Sharks are thriving at the Kermadec Islands, but not the rest of New Zealand, amid global decline




Adam Smith, Massey University

A recent global assessment of shark populations at 371 coral reefs in 58 countries found no sharks at almost 20% of reefs and alarmingly low numbers at many others.

The study, which involved over 100 scientists under the Global FinPrint project, gave New Zealand a good score card. But because it focused on coral reefs, it included only one region — Rangitāhua (Kermadec Islands), a pristine subtropical archipelago surrounded by New Zealand’s largest marine reserve.

It is a different story around the main islands of New Zealand. Many coastal shark species may be in decline, and less than half a percent of territorial waters is protected by marine reserves.

The first global survey of reef sharks shows they are virtually absent in many areas.



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Sharks in Aotearoa

In New Zealand, there are more than a hundred species of sharks, rays and chimaeras. They belong to a group of fishes called chondrichthyans, which have skeletons of cartilage instead of bone.

Some 55% of New Zealand’s chondrichthyan species are listed as “not threatened” by the International Union for Conservation of Nature (IUCN). Not so encouraging is the 32% of species listed as “data deficient”, meaning we don’t know the status of their populations. Most species (77%) live in waters deeper than 200 metres.

Seven species are fully protected under the Wildlife Act 1953. They are mostly large, migratory species such as the giant manta ray. Some are threatened with extinction according to the IUCN, including great white sharks, basking sharks, whale sharks and oceanic white tip sharks.

Basking shark and snorkellers
Basking sharks were once common in some coastal areas in New Zealand.
Martin Prochazkacz/Shutterstock

Historically, basking sharks were caught as bycatch in New Zealand fisheries, and seen in their hundreds in some inshore areas. Sightings of these giant plankton-feeders suddenly dried up over a decade ago. We don’t know why.

Commercial shark fisheries

Eleven chondrichthyan species are fished commercially in New Zealand under the quota management system. Commercial fisheries for school shark, rig and elephant fish took off from the 1970s and now catch around 8,000 tonnes per year in total.

Finning of sharks has been illegal throughout New Zealand since 2014.

Most of New Zealand’s shark fisheries are considered sustainable. But a sustainable fishery can mean sustained at low levels, and we must tread carefully. School shark was recently added to the critically endangered list after the collapse of fisheries in Australia and elsewhere, and there’s a lot we don’t know about the New Zealand population.

We do know sharks were much more abundant in pre-European times. In Tīkapa Moana (Hauraki Gulf), sharks have since declined by an estimated 86%. An ongoing planning process provides some hope for the ecosystems of the gulf.

Protecting sharks

Not surprisingly, the global assessment found a ban on shark fishing to be the most effective intervention to protect sharks. Several countries have recently established large shark sanctuaries, sometimes covering entire exclusive economic zones.

These countries tend to have ecotourism industries that provide economic incentives for protection — live sharks can be more valuable than dead ones.

Other effective interventions are restrictions on fishing gear, such as longlines and set nets.

Waters within 12 nautical miles of the Kermadec Islands have been protected by a marine reserve since 1990. In 2015, the Kermadec Ocean Sanctuary was announced but progress has stalled. The sanctuary would extend the boundaries to the exclusive economic zone, some 200 nautical miles offshore, and increase the protected area 83-fold.

A large population of Galapagos sharks, which prefer isolated islands surrounded by deep ocean, thrive around the Kermadec Islands but are found nowhere else in New Zealand. Great white sharks also visit en route to the tropics. Many other species are found only at the Kermadecs, including three sharks and a sex-changing giant limpet as big as a saucer.

Galapagos sharks
Galapagos sharks were recorded around Raoul Island in the Kermadec archipelago.
Author provided



Read more:
Squid team finds high species diversity off Kermadec Islands, part of stalled marine reserve proposal


New technologies are revealing sharks’ secrets

What makes the Global FinPrint project so valuable is that it uses a standard survey method, allowing data to be compared across the globe. The method uses a video camera pointed at a canister of bait. This contraption is put on the seafloor for an hour, then we watch the videos and count the sharks.

