A Discussion of the Need for Inclusion of the

Murray Submarine Canyons in

Conservation Assessments

for the South East Regional Marine Plan

 

from

 

Australian Conservation Foundation

Whale and Dolphin Conservation Society

Australian Marine Conservation Society

Conservation Council of South Australia

Victorian National Parks Association

 

 

 

This discussion paper seeks to prompt

the Commonwealth Government

to include the Murray Submarine Canyon System

In Conservation Assessments for the Marine Protected Areas in the South East Regional Marine Planning Process

and implement an adequate framework

for ecosystem based management

of the Murray Submarine Canyon System.

The Need for Inclusion of the Murray Submarine Canyons in Conservation Assessments for the South East Regional Marine Plan.

 

 

The Murray Submarine Canyon Group is a vast system of deep-sea canyons of some sixty kilometres south of Kangaroo Island.

 

The Australian Conservation Foundation, Whale and Dolphin Conservation Society, Australian Marine Conservation Society, Conservation Council of South Australia and the Victorian National Parks Association are seeking a Conservation Assessment of  this significant area within the South East Regional Marine Plan.

 

These organisations are supportive of a proposal to establish a Commonwealth Marine Protected Area to protect, conserve and manage the area which incorporates areas of high conservation.

 

Whilst recognising the value of a multiple use approach within the National Representative System of Marine Protected Areas, MPAs must provide an additional level of protection than would otherwise be achieved in surrounding waters. Incorporate areas ranging from highly protected areas (no-take) to sustainable multiple use areas that accommodate a wide spectrum of human activities. Highly protected areas (‘no-take’) areas must be of sufficient size to maintain populations and close enough to reflect ecosystem linkages and connectivity of the surrounding system.

 

This is a brief discussion paper which seeks to prompt the Commonwealth Government to include the Murray Submarine Canyon System in Conservation Assessments for the Marine Protected Areas in the South East Regional Marine Planning Process.

 

It is based on brief assessment of early findings of geologists and oceanographers and more recent evidence of significant whale stranding records and recommendations from the Commonwealth Government's Action Plan for Australian Cetaceans.

 

Further examination of recent technical data and biological information should be undertaken by the Commonwealth as part of a formal Conservation Assessment process for potential marine protected area in the South east Regional Marine Plan.

 

Previously informal discussions about the need for Conservation Assessment has been undertaken with the previous Environment Minister and Environment Australia, but no formal action appears to have been undertaken, despite the apparent significance of these spectacular submarine formations and associated cetaceans.

 

There is an urgent need for this area to be conserved and a framework for ecosystem based management developed and implemented.

 

 

Summary

 

The Murray Canyons are a unique geophysical characteristic of the South East Marine region and have significant biological features and ecosystem functions.

 

Unique geophysical, geological and biological features include:

 

 

 

 

 

 

 

 

 

 

 

Description

 

The Murray Submarine Canyon Group is a vast system of deep-sea canyons of some sixty kilometres south of Kangaroo Island.

 

These underwater canyons are the relicts of the ancient River Murray system during former low sea-levels. They are deeply incised and complex, up to 4600 meters deep in some areas.

 

Described by Sprigg in the late 1940’s, some bathometry and oceanographic work has been undertaken; however biologically the canyons are still relatively unexplored.

 

The geologists who originally described these areas claimed that one of these deep-sea canyons, the Sprigg Canyon could quite comfortable hold the Grand Canyon of the Colorado River with room to spare.

 

Whilst such continental slope canyons are common to all continents, the Murray Canyons are some of the most extensive and largest submarine canyons in the world.

 

Geologically they are significant as they provide information on the origin of the continental margin and of the changes which have occurred over the last 1.8 million years of earth history during the Pleistocene age. (von der Borch, 1989, Lewis et. al., 1998)

 

             

 

Bathymetry of the Ocean South of Kangaroo Island - depth contours in fathoms

(From von der Borch, 1989)

These major submarine canyons are entrenched into the slope and provide conduits for shelf to ocean floor sediment transport as well as windows into underlying strata exposed in the canyon walls. (Lewis et. al. 1998).

