Influential conservation ecology papers of 2019

24 12 2019

Bradshaw-Waves breaking on rocks Macquarie Island
As I’ve done for the last six years, I am publishing a retrospective list of the ‘top’ 20 influential papers of 2109 as assessed by experts in F1000 Prime (in no particular order). See previous years’ lists here: 20182017, 20162015, 2014, and 2013.







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Influential conservation ecology papers of 2018

17 12 2018

For the last five years I’ve published a retrospective list of the ‘top’ 20 influential papers of the year as assessed by experts in F1000 Prime — so, I’m doing so again for 2018 (interesting side note: six of the twenty papers highlighted here for 2018 appear in Science magazine). See previous years’ posts here: 2017, 20162015, 2014, and 2013.

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Penguins cheated by ecosystem change

13 03 2018

Jorge Drexler sings “… I was committed not to see what I saw, but sometimes life is more complex than what it looks like …”*. This excerpt by the Oscar-winning Uruguayan singer seems to foretell the theme of this blog: how the ecological complexity of marine ecosystems can elicit false signals to their predators. Indeed, the fidelity of marine predators to certain feeding areas can turn demographically detrimental to themselves when the amount of available food shrinks. A study of jackass penguins illustrates the phenomenon in a context of overfishing and ocean warming.


Adult of jackass penguin (Spheniscus demersus) from Robben Island (South Africa) — in the inset, one of the first juveniles released with a satellite transmitter on its back. The species is ‘Endangered’ under IUCN’s criteria (28), following a recent halving of the total population currently estimated at ~ 80,000 adults. Jackass penguins are the only penguins living in Africa, and owe their common name to their vocalisations (you can hear their braying sounds here); adults are ~ 50 cm tall and weigh ~ 3 kg. Photos courtesy of Richard Sherley.

Surface temperature, dissolved oxygen, acidity and primary productivity are, by and large, the top four environmental factors driving the functionality of marine ecosystems (1). Growing scientific evidence supports the idea that anthropogenic warming of the atmosphere and the oceans correlates with this quartet (2). For instance, marine primary productivity is enhanced by increased temperatures (3), but a warmer sea surface intensifies stratification, i.e., stacked layers of seawater with contrasting physical and chemical properties.

In coastal areas experiencing ‘upwelling’ (where winds displace surface water, allowing deep water laden with nutrients to reach the euphotic zone where plankton communities feast), stratification weakens upwelling currents and, in turn, limits the growth of plankton (4) that fuels the entire trophic web, including our fisheries. The study of these complex trophic cascades is particularly cumbersome from the perspective of large marine predators because of their capacity to move long distances, from hundreds to thousands of kilometres (5), with strong implications for their conservation (6).

With those caveats in mind, Richard Sherley and colleagues satellite-tracked the movement of 54 post-fledged, juvenile jackass penguins (Spheniscus demersus) for 2-3 years (7). All individuals had been hatched in eight colonies (accounting for 80% of the global population), and were equipped with platform terminal transmitters. Jackass penguins currently nest in 28 island and mainland locations between South Africa and Namibia. Juveniles swim up to 2000 km in search of food and, when approaching adulthood, return to their native colonies where they reproduce and reside for the remainder of their lives (watch individuals swimming here).

The natural history of this species is linked to the Southern Hemisphere’s trade winds (‘alisios’ for Spanish speakers), which blow from the southeast to the tropics. In the South Atlantic, trade winds sustain the Benguela Current, the waters of which surface from some 300 m of depth and fertilise the marine ecosystems stretching from the Western coasts of South Africa to Angola (8). Read the rest of this entry »

Offshore Energy & Marine Spatial Planning

22 02 2018


I have the pleasure (and relief) of announcing a new book that’s nearly ready to buy, and I think many readers of might be interested in what it describes. I know it might be a bit premature to announce it, but given that we’ve just finished the last few details (e.g., and index) and the book is ready to pre-order online, I don’t think it’s too precocious to advertise now.


