Predicting sustainable shark harvests when stock assessments are lacking

26 03 2018
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© Andrew Fox

I love it when a good collaboration bears fruit, and our latest paper is a good demonstration of that principle.

It all started a few years ago with an ARC Linkage Project grant we received to examine how the whaler shark fishing industry in Australia might manage its stocks better.

As I’m sure many are aware, sharks around the world aren’t doing terribly well (surprise, surprise — yet another taxon suffering at the hands of humankind). And while some populations (‘stocks’, in the dissociative parlance of the fishing industry) are doing better than others, and some countries have a better track record in managing these stocks than others, the overall outlook is grim.

One of the main reasons sharks tend to fair worse than bony fishes (teleosts) for the same fishing effort is their ‘slow’ life histories. It doesn’t take an advanced quantitative ecology degree to understand that growing slowly, breeding late, and producing few offspring is a good indication that a species can’t handle too much killing before populations start to dwindle. As is the case for most large shark species, I tend to think of them in a life-history sense as similar to large terrestrial mammals.

Now, you’d figure that a taxon with intrinsic susceptibility to fishing would have heaps of good data with which managers could monitor catches and quotas so that declines could be avoided. However, the reality is generally the inverse, with many populations having poor information regarding vital rates (e.g., survival, fertility), age structure, density feedback characteristics, and even simple estimates of abundance. Without such key information, management tends to be ad hoc and often not very effective. Read the rest of this entry »





Bring it back

13 02 2018
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Protea compacta in fynbos, a form of shrubland at Soetanysberg, South Africa. Photo: Brian van Wilgen

Restoration of lost habitats and ecosystems hits all the right notes — conservation optimism, a can-do attitude, and the excitement of seeing biologically impoverished areas teem with life once more.

The Strategic Plan of the Convention on Biological Diversity includes a target to restore at least 15% of degraded ecosystems. This is being enthusiastically taken up in many places, including through initiatives such as the Bonn Challenge, a global aspiration to restore 350 million hectares of deforested and degraded land by 2030. This is in recognition of the importance of healthy ecosystems in not just conserving biodiversity, but also in combating climate change. Peatlands and forests lock away carbon, while grassland diversity stabilises ecosystem productivity during extreme weather events. So how can we make sure that these restoration efforts are as effective as possible? Read the rest of this entry »





Cartoon guide to biodiversity loss XLVI

25 01 2018

The first set of biodiversity cartoons for 2018. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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When devils and thylacines went extinct

17 01 2018

devil-thylacine-extinctWe’ve just published an analysis of new radiocarbon dates showing that thylacines (Tasmanian ‘tigers’, Thylacinus cynocephalus) and Tasmanian devils (Sarcophilus harrisi) went extinct on the Australian mainland at the same time — some 3200 years ago.

For many years, we’ve been uncertain about when thylacines and devils went extinct in mainland Australia (of course, devils are still in Tasmania, and thylacines went extinct there in the 1930s) — a recent age for the devil extinction (500 years before present) has recently been shown to be unreliable. The next youngest reliable devil fossil is 25000 years old.

So, knowing when both species went extinct is essential to be able to determine the drivers of these extinctions, and why they survived in Tasmania. If the two extinctions on the mainland happened at the same time, this would support the hypothesis that a common driver (or set of drivers) caused both species to go extinct. Read the rest of this entry »





Cartoon guide to biodiversity loss XLV

6 12 2017

The last set of biodiversity cartoons for 2017. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss XLIV

9 10 2017

Here’s another set of biodiversity cartoons to make you giggle, groan, and contemplate the Anthropocene extinction crisis. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Two new postdoctoral positions in ecological network & vegetation modelling announced

21 07 2017

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With the official start of the new ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH) in July, I am pleased to announce two new CABAH-funded postdoctoral positions (a.k.a. Research Associates) in my global ecology lab at Flinders University in Adelaide (Flinders Modelling Node).

One of these positions is a little different, and represents something of an experiment. The Research Associate in Palaeo-Vegetation Modelling is being restricted to women candidates; in other words, we’re only accepting applications from women for this one. In a quest to improve the gender balance in my lab and in universities in general, this is a step in the right direction.

The project itself is not overly prescribed, but we would like something along the following lines of inquiry: Read the rest of this entry »