Finding a species that’s entirely new to science is always exciting, and so we were delighted to be a part of the discovery of two new sixgill sawsharks (called Pliotrema kajae and Pliotrema annae) off the coast of East Africa.
We know very little about sawsharks. Until now, only one sixgill species (Pliotrema warreni) was recognised. But we know sawsharks are carnivores, living on a diet of fish, crustaceans and squid. They use their serrated snouts to kill their prey and, with quick side-to-side slashes, break them up into bite-sized chunks.
Sawsharks look similar to sawfish (which are actually rays), but they are much smaller. Sawsharks grow to around 1.5 metres in length, compared to 7 metres for a sawfish and they also have barbels (fish “whiskers”), which sawfish lack. Sawsharks have gills on the side of their heads, whereas sawfish have them on the underside of their bodies.
Together with our colleagues, we discovered these two new sawsharks while researching small-scale fisheries that were operating off the coasts of Madagascar and Zanzibar. While the discovery of these extraordinary and interesting sharks is a wonder in itself, it also highlights how much is still unknown about biodiversity in coastal waters around the world, and how vulnerable it may be to poorly monitored and managed fisheries.
Fishing in the dark
Despite what their name might suggest, small-scale fisheries employ around 95% of the world’s fishers and are an incredibly important source of food and money, particularly in tropical developing countries. These fisheries usually operate close to the coast in some of the world’s most important biodiversity hotspots, such as coral reefs, mangrove forests and seagrass beds.
For most small-scale fisheries, there is very little information available about their fishing effort – that is, how many fishers there are, and where, when and how they fish, as well as exactly what they catch. Without this, it’s very difficult for governments to develop management programmes that can ensure sustainable fishing and protect the ecosystems and livelihoods of the fishers and the communities that depend on them.
While the small-scale fisheries of East Africa and the nearby islands are not well documented, we do know that there are at least half a million small-scale fishers using upwards of 150,000 boats. That’s a lot of fishing. While each fisher and boat may not catch that many fish each day, with so many operating, it really starts to add up. Many use nets – either driftnets floating at the surface or gillnets, which are anchored close to the sea floor. Both are cheap but not very selective with what they catch. Some use longlines, which are effective at catching big fish, including sharks and rays.
In 2019, our team reported that catch records were massively underreporting the number of sharks and rays caught in East Africa and the nearby islands. With the discovery of two new species here – a global hotspot for shark and ray biodiversity – the need to properly assess the impact of small-scale fisheries on marine life is even more urgent.
How many other unidentified sharks and other species are commonly caught in these fisheries? There is a real risk of species going extinct before they’re even discovered.
Efforts to monitor and manage fisheries in this region, and globally, must be expanded to prevent biodiversity loss and to develop sustainable fisheries. There are simple methods available that can work on small boats where monitoring is currently absent, including using cameras to document what’s caught.
The discovery of two new sixgill sawsharks also demonstrates the value of scientists working with local communities. Without the participation of fishers we may never have found these animals. From simple assessments all the way through to developing methods to alter catches and manage fisheries, it’s our goal to make fisheries sustainable and preserve the long-term future of species like these sawsharks, the ecosystems they live in and the communities that rely on them for generations to come.
Unlike the many species which stalk the shallow, coastal waters that fisheries exploit all year round, pelagic sharks roam the vast open oceans. These are the long-distance travellers of the submarine world and include the world’s largest fish, the whale shark, and also one of the fastest fish in the sea, the shortfin mako shark, capable of swimming at 40mph.
Because these species range far from shore, you might expect them to escape most of the lines and nets that fishing vessels cast. But over the last 50 years, industrial scale fisheries have extended their reach across the world’s oceans and tens of millions of pelagic sharks are now caught every year for their valuable fins and meat.
On average, large pelagic sharks account for over half of all shark species identified in catches worldwide. The toll this has taken on species such as the shortfin mako has prompted calls to introduce catch limits in the high seas – areas of the ocean beyond national jurisdiction where there is little or no management for the majority of shark species.
We wanted to know where the ocean’s shark hotspots are – the places where lots of different species gather – and how much these places are worked by fishing boats. We took up the challenge of finding out where pelagic sharks hang out by satellite tracking their movements with electronic tags. This approach by our international team of over 150 scientists from 26 countries has an important advantage over fishery catch records. Rather than showing where a fishing boat found them, it can precisely map all of the places sharks visit.