Grey reef, silver tip and hammerhead sharks circle a baited camera station set up near Walpole Island in the Southwest Pacific.

Baited cameras have been used in a few places in New Zealand but there are no systematic surveys at a national scale. We lack fundamental knowledge about the distribution and abundance of sharks in our coastal waters, and how they compare to the rest of the world.

Satellite tags are another technological boon for shark research. It is difficult to protect sharks without knowing where they go and what habitats they use. Electronic tags that transmit positional data via satellite can be attached to live sharks, revealing the details of their movements. Some have crossed oceans.

Sharks have patrolled the seas for more than 400 million years. In a few decades, demand for shark meat and fins has reduced their numbers by around 90%.

Sharks are generally more vulnerable to exploitation than other fishes. While a young bony fish can release tens of millions of eggs in a day, mature sharks lay a few eggs or give birth to a few live young. Females take many years to reach sexual maturity and, in some species, only reproduce once every two or three years.

These biological characteristics mean their populations are quick to collapse and slow to rebuild. They need careful management informed by science. It’s time New Zealand put more resources into understanding our oldest and most vulnerable fishes, and the far-flung subtropical waters in which they rule.The Conversation

Adam Smith, Senior Lecturer in Statistics, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Scientists fear insect populations are shrinking. Here are six ways to help


Scientists need your help to protect Australia’s insects and track their numbers.
Joe Castro/AAP

David Yeates, CSIRO; Katja Hogendoorn, University of Adelaide, and Manu Saunders, University of New England

Are you planning a big garden clean-up this summer, or stocking up on fly spray to keep bugs at bay? Before you do, it’s worth considering the damage you might cause to the insects we share the planet with.

Australia’s insect populations are under pressure. The problem is better known in the Northern Hemisphere, where over the past few years scientific studies have reported alarming declines in insect numbers.

We don’t yet have a true understanding of what is happening in Australia. This week, scientists gathered in Brisbane at the Australian Entomological Society conference to discuss the extent of the problem. Evidence suggests several species and populations are under threat.

Some might see insects as small and insignificant, but they perform functions crucial to sustaining life on Earth. There are several simple steps you can take to address insect decline in your area, or even help scientists keep tabs on the problem.

A gold wasp. Australian insect declines have not been well documented.
Oliver Niehuis/Australian Science Media Centre

We need to know more

In Australia, we know iconic species such as the bogong moth, green carpenter bee and Key’s matchstick grasshopper are in decline. There is documented evidence for the extinction of two Australian insect species, but this is probably just the tip of the iceberg.

A research review published this year suggested more than 40% of insect species globally are threatened with extinction over the next few decades. However, this estimate was based on limited studies of a few iconic insect groups in western Europe and the US.




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Such findings should be taken with caution. We do not have enough evidence to extrapolate to the whole planet.

Despite this, factors affecting insect populations overseas – such as habitat loss, climate change and insecticide use – most likely also apply in Australia. Bushfires and drought on this continent can also affect insect populations.

There are no published studies documenting insect decline in Australia, but anecdotal reports from entomologists suggest lower than average populations across a number of species. However, very few of our estimated 250,000 insect species are being formally monitored.

A Pelecorhynchid fly. Studies suggest insect populations are declining, but data in Australia is scarce.
CSIRO Entomology

Why you should care

Insects pollinate plants, dispose of waste and control pests, among other functions. The planet would cease to support life without the services insects provide.

If insect populations are in decline, so are the populations of larger animals such as birds and lizards that feed on them.




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In NSW, bogong moths are a staple food for mountain pygmy possums. A collapse in the moth population would lead to possums going hungry, which affects their breeding success.

Australia’s threatened species strategy prioritises action to protect 20 bird species – 14 of which feed partially or solely on insects.

Mountain pygmy possums feed on bogong moths.
Tim Bawden

Six ways to help insects

Insects are small and can inhabit hidden places, so you may not realise how many exist around you. Here are a few ways to help prevent insect decline in your home and elsewhere:

Household insecticide use can damage local insect populations.
Flickr

1. Entice insects to your garden: Lawn is a virtual desert for insects, so if you don’t really need it, cultivate insect-friendly native plants instead. Plan to have something flowering most of the year and aim for a variety of plant heights and structures, such as tall trees, thick shrubs and ground cover.

