What whales and dolphins can tell us about the health of our oceans



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Dolphins contribute important knowledge about ocean health.
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Stephanie Plön, Nelson Mandela University

From the poles to the equator, marine mammals such as seals, dolphins and whales, play an important role in global ecosystems as apex predators, ecosystem engineers and even organic ocean fertilisers. The ocean off the coast of South Africa is home to a high diversity of these mammals and is recognised as a global marine biodiversity hotspot.

Marine mammals are often referred to as “sentinels” of ocean health. Numerous studies have explored the effects of both noise and chemical pollution, habitat degradation, changes in climate and food webs on these marine apex predators. Yet the interplay of these factors isn’t well understood.

Our research on the unfortunate dolphins incidentally caught in shark nets off South Africa’s KwaZulu-Natal coast has helped fill in some of the gaps. By assessing the health of these dolphins we have provided valuable baseline information on conditions affecting coastal dolphin populations in South Africa. This is the first systematic health assessment in incidentally caught dolphins in the Southern Hemisphere.

But to gain a fuller picture of the health of marine mammals in these waters I am now combining this contemporary field research with historical data, like the collection at the Port Elizabeth Museum Bayworld.

The combination of data on diet, reproduction, population structure and health helps us gain a better understanding of the pressures and changes these apex predator populations face. And it helps us understand it in relation to global change, including both climate change and pressures brought about by human behaviour.

My research sheds light on multiple factors: pollutant levels, parasites, and availability of prey, all have an impact on individuals as well as populations.

Understanding the health of these animals also gives us insight into the state of the world’s oceans. This is relevant because oceans affect the entire ecosystem including food security, climate and people’s health. This degree of connectedness is highlighted by recent discoveries about how whales act as ecosystem engineers.

The accumulation of this knowledge is important because the planet’s oceans aren’t being protected. Recent popular documentaries such as “Sonic Sea” and “Plastic Ocean” have highlighted their exploitation and pollution.

What’s missing

Without baseline knowledge it’s challenging to establish the potential effects that new anthropogenic developments (those caused by human behaviour) have on local whale and dolphin populations.

For example, we know that whales are sensitive to shipping noise, so what potential impact could a new deep water port have on mothers and their calves? Could it drive them away from these nursery areas, or could it lead to an increased risk of whales and ships colliding? To answer this and monitor the change that a new port brings with it, we are investigating the soundscape of two bays in the Eastern Cape (one with a new port, one without) in parallel with baleen whale mother-calf behaviour.

Another example is understanding how changes in the Sardine run over the past 15 years have affected the diets of these mammals. The Sardine run is an annual phenomenon when large shoals of Sardine migrate northwards along the coast into KwaZulu-Natal waters to spawn. Using long-term data and samples from the Port Elizabeth Museum research collection, we have been able to establish that over the the past 20 or so years the main predator in the Sardine run – the long-beaked common dolphin – has shifted its diet to mackerel. Although such changes in diet can have potential impacts on the health of the dolphins, parallel investigations on the trophic level these animals feed at (using isotope data from teeth) and the body condition of the dolphins (using long-term data on blubber thickness), indicated no adverse effects to the dolphins.

Our analysis highlights how marine mammals may be used as indicators of environmental change and why research is important.

Finding answers to intricate questions on environmental change is not always easy. But a better understanding and knowledge of the environment these animals live in has to be incorporated into studies contributing to their conservation and management. Such studies are becoming increasingly relevant as they highlight the fast degradation of the marine environment.

For example, a recent study identified antibiotic resistant bacteria in both sea water samples and exhaled breath samples from killer whales. This suggests that the marine environment has been contaminated with human waste which in turn has significant medical implications for humans.

Gaining such information is particularly important given the rapid changes taking place in the oceans, such as those on South Africa’s southern and eastern coastline. This includes increasing coastal development, new deep water ports being built or expanded, and parts of the deep sea being explored for oil and gas.

To assess these changes and what they mean for the environment, baseline studies need to be carried out so that potential effects can be assessed. Whales and dolphins are increasingly being recognised as indicators of ocean health in this endeavour.

