More than leftovers: getting marine parks right in Australia

7 08 2011
Taken by user Hossen27

Image via Wikipedia

A few weeks back I cosigned a ‘statement of concern’ about the proposal for Australia’s South West Marine Region organised by Hugh Possingham. The support has been overwhelming by Australia’s marine science community (see list of supporting scientists below). I’ve reproduced the letter addressed to the Australian government – distribute far and wide if you give more than a shit about the state of our marine environment (and the economies it supports). Basically, the proposed parks are merely a settlement between government and industry where nothing of importance is really being protected. The parks are just the leftovers industry doesn’t want. No way to ensure the long-term viability of our seas.

On 5 May 2011 the Australian Government released a draft proposal for a network of marine reserves in the Commonwealth waters of the South West bioregional marine planning region.

Australia’s South West is of global significance for marine life because it is a temperate region with an exceptionally high proportion of endemic species – species found nowhere else in the world.

Important industries, such as tourism and fisheries, depend on healthy marine ecosystems and the services they provide. Networks of protected areas, with large fully protected core zones, are essential to maintain healthy ecosystems over the long-term – complemented by responsible fisheries management1.

The selection and establishment of marine reserves should rest on a strong scientific foundation. We are greatly concerned that what is currently proposed in the Draft South West Plan is not based on the three core science principles of reserve network design: comprehensiveness, adequacy and representation. These principles have been adopted by Australia for establishing our National Reserve System and are recognized internationally2.

Specifically, the draft plan fails on the most basic test of protecting a representative selection of habitats within the bioregions of the south-west. There are no highly protected areas proposed at all in three of the seven marine bioregions lying on the continental shelf3. Overall less than 3.5% of the shelf, where resource use and biodiversity values are most intense, is highly protected. Further, six of the seven highly protected areas that are proposed on the shelf are small (< 20 km in width)4 and all are separated by large distances (> 200 km)5. The ability of such small isolated areas to maintain connectivity and fulfil the goal of protecting Australia’s marine biodiversity is limited. Read the rest of this entry »

Colour-blind sharks

3 02 2011

A few weeks ago I was interviewed on Channel 10 (Adelaide) about some new research coming out of the University of Western Australia regarding shark colour vision.

I’ve received permission from Channel 1o to reproduce the news snippet here. The first bloke interviewed is Associate Professor Nathan Hart, the study‘s lead author. I’m the bald one appearing in the middle at at the end.

It certainly was an interesting story, although two claims were made that probably needed better contextualisation.

First, the authors claim that because of this taxon’s colour blindness, they probably notice pigment transitions more when using visual cues to identify potential prey. What this means is that bright colours set against duller backgrounds might provide that contrast enough to attract sharks. The upshot from the interview is that brightly coloured and patterned togs (bathers) might make sharks think you are potentially a tasty treat. Read the rest of this entry »

Want a cool conservation job in beautiful southern Australia?

14 12 2010

I was asked to post this cool-sounding job on – relevant punters welcome to respond.

Australian Wildlife Conservancy (AWC) is a non‐profit organisation dedicated to the conservation of Australia’s threatened wildlife and their habitats. AWC now owns and manages more land than any other private conservation organisation in Australia ‐  21 properties, covering more than 2.6 million hectares ‐ protecting more than 1,200 fauna species through active land management informed by strategic scientific research.

AWC is seeking an experienced and committed ecologist who will be pivotal in the development and implementation of the conservation and science program throughout south‐eastern Australia. The position will be based at Scotia Wildlife Sanctuary (where on‐site accommodation will be provided), but will include work at other AWC sanctuaries, especially Kalamurina (Lake Eyre), Buckaringa (Flinders Ranges), Yookamurra (Riverlands), Dakalanta (Eyre Peninsula), Bowra (Mulga Lands) and North Head (Sydney) sanctuaries.

Scotia is a large property (65,000 ha) that lies on the NSW‐SA border between Wentworth and Broken Hill, and includes Australia’s largest area free of foxes, cats and rabbits (8,000 ha) and where seven regionally extinct species have been reintroduced (bilby, boodie, woylie, bridled nailtail wallaby, numbat, greater stick‐nest rat, mala and black‐eared miner). In addition, the property has outstanding conservation values because it protects habitats, in good condition, that have been extensively cleared in western NSW.