Nowhere to hide
For a new study published in Nature we tracked nearly 2,000 sharks from 23 different species, including great whites, blue sharks, shortfin mako and tiger sharks. We were able to map their positions in unprecedented detail and discern the most visited hotspots where sharks feed, breed and rest.
Hotspots were often located in frontal zones – boundaries in the sea between different water masses that can have the best conditions of temperature and nutrients for phytoplankton to bloom, which attracts masses of zooplankton, as well as the fish and squid that sharks eat.
Then we calculated how much these hotspots overlapped with global fleets of large, longline fishing vessels, which we also tracked by satellite. This type of fishing gear is used very widely on the high seas and catches more pelagic sharks than trawls and other gear. Each longline vessel is capable of deploying a 100km long line bearing over 1,000 baited hooks.
We found that even the most remote parts of the ocean that are many miles from land offer pelagic sharks little refuge from industrial-scale fishing fleets. One in four of the places sharks visited each month overlapped with the areas longline fishing vessels operated in.
Sharks such as the North Atlantic blue and the shortfin mako – which fishers also target for their fins and meat – were much more likely to encounter these vessels, with as much as 76% of the places these species visited most in each month overlapping with where longline vessels were fishing. Even internationally protected species such as great whites and porbeagle sharks encountered longline vessels in half of their tracked range.
It’s now clear that much of the world’s fishing activity on the high seas is centred on shark hotspots, which longlines rake for much of the year. Many large sharks, which are already endangered, face a future without refuge from industrial fishing in the places they gather.
High seas marine protected areas
The maps of shark hotspots and longline fishing activity that we created can at least provide a blueprint for where large-scale marine protected areas aimed at conserving sharks could be set. Outside of these, strict quotas could reduce catches.
The United Nations is creating a high seas treaty for protecting ocean biodiversity – negotiations are due to continue in August 2019 in New York. They’ll consider large-scale marine protected areas for the high seas and we’ll suggest where these could be located to best protect pelagic sharks.
Satellite monitoring could give real-time signals of where sharks and other threatened creatures such as turtles and whales are gathering. Tracking where these species roam and where fishers interact with them will help patrol vessels monitor these high-risk zones more efficiently.
Such management action is overdue for many shark populations in the high seas. Take North Atlantic shortfin makos – not only are they overfished
and endangered, but now we know they have no respite from longline fishing during many months of the year in the places they gather most often. Some of these shark hotspots may not exist in the near future if action isn’t taken now to conserve these species and the habitats they depend on.
One hectare of ocean in which fishing is not allowed (a marine protected area) produces at least five times the amount of fish as an equivalent unprotected hectare, according to new research published today.
This outsized effect means marine protected areas, or MPAs, are more valuable than we previously thought for conservation and increasing fishing catches in nearby areas.
Previous research has found the number of offspring from a fish increases exponentially as they grow larger, a disparity that had not been taken into account in earlier modelling of fish populations. By revising this basic assumption, the true value of MPAs is clearer.
Marine protected areas are ocean areas where human activity is restricted and at their best are “no take” zones, where removing animals and plants is banned. Fish populations within these areas can grow with limited human interference and potentially “spill-over” to replenish fished populations outside.
Obviously MPAs are designed to protect ecological communities, but scientists have long hoped they can play another role: contributing to the replenishment and maintenance of species that are targeted by fisheries.
Yet fishers remain sceptical that any spillover will offset the loss of fishing grounds, and the role of MPAs in fisheries remains contentious. A key issue is the number of offspring that fish inside MPAs produce. If their fecundity is similar to that of fish outside the MPA, then obviously there will be no benefit and only costs to fishers.
Traditional models assume that fish reproductive output is proportional to mass, that is, doubling the mass of a fish doubles its reproductive output. Thus, the size of fish within a population is assumed to be less important than the total biomass when calculating population growth.
But a paper recently published in Science demonstrated this assumption is incorrect for 95% of fish species: larger fish actually have disproportionately higher reproductive outputs. That means doubling a fish’s mass more than doubles its reproductive output.
When we feed this newly revised assumption into models of fish reproduction, predictions about the value of MPAs change dramatically.
Fish are, on average, 25% longer inside protected areas than outside. This doesn’t sound like much, but it translates into a big difference in reproductive output – an MPA fish produces almost 3 times more offspring on average. This, coupled with higher fish populations because of the no-take rule means MPAs produce between 5 and 200 times (depending on the species) more offspring per unit area than unprotected areas.