 

Importantly a number of the Murray Canyons such as Echidna and Du Couedic canyons host seasonal saline outflows from Spencer Gulf which travel across the shelf and cascade over the shelf break. More westerly canyons, such as Ceduna and Thevenard canyons, appear to be currently inactive (Lewis et al 1998).

 

Text Box: Depth profile of Sprigg Canyon, showing deep incisions up to 2000 fathoms (over 3,600metres) (after von der Borch 1989) Elsewhere it is known that up-welling water from deeper oceanic levels moves up submarine canyons into shallower shelf regions contributing nutrients to marine ecosystems (von der Borch, 1989). 

         

Typically the transition from the deep-sea environment to outer continental shelf, provide habitat for a wide diversity of species.

 

Dense deep scattering layers caused by organisms have been noted around canyon heads as early as 1963 (von der Borch 1989).

 

 

Importance of the Murray Canyons as a Geological Monument

 

The sediments of the canyon walls could also contain a record of the major geological changes that occurred during the evolution of the South Australian continental margin.  GLORIA sidescan sonar images reveal steep, rugged topography that would probably contain some unique, little known ecosystems (Von der Borch pers. comm. from Edyvane 1999).

 

 

IUCN Conservation and Management Values

 

Edyvane (1999) has previously assessed the Canyon habitats of the Sprigg and Murray Canyon, and basement highs of Sanders and Carter Knoll as having Prime IUCN Management Objective: biodiversity, research (IUCN Category IB).  

 

IUCN Identification Criteria were identified by Edyvane as

·         Naturalness (not subject to human induced change, wilderness values),

·         Biogeographic (deepwater canyon habitat-Sprigg and Murray Canyons, basement highs-Sanders and Carter Knoll),

·         Ecological (importance for preservation of unknown canyon ecosystems and habitats, reef flora and fauna of basement highs),

·         Economic (fisheries-unknown),

·         National (potential for listing on the Register of the National Estate), practicality (insulation from external threats).

 

 

 

Linkages of Oceanographic processes with the Bonney Upwelling

 

The Bonney upwelling (currently under Conservation Assessment by the Commonwealth) and the Murray Canyons are potentially very important "pathways" of upwelling water.  It is unknown at present as to what extent the Murray Canyons are involved in this upwelling (as an important conduit). There is a lack of knowledge of the pathways of upwelling water onto the shelf. It is also unclear as to what the magnitude (and frequency) of the Bonney Upwelling is.

 

As such in determining a conservation Assessment of the Bonney upwelling there is also a further need to fully investigate the role of the Murray Canyon System, and its role in ecological functions of the South East Marine region.

 

Surface sea temperature image showing strong cold water upwellings in the South East Region in March 1995. Cooler water is present along the Bonney Coast to areas around the Murray Submarine Canyons and off Kangaroo Island.

Source: Assessment of the Conservation Values of the Bonney Upwelling Area, Butler et al Environment Australia, August 2002.

 
 

 

The recent Assessment of the Conservation Values of the Bonney Upwelling Area, describes the "underlying mechanism associated with coastal upwelling. This is based on simple Ekman dynamics. If the ocean surface is forced by a steady wind stress there is a net transport of water at right angles to the left of the wind direction (southern hemisphere). This water movement occurs within a relatively shallow surface layer (called the Ekman layer)." (Butler et. al. 2002)

 