Read the rest of this entry »

Blog Action Day 2010 – Water neutrality and its biodiversity benefits

16 10 2010

In my little bid to participate in’s Blog Action Day 2010 – Water, I’ve re-hashed a post from 2008 on ‘water neutrality’. This will also benefit my recently joined readers, and re-invigorate a concept I don’t think has received nearly enough attention globally (or even in parched Australia where I live). So here we go:

The world’s freshwater ecosystems are in trouble. We’ve extracted, poisoned, polluted, damned and diverted a large proportion of the finite (and rather small!) amount of freshwater on the planet. Now, most people might immediately see the problem here from a selfish perspective – no clean, abundant water source = human disease, suffering and death. Definitely something to avoid, and a problem that all Australians are facing (i.e., it’s not just restricted to developing nations). Just look at the Murray-Darling problem.

In addition to affecting our own personal well-being, freshwater ecosystems are thought to support over 10000 fish species worldwide (see also a recent post on Africa’s freshwater biodiversity’s susceptibility to climate change), and the majority of amphibians and aquatic reptiles. Current estimates suggest that about 1/3 of all vertebrate biodiversity (in this case, number of species) is confined to freshwater. As an example, the Mekong River system alone is thought to support up to 1700 different species of fish.

So, what are some of the ways forward? The concept of ‘water neutrality’ is essentially the wet version of carbon neutrality. It basically means that water usage can be offset by interventions to improve freshwater habitats and supply. Read the rest of this entry »

Student opportunities with Australian Wildlife Conservancy

8 09 2010

A colleague of mine, Dr. Matt Hayward of the Australian Wildlife Conservancy (AWC), asked me to circulate some Honours, MSc and PhD student project opportunities. I thought this would be best done by publishing the call as a blog post.

The AWC is a non-government, non-profit organisation dedicated to the conservation of Australia’s wildlife and their habitats. AWC’s south-east region has a team of 7 ecologists who work closely with the land managers to carry out AWC’s Conservation and Science Program. The Science Program includes strategic research designed to help us manage threatened species more effectively. Several of these research projects are suitable for Honours, Masters or PhD projects.

This prospectus provides an outline of the student projects that are currently on offer in the south-east region. The majority of the projects are based on one sanctuary, although some aspects of the research may be done on other AWC sanctuaries and/or government conservation areas.

AWC will partially support these projects with equipment, staff time and expertise, and accommodation. In some cases, AWC may also provide some vehicle use and office facilities onsite at The Scotia Field Research Centre. We anticipate these projects will be collaborative efforts with input from students, academics and AWC staff, with appropriate acknowledgement for all involved. These projects are offered on a first in, first approved basis and have been offered to multiple universities.

More details on the sanctuaries and AWC are available here. If you are keen do one of these projects, please contact Matt Hayward and we will then formulate a research proposal and research agreement. Eight project descriptions follow. Read the rest of this entry »

How to restore a tropical rain forest

6 11 2009

thiakiHere’s a little story for you about how a casual chat over a glass of wine (or many) can lead to great scientific endeavours.

A few years ago I was sitting in the living room of my good friends Noel Preece and Penny van Oosterzee in Darwin chatting about life, the universe, and everything. They rather casually mentioned that they would be selling their environmental consulting company and their house and moving to the Queensland rain forest. Ok – sounded like a pretty hippy thing to do when you’re thinking about ‘retiring’ (only from the normal grindstone, at least). But it wasn’t about the easy life away from it all (ok, partially, perhaps) – they wanted to do something with their reasonably large (181 ha), partially deforested (51-ha paddock) property investment. By ‘something’, I mean science.

So they asked me – how would we go about getting money to investigate the best way to reforest a tropical rain forest? I had no idea. As it turns out, no one really knows how to restore rain forests properly. Sure, planting trees happens a lot, but the random, willy-nilly, unquantified ways in which it is done means that no one can tell you what the biggest biodiversity bang for your buck is, or even if it can compete on the carbon sequestration front.

Why carbon sequestration? Well, in case you’ve had your head up your bum for the last decade, one of the major carbon mitigating schemes going is the offset idea – for every tonne of carbon you emit as a consumer, you (or more commonly, someone else you pay) plant a certain number of trees (because trees need carbon to grow and so suck it out of the atmosphere). Nice idea, but if you deforest native ecosystems just to bash up quick-growing monoculture plantations of (usually) exotic species with little benefit to native biota, biodiversity continues to spiral down the extinction vortex. So, there has to be a happy medium, and there has to be a way to measure it.