A little history is in order. The brilliant and hard-working Katherine Yates (now at the University of Salford in Manchester, UK) approached me back in 2014 to assist her with co-editing the volume that she wanted to propose for the Routledge Earthscan Ocean series. I admit that I reluctantly agreed at the time, knowing full well what was in store (anyone who has already edited a book will know what I mean). Being an active researcher in energy and biodiversity (perhaps not so much on the ‘planning’ side per se) certainly helped in my decision.

And yes, there were ups and downs, and sometimes it was a helluva lot of work, but Katherine certainly made my life easier, and she has finally driven the whole thing to completion. She deserves most of the credit.

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Disadvantages of marine protected areas

29 02 2016




Stop wasting time

Stop wasting time

Influential conservation papers of 2015

25 12 2015

most popularAs I did last year and the year before, here’s another arbitrary, retrospective list of the top 20 influential conservation papers of 2015 as assessed via F1000 Prime.

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All (fisheries) models are wrong, but some are useful (to indigenous people)

1 08 2015

miracle_cartoonAnother post from Alejandro Frid. (Note: title modified from George Box‘s most excellent quote).

As an ecologist working for indigenous people of coastal British Columbia, western Canada, I live at the interface of two worlds. On the one hand, I know that computer models can be important management tools. On the other hand, my job constantly reminds me that whether a model actually improves fishery management depends, fundamentally, on the worldview that shapes the model’s objectives. To explore why, I will first review some general concepts about what models can and cannot do. After that, I will summarize a recent model of herring populations and then pull it all together in a way that matters to indigenous people who rely on marine resources for cultural integrity and food security.

Models do a great job of distilling the essence of how an ecosystem might respond to external forces—such as fisheries—but only under the specific conditions that the modeller assumes to be true in the ‘world’ of the model. Sometimes these assumptions are well-grounded in reality. Sometimes they are blatant but necessary simplifications. Otherwise, it would be difficult to ask questions about how major forces for which we have no historical precedent—such as the combined effects of industrial fisheries, ocean acidification and climate change—might be altering the ocean. For instance, due to our greenhouse gas emissions, the ocean is warming and contains less dissolved oxygen. These stressful conditions hamper the capacity of fish to grow, and appear to be on their way to shrinking the body sizes of entire fish communities1. If you want even to begin to comprehend what the ocean will look like in the long term due to these effects of climate change, it makes sense to assume, in the ‘world’ of your model, that fishing does not exist, even though you know it does. Of course, you would then acknowledge that climate change probably exacerbates the effects of fisheries, which highlights that you still have to examine the combination of these effects. And that is exactly what an excellent team of modellers did1. Read the rest of this entry »

Grim tale of global shark declines

25 06 2015
Please don't eat me

Please don’t eat me

How do you prevent declines of species you cannot even see? This is (and has always been) the dilemma for fisheries because, well, humans don’t live underwater. Even when we strap on a metal tank full of air and a pair of fins, we’re still more or less like wounded astronauts peering through a narrow window of glass at the huge, largely empty, ocean space. It’s little wonder then that we have a fairly crap system of estimating fish abundance, and an even worse track record of managing them sustainably.

But humans love to eat fish – the total world estimate of legal fisheries landings is something in the vicinity of 190 million tonnes in 2013, up from 18 million tonnes in 1950 (according to FAO). We’re probably familiar with some of the losers of that massive harvest, with species like tunas, bill fishes and orange roughy making the news for catastrophic declines in abundance over the last 30-40 years. And we’re not even talking about the estimated tragedy that is illegal, unreported and unregulated (IUU) fishing.

Back in 1999, the FAO started to report that sharks – the new-ish target of many world fisheries resulting from the commercial extinction of many other fin fish fisheries – we’re starting to take the hit. Once generally ignored by fishing industries, sharks soon became popular target species. Then in 2003, Julia Baum and colleagues famously (and somewhat controversially) sounded the alarm for sharks in the Gulf of Mexico by some claims of major and catastrophic declines of large, predatory sharks. While some of the subsequent to-ing and fro-ing in the literature challenged these claims, Baum’s excellent work was ultimately vindicated.