"Throughout the summer period (November-March), a succession of slowly propagating, highpressure, features move eastwards to the south of the continent. Due to their orientation, certain sections of the southern shelf are subject to southeasterly winds that produce upwelling favourable conditions. This happens off the Eyre Peninsula, Kangaroo Island, the Bonney Coast (Robe to Portland) and eastern Victoria (Lakes Entrance to Croajingalong). The most prominent of these is along the Bonney Coast where classical upwelling plumes are regularly observed. .... The upwelling plume is not restricted to our focus area, but reaches further northwesterly into Discovery Bay. It is possible that there is a southeasterly subsurface extension of this upwelling reaching into western Bass Strait. The upwelling observed along the Eyre Peninsula occurs even when the local winds are not favourable in the terms described above. In winter, the weather patterns are rather different; the belt of high pressure moves northward over the continent, producing persistent westerly winds." (Butler et. al. 2002)

 

 

Marine Protected Area Recommendations from

The Action Plan for Australian Cetaceans

 

The Action Plan for Australian Cetaceans identified that "Effective conservation measures for most Australian cetaceans are likely to involve conservation of appropriate habitats and the resources found within them. Identification of key habitats for Australian cetaceans is therefore an important element in developing strategies for their conservation" (Bannister et. al. 1996).

 

Until recently with a few exceptions (Hervey Bay, Queensland for migrating humpbacks, Monkey Mia, WA for resident bottlenose dolphins Head of the Bight, SA or calving Southern Right Whales) cetacean habitats in Australia are protected in reserves only by coincidence (Bannister et. al. 1996).

 

The Action Plan recognised that more reserves which specifically protect cetacean resources are needed because of the already high, or increasing, human impact on much of the inshore region. Knowledge of at least the distribution requirements of several species is adequate for a number of additional areas to be considered (Bannister et. al. 1996).

 

The Commonwealth Action Plan for Australian Cetaceans recommended that urgent consideration be given to nomination of reserves for protection of cetacean habitats in Australia. It specifically identified a number of offshore areas of high productivity occur in Australian waters known to be important locations for cetaceans including:

 

·         Up-welling areas of high productivity such as off south-eastern South Australia, south and west of  Kangaroo Island

 

·         Along the continental slope off southern Australia south-west of Kangaroo Island, SA.

The Action Plan recognised the considerable difficulties involved in considering such areas for effective management, not only because of the large extent and remoteness of some, but also through competing interests, e.g. from existing commercial fisheries.

 

However, they are areas where an ecosystem management approach to marine environment conservation, including cetaceans, could be focused (Bannister et. al. 1996).

 

 

The Importance of Murray Canyon Area to Cetaceans

 

Extreme canyons on edge of the continental shelf, extending down the slope provides a link between the shallow temperate faunas on the shelf near Kangaroo Island and deep-water faunas influenced by oceanic circulation.

 

The Action Plan for Australian Cetaceans identified up-welling areas of high productivity off south-eastern South Australia, south and west of Kangaroo Island on the North-West Shelf, WA and areas along the continental slope off southern Australia south-west of Kangaroo Island, SA, off Albany, WA and west of Tasmania, as important habitats for:

 

Sperm whales (Physeter macrocephalus)

Beaked whales (Ziphidae)

Pygmy sperm whales Kogia breviceps

Dwarf sperm whales Kogia simus

Risso’s dolphins (Grampus griseus)

False killer whales (Pseudorca crassidens)

Pilot whales (Globicephala melas, G. macrorhynchus)

 

The adjacent South Australian coastline is globally significant for records of stranded beaked whale species, many of which are known from only a few records worldwide. The canyons provide suitable feeding habitat for up to eight cryptic beaked whale species

 

As well as being important feeding grounds and habitat for beaked whales such as the Southern bottlenose whale (Hyperoodon planifrons), Grey’s Beaked Whale (Mesoplodon grayi) and Strap-toothed beaked whale (M. layardii), these bathymetrically complex areas of the continental shelf are probably important for other cetaceans such as the Pygmy sperm whale (Kogia breviceps) and Sperm whales (Physeter macrocephalus).  Known Sperm Whales concentrations occur south-west of Kangaroo Island.