And a continuation of the research we did on dolphins caught in nets will help document the cyclic changes that can be seen as normal variation in a population. This could prove important for assessing future catastrophic events, such as the Deep Horizon oil spill.

What next

The oceans absorb over 25% of the world’s carbon pollution as well as heat generated by global warming. They also produce at least 50% of the planet’s oxygen, and are home to 80% of all life on earth. Yet only 5% of this vital component of our planet has been explored.

The ConversationResearch on whales and dolphins contributes important knowledge about ocean health. Historical data increasingly provides a guideline to teasing out natural variations in populations and assessing the contribution that multiple factors have on these animals. In time, this will ensure that policy makers are being given sound scientific information. It will also provide us with a good barometer of the overall health of our oceans.

Stephanie Plön, Researcher, Earth Stewardship Science Research Institute, Nelson Mandela University

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

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Noise from offshore oil and gas surveys can affect whales up to 3km away



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Migrating humpback whales avoid loud, nearby sounds.
BRAHSS, Author provided

Rebecca Dunlop, The University of Queensland and Michael Noad, The University of Queensland

Air guns used for marine oil and gas exploration are loud enough to affect humpback whales up to 3km away, potentially affecting their migration patterns, according to our new research.

Whales’ communication depends on loud sounds, which can travel very efficiently over distances of tens of kilometres in the underwater environment. But our study, published today in the Journal of Experimental Biology, shows that they are affected by other loud ocean noises produced by humans.

As part of the BRAHSS (Behavioural Response of Humpback whales to Seismic Surveys) project, we and our colleagues measured humpback whales’ behavioural responses to air guns like those used in seismic surveys carried out by the offshore mining industry.


Read more: It’s time to speak up about noise pollution in the oceans


Air guns are devices towed behind seismic survey ships that rapidly release compressed air into the ocean, producing a loud bang. The sound travels through the water and into the sea bed, bouncing off various layers of rock, oil or gas. The faint echoes are picked up by sensors towed by the same vessel.

During surveys, the air guns are fired every 10-15 seconds to develop a detailed geological picture of the ocean floor in the area. Although they are not intended to harm whales, there has been concern for many years about the potential impacts of these loud, frequent sounds.

Sound research

Although it sounds like a simple experiment to expose whales to air guns and see what they do, it is logistically difficult. For one thing, the whales may respond to the presence of the ship towing the air guns, rather than the air guns themselves. Another problem is that humpback whales tend to show a lot of natural behavioural variability, making it difficult to tease out the effect of the air gun and ship.

There is also the question of whether any response by the whales is influenced more by the loudness of the air gun, or how close the air blast is to the whale (although obviously the two are linked). Previous studies have assumed that the response is driven primarily by loudness, but we also looked at the effect of proximity.

We used a small air gun and a cluster of guns, towed behind a vessel through the migratory path of more than 120 groups of humpback whales off Queensland’s sunshine coast. By having two different sources, one louder than the other, we were able to fire air blasts of different perceived loudness from the same distance.

We found that whales slowed their migratory speed and deviated around the vessel and the air guns. This response was influenced by a combination of received level and proximity; both were necessary. The whales were affected up to 3km away, at sound levels over 140 decibels, and deviated from their path by about 500 metres. Within this “zone”, whales were more likely to avoid the air guns.

Each tested group moved as one, but our analysis did not include the effects on different group types, such as a female with calf versus a group of adults, for instance.

The ConversationOur results suggest that when regulating to reduce the impact of loud noise on whale behaviour, we need to take into account not just how loud the noise is, but how far away it is. More research is needed to find out how drastically the whales’ migration routes change as a result of ocean mining noise.

Rebecca Dunlop, Senior Lecturer in Physiology, The University of Queensland and Michael Noad, Associate Professor, The University of Queensland

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

With a less confrontational approach to whaling, more whales could be saved


Steven Freeland, Western Sydney University

Whales had another big win last week – allegedly. The Australian-sponsored resolution adopted by the International Whaling Commission will, in theory, make it harder for nations such as Japan to award themselves special permits for “scientific” whaling.

