern records of right whales in Australia. Sightings at latitudes between 27°S and 38°S are now increasingly frequent (Fig. 1).

Figure 1. Recent sighting locales of Southern Right Whales (solid squares) on the east and west coasts of Australia. Proposed Southern Right Whale distribution around the Australian coastline (solid lines) and potential future ranging (dashed lines) within the EEZ (shaded). Important habitat areas (open circles) and habitat critical to survival of the species (solid triangles; modified from Department of Environment and Heritage).

Entanglements of right whales have occurred on at least five occasions around Australia, with one confirmed fatality (Costello and Coughran 2002; D. Coughran pers. comm.; S. Gibbs pers. comm.; R. McCulloch pers. comm.). The lines, ropes, nets and buoys associated with shark meshing and fishing operations have also entangled no fewer than five Humpback Whales on the east coast in the five years prior to 2003, three of which resulted in fatalities (Environment Australia 2002; SA pers. obs). On the west coast, five Humpback Whales were entangled in 2002 alone (D. Coughran pers. comm.).

DISCUSSION

The latest right whale sightings around the Australian coastline have included cow-calf pairs at locations that overlap with, or are considerably north of, shark meshing and proposed aquaculture sites. These sightings seem indicative of the population's recovery from overexploitation and, whether the whales are re-populating historical haunts or moving into new areas, they represent an indisputable expansion of range from recent decades to include Australian temperate and sub-tropical waters. The Southern Right Whale's current winter distribution can therefore be described as: Shark Bay in the west around the southern coastline to Moreton Bay on the east coast, or, the southern Australian coastline up to ~25°S on the east and west coasts. Individuals and cow-calf pairs may range further than these latitudes and, regardless of whether or not long-range northerly movements are anomalous events, the reduction of risk to endangered species should apply to potentially critical habitats as well as to established aggregation areas.

The seriousness of entanglement and ship strike at the population level can be seen in the endangered North Atlantic Right Whales Eubalaena glacialis. This species was also hunted to near extinction by 1900, and then thought to be recovering subsequent to the whaling era. However, population growth was not sustained through the early 1990s, dropping to 0.976 in 1994 (Caswell et al. 1999). Anthropogenic impacts were, and still are, the major source of mortality. Fifty-seven percent of well-photographed, living individuals bore evidence of fishing gear entanglement (Kraus 1990) and in the years between 1970 and 1999, 36% of all known mortalities (n=45) were due to ship strike and 7% were due to entanglement in fishing gear (Knowlton and Kraus 2001). The fate of North Atlantic Right Whales is dependent upon minimising ship strike and entanglement rates, with population extinction expected in 208 years if current levels of human-caused mortality continue (Fujiwara and Caswell 2001). Preventing only two human-caused deaths of female North Atlantic Right Whales per year would, nevertheless, restore population growth to replacement level (Fujiwara and Caswell 2001).

Measures to reduce the level of anthropogenic injuries and mortalities of North Atlantic Right Whales have included restriction of fishing operations in prime habitat (National Oceanic and Atmospheric Administration 1997). Most recently, the International Maritime Organization approved and adopted an amendment to relocate a portion of the Bay of Fundy (Canada) Traffic Separation Scheme away from an area of higher concentration of whales (M. Brown, pers. comm.). Acoustic deterrents to keep whales away from potential sources of mortality such as fishing gear remain largely untested for baleen whales, and the one test of an alarm for approaching ships elicited responses likely to increase, rather than decrease, the risk of collision (Nowacek et al. in press).

In Australia, sanctuary areas that exclude fishing and boating activity are in place for right whales in South Australia's Great Australian Bight Marine Park, a 9km² temporal exclusion zone for boating activity exists on the western Victorian coastline and disentanglement workshops are being conducted for government agency staff in several States (C. Cartwright pers. comm.; S. Clark pers. comm.; M. Watson pers. comm.). While these measures represent steps in the right direction for conservation of the species, they are inadequate in terms of protecting animals that socialise and calve around half of Australia's 33 000 km of coastline. They also have little bearing on the fate of the increasing number of whales moving up the east and west coasts.

The close inshore nature of Southern Right and Humpback Whale winter migrations, steady increase in whale population sizes and expansion of inshore marine aquaculture can only increase the risk of entanglement. Given the endangered status of right whales (Commonwealth of Australia 1999) and the vulnerability of small populations already fragmented into genetically discrete stocks (Baker 1999; Patenaude 2002), we recommend fulfilment of both national and international obligations to conservation by adherence to:

1. the Precautionary Principle, a key tenet of Agenda 21, to which the Australian Government is a signatory and Local Governments are obliged to implement (United Nations Conference on Environment and Development 1992), and,
2. the National Strategy for Ecologically Sustainable Development, which has underpinned the Australian Government's commitment to natural resource management for some ten years (Commonwealth of Australia 1992).

Recent visits by right whales to Sydney Harbour have been attributed to water quality improvements and soundness in tackling environmental issues in the New South Wales Government's electoral campaign. With such a conspicuous species at risk, future assessments of inshore marine developments might benefit by encompassing a broader acceptance of the inherent risks to environments and their inhabitants, promoting sound strategies for ameliorating negative impacts and offering viable compromises between development and sustainability.

Achieving such goals may be facilitated by the formation of a National Marine Animal Entanglement Committee. Such a committee, with members from the fisheries, planning, research and conservation sectors, would serve to make impartial and objective appraisals of development applications (a form of peer review) and as a board for consultation in the increasingly likely event of entanglement. It might also be prudent for such a committee to be pro-active in overseeing ongoing workshops on entanglement, informing management agencies of international developments in prevention and response to entanglements and disseminating information on current threats to species recovery.

ACKNOWLEDGEMENTS

SA was supported by an Australian Research Council SPIRT Grant and LB was supported by grants from the Danish Research Academy, the Patrick Lett Fund and PADI. We would like to thank the observers listed in Table 1 and those who provided invaluable personal communications. Liz Allen, Stephen Allen, John Bannister, Nick Gales, David Grice, Neil Lazarow, Nathalie Patenaude, Peter Shaughnessy, Aaron Wirsing and two anonymous reviewers provided helpful comments on the manuscript. Moira Brown, Amy Knowlton, Scott Kraus, Michael Moore, Doug Nowacek and Andrew Read pointed us in the right (whale) direction on several important issues. The base map for figure one was generously provided by the Australian Department of Environment and Heritage and deftly modified by David Allen.

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