Article: Smithsonian on whether shark repellents really work

The Freedom7 SharkShield unit outside its neoprene case
The Freedom7 SharkShield unit outside its neoprene case

Here’s a quick read on shark repellents from While it only takes a few paragraphs to explain the different attempts humans have made to avoid encountering sharks while using the ocean, the task of actually developing technology to do this is far more complex. Testing shark repellents is also ethically difficult – in the same way that it’s hard to test medications for use during pregnancy, as one could be causing harm to human subjects.

(It’s worth reading a bit about the Shark Shield device pictured above for more on testing. Testing the efficacy of stripy wetsuits, on the other hand, is almost impossible, and for this reason they can be almost impossibly lucrative – imagine a product where you don’t have to prove whether it works, and when it fails you can (a) throw up your hands and make an excuse along the lines of “it was a freak event”/”the guy must have been wearing it incorrectly” or (b) close the company and disappear.)

The “electronic fence” mentioned at the end of the article is the shark repellent cable that the KwaZulu Natal Sharks Board tested at Glencairn last summer. You can read more about that (also from here.

To bring our attention back to the original topic: here is the article on shark repellents at, with ample links for you to pursue interesting avenues of exploration!

Article: The New Yorker on sharing the sea with sharks

You have probably all read this article, and if you haven’t you should. South African-born social anthropologist Ceridwen Dovey does an excellent job of introducing and interrogating the various shark bite mitigation measures available in the New Yorker, no less. The subject has been in and out of the news with increasing frequency for at least two years, owing largely to sensational reports of sharks repeatedly biting people in Australia and Reunion. The Western Australian response to a spate of shark bites at beaches in the state has been to fish out sharks using nets and drumlines – the same approach taken by the KZN Sharks Board here in South Africa.

Dovey speaks to Christopher Neff, who thinks deeply about the language we use to speak about shark bites, and their political and social ramifications. Cape Town’s amazing Shark Spotters program gets a mention, as does the SharkShield. There are many non-lethal measures currently in testing – not all of them as location and species dependent as Shark Spotters (which works because Cape Town’s great white sharks are a surface-swimming species and are visible from high ground close to the coast). It is a hopeful time for relations between sharks and humans, as long as the scientific impetus is not allowed to flag.

Full article here.

Article: The New Yorker on sponges

Orange wall sponge
Orange wall sponge

My favourite science writer, Ed Yong, explores sponges for the New Yorker in an article entitled “Consider the Sponge”. Sponges are deceptively simple creatures with jelly-like interiors and no symmetry. They are, however, covered in microbes which have provided treatments for leukemia, herpes, breast cancer, and a drug that fights HIV/AIDS. Consider the sponge, indeed!

Yong explains that

Last month, in the journal Trends in Ecology & Evolution, a group of scientists published a tub-thumping defense of sponges and other supposedly simple animals. In their paper, Casey Dunn, Sally Leys, and Steve Haddock argue that humans have systematically underestimated these creatures, largely because of our innate bias against organisms outside our taxonomic clique.

… But these creatures, according to Dunn, Leys, and Haddock, are not primitive relics; they are modern animals that excel at their own particular life styles. By ignoring them, we blind ourselves to a wondrous hidden biology and get a misleading view of evolution.


Sponges are wonderful, it turns out, and Yong’s article is wonderfully written. Read the full article here.

Article: Wired on mapping a sunken aircraft carrier reported on efforts by NOAA to survey and map the USS Independence, a sunken aircraft carrier lying in over 800 metres of water near the Farallon Islands. She was scuttled in 1951 about 50 kilometres off the Californian coast. Wanting to test an underwater autonomous vehicle called the Echo Ranger, the scientists deployed the five ton unmanned mini-submarine from a 25 metre catamaran, and flew her 50 metres above the wreck to take sonar readings.

This kind of technology is fantastic, and will enable the US government to get a better idea of the state all the junk that has been dumped in the region of the Farallons during the 20th century. I imagine a similar survey of parts of False Bay and south of Cape Point (in the areas marked “ammunition dump” on the hydrographic charts) would reveal similarly interesting items…

Read the full article here.

Article: The Atlantic on motion sickness

Tony checking out the fishing boat
Tony checking out the fishing boat

Travelling – by boat, car, bus – is supposed to be fun. If you suffer from motion sickness (sea sickness while on a boat), it isn’t. This feels like punishment, and Julie Beck in The Atlantic puts it better than I could:

For so long as man has attempted to tame and traverse the sea, the sea has punished him for it. With barfing.