2. Put the fly spray away: Insecticides have become very efficient in recent years. They indiscriminately kill all insects, not just the ones you’re trying to get rid of. If you have to use insect spray, do so sparingly.

And whenever you can, choose food produced without lots of pesticides. These products are sold with labels such as organic, biodynamic, or chemical-free.

3. Turn off the lights: If you don’t need that outdoor light on all night, turn it off: the moths in your area will thank you. Many nocturnal insects can’t resist the light, but it disrupts their navigation system. This plays havoc with their ability to feed and reproduce.

4. Build them a home: Think about installing an insect hotel – a small structure of hollows for insects to rest and lay eggs in. Or simply leave dead wood or small areas of bare ground for insects to build nests in. If you don’t have a garden, join a local tree-planting group, or convince your council to plant more natives.

A flower fly. Scientists need help form the public to track insect numbers.
Denis Anderson/CSIRO



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5. Resist the urge to clean up: If there is a section of your garden, local park or nature strip that is unkempt, leave it that way. What looks untidy to you is a great place for insects to live.

6. Track insects on your smart phone: Scientists need help to better understand what is happening to our insects. Citizen science apps such as iNaturalist Australia, Wild Pollinator Count, the Atlas of Living Australia and Butterflies Australia help gather valuable information about insect biodiversity, so solutions can be targeted to problem areas.The Conversation

David Yeates, Director of the Australian National Insect Collection, CSIRO; Katja Hogendoorn, University of Adelaide, and Manu Saunders, Research fellow, University of New England

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Tassie devils’ decline has left a feast of carrion for feral cats



File 20181127 76737 frgu15.jpg?ixlib=rb 1.1
Healthy Tasmanian devil populations have cornered the market on carrion.
Menna Elizabeth Jones, Author provided

Calum Cunningham, University of Tasmania; Christopher Johnson, University of Tasmania; Menna Elizabeth Jones, University of Tasmania, and Tracey Hollings, University of Melbourne

The decline of Tasmanian devils is having an unusual knock-on effect: animal carcasses would once have been gobbled up in short order by devils are now taking many days longer to disappear.

We made the discovery, published today in the journal Proceedings of the Royal Society B, by placing carcasses in a range of locations and watching what happened. We found that reduced scavenging by devils results in extra food for less efficient scavengers, such as feral cats.

Tasmanian devils have struggled for two decades against a typically fatal transmissible cancer, called devil facial tumour disease. The disease has caused devil populations to plummet by about 80% on average, and by up to 95% in some areas.

DFTD has spread across most of Tasmania over a 20-year period. Dashed lines show the estimated disease front.
Calum Cunningham/Menna Jones

Scavengers are carnivores that feed on dead animals (carrion). Almost all carnivores scavenge to a greater or lesser degree, but the devil is Tasmania’s dominant scavenger. Since the extinction of the Tasmanian tiger, it is also the island’s top predator.

A scavenging experiment

In our study, we put out carcasses of the Tasmanian pademelon (a small wallaby weighing roughly 5kg) in a variety of places, ranging from disease-free areas with large devil populations, to long-diseased areas where devil numbers are very low. We then used motion-sensor cameras to record all scavenger species that fed on the carcasses.

The Carnivores of Tasmania: a Scavenging Experiment.

Unsurprisingly, much less carrion was consumed by devils in areas where devil populations have declined. This has increased the availability of carrion for other species, such as the invasive feral cat, spotted-tailed quoll, and forest raven. All of these species significantly increased their scavenging in places with fewer devils.

Consumption of experimentally placed carcasses.
Proceedings of the Royal Society B

The responses of native scavengers (quolls and ravens) were subtly different to those of feral cats. The amount of feeding by quolls and ravens depended simply on how much of each carcass had already been consumed by devils. Ravens and quolls are smaller and less efficient than devils at consuming carcasses, so they get the chance to feed only when devils have not already monopolised a carcass.