Put another way, one hectare of MPA is worth at least 5 hectares of unprotected area in terms of the number of offspring produced.
We have to remember though, just because MPAs produce disproportionately more offspring it doesn’t necessarily mean they enhance fisheries yields.
For protected areas to increase catch sizes, offspring need to move to fished areas. To calculate fisheries yields, we need to model – among other things – larval dispersal between protected and unprotected areas. This information is only available for a few species.
We explored the consequences of disproportionate reproduction for fisheries yields with and without MPAs for one iconic fish, the coral trout on the Great Barrier Reef. This is one of the few species for which we had data for most of the key parameters, including decent estimates of larval dispersal and how connected different populations are.
We found MPAs do in fact enhance yields to fisheries when disproportionate reproduction is included in relatively realistic models of fish populations. For the coral trout, we saw a roughly 12% increase in tonnes of caught fish.
There are two lessons here. First, a fivefold increase in the production of eggs inside MPAs results in only modest increases in yield. This is because limited dispersal and higher death rates in the protected areas dampen the benefits.
However the exciting second lesson is these results suggest MPAs are not in conflict with the interests of fishers, as is often argued.
While MPAs restrict access to an entire population of fish, fishers still benefit from from their disproportionate affect on fish numbers. MPAs are a rare win-win strategy.
It’s unclear whether our results will hold for all species. What’s more, these effects rely on strict no-take rules being well-enforced, otherwise the essential differences in the sizes of fish will never be established.
We think that the value of MPAs as a fisheries management tool has been systematically underestimated. Including disproportionate reproduction in our assessments of MPAs should correct this view and partly resolve the debate about their value. Well-designed networks of MPAs could increase much-needed yields from wild-caught fish.
Australia has some of the most spectacular marine ecosystems on the planet – including, of course, the world-famous Great Barrier Reef. Many of these places are safe in protected areas, and support a myriad of leisure activities such as recreational fishing, diving and surfing. No wonder eight in ten Aussies live near the beach.
Yet threats to marine ecosystems are becoming more intense and widespread the world over. New maps show that only 13% of the oceans are still truly wild. Industrial fishing now covers an area four times that of agriculture, including the farthest reaches of international waters. Marine protected areas that restrict harmful activities are some of the last places where marine species can escape. They also support healthy fisheries and increase the ability of coral reefs to resist bleaching.
One hundred and ninety-six nations, including Australia, agreed to international conservation targets under the United Nations Convention on Biological Diversity. One target calls for nations to protect at least 10% of the world’s oceans. An important but often overlooked aspect of this target is the requirement to protect a portion of each of Earth’s unique marine ecosystems.
We found that since 1982, the year nations first agreed on international conservation targets, an area of the ocean almost three times the size of Australia has been designated as protected areas in national waters. This is an impressive 20-fold increase on the amount of protection that was in place beforehand.
But when we looked at specific marine ecosystems, we found that half of them fall short of the target level of protection, and that ten ecosystems are entirely unprotected. For example, the Guinea Current off the tropical West African coast has no marine protected areas, and thus nowhere for its wildlife to exist free from human pressure. Other unprotected ecosystems include the Malvinas Current off the southeast coast of South America, Southeast Madagascar, and the North Pacific Transitional off Canada’s west coast.
Australia performs comparatively well, with more than 3 million square km of marine reserves covering 41% of its national waters. Australia’s Coral Sea Marine Park is one of the largest marine protected areas in the world, at 1 million km². However, a recent study by our research group found that several unique ecosystems in Australia’s northern and eastern waters are lacking protection.
To assess the scope for improvement to the world’s marine parks, we predicted how the protected area network could have been expanded from 1982.
With a bit more strategic planning since 1982, the world would only need to conserve 10% of national waters to protect all marine ecosystems at the 10% level. If we had planned strategically from as recently as 2011, we would only need to conserve 13% of national waters. If we plan strategically from now on, we will need to protect more than 16% of national waters.
If nations had planned strategically since 1982, the world’s marine protected area network could be a third smaller than today, cost half as much, and still meet the international target of protecting 10% of every ecosystem. In other words, we could have much more comprehensive and less costly marine protection today if planning had been more strategic over the past few decades.
The lack of strategic planning in previous marine park expansions is a lost opportunity for conservation. We could have met international conservation targets long ago, with far lower costs to people – measured in terms of a short-term loss of fishing catch inside new protected areas.