So I said to Penny and Noel “Why don’t we bash together a proposal and get some experts in the field involved and submit it to the Australian Research Council (ARC) for funding?” They thought that was a smashing idea, and so we did.

Fast forward a few years and … success! The Thiaki Project was born (‘Thiaki’ is the name of the Creek flowing through the property north of Atherton – seems to be of Greek origin). We were extremely lucky to find a new recruit to the University of Queensland, Dr. Margie Mayfield (who worked previously with Paul Ehrlich), who was not only an expert in the area of tropical reforestation for biodiversity, she also had the time and energy to lead the project. We garnered several other academic and industry partners and came up with a pretty sexy experiment that is just now getting underway thanks to good old Mr. ARC.

The project is fairly ambitious, even though the experiments per se are fairly straight forward. We’re using a randomised block design where we are testing 3 tree diversity treatments (monoculture, 1 species each from 6 families, and 5 species each from those same 6 families) and two planting densities (high and low). The major objective is to see what combination of planting density and native tree species provides the most habitat for the most species. We’re starting small, looking mainly at various insects as they start to use the newly planted blocks, but might expand the assessments (before planting and after) to reptiles, amphibians and possibly birds later on.

But we’re not stopping there – we were fortunate enough to get get a clever soil scientist, Dr. David Chittleborough of the University of Adelaide, involved so we could map the change in soil carbon during the experiment. Our major challenge is to find the right combination of tree species and planting techniques that restore native biodiversity the most effectively, all the while maximising carbon sequestration from the growing forest. And of course, we’re trying to do this as most cost-effectively as we can – measuring the relative costs will give landowners contemplating reforestation the scale of expenditures expected.

I’m pretty proud of what Margie, Noel, Penny and the rest of the team have accomplished so far, and what’s planned. Certainly the really exciting results are years away yet, but stay tuned – Thiaki could become the model for tropical reforestation worldwide. Follow the Thiaki Project website for regular updates.

I’d also love to recreate the Thiaki Project in southern Australia because as it turns out, no one knows how to maximise biodiversity and carbon sequestration for the lowest cost in temperate reforestation projects either. All we need is a few hundred hectares of deforested land (shouldn’t be hard to find), about $1 million to start, and a bit of time. Any takers?

CJA Bradshaw

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carbon offset

© C. Madden

Burning away ecological ignorance

24 08 2009

This is the last post from the 10th International Congress of Ecology (INTECOL) in Brisbane. I’ve just returned after a long, but good week.


© ABC Landline

Following my last two posts (here and here) from INTECOL, I end with a post about the very final talk of the Congress by a very well-known conservation ecologist, Professor David Lindenmayer of the Australian National University. David is a prolific and highly respected ecologist specialising in long-term ecological studies measuring forest biodiversity change. What made this final talk so compelling (and compelling it had to be after 5 straight days of talks) was not that it was essentially his acceptance ‘speech’ for winning the Ecological Society of Australia‘s Australian Ecology Research Award (AERA), it was the personal side of his science that kept the audience rapt.

As many CB readers will know, Australia (the state of Victoria in particular) suffered earlier this year some of the worst forest fires on record. Many died and many millions in property were damaged. Since then, everyone from Germaine Greer to MP Wilson Tuckey has become a laughably unqualified fire expert, but few have sufficient knowledge or experience to prescribe the most parsimonious fire regime for Victoria’s wet temperate forests.

Now, I think David was unfortunate to lose either friends or family in those fires, and he’s been collecting biodiversity data there and studying the ecology of south Australian fires for over two decades. Suffice it to say, he probably knows what he’s talking about.

So when the baying hounds of public misunderstanding demand that the remaining bush fragments of Victorian forests be cleared to protect people and property (so-called ‘hazard-reduction burning’), I think we should listen instead to David Lindenmayers of this world.

David’s talk was about just this – how the fires are portrayed as the Apocalypse itself by the media, when in reality ecosystems generally bounce back very quickly. Indeed, even in some of the most heavily burnt sites, most of the standing carbon in the vegetation remains (despite appearances). He also explained that our knowledge of temperate fire regimes is rudimentary at best, and that available evidence from the Northern Hemisphere suggests that clearing forests actually can lead to a HIGHER fire proneness, intensity and frequency. He explained how the homogenisation of fire patterns destroy are weakening essential ecosystem functions, and that spatial and temporal fire patchiness is essential to maintain ecosystems and the people living in them.