 

In Australian waters all of the beaked whales are insufficiently known to determine status. However the threats identified for all species include competition from expanding fisheries, especially pelagic squid, as well as pollution concerns (Bannister, et. al. 1996).

 

As such a conservation assessment should be undertaken to determine the feasibility of marine protected areas status for the Murray Submarine Canyons. One of the principle aims of a conservation assessment should be to examine potential for resource protection of important cetacean prey species, as well as habitat protection.

 

 

Sperm Whales (Physeter macrocephalus)

 

Whilst little direct work on cetaceans has been done in this area, the coastline South-east of these areas have the highest records of sperm whale strandings in Australia. (Kemper, C.M. & Ling, J.K., 1991)

 

Sperm whales are found in areas of high underwater relief, as well as areas of high primary and secondary productivity (over large time and area scales). It has been generally accepted that groups of female and immature sperm whales are mostly found in waters deeper than 1,000 metres and that only males venture into shallower areas. (Jaquet, N. & Gendron, D. 2002)

 

Recent studies in the Gulf of California have related sperm whale distribution and relative abundance to the abundance of their main prey items. Sperm whales feed predominantly on meso-and bathypelagic cephalopods for which effective sampling methods have not been developed. (Jaquet, N. & Gendron, D. 2002)

 

Sperm whales aggregate more at times of greater local food abundance. Studies in California and the South Pacific estimate the area covered by sperm whale "super-aggregations" to be about 55–75 km, and possibly lasting up to a month, and appear to be strongly associated with size of prey patches.

 

 

Beaked Whales (Ziphiidae)

 

Beaked whales prefer deep oceanic waters, typically deeper than 1800 meters, and or in the vicinity of sea mounts and submarine escarpments which generally are regions of higher prey densities.

 

Importantly the deeply incised canyons may provide a possible deep-water corridor from oceanic waters to seasonally feeding areas of higher productivity adjacent to the continental slope and adjacent waters for calving.

 

Stranding records of beaked whales along the South Australian coast are globally significant (Kemper et al 1991). This is an indication that southern canyon areas are likely to be important habitat for these cryptic, deep water Beaked whale species.

 

There are five main genera of beaked whales placed in the Family Ziphiidae (derived from the Greek xiphos for sword). Up to twenty species are found globally, (some taxonomy is still unclear).  Recently another species of Beaked Whale, Mesoplodon peruvianus was described from New Zealand. With further investigation taxonomists are likely to proclaim some new species.

 

Of the eight species of beaked whale recorded in South Australian waters five are considered rare. The other three species Southern Bottle-nosed, Gray’s (or Scamperdown) and Strap-toothed beaked whale are cryptic and rarely reported at sea as live sightings (Judd, M, et. al. 1993).

 

Beaked Whales recorded in South Australian waters (Judd, M, et. al. 1993)

Arnoux's Beaked Whale

Berardius arnuxii,

Southern Bottle-nosed Whale

Hyperoodon planifrons

Hector's beaked Whale

Mesoplodon hectori

Andrews Beaked Whale

Mesoplodon bowdoini

Gray’s or Scamperdown whale

Mesoplodon grayi

Strap-toothed beaked whale

Mesoplodon layardii

Shepherd's Beaked Whale

Tasmacetus shepherdi

Cuvier's beaked Whale

Ziphius cavirostris

                       

No species survival status categories have been assigned for any of these beaked whale species either due to because of insufficient information. Some species are possibly secure. IUCN status for all species is “insufficiently known”.

                       

Beaked whales may well rival and surpass the sperm whale for their deep-sea diving exploits. They tend to live in deep waters (greater than 200 metres) beyond the continental shelf, and underwater canyon areas such as the Murray Canyons and those in the Great Australian Bight are likely to be important feeding areas. Beaked whales’ main prey are deep-sea squid species.

 

A number of species of the genus Mesoplodon occur in the region. These beaked whales tend to have only one or two pairs of teeth adorning their lower jaws. A combination of numerous body scars and that the teeth are usually more prominent in males suggests that the teeth are used more for sparring and social interaction rather than feeding.