This is not to discount the progress made in marine conservation over the past three decades. The massive increase of marine protected areas, from a few sites in 1982, to more than 3 million km² today, is one of Australia’s greatest conservation success stories. However, it is important to recognise where we could have done better, so we can improve in the future.
In 2020, nations will negotiate new conservation targets for 2020-30 at a UN summit in China. Targets are expected to increase above the current 10% of every nation’s marine area.
We urge governments to rigorously assess their progress towards conservation targets so far. When the targets increase, we suggest they take a tactical approach from the outset. This will deliver better outcomes for nature conservation, and have less short-term impact on the fishing industry.
Strategic planning is only one prerequisite for marine protected areas to effectively protect unique and threatened species, habitats and ecosystems. Governments also need to ensure protected areas are well funded and properly managed.
These steps will give protected areas the best shot at halting the threats driving species to extinction and ecosystems to collapse. It also means these incredible places will remain available for us and future generations to enjoy.
More than 70% of recreational fishers support no-take marine sanctuaries according to our research, published recently in Marine Policy.
This study contradicts the popular perception that fishers are against establishing no-take marine reserves to protect marine life. In fact, the vast majority of fishers we surveyed agreed that no-take sanctuaries improve marine environmental values, and do not impair their fishing.
No-take marine sanctuaries, which ban taking or disturbing any marine life, are widely recognised as vital for conservation. However, recent media coverage and policy decisions in Australia suggest recreational fishers are opposed to no-take sanctuary zones created within marine parks.
This perceived opposition has been reinforced by recreational fishing interest groups who aim to represent fishers’ opinions in policy decisions. However, it was unclear whether the opinions expressed by these groups matches those of fishers on-the-ground in established marine parks.
To answer this, we visited ten state-managed marine parks across Western Australia, South Australia, Queensland and New South Wales. We spoke to 778 fishers at boat ramps that were launching or retrieving their boats to investigate their attitudes towards no-take sanctuary zones.
Our findings debunk the myth that recreational fishers oppose marine sanctuaries. We found 72% of active recreational fishers in established marine parks (more than 10 years old) support their no-take marine sanctuaries. Only 9% were opposed, and the remainder were neutral.
We also found that support rapidly increases (and opposition rapidly decreases) after no-take marine sanctuaries are established, suggesting that once fishers have a chance to experience sanctuaries, they come to support them.
Fishers in established marine parks were also overwhelmingly positive towards marine sanctuaries. Most thought no-take marine sanctuaries benefited the marine environment (78%) and have no negative impacts on their fishing (73%).
We argue that recreational fishers, much like other Australians, support no-take marine sanctuaries because of the perceived environmental benefits they provide. This is perhaps not surprising, considering that appreciating nature is one of the primary reasons many people go fishing in the first place.
Our findings suggest that these policy decisions do not reflect the beliefs of the wider recreational fishing community, but instead represent the loud voices of a minority.
We suggest that recreational fishing groups and policy makers should survey grass roots recreational fishing communities (and other people who use marine parks) to gauge the true level of support for no-take marine sanctuaries, before any decisions are made.
Despite what headlines may say, no-take marine sanctuaries are unlikely to face long lasting opposition from recreational fishers. Instead, our research suggests no-take marine sanctuaries provide a win-win: protecting marine life whilst fostering long term support within the recreational fishing community.
A new United Nations report on fisheries and climate change shows that Australian marine systems are undergoing rapid environmental change, with some of the largest climate-driven changes in the Southern Hemisphere.
Reports from around the world have found that many fish species are changing their distribution. This movement threatens to disrupt fishing as we know it.
While rapid change is predicted to continue, researchers and managers are working with fishers to ensure a sustainable industry.
Large climate-driven changes in species distribution and abundance are evident around the world. While some species will increase, global models project declining seafood stocks in tropical regions, where people can least afford alternative foods.
The global concern for seafood changes led the UN Food and Agriculture Organisation (FAO) to commission a new report on the impacts of climate change on fisheries and aquaculture. More than 90 experts from some 20 countries contributed, including us.
The report describes many examples of climate-related change. For instance, the northern movement of European mackerel into Icelandic waters has led to conflict with more southerly fishing states, and apparently contributed to Iceland’s exit from negotiations over its prospective European Union membership.