But as pointed out in The Conversation at the time, the non-binding resolution is likely to have little material effect on whales themselves.

Australia’s delight at the new resolution echoes its response to the International Court of Justice’s 2014 ruling that Japan’s JARPA II whaling program was unlawful.

But since then it has been business as usual for Japan, which simply created a new and different research program – one that makes it very difficult for Australia or anyone else to take it to The Hague again. It is hard to see what these legal and diplomatic victories have achieved in a practical sense, beyond prompting Japan to entrench its resolve to continue with its whaling programs.

It is time for some new tactics. Legal and diplomatic skirmishes with Japan and other pro-whaling nations might feel like the right thing to do. But they deliver little benefit to the whales, and could potentially provoke pro-whaling nations into leaving the IWC altogether.

Longstanding impasse

Before setting out my views as to the way forward, I must state that, on a personal and moral basis, I am absolutely opposed to any whaling whatsoever. I would like to see the complete cessation of whaling by any country in the world.

Unfortunately, however, it does not appear that the events at the recent IWC meeting will change much in practical terms. To be sure, any reform of the IWC is welcome. However, the failure to achieve the required three-quarters majority for the establishment of a South Atlantic whale sanctuary, coupled with the non-binding character of such resolutions, means the IWC has once again proven itself incapable of achieving a strong consensus on contentious issues relating to the protection of whales.

Herein lies the problem. Although this might sound strange coming from a law professor, I believe that the formal legal system is not an effective way to resolve long-entrenched impasses in a way that best serves the interests of the whales themselves.

This is particularly true when the issue draws such emotional responses from all sides. Using the IWC as an ideological battleground does not get us very far in terms of protecting whales.

In its early years, the IWC was characterised as a “whalers’ club”, allocating quotas to member states at levels that significantly harmed whale numbers. Over the past 30-40 years, however, nations such as Australia, New Zealand and Britain have become fiercely anti-whaling, and the commercial whaling industry has met its demise.

As a result, the IWC has over time adopted a much stronger anti-whaling stance, putting it at odds with the whaling states (including Japan, Norway and Iceland) and causing considerable tensions within the IWC.

These tensions have been exacerbated by the fact that, even though the underlying sentiment of many member states has changed, the terms of the 70-year-old treaty have not. That makes it hard for the IWC to morph seamlessly from a resource-management body into a conservation forum.

The logical endpoint

The worst-case outcome would be if Japan (or any other whaling state) feels it is being pushed too far at IWC meetings, and decides to withdraw altogether, which nations can do with as little as six-months’ notice under Article XI of the Convention. Such a country would no longer be bound by any of the restrictions established under the treaty regime – including the moratorium on commercial whaling that has been in effect since the mid-1980s.

Breaking away from the IWC would undoubtedly bring with it significant political and diplomatic costs, making it perhaps unlikely that nations will seriously consider it for now. But if the adversarial tensions continue, pro-whaling states could eventually decide simply to leave the IWC process in order to pursue commercial whaling with little or no international controls. If this were to happen the IWC would have presided over an ecological catastrophe for whales.

Japan’s response to recent developments has shown that a complete cessation of whaling cannot be achieved, at least in the short term. The only rational and pragmatic response is therefore to ensure that as few whales as possible are taken.

I believe the only way for that to happen is for IWC members to agree a compromise based on widely accepted environmental principles such as sustainability. The sad fact for strong anti-whalers such as myself is that this may involve some whaling, albeit on a far more controlled basis than at present.

In this way, the dubious reliance on “scientific” purposes as a disguise for what many observers regard as commercial whaling would end, replaced by a credible system to which everyone has agreed.

It is important not to lose sight of the ultimate purpose here: to preserve whales and do everything possible to protect them. The current emotionally charged legal and diplomatic battles, no matter how worthy and principled, aren’t really in the best interests of these magnificent creatures. An international management regime based on cooperation and clear, objective principles offers a far more promising prospect for their future than the current stalemate.

The Conversation

Steven Freeland, Professor of International Law, Western Sydney University

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