 

Recent examinations of the anatomy of these whales suggests that they hunt by sucking up their prey, although their snouts do have quite hard edges which may be used to seize their prey.

 

One exception to the near -toothless trend in beaked whales is Shepherd’s Beaked whale, Tasmacetus shepherdi, which has a relatively large number of teeth and is thought to prey more on fish.

 

Strandings of beaked whales along the South Australian coast tend to occur in summer, leading researchers to speculate that there is some seasonal movement closer inshore for breeding (Kemper, et. al. 1991, Bannister, et. al., 1996).

 

Many beaked whale strandings are of small groups of animals - with evidence in a number of stranding events that one of the animals often has died some time prior to the others - suggesting there is a strong social bond amongst the groups. Strandings for many of these whales may indicate localised populations.

 

The Strap Toothed Whale (Mesoplodon layardii) is the most commonly stranded beaked whale (by common researchers allude to some seventy known records up until 1994) with the majority of these in South Australia. Older males are aptly named, with 30 centimetre long teeth arching over their “snout” or rostrum - which would appear to restrict their ability to open their mouths - giving further ground for a "squid-sucking" method of capture. 

 

Most of the fourteen or so squid species recorded in stomachs of strap-toothed whales occur at great depth.

 

Typically the beaked whales are wary of ships and rarely seen at sea.  Some species found in Australasia, like the Andrew’s Beaked Whale (Mesoplodon bowdoini) were only discovered as recently as 1904.

 

Scientific knowledge of Andrew’s Beaked Whale is typical for that of the Ziphid whales. It is known from less than two dozen strandings in Australia and New Zealand and a few records from the Falklands and Chile.

 

The South Australian Museum retrieved one of the few specimens from a 1995 stranding at Nene Valley in the South East of South Australia.

 

 

 

 

Potential Resource Competition from Development of Squid Fisheries

 

Of particular concern for the future of these whales would be the development of large factory-style squid fisheries.  However as yet there has been little publicly scrutinised assessment of the potential of these areas for these developing fisheries.

 

The Action Plan for Australian Cetaceans (Bannister, et al 1996) noted the need to monitor development of fisheries directed at pelagic squid, possibly important in the diet of beaked whales (including Berardius arnuxii, Hyperoodon planifrons, Mesoplodon hectori, M. bowdoini, M. grayi, M. layardii, Tasmacetus shepherdi, Ziphius cavirostris) and the need to minimise possible detrimental effects on population(s), e.g. from fishing operations for Sperm Whale

 

A global increase in squid fisheries and in particular northern hemisphere squid fisheries has resulted in rapid declines in catch in previously rich grounds related to intense mechanical harvesting techniques. As global fisheries decline, there may be an increasing trend to exploit southern water species of squid (Nototodus, Todarodes and other species) and other marine life that are important prey items for cetaceans and oceanic seabirds such as albatross. 

 

The status of squid populations in Australian and offshore waters is unknown, and typically such fisheries, when newly exploited may expand beyond the level necessary to ensure sustainable catches in the future. (Kailola, P. et al. (1993).

 

Overseas, some states have sought to act in a precautionary way to limit expansion of squid fisheries.  California enacted legislation in the late 1990's to restrict expansion of its squid fishery in response to Federal US procrastination to introduce pelagic species management plans.

 

The rationale for protecting our deep-sea canyon areas is outlined in the Commonwealth Government’s Cetacean Action Plan, which recommends the need to manage fisheries for the reduction of resource competition.

 

In the plan, all Beaked whales are insufficiently known to determine status. Potential threats identified for all species include competition from expanding fisheries, especially pelagic squid, as well as pollution concerns. It is therefore important that some offshore depressions and rises and other important or complex bathymetric features be given suitable protection. 