Changes in fish abundance and behaviour can lead to conflicts in harvesting, as occurred in the Maine lobster fishery. Indirect effects of climate change, such as disease outbreaks and algal blooms, have already temporarily closed fisheries in several countries, including the United States and Australia.
All these changes in turn impact the people who depend on fish for food and livelihoods.
Climate change and fisheries in Australia
The Australian chapter summarises the rapid ocean change in our region. Waters off southeastern and southwestern Australia are particular warming hotspots. Even our tropical oceans are warming almost twice as fast as the global average.
More than 100 Australian marine species have already begun to shift their distributions southwards. Marine heatwaves and other extreme events have harmed Australia’s seagrass, kelp forests, mangroves and coral reefs. Australia’s marine ecosystems and commercial fisheries are clearly already being affected by climate change.
In the Australian FAO chapter, we present information from climate sensitivity analysis and ecosystem models to help managers and fishers prepare for change.
We need to preparing climate-ready fisheries, to minimise negative impacts and to make the most of new opportunities that arise.
Experts from around Australia have rated the sensitivity of more than 100 fished species to climate change, based on their life-history traits. They found that 70% of assessed species have moderate to high sensitivity. As a group, invertebrates are the most sensitive, and pelagic fishes (that live in the open ocean sea) the least.
As fish abundance and distribution changes, predation and competition within food webs will be affected. New food webs may form, changing ecosystems in unexpected ways. In some regions (such as southeastern Australia) the ecosystem may eventually shift into a new state that is quite different to today.
How can Australian fisheries respond?
Our ecosystem models indicate that sustainable fisheries are possible, if we’re prepared to make some changes. This finding builds on Australia’s strong record in fisheries management, supported by robust science, which positions it well to cope with the impacts of climate change. Fortunately, less than 15% of Australia’s assessed fisheries are overfished, with an improving trend.
As ecosystem changes span state and national boundaries, greater coordination is needed across all Australian jurisdictions, and between all the users of the marine environment. For example, policy must be developed to deal with fixed fishing zones when species distribution changes.
Fisheries policy, management and assessment methods need to prepare for both long-term changes and extreme events. Australian fisheries have already shifted to more conservative targets which have provided for increased ecological resilience. Additional quota changes may be needed if stock productivity changes.
In areas where climate is changing rapidly, agile management responses will be required so that action can be taken quickly and adjusted when new information becomes available.
Ultimately, we may need to target new species. This means that Australians will have to adapt to buying (and cooking) new types of fish.
Researchers from a range of organisations and agencies around Australia are now tackling these issues, in partnership with the fishing industry, to ensure that coastal towns with vibrant commercial fishing and aquaculture businesses continue to provide sustainable seafood.
In a significant development for global fisheries, blockchain technology is now being used to improve tuna traceability to help stop illegal and unsustainable fishing practices in the Pacific Islands tuna industry.
The World Wildlife Fund (WWF) in Australia, Fiji and New Zealand, in partnership with US-based tech innovator ConsenSys, tech implementer TraSeable and tuna fishing and processing company Sea Quest Fiji Ltd, has just launched a pilot project in the Pacific Islands tuna industry that will use blockchain technology to track the journey of tuna from “bait to plate”.
A blockchain is a digital ledger that is distributed, decentralised, verifiable and irreversible. It can be used to record transactions of almost anything of value.
Essentially, it is a shared (not copied) database that everyone in the network can see and update. This system provides multiple benefits for supply chains, including high levels of transparency. This is because everyone in the network can see and verify the ledger, and no individual can alter or delete the history of transactions.
For consumers, this means you will be able to scan a code on an item you want to buy and find out exactly where it has been before landing in your hands. It will be easy to answer those tricky questions about whether or not an item – such as a fish – is sustainable, ethical or legal.
Using blockchain to trace tuna
The WWF pilot project will use a combination of radio-frequency identification (RFID) tags, quick response (QR) code tags and scanning devices to collect information about the journey of a tuna at various points along the supply chain. While this use of technology is not new for supply-chain tracking, the exciting part is that the collected information will then be recorded using blockchain technology.
Tracking will start as soon as the tuna is caught. Once a fish is landed, it will be attached with a reusable RFID tag on the vessel. Devices fitted on the vessel, at the dock and in the processing factory will then detect the tags and automatically upload information to the blockchain.