In summary, we have failed to learn lessons from northern Australia about buggering up the natural fire regime (see previous post). We as a society fall victim to sensationalist and uninformed media reports and develop ill-advised, knee-jerk policies as a result. Ecological considerations for our own welfare have been overlooked too long. It’s time politicians stop fuelling the fires of public ignorance and listen to the ecologists out there who know a thing or two about complex ecosystem structure and the disturbance regimes that create them.

Thanks, David, for a sobering reminder of the importance of our work.

CJA Bradshaw

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Charles Darwin, evolution and climate change denial

5 08 2009

DarwinThis week a mate of mine was conferred her degree at the University of Adelaide and she invited me along to the graduation ceremony. Although academic graduation ceremonies can be a bit long and involve a little too much applause (in my opinion), I was fortunate enough to listen to the excellent and inspiring welcoming speech made by the University of Adelaide’s Dean of Science, Professor Bob Hill.

Professor Hill is a world-renown expert in plant evolution, systematics and ecophysiology, and he gave a wonderful outline of the importance of Darwin’s legacy for today’s burgeoning problem solvers. I am reproducing Prof. Hill’s speech here (with his permission) as a gift to readers of I hope you enjoy it as much as I did.

Chancellor, Vice Chancellor, distinguished guests, members of staff, friends and family of graduates, and, most importantly of all, the new graduates, I am very pleased to have been asked to speak to you today, because 2009 marks one of the great anniversaries that we will see in our lifetimes. 200 years ago, on February 12th 1809, Charles Robert Darwin was born. To add to the auspicious nature of this year, 150 years ago, John Murray published the first edition of Darwin’s most famous book, titled On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, better known to us all today as The Origin of Species.

I believe that from a modern perspective, Darwin was the most influential person who has ever lived. Darwin’s impact on how we think and work is much more profound than most people realise. He changed the entire way in which we go about living. Today, I want to talk to you briefly about how Darwin had this impact.

Darwin was a great observer and a great writer, but above all he was a great critical thinker. He became a scientist by a round about route, planning to be a doctor and a minister of religion along the way, although his passion was always natural history. He was not a great undergraduate student, but he benefited enormously from contact he had with University staff outside the formal classroom. His potential must have been obvious, because he was strongly recommended at a relatively young age, to take the position of naturalist and gentleman companion to Captain Robert Fitzroy on his famous five year voyage of the Beagle. Following this voyage, Darwin never physically left Britain again, but intellectually he roamed far and wide. Darwin was one of the great letter writers. He wrote thousands of letters to contacts all over the world, requesting specimens, data and opinions, and he worked relentlessly at analysing what he received back.

Over many years as a practising scientist I have met a lot of people with a passion for natural history, some of them trained scientists like Darwin, some of them gifted amateurs. There is a very obvious distinction between those with and without formal scientific training at a Tertiary level, but it took me a long time to work out what that distinction is. Let me digress slightly before I explain it.

In today’s terminology we talk a lot about graduate attributes. For some graduates, it is reasonably simple to define the kinds of attributes you expect them to have. I prefer engineers whose bridges don’t fall down, lawyers who keep me out of jail unnecessarily, accountants who can add up and doctors who do their best to keep me alive and healthy. However, the key attributes we expect of Science graduates are not so simple to define. You will all have one or more specialities where you have more knowledge than those who did not do the relevant courses, but if you are anything like I was when I was sitting out there waiting to graduate, you probably think you did what you had to do in order to pass your exams and you now think you have forgotten most of what you were taught. I can assure you that you haven’t, but I can also assure you that specific knowledge of a scientific subject is not the most important thing you have been taught here.

So what is that special something that separates out a professional scientist? It is the capacity for critical scientific thinking. You are now ready to work as professionals in many fields, and employers will actively seek to hire you because they know you have been trained here to apply a particular approach to problem solving. That approach is not easily obtained and has been taught to you in the most subtle way over the full breadth of what you have been exposed to during your time here. I suspect most of you don’t even know that you now have this skill, but you do. Darwin had it in the most sublime fashion.

When Darwin published the Origin of Species it was the culmination of decades of data gathering, backed up by meticulous analysis. Darwin never swayed from that rigorous approach, which strongly reflected the training he received as a student.