Since then, more and more evidence that sharks are in trouble has surfaced, including the assessment of the reported (again, only legal) catch indicated heavy depletion of coastal sharks even by 1975, and the estimate that 25% of all shark and ray species have an elevated extinction risk, mainly resulting from overfishing. Now even the direct fisheries landings statistics are confirming this grim tale. Read the rest of this entry »

Influential conservation papers of 2013

31 12 2013

big-splash1This is a little bit of a bandwagon – the ‘retrospective’ post at the end of the year – but this one is not merely a rehash I’ve stuff I’ve already covered.

I decided that it would be worthwhile to cover some of the ‘big’ conservation papers of 2013 as ranked by F1000 Prime. For copyright reasons, I can’t divulge the entire synopsis of each paper, but I can give you a brief run-down of the papers that caught the eye of fellow F1000 faculty members and me. If you don’t subscribe to F1000, then you’ll have to settle with my briefest of abstracts.

In no particular order then, here are some of the conservation papers that made a splash (positively, negatively or controversially) in 2013:

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Oceans need their giants

2 11 2011

Another great post from Salvador Herrando Pérez.


Commercial and sport fishing establish minimum body sizes for catches of many species to preserve fish stocks. Recent work reveals that sustainable fisheries also depend on the regulation of the harvest of the biggest fish, at least in long-lived species.

Growing up in Spain in the 1980s, I was taken by a Spanish television spot featuring a shoal of little fish sucking colourful dummies, and at the same time (how they managed, I never questioned) singing the motto Little fish? No, thanks. The then Ministry of Agriculture, Fishery and Food created this media campaign to create awareness among consumers not to buy immature fish at local markets – “…a 60-gram hake will only weigh 2 kg after two years” the add stated.

Indeed, the regulation of fish harvest by age classes is substantial to any fishery. In particular, the protection of younger fish has been a beacon of fishery policy and management that dates back to the 19th century when, among others, the British ichthyologist Ernst Holt concluded that: “…it is desirable that fish should have a chance of reproducing their species at least once before they are destroyed” 1. Very much in line with such principles, conventional fish stock management has in practice neglected the mature age classes2, other than for the fact that they are the end point of extraction and what we consumers eat on the table. Read the rest of this entry »

Does the pope wear a funny hat?

5 04 2011

Does a one-legged duck swim in circles? Does an ursid defecate in a collection of rather tall vascular plants? Does fishing kill fish?

Silly questions, I know, but it’s the kind of question posed every time someone doubts the benefits (i.e., for biodiversity, fishing, local economies, etc.) of marine reserves.

I’ve blogged several times on the subject (see Marine protected areas: do they work?The spillover effectInterview with a social (conservation) scientist, and Failing on ocean protection), but considering Hugh Possingham is town today and presenting the case to the South Australian Parliament on why this state NEEDS marine parks, I thought I’d rehash an old post of his published earlier this year in Australasian Science:

Science has long demonstrated that marine reserves protect marine biodiversity. Rather than answer the same question again, isn’t it about time we started funding research that answers some useful scientific questions?

As marine reserves spread inexorably across the planet, the cry from skeptics and some fishermen is: “Do marine reserves work?” The science is pretty clear but acknowledgement of this by the public is another story. Let me begin with a story of my experience answering this question while communicating to stakeholders the subtleties of marine conservation planning during the rezoning of Moreton Bay.

I was asked by the then-Queensland Environmental Protection Agency to explain to stakeholders the process of marine reserve system design as it applied to the Moreton Bay rezoning. I told the gathering that the rezoning was about conserving a fraction of each mappable biodiversity attribute (species and habitats) for the minimum impact on the livelihood of others. Read the rest of this entry »

International Conspiracy to Catch All Tunas

2 11 2008

tuna-660x433Otherwise known as the International Commission for the Conservation of Atlantic Tunas (ICCAT) based in Madrid, ICCAT is charged with “the conservation of tunas and tuna-like species in the Atlantic Ocean and its adjacent seas”. However, according to a paper entitled Impending collapse of bluefin tuna in the northeast Atlantic and Mediterranean to forthcoming in Conservation Letters (read post about the journal here) by Brian MacKenzie of the Technical University of Denmark, they don’t seem to be doing their job very well.