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In contrast, feral cats tended to scavenge only at sites where devils were at very low abundance. This suggests that healthy devil populations create a “landscape of fear” that causes cats to avoid carcasses altogether in areas where they are likely to encounter a devil. It seems that the life of a feral cat is now less scary in the absence of devils.

Predator prevalence

By looking at 20 years of bird surveys from BirdLife Australia, we also found that the odds of encountering a raven in Tasmania have more than doubled from 1998 to 2017. However, we were unable to directly link this with devil declines. It is likely the raven population is growing in response to a range of factors that includes land-use change and agricultural intensification, as well as reduced competition with devils.

Other studies have shown that cats have also become more abundant in areas where devils have declined. This highlights the potential for devils to act as a natural biological control on cats. Cats are a major threat to small native animals and are implicated in most Australian mammal extinctions.

Carcass concerns

Although smaller scavengers consumed more carrion as devils declined, they were unable to consume them as rapidly as devils. This has resulted in the accumulation of carcasses that would previously have been quickly and completely eaten by devils.

In places with plenty of devils, carcasses were completely eaten within an average of five days, compared with 13 days in places where devil facial tumour disease is rife. That means carcasses last much longer where devils are rare.

DFTD has spread across most of Tasmania over a 20-year period. Dashed lines show the estimated disease front.
Calum Cunningham/Menna Jones

Around 2 million medium-sized animals are killed by vehicles or culled in Tasmania each year, and most are simply left to decompose where they fall. With devils consuming much less carrion, it is likely that carcasses are accumulating across Tasmania. It is unclear how much of a disease risk they pose to wildlife and livestock.

Conserving carnivores

Large carnivores are declining throughout the world, with knock-on effects such as increasing abundance of smaller predators. In recent years, some large carnivores have begun returning to their former ranges, bringing hope that their lost ecological roles may be restored.

Carnivores are declining for many reasons, but an underlying cause is that humans do not necessarily appreciate their pivotal role in the health of entire ecosystems. One way to change this is to recognise the beneficial services they provide.




Read more:
Tasmanian devils are evolving rapidly to fight their deadly cancer


Our research highlights one of these benefits. It supports arguments that we should help the devil population recover, not just for their own sake but for other species too, including those threatened by feral cats.

The devil seems to be solving the disease problem itself, rapidly evolving resistance to facial tumours. Any management plan will need to help this process, and not hinder it. Potentially, returning devils to mainland Australia could provide similar benefit to wildlife threatened by feral predators.The Conversation

Calum Cunningham, PhD candidate, University of Tasmania, University of Tasmania; Christopher Johnson, Professor of Wildlife Conservation and ARC Australian Professorial Fellow, University of Tasmania; Menna Elizabeth Jones, Associate professor, University of Tasmania, and Tracey Hollings, Senior Scientist, Ecological Modelling at Arthur Rylah Institute for Environmental Research, and Honorary Research Fellow, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia: Large Fish Species in Serious Decline


The link below is to an article reporting on the serious decline in large fish species across Australia.

For more visit:
https://www.theguardian.com/environment/2018/jun/05/australias-large-fish-species-declined-30-in-past-decade-study-says

Citizen scientists count nearly 2 million birds and reveal a possible kookaburra decline


Kerryn Herman, Deakin University

The fourth Aussie Backyard Bird Count has just ended, with nearly 2 million birds from 635 species submitted to the BirdLife Australia app. The count, which is in its fourth year, has created a national database of birds found in our backyards.

We don’t know yet exactly how many people participated this year, but more than 60,000 people submitted checklists in 2016. Participants span the whole country, though participation is highest in our urban areas. By surveying our backyards (rather than “good” bird spots), these citizen scientists provide ecologists – like me – with information from urban areas we would not otherwise sample.

This includes data on a range of common bird species that are not frequently analysed because these species are believed to be secure. One of the most surprising results is a decline in the frequency of occurrence of the laughing kookaburra across southeast Australia.

Counting birds

Everyone has a bird story – and fortunately for ecologists, everyone is willing to share them. With 85% of Australia’s population living in cities and towns, birds are an important connection to our natural environment.