When you are exposed to a new problem, you will approach the solution in a similar way to Darwin. Let me consider the example of climate change. There is a remarkable parallel between the public reaction to the publication of the Origin of Species and the current public reaction to climate change. Darwin suffered a public backlash from people who were not ready to accept such a radical proposition as evolution by means of natural selection and this was reinforced by a significant number of professional scientists who were willing to speak out against him and his theory. As time went by, professional scientists were gradually won over by the weight of evidence, to the point where mainstream science no longer considers evolution as a theory but as scientific fact.

The reality of climate change and its potential impacts has not had a single champion like Darwin, but it has involved a similar slow accumulation of data and very careful analysis and critical thinking over the implications of what the data tell us. Initially, there were many scientists who spoke against the human-caused impact on climate change, but their number is diminishing. Most significantly, the critical analysis undertaken by thousands of mainstream scientists has gained broad political acceptance, despite the best efforts of special interest lobbyists. I suspect Darwin would be fascinated by the way this debate has developed.

Lobbyists who write stern words about how scientists as a whole are engaged in some conspiracy theory to alarm the general population simply do not understand or choose to ignore how scientists work. The world needs the critical and analytical thinking that scientists bring more than ever before. We live on a wonderful, resilient planet, that will, in the very long run, survive and thrive no matter what we do to it. But we are an extremely vulnerable species, and our survival in a manner we would consider as acceptable, is nowhere near as certain. That is the legacy of my generation to yours. I have faith that your generation will be wiser than mine has been, and I know that good science will lead the charge towards providing that wisdom.

Charles Darwin was the greatest scientist of all, and that is partly because he was a great observer and a great writer. But most of all, Darwin was the consummate critical thinker – he collected masses of data himself and from colleagues all over the world and he fashioned those data into the most relevant and elegant theory of all. I will conclude with a brief and well known passage from the first edition of the Origin of Species, which clearly demonstrates the power of Darwin’s writing:

Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

I hope that the next Charles Darwin is sitting amongst you today. I know that at the very least I am standing in front of a group of people who have all the attributes necessary to be great contributors to the well-being of society and the planet. Be confident of your training and use your skills well. You have a grand tradition to uphold.

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Eastern Seaboard Climate Change Initiative

30 04 2009
© A. Perkins
© A. Perkins

I’ve just spent the last few days in Sydney attending a workshop on the Eastern Seaboard Climate Change Initiative which is trying to come to grips with assessing the rising impact of climate change in the marine environment (both from biodiversity and coastal geomorphology perspectives).

Often these sorts of get-togethers end up doing little more than identifying what we don’t know, but in this case, the ESCCI (love that acronym) participants identified some very good and necessary ways forward in terms of marine research. Being a biologist, and given this is a conservation blog, I’ll focus here on the biological aspects I found interesting.

The first part of the workshop was devoted to kelp. Kelp? Why is this important?

As it turns out, kelp forests (e.g., species such as Ecklonia, Macrocystis, Durvillaea and Phyllospora) are possibly THE most important habitat-forming group of species in temperate Australia (corals and calcareous macroalgae being more important in the tropics). Without kelp, there are a whole host of species (invertebrates and fish) that cannot persist. The Australian marine environment is worth something in the vicinity of $26.8 billion to our economy each year, so it’s pretty important we maintain our major habitats. Unfortunately, kelp is starting to disappear around the country, with southern contractions of Durvillaea, Ecklonia and Hormosira on the east coast linked to the increasing southward penetration of the East Australia Current (i.e., the big current that brings warm tropical water south from Queensland to NSW, Victoria and now, Tasmania). Pollution around the country at major urban centres is also causing the loss or degradation of Phyllospora and Ecklonia (e.g., see recent paper by Connell et al. in Marine Ecology Progress Series). There is even some evidence that disease causing bleaching in some species is exacerbated by rising temperatures.