 

 

The Commonwealth Action Plan for Australian Cetaceans recommended:

 

·         That the expanding exploitation of living marine resources (harvesting of fish, crustaceans, squid and other molluscs, seaweeds, etc) be planned and regulated with a view to ecological relationships, and with special reference to the identification and protection or conservative management of keystone species within marine ecosystems

 

·         That where management plans are prepared (e.g. Under the commonwealth fisheries management act) for fisheries targeting particular marine species or stocks, responsible commonwealth, state and territory agencies take into account the impacts of that exploitation on other species and other trophic levels within the ecosystem sustaining those targeted species or stocks

 

·         That in the design of research into stocks of fish (and of other marine organisms) and the calculation of catch quotas, fishery biologists and managers

–        Consider the role and food requirements of cetaceans in the food webs that include the targeted commercial species

–        Seek relevant advice from cetacean biologists.

(Bannister, et. al. 1996)

 

 

Ecosystem Context in Relation to the Exploitation of Marine Resources

 

The Following extract from the Commonwealth Action Plan for Australian Cetaceans (Bannister, et. al. 1996) highlights the relevance of an ecosystem -based management approach to cetacean management.

 

"Marine and terrestrial environments are intimately interconnected by the cyclic movement of water (via evaporation and rain) and of gases (especially O2 and CO2), and by global climate systems (especially deriving from seasonal fluctuations of the South Polar Ice Cap and Antarctic ice sheet).

 

Land-based urban, industrial and agricultural activities inevitably and increasingly have an impact on marine ecosystems via these cycles and in other ways. Management to protect or to enhance cetacean populations must fundamentally be directed at the integrity and productivity of the ecosystems which sustain them.

 

Many cetaceans and especially the larger odontocetes are predators at relatively high trophic levels within complex food webs. The large Southern Ocean mysticetes depend on and are major consumers of invertebrates (euphausiid and copepod crustaceans) at a low trophic level in a restricted and relatively uncomplicated food web.

Cetaceans are particularly vulnerable to perturbations within marine ecosystems which have major impacts on species important in their diet, e.g. extensive, intensive and expanding fisheries on keystone species such as Antarctic krill, Euphausia superba, in the Southern Ocean, and trawl and purse-seine fisheries for clupeoids (e.g. anchovy and pilchard), other fish and squid in state, Northern Territory and Commonwealth waters.

 

Poor knowledge of the status and biology of most cetaceans prejudices understanding and appropriate recognition of their role within marine ecosystems, and does not allow for their requirements in the face of increasing human impacts on the resources on which they depend.

 

This concern is particularly pertinent to Australian fisheries, which are currently undergoing a phase of expansion in the variety of stocks targeted and in the development of harvesting techniques and technology.

 

The impact on cetaceans of present and future competition for food resources is unknown. The dearth of specific information on the diet and population status of cetaceans inhabiting Australian waters has meant that their resource needs are rarely, if ever, taken into account when fishery catch limits are determined.

 

On the other hand, general information is available for many species and can be used as a first approximation.  The possibility cannot be ruled out of legislated changes to fisheries management policy in Australia, whereby governments opt to sell marine fish resources into medium- to long-term private ownership via an instrument of title or exclusive licence. The Native Titles Act 1993 also has potential implications in relation to new arrangements for managing fisheries operations in areas subject to sea claims by Aboriginal communities.

 

Where governments overseas have relinquished direct management of fishery resources to private operators, whose motivations are competition and profit, there has been increased potential for over-exploitation and environmental degradation. "

 

With regard to Exploitation of Marine Resources, The Action Plan for Australian Cetaceans recommended:

 

·         That the expanding exploitation of living marine resources (harvesting of fish, crustaceans, squid and other molluscs, seaweeds, etc) be planned and regulated with a view to ecological relationships, and with special reference to the identification and protection or conservative management of keystone species within marine ecosystems

 

·         That where management plans are prepared (e.g. Under the commonwealth fisheries management Act) for fisheries targeting particular marine species or stocks, responsible commonwealth, state and territory agencies take into account the impacts of that exploitation on other species and other trophic levels within the ecosystem sustaining those targeted species or stocks