If you are susceptible, you may have attempted to manage your motion sickness by various means, not excluding ginger biscuits. You may have settled on a gentle medical solution, which works quite well if you remember to take it before setting off on a journey.

The science of motion sickness turns out to be fairly complex and our understanding of it is not yet settled. Beck’s article explains the physical mechanisms at work when we get motion sick and the theories that explain the phenomenon, some of which are supported by the results of new genetic studies done by 23andMe. Sufferers will receive small consolation to hear that their sea sickness can be partly explained by their gender  or age, but may glean some understanding of when they are most susceptible to an uncomfortable ride.

Read the full article here.

Article: Nautilus on sea lamprey

Nautilus ran an article earlier this year about lampreys, fish that look like something out of the X Files. They are probably close relatives of hagfish; like hagfish, lampreys are jawless. They attach their round mouths to other fish and feed on their bodily fluids. They do not have a reputation as civilised dinner conversationalists.

While hagfish are marine animals, lampreys are anadromous: they return to fresh water (usually rivers) to spawn, in the same way that salmon do. When they’ve spawned, they die, fertilising the rivers and surrounding land with the nutrients from their bodies (in the same way as salmon do, but on a smaller scale).

Rehabilitation of North American rivers, along with the removal of dams, opens the way for fish such as salmon and alewives to return. Lampreys have returned too. Until recently they were viewed as invasive pests:

… the conventional American wisdom on sea lampreys was conceived following the late-19th- and early-20th-century collapse of world-renowned trout populations. The lampreys were invasive, having infiltrated the region through shipping canals; Great Lakes fish could not adapt to their ravages. Historical records describe the ease with which nets could be lowered to lake bottoms, then pulled back up with a cargo of sea lamprey-holed carcasses.

More recent research suggests that lampreys are native to at least Lake Ontario and several other lakes in the region, and were only able to colonise the rest of the Great Lakes when their native fish populations were all but destroyed by removing too many fish and modifying the ecosystem through damming, logging and agriculture.

Although they aren’t pretty, lampreys may be less of an invasive parasite and more of an essential participant in a balanced ecosystem than they were once thought to be. Read the Nautilus article here.

Article: The Guardian on a bungled tuna fishing IPO

Here’s a rare intersection of something tangentially related to my job, and this blog. An IPO, or initial public offering, is when a privately owned company lists its shares on a stock exchange. It is a capital raising exercise: shareholders pay for part-ownership in the company, and will usually expect to receive a portion of the company’s future earnings in the form of dividends. Shares in the company will trade publicly on whatever stock exchange the company has listed on. The firm receives a cash injection from the shareholders when it lists, and can use this to expand, or for other capital-intensive projects.

China Tuna Industry Group, a tuna fishing company, attempted to list on the Hong Kong stock exchange last June. The firm targets bigeye and yellowfin tuna, which are IUCN redlisted as vulnerable and near threatened respectively. In its prospectus – a document meant to entice investors to sign up to purchase shares in the IPO – the company states that it can catch more tuna than quotas allow, because there is no enforcement of catch limits. As the excellent Guardian article on the IPO states (emphasis mine):

In a series of circular arguments, the document stated that China, which presides over the world’s largest long-distance fishing fleet, would not crack down on companies engaged in illegal fishing because it never had in the past; that the catch limits set by the Regional Fisheries Management Organizations apply only to China the country, not to actual Chinese fishing boats; and that even if the catch limits did apply, the regional fisheries organizations would not enforce them because “there is no sanction for non-compliance with Bigeye catch limits.”

The IPO was cancelled because of negative publicity, which escalated when Greenpeace got involved. The Chinese government and the investment bank handling the IPO (shame on them) were, respectively, amazed (sure) and silent on the subject.

Read the Guardian article here. It’s an revealing journey through the legal loopholes, apathy, and big money that characterise so much of what is wrong with global fisheries, and China’s in particular.

Article: Phenomena on ocean calamities

The news article/paper that we read yesterday was a serious, yet hopeful assessment of the current and future state of ocean animals. Today’s article is also by Carl Zimmer, writing for Phenomena, and covers an opinion piece that appeared in Bioscience. A group of marine biologists criticises the tendency of scientists to generalise local effects into a supposed global “ocean calamities”. This breeds pessimism and inaction, as the general public is assailed by one apparent disaster scenario after another, and a point of fatigue is reached. The authors contend that

… the marine research community may not have remained sufficiently skeptical in sending and receiving information on the problems caused by human pressures in the ocean and that there is a need to revisit the process by which potential or isolated problems escalate to the status of ocean calamities.