In perhaps the best example of the plundering of the seas for overt profit instead of food provision per se, the north-east Atlantic and Mediterranean population of bluefin tuna (Thunnus thynnus) has been overfished and will continue to decline to near extinction if the harvest isn’t stopped immediately and for several years to come.

Chronically obese probability.

The demand (and money) associated with tuna harvest appears to negate all scientific evidence that the population is in serious trouble – because of us. The Economist recently featured the paper’s results and therein quoted the opinion of independent ICCAT reviewers who described the situation as “an international disgrace” (read full article here).

I want to list MacKenzie et al.’s paper forthcoming in Conservation Letters as a ‘Potential‘ here at, but I doubt it will change the tuna’s situation that much, and it may only ruffle a few European (and Japanese) feathers (scales?). Who knows? Perhaps the paper will result in a massive down-scaling of the harvest and some serious commitment to REAL tuna conservation.

CJA Bradshaw

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Classics: Fishing down the web

17 09 2008

A Classic

Fishing_down_the_food_webDaniel Pauly and colleagues’ classic paper in Science, Fishing down marine food webs, is one that merits citation in Classics section. The trend identified by Pauly and colleagues is fairly simple – data from the Food and Agriculture Organisation (FAO) of the United Nations revealed that the average trophic level (i.e., the position in the food web relative to autotrophs – primary producers such as phytoplankton) has declined by an overall average of 0.2 units. In this case, a trophic unit varied from 1 (phytoplankton) to 4.6 (e.g., snappers, family Lutjanidae). The trends varied by region and whether or not one takes certain overrepresented species into account, but the average decline was more or less consistent across the dataset.

What does all this reveal? Put simply, it means that fishing on a massive and global commercial scale has essentially removed many of the larger species to the point where it has become no longer economically viable to sustain a targeted fishery. This does not necessarily mean that these species have disappeared, but it does indicate a large drop in relative abundance (and thus, ease of capture) necessary to support an industry, with the corollary that highly reduced populations are now much more extinction-prone if they fall below their minimum viable population size. The corollary is that marine species we wouldn’t consider palatable for a dog 50 years ago are now considered top-quality market delicacies.

The paper did not go without critique – Caddy and colleagues argued that Pauly and colleagues oversimplified the case for marine fishes and misinterpreted some data; however, a subsequent paper by Pauly’s team published in 2005, Fishing down marine food web: it is far more pervasive than we thought, argued that the original paper didn’t go far enough, and that fisheries over-exploitation worldwide is much worse than originally reported. Indeed, there are certainly some high-profile examples to support the case (e.g., the Atlantic cod and Peruvian anchoveta fisheries collapses, to name a few).

What did this do for biodiversity conservation? I think it can be argued that this is one of the first big papers to identify that the over-fishing problem was global in extent and massive in magnitude, and that high-seas over-exploitation was stripping our seas of its bigger (generally slower-growing and more extinction-prone) species. I believe things have changed for the better, but we’re still a long way off. Fishing in international waters still operates without an international body to enforce regulation and document catch precisely, and the classic tragedy of the commons applies so well to fisheries that it should be one of the principal examples used to illustrate the concept. People tend to jump up and down about elephants, pandas and whales, but the reduction in fish worldwide is a biodiversity crisis in progress that has not attracted nearly enough attention. We need more papers like Pauly’s on this issue, as well as demonstrations of the loss of marine ecosystem function and services with the loss of species brought about by excessive fishing harvests. Only then can we expect the careless greed driving quick-profit high-seas fisheries to ease up enough to prevent extinctions on a massive scale.

CJA Bradshaw

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