 

·         That in the design of research into stocks of fish (and of other marine organisms) and the calculation of catch quotas, fishery biologists and managers

o        Consider the role and food requirements of cetaceans in the food webs that include the targeted commercial species  – seek relevant advice from cetacean biologists, possibly via the proposed advisory body

 

·         That relevant authorities be encouraged to  – regulate the use of agricultural biocides and the disposal of industrial and urban wastes to prevent or allow their entry into aquatic environments only within safe levels

o        Monitor the levels of pollutants in aquatic environments regularly at strategic sites, to assess water quality in relation to accumulation of toxic substances at different trophic levels within the biota

o        Develop improved methods of disposal of industrial and urban wastes and of monitoring to ensure the effectiveness of regulatory systems

 

·         That relevant authorities consult with extractive industries (oil, gas, minerals) and ancillary industries (e.g. Bulk tanker shipping) which operate within marine environments to ensure that exploration, extraction and transport of their products is conducted according to the highest levels of awareness and safety, and of preparedness for dealing with accidents and disasters (e.g. Oil spills) that could have a detrimental impact on cetaceans and their habitats.

 

 

Research: Need for Acoustic and Other Surveys of Region

 

To fully evaluate the occurrence of these cryptic marine mammals it would be necessary to conduct acoustic surveys off the relevant canyon areas. Using a series of hydrophones suspended below retrievable buoys and left at sea away from shipping lanes one might be able to build up a sonic picture of the occurrence of beaked and other whales. An acoustic library of beaked-whale sounds - whilst initiated and being expanded in the Northern Hemisphere is still needed for our southern waters.

 

International interest has been raised recently over the potential of acoustic methods for investigating behaviour, seasonal movement and distribution of cetaceans over large ocean areas. In 1993 studies using existing US Navy passive hydrophone arrays in the North Atlantic proved very successful in detecting individual whales and tracking them over considerable distances, providing information on seasonal distribution, movement and behaviour for three species - blue, fin and minke whales. More acoustic material was acquired in one year than exists in all the cetacean sound libraries combined, worldwide (Bannister et. al. 1996).

 

Given concerns expressed over the difficulty of estimating the abundance of Blue Whales in the southern hemisphere, the International Whaling Commission’s Scientific Committee has strongly recommended that the potential of such methods, both for identifying areas of Blue Whale concentrations and for assessing their abundance, be determined (Bannister et. al. 1996).

 

The Commonwealth Action Plan for Australian Cetaceans recommended that the potential for obtaining information on whale distribution, movements and behaviour be investigated. It also recommended investigations should include assessments of

 

·         Current naval and CSIRO acoustic capacity and material

 

·         The need for acquisition or development of equipment for deployment on suitable vessels

 

·         Provision of trained observers on naval, Antarctic supply and national oceanographic and fisheries research vessels

 

·         The applicability and reliability of obtaining estimates or indices of abundance from acoustic data, comparable to those already developed in sightings theory.

(Bannister et. al. 1996)

 

Additionally discussions should be conducted with Australian defence forces to investigate the use of satellite imaging, acoustic and other submarine detection technology and sharing of data with cetacean researchers  in the possible use of cetacean surveys.

 

 

Use of Cetaceans to Determine the Boundaries for a Conservation Area

 

Canada is already in the process of establishing a significant marine reserve for its largest submarine canyon off the coast of eastern Canada “The Gully”. The need for establishment has been prompted by increasing interest in oil and gas production on the Scotian Shelf. Canadian researchers involved believe that cetaceans provide a reliable means to determine the boundaries for a conservation area in this region.