Some of the key kelp research recommendations coming out of the workshop were:

  1. Estimating the value of kelp to Australians (direct harvesting; fishing; diving)
  2. Physical drivers of change: understanding how variation in the East Australian Current (temperature, nutrients) affects kelp distribution; understanding how urban and agricultural run-off (nutrients, pollutants, sedimentation) affects distribution and health; understanding how major storm events (e.g., East Coast Lows and El Niño-Southern Oscillation) affects long-term persistence
  3. Monitoring: what is the distribution and physical limits of kelp species?; how do we detect declines in ‘health’?; what is the associated biodiversity in kelp forests?
  4. Experimental: manipulations of temperature/nutrients/pathogens in the lab and in situ to determine sensitivities; sensitivity of different life stages; latitudinal transplants to determine localised adaption
  5. Adaptation (management): reseeding; managing run-off; managing fisheries to maintain a good balance of grazers and predators; inform marine protected area zoning; understanding trophic cascades

The second part of the discussion centred on ocean acidification and increasing CO2 content in the marine environment. As you might know, increasing atmospheric CO2 is taken up partially by ocean water, which lowers the availability of carbonate and increases the concentration of hydrogen ions (thus lowering pH or ‘acidifying’). It’s a pretty worrying trend – we’ve seen a drop in pH already, with conservative predictions of another 0.3 pH drop by the end of this century (equating to a doubling of hydrogen ions in the water). What does all this mean for marine biodiversity? Well, many species will simply not be able to maintain carbonate shells (e.g., coccolithophore phytoplankton, corals, echinoderms, etc.), many will suffer reproductive failure through physiological stress and embryological malfunction, and still many more will be physiologically stressed via hypercapnia (overdose of CO2, the waste product of animal respiration).

Many good studies have come out in the last few years demonstrating the sensitivity of certain species to reductions in pH (some simultaneous with increases in temperature), but some big gaps remain in our understanding of what higher CO2 content in the marine environment will mean for biota. Some of the key research questions in this area identified were therefore:

  1. What is the adaptation (evolutionary) potential of sensitive species? Will many (any) be able to evolve higher resistance quickly enough?
  2. In situ experiments outside the lab that mimic pH and pCO2 variation in space and time are needed to expose species to more realistic conditions.
  3. What are the population consequences (e.g., change in extinction risk) of higher individual susceptibility?
  4. Which species are most at risk, and what does this mean for ecosystem function (e.g., trophic cascades)?

As you can imagine, the conversation was complex, varied and stimulating. I thank the people at the Sydney Institute of Marine Science for hosting the fascinating discussion and I sincerely hope that even a fraction of the research identified gets realised. We need to know how our marine systems will respond – the possibilities are indeed frightening. Ignorance will leave us ill-prepared.

CJA Bradshaw

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Fishing for conservation

3 04 2009

Here’s a guest post from one of my newest PhD students, Jarod Lyon of the Arthur Rylah Institute in Victoria. He’s introducing some of his ongoing work and how he incorporates anglers into conservation research.

As most conservationists know, snags (fallen trees and branches in rivers) are the riverine equivalent of marine reefs, providing critical habitat for many plants and animals, from microscopic bacteria, fungi and algae through to large native fish. They are the places where the greatest numbers and diversity of organisms occur in lowland sections of rivers. Their presence has an important influence on the overall health of these rivers.

Murray River, Australia
Figure 1

Ins southern Australia, Murray cod, trout cod and golden perch are three iconic fish species that occur in the Murray River (Figure 1). Recent investigations into the ecology of these species have demonstrated a strong dependence on the presence of snags – a relationship well-known to recreational anglers who target both Murray cod and golden perch. Unfortunately, the abundance of these species has declined over the past 100 years and they are now considered threatened. Excessive removal of snags has been identified as a primary cause for this decline. For example, in the Lake Hume to Lake Mulwala reach of the Murray River, over 25000 snags were removed in the 1970s and 1980s to improve the passage of water between Lake Hume and the large irrigation channels at Yarrawonga.

Figure 2
Figure 2

The largest resnagging project ever undertaken in Australia is now in full swing. It aims to reverse the legacy of clearing snags that has occurred along the Murray reaches since European settlement. The resnagging is occurring in the Hume-Mulwala reach of the Murray using trees that were cleared for the Hume Highway extension between Albury and Tarcutta, and will create substantially more physical habitat for native fish in this reach of the river. By creating this habitat, the size of the native fish population in this reach is expected to increase thereby improving the conservation status of the native species present, and improving the quality of the recreational fishery for native species (particularly Murray cod and golden perch). It is the largest project of its kind ever undertaken in Australia, and is a great step towards recovering fish populations. The project is funded under the Murray Darling Basin Commission‘s Living Murray Program, and is being undertaken by a variety of state and national organisations, in particular NSW Department of Primary Industries and Victorian Department of Sustainability and Environment (DSE).