It must be tempting, as a conservation biologist or environmental activist (two different professions) to talk up the dire threats facing coral reefs, or sharks, or whales, in order to attract attention or funding. But it is important to keep things in their proper context and perspective. Furthermore, all of us have a duty to remain skeptical, to investigate claims that seem extreme, and to do a little research beyond the headlines, tweets and facebook status updates. Make no mistake, this is not about being skeptical of science and its capacity to assist us in understanding the world around us; it is about being skeptical about how facts are presented, paraphrased, and – after enough repetition – possibly distorted.

Read Zimmer’s full article here. As an aside, he mentions his New York Times article on the Science paper concerning the health of the world’s oceans that we discussed yesterday. He asked the authors of the ocean calamities paper whether the Science paper was overstating the threats to marine life. Their response was that the paper was balanced and an accurate assessment of the current state of affairs.

I also encourage you to check out the original paper that Zimmer is writing about, which runs through several well-known “ocean calamities” (jellyfish blooms, harmful algal blooms, overfishing, invasive species, etc) and assesses the extent of the evidence for each one to qualify as a global threat to the oceans.

Article: New York Times on the health of the ocean

Humans began adjusting ecosystems on land thousands of years before they were able to do significant damage to the ocean, but in the last five hundred years or so we have been catching up in the marine environment. If you think that five hundred years of significant human impact on the oceans sounds too long and the number should be more like 50 years, read Callum Roberts’s book Ocean of Life – in fact, do that anyway.

In this vein, Carl Zimmer wrote for the New York Times about a recent paper (paywalled on Science) about extinctions and reduction in numbers of animals in the world’s oceans. The article received a large amount of attention and was featured prominently, which is great for science and for the ocean.

When writing about conservation issues it is a challenge to maintain an air of hopefulness, in order to spur the reader on to positive action rather than smothering them in despair. Many books about the health of the world’s oceans struggle to walk this line. Authors sometimes appear unnaturally chirpy about terrible subjects, or to change their minds three quarters of the way through the book, becoming a cheerleader after seven chapters of doom and gloom. Unusually, Zimmer’s article (and, by extension the paper it stems from) are genuinely hopeful, because the paper’s authors sincerely believe there is something that can be done.

(The timeline below is from the paper; click on the image to go to the original on the Science website.)

Timeline of animal loss
Timeline of animal loss

While the paper sounds a warning that “today’s low rates of marine extinction may be the prelude to a major extinction pulse, similar to that observed on land during the industrial revolution, as the footprint of human ocean use widens” and “the terrestrial experience and current trends in ocean use suggest that habitat destruction is likely to become an increasingly dominant threat to ocean wildlife over the next 150 years”, the authors are convinced that prompt and decisive action can make a significant difference. The action would need to be primarily in the form of massive marine protected areas, strategically located, as well as a decrease in carbon emissions.

Zimmer’s full article can be read here. One of the authors of the paper he reviews is Stephen Palumbi, whose Extreme Life of the Sea is an excellent introduction to the entire ocean ecosystem, written in bite sized chunks with the flair of the Guinness Book of Records (but more academic prowess, obviously).



Article: Phenomena on the size of marine animals

Ed Yong reports for Phenomena (a National Geographic blog) that a team of scientists has published a paper on the subject of how large marine animals grow. Not having to work against gravity, marine fauna can attain sizes that are beyond the reach of the largest land animals. There is, however, a tendency among those who make a living from the sea to – shall we say – exaggerate the dimensions of the creatures they catch, watch or photograph. Tony and I chuckle to ourselves about accounts (on facebook, unsurprisingly) of nearly six metre white sharks being spotted weekly in False Bay. In reality a great white shark of that size is uncommon.

Huge sea cucumber
Huge sea cucumber

The authors did exhaustive research to come up with best estimates for the maximum sizes of a range of creatures from whale sharks to giant isopods. They trawled museum collections, the scientific literature, newspaper archives, and even eBay to get hold of verifiable, accurate measurements for each creature. For some species the researchers were able to produce a size distribution – useful because, as Yong points out, “life mostly plays out in the middle.” The average-sized specimens (including False Bay’s white sharks) are the ones most likely to be seen. For some species, including white sharks, evidence suggests that their average size has been decreasing through time, which is a cause for concern.

Read the article here, and find the full scientific paper here. There’s more on an accompanying website called Story of Size.