 

Compared with other parts of the Canadian Scotian Shelf and Slope the abundance of cetaceans was higher in the Gully. With the greatest correlation with depth, with five of the 11 cetacean species commonly found in the Gully concentrated in the deep (200 - 2000 m) mouth of the canyon. However other factors such as sea surface temperature and month also affected abundance. A similar situation with regards to season and temperature may exist in our Southern waters - with the stranding records of beaked whales being noticeably higher in summer months - suggesting seasonal movements (Sascha et.al.1999).

 

Canadian researchers (Sascha et. al. 1999) have suggested a year-round marine protected area is necessary for the Gully. A core protection zone should be defined in the Gully based on depth and bounded by the 200-m isobath. A buffer zone around the core zone should be defined to provide protection from activities with further-reaching effects, such as noise, dredging, and chemical pollution. The Canadian Department of Fisheries and Oceans is leading a planning process, the Sable Gully conservation Strategy including a pilot Marine protected area was endorsed by the Canadian Fisheries minister.

 

 

 

 

 

Need for a Proactive approach to Conservation of Cryptic Cetaceans

 

It is likely to take decades to unravel the mysteries of these bizarre and cryptic whales, and of the other unknown denizens of our largest submarine canyons. However we have the opportunity to be pre-emptive and start conserving suitable habitat before any intensive resource exploitation starts.

 

Ecosystem based management is widely acknowledged to be fundamental to long-term, sustained use of marine resources, but progress towards that goal is slow and is hampered by the lack of reliable data on population sizes, predator-prey dynamics and other relationships within ecosystems (Bannister et. al. 1996).

 

Because they are rarely sighted at sea, any decline of these whales related to threats such as increased exploitation of squid stocks is likely to go unnoticed - except that, with the passage of time someone may might notice a decline in the few strandings that do occur along our shores. One day we may realise they simply are no longer there.

 

 

 

References

 

Bannister, J L, Kemper, C M, Warneke R M 1996, The Action Plan for Australian Cetaceans, Biodiversity Group, Environment Australia September 1996.

 

Butler, A., Althaus, F. ,Furlani, D., Ridgway, K. (2002), Assessment of the Conservation Values of the Bonney Upwelling Area, A component of the Commonwealth Marine Conservation Assessment Program 2002-2004, Report To Environment Australia, August 2002.

 

Chris von der Borch, in Natural History of Kangaroo Island, Royal Society of SA, 1989.

 

Edyvane K. (1999) Conserving Marine Biodiversity in South Australia. SARDI Report Series. Report Numbers 38 and 39. SARDI Aquatic Sciences, South Australia.

 

Jaquet, N. and Gendron, D. (2002). Distribution and relative abundance of sperm whales in relation to key environmental features, squid landings and the distribution of other cetacean species in the Gulf of California, Mexico. Marine Biology 141: 591-601.

 

Judd, M., Kemper, C., Ling, J.K., Olman, J., A Guide To Whales And Whale Watching in South Australia, South Australian Museum, 1993.

 

Kailola, P. et al. (1993). Australian Fisheries Resources. Bureau of Resource Sciences, DPI, Canberra.

 

Kemper, 1994; Possible influences of Oceanographic Features of GAB on Cetaceans in The Great Australian Bight Marine Park, Ceduna Workshop Discussion papers, South Australian Research and Development Institute.

 

Kemper, C.M. & Ling, J.K., Whale Strandings in South Australia (1881-1989) in Transactions of the Royal Society of S. Aust. 1991, 115 (1), 37 -52.

 

Lewis, R., Edyvane, K. & Newland, N., 1998. The State of Our Seas and Coasts - Description, Uses and Impacts on South Australia's Marine and Estuarine Environment. A Technical Reference Document for the Government of South Australia     (Publisher), Adelaide, 142 pp.

 

Ritter, G., 1982, The SE Australian Squid Industry, status and development, SAIT. Adelaide.

 

Sascha K. Hooker, Hal Whitehead, and Shannon Gowans. 1999, Marine protected area design and the spatial and temporal distribution of cetaceans in a submarine canyon, Conservation Biology. 13(3): 592-602.