BirdLife Australia

But birds are also good environmental indices. They’re generally easy to measure, they respond quickly to environmental change and we know a reasonable amount about the ecology of most species.

Between 1998 and 2014, BirdLife Australia volunteers collected a significant amount of data. This was used to develop a terrestrial bird index in 2015 – a bird “Dow Jones” to track our biodiversity. It was here that the decline in kookaburras was first identified.

The data were drawn from BirdLife Australia’s ongoing atlas project, now called Birdata. However, there are biases in this data set, as people obviously like to go birdwatching where they will see more birds. This may inflate the frequency of encountering some species and decrease the chances of encountering others – particularly rare and cryptic species.

For the last four years, we’ve asked volunteers to add to this data by counting birds around their home for a week in October, when many birds are highly active and visible. These counts complement the data already available in Birdata by allowing access to backyards across Australia, which are generally poorly represented in the larger data set.

While there are still limitations in the Backyard Bird Count data, such as the risk of mis-identification, for common species like the laughing kookaburra we can generally be confident that the identification is correct. Even if the same bird is counted multiple times, our models report only a species’ presence or absence, so inflated numbers don’t affect the trend.

Are kookaburras really declining?

The below figures show modelled trends for the kookaburra across metropolitan Melbourne and Sydney. These figures are derived from the volunteer-collected Birdata, much of which comes from green spaces and remnant vegetation in these landscapes.

I wondered whether these declines are true changes in the populations, or reflect a change in the way kookaburras are using the landscape, possibly moving into the matrix of urban backyards that just don’t get surveyed. Looking solely at the backyard count data, I found similar trends in the reporting rates of kookaburras as those in the models, supporting that this decline is at the population level. What started out in 2014 as a way of engaging the broader community with their birds is now collecting useful ecological data.

Further exploration of the ABBC data across other capital cities found some interesting things. In both Perth and Hobart, where the kookaburra is considered an introduced species, the birds are recorded more frequently than in Melbourne and across the ACT. In Perth, increases in 2016 compared to previous years suggest an increase in the species there.

Modelled trends for Kookaburras from 1998-2014. The figure on the left is for Melbourne, and on the right is for Sydney. The reporting rate shows the percentage of surveys where kookaburras were recorded as present. The thick black line is the modelled trend (with confidence intervals in dashed line), the pink line shows the statistically significant linear trend, the thin black line shows the monthly calculated reporting rate, and the green spots show acceleration (or a favourable change) in the trend. Note that due to modelling method, the ends of figures tend to blow out as there is no data from which to predict trend.
Unpublished models/K. Herman/BirdLife Australia, Author provided

While three years does not make a trend, Aussie Backyard Bird Count data from heavily urbanised areas suggest we are seeing a decline in this iconic species in the eastern capitals. Likely reasons for this are the loss of nesting hollows and possibly reductions in the availability of prey as we increasingly modify our urban landscapes. We don’t really know as this is not an area that has been researched.

We need citizen scientists

Collecting enough data (especially from the backyards of towns and cities) to detect these kinds of changes can be an overwhelming task. This is where citizen science programs like the Aussie Backyard Bird Count can help.

As well as helping ecologists track large-scale biodiversity trends, it also gives people the chance to connect with their natural environment and gain a greater appreciation of our unique fauna.

As with all citizen science projects, there are limitations in the data being collected. However, the Backyard Bird app has been designed to make counting as simple and standardised as possible, providing confidence in the tally of common and “iconic” species, and filling in the gaps found in other data sets.

The good old kookaburra is neither rare or cryptic. If anything, if people are seeking out “good” bird habitat to survey we would expect that kookaburras would be one of those species subject to inflated reporting. But this is not what we encountered.

The ConversationIf we are starting to see declines in species that we have traditionally considered secure, what does this mean for those that are already at risk? Once all the data from the Aussie Backyard Bird Count have been collated and vetted we will continue to explore the developing trends in Australia’s urban birds. Increasing engagement and awareness in our communities can help ensure our backyard birds are still around to count next year.

Kerryn Herman, Research Ecologist, Deakin University

This article was originally published on The Conversation. Read the original article.