To ensure that the resnagging is having a beneficial effect on the numbers of native fish in the reach, a comprehensive monitoring and evaluation program is being implemented by scientists from the DSE’s Arthur Rylah Institute. This program is determining whether an increase in the size of the native fish populations is the result of:

  • Increased recruitment in the reach
  • Increased survival of adults in the reach
  • Increased immigration of adults and juveniles form Lake Mulwala and the Ovens River
  • Decreased emigration form the reach

To measure these changes, the fish populations between Hume Dam and Lake Mulwala are being surveyed once a year to determine the population size and level of recruitment. For the purpose of comparison, surveying between Yarrawonga and Tocumwal, in the lower Ovens River, and in Lake Mulwala, is also being undertaken.

Figure 2
Figure 3

Some of the fish caught (Figure 2) will be tagged with an external tag, internal tag or radio transmitter (Figures 3 & 4). All tags have a unique number that identifies the individual. The recapture of these individuals, both by researchers and by anglers, allows survival and movement patterns to be measured.

The external tags are plastic polymer tags and are easily visible, protruding from the dorsal fin area. These tags are used to allow information from anglers to be directly used in the monitoring. A phone number is printed on each tag and when anglers call this number to report that they have caught a tagged fish, this provides valuable information on the not only fish survival and growth, but also the performance of the recreational fishery. These tags have a lifespan of 2-5 years. Anglers who call in tag information are also eligible for a reward (usually a stubby holder or lure) and get sent a certificate which gives details of the history of the fish which they have captured and reported.

The internal tags are implanted into the area to the front of the pectoral fin, are not visible, and unlike the external tags, are permanent. The tags are passive integrated transponder (PIT) tags (Figure 4), similar to those used in the pet and livestock industry. The tags are important as they allow a long-term record of fish survival, growth and movement to be measured. Fishways across the Murray Darling Basin are increasingly being installed with readers that can detect these tags. This can give researchers valuable information on long-range movements. For example, one fish (a 20-kg Murray cod) that was tagged in the Murray river near Corowa, was picked up on a PIT tag reader at the bottom of the Torrumbarry Weir fishway – a fair feat when you consider that this fish has had to get through both Mulwala and Torrumbarry Weirs, as well as travel a distance of over 200 river km downstream!

Figure 3
Figure 4

Radio transmitters are surgically inserted into the body cavity of the fish (Figure 3). These tags emit a radio signal that can be tracked continuously (Figure 5), and allow a rapid assessment of the movements (i.e., emigration and immigration rates) of a population to be determined. The tags are also detected by an array of 18 logging stations located along the river between Lake Hume and Barmah (Figure 1). Approximately 1000 radio tags will be implanted over the life of the project – making it possibly the largest radio-tagging program in the country.

If you catch a tagged fish, please record the type of fish, its number, its length (and its weight if possible) and the location of its capture and report this information on the phone number printed on the tag. These angler records improve the quality of the data collected and reporting of angler captures is encouraged through the rewards program.

As well as the general tag return program, a more targeted “Research Angler Program” is being undertaken. The angler program commenced operations in July 2007. The project was developed to assist with the scientific monitoring and communication requirements of the native fish habitat restoration project.

This section of the monitoring recognises that local anglers can contribute information about the state of native fish in the River Murray by recording their fishing effort and the amount of fish captured. Such information, in addition to greatly increasing the community awareness of the monitoring program, also adds another ‘string to the monitoring bow’ in that it will form a long-term dataset of fish captures, which can eventually be linked to the resnagging effort. The information gathered will be entered into a database and analysed to help assess changes in fish population size in relation to the habitat rehabilitation project.

Figure 5

Figure 5

Instream woody habitat is a vital component to the lifecycle of Murray Cod and the endangered trout cod. The resnagging of the River Murray – Hume Dam to Yarrawonga, will conserve and enhance native fish communities. Continual monitoring and interactions with the local angling fraternity is a crucial part of the success of this project.

The anglers have logbooks and have been trained in removing the otoliths, which are the earbones, from fish that they are taking for the table. We can then use the otoliths to determine the age and growth of the fish in response to the resnagging work.

Since December 2007 the fishers with the resnagging Angler Monitoring Program have captured over 65 Murray Cod, with over 95% of these fish released. Anglers have caught and released other native species such as golden perch and the endangered trout cod.

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