Environmental score card shows Australia is once again in decline


David Summers, Australian National University and Albert Van Dijk, Australian National University

After some unusually wet years, our landscape and ecosystems have once again returned to poorer conditions that were last experienced during the Millennium Drought.

That is the main conclusion of Australia’s Environment in 2015 – an environmental score card and accompanying data explorer that we have just released.

Australia’s natural environment is the bedrock of our economy, and our unique ecosystems and landscape are a fundamental part of our society and national identity. This latest report shows that for most of the country, our environmental fortunes are closely tied to the highs and lows of rainfall.

We combined and analysed huge amounts of satellite imagery, ground data and landscape modelling and compiled this data into 13 environmental indicators. With most data extending back to the year 2000, we can start to see how Australia’s environment is changing over time.

The big picture

National level environmental indicators show that soil moisture and river flows fell to near record lows in 2015, while tree cover continued its decline to reach the lowest level since 1972. Soil exposure, the lack of protection from vegetation or mulch cover, also returned to levels last seen during the drought.

Many of these changes are strongly driven by changes in rainfall. Other processes also play a role, however. For example, some of the estimated 530,000 hectares reduction in forest area in 2015 was due to clearing, particularly in southern Queensland, where around 300,000 ha were cleared in 2013-2014 (land clearing data for 2015 are not yet available).

Change in tree cover as percentage of country area

We can combine some of these indicators to get an overall score of the environment’s condition. Such a measure can only ever be an artificial and subjective index, similar to composite indices used for the economy, for example.

But because most environmental indicators are strongly linked to water availability, the overall pattern still remains similar if different calculations are made.

Change in national environmental condition score

The national environmental score declined from around average in 2014 (4.8) to well below average in 2015 (3.6). This is a cause for concern, particularly given the relatively short time since the plentiful rains that saw off the drought in 2010.

Winners and losers

While useful to understand general trends, the national indicators hide much regional variation. For example, scores increased to above average values in the Australian Capital Territory and New South Wales, which received good rains across most of the state in 2015.

On the other hand, in Queensland conditions were already relatively poor in 2014 and declined further in 2015, in some parts of the state to the worst conditions since at least 2000.

Environmental condition scores and changes from 2014

The different indicators also did not always change in the same way. For example tree cover declined in all states and territories except in Tasmania, where new plantations exceeded harvesting rates. (These numbers do not include the impact of large bushfires in early 2016).

Tree cover also increased in some other regions, whereas relatively strong losses occurred not only in Queensland, but also as a result of urban expansion in most metropolitan areas.

On the other hand, despite the general decline of agricultural land, the majority of our national parks remained in good shape in 2015. (You can see these regional patterns in our data explorer, which shows indicators by state, council area, catchment, national park, wetland, and so on.)

Tree cover change by region, showing largest decreases in red and increases in blue

Back to lean years

The Millennium Drought was arguably the worst drought on our historical record. Lasting around a decade, it had profound impacts on water resources, rivers and wetlands, ecosystems and agriculture.

The very wet years that followed brought some much needed relief to the desiccated ecosystems. Unfortunately, our report shows that the bounce was short lived, and that environmental indicators are once again in the red.

While this is a concern, we are still some way from experiencing the worst impacts of the Millennium Drought. We have only had three years with relatively low rainfall rather than ten, and some of the events that occurred towards the end of the Millennium Drought have not yet come to pass.

For example, many wetlands in eastern Australia have declined in extent, but not quite yet to the record lows observed before. The same is true for many of our water storage reservoirs, which have returned to the low levels seen during the first half of the last drought, but not yet the lows of later years.

Still, it is concerning that the lean years have come back so fast. Apparently, the rainfall abundance of 2010-2012 did not create a long lasting reserve, once more leaving our environment exposed to the next drought.

Indeed, we may already be in it.

The Conversation

David Summers, Research academic, Fenner School of Environment & Society , Australian National University and Albert Van Dijk, Professor of Water Science and Management, Fenner School of Environment & Society, Australian National University

This article was originally published on The Conversation. Read the original article.