Once the fish has been processed, the reusable RFID tag will be switched for a cheaper QR code tag, which will be attached to the product packaging. The unique QR code will be linked to the blockchain record associated with the particular fish and its original RFID tag. The QR code tag will be used to trace the rest of the journey of the fish to the consumer.
At the moment, linking tags is not difficult because the project is focusing on whole round exports – that is, the whole fresh fish minus head, gills and guts. It gets a little more complicated when the fish is cut up into loins, steaks, cubes and cans, but the project team is now able to link the QR code tags on the packages of the processed fish with the record of the original fish on the blockchain.
While it may be possible to use RFID tags throughout the whole process, the expense of these tags could prohibit smaller operators in the fishing industry from participating in the scheme if it expands. There is also potential to use near field communicator (NFC) devices to track the fish all the way to the consumer in the future.
Bringing much-needed transparency to the industry
While this use of the blockchain is the first of its kind for the Pacific Islands region, it is not a world first. A company called Provenence and the International Pole and Line Association (IPLA) has already completed a successful pilot project tracing products from Indonesian tuna fisheries to consumers in the UK.
Provenance is also working on using blockchain to track a range of other physical things – including cotton, fashion, coffee and organically farmed food products. However, the potential of blockchain goes further. For example, Kodak recently launched its own cryptocurrency to help photographers track and protect their digital intellectual property.
Blockchain technology is just starting to change the way business is done. If it delivers on its promise of supply-chain transparency, it will be a great tool to help ensure that industries – including the tuna industry – are doing the right thing.
This will give consumers more information on which to base their purchasing decisions. For the global tuna industry, which has historically struggled with illegal and environmentally dubious fishing practices, this could be a turning point as visionary fishing companies demonstrate true stewardship and begin to open up the industry to full transparency.
Shopping can be confusing at the best of times, and trying to find environmentally friendly options makes it even more difficult. Welcome to our Sustainable Shopping series, in which we ask experts to provide easy eco-friendly guides to purchases big and small.
Tuna is a massive industry and most of this catch ends up in cans. But while each can of tuna might look similar, the environmental impacts of different brands vary. So, with a sea of “eco-friendly” labels and choices, how do you know which is the most sustainable?
Australia produces large amounts of high-end seafood such as rock lobster, abalone and fresh tuna, but most of this doesn’t end up in our supermarkets – it is exported to countries willing to pay more. Instead, roughly 70% of all seafood eaten in Australia is imported. Most of this includes lower-value products such as frozen fish, frozen prawns and canned tuna.
Australia is a major market for canned tuna. Almost all of the canned tuna sold here comes from Thailand, which processes about half of the world’s tuna supply. It is now almost impossible to buy Australian-produced canned tuna since large-scale production in Australia ended in May 2010.
While it is not unusual for a developed country to import large amounts of seafood, Australia is failing to meet international standards for sustainable seafood trade. Australia has strict requirements for seafood exports, but seafood imports are largely unregulated. This means it can be difficult to know if the imported seafood you buy was caught sustainably or even legally.
Catching 7.4 million tonnes of tuna
High global demand drives unsustainable fishing practices. These practices include overfishing, issues related to bycatch (which is the accidental catch of other marine animals like dolphins, turtles and seabirds), and “illegal, unregulated and unreported” (IUU) fishing. Now, 77% of the world’s fisheries are fished at their limit or beyond.
Unsustainable fishing practices have devastating effects on the health of the marine ecosystem and the livelihoods of fishers. With this in mind, it is more important than ever to know about the origin of your fish.
Some species of tuna are fished at sustainable rates, whereas others are overfished. The most common species that end up in cans are skipjack and yellowfin tuna. Both of these species have sustainable stocks in the Western and Central Pacific Ocean (WCPO). Skipjack also has sustainable stocks in the Indian Ocean. Higher-value species such as bigeye and bluefin varieties are usually reserved for sushi and sashimi markets. Southern bluefin tuna is overfished and is listed as critically endangered by the IUCN.
The most sustainable fishing methods for tuna are “pole-and-line” and “FAD-free purse seine”. However, each method has a catch.
Pole-and-line fishing is the traditional method of using a pole, line and hook to catch fish. The rate of bycatch is small because fishers can catch and release non-tuna species. However, bait fish are used to attract the tuna, which can have a large impact if the bait fish is not caught in a sustainable way. Due to the labour-intensive nature of pole-and-line fishing and dependence on bait fish, this method makes up only a small proportion of the total tuna caught and is unable to supply tuna in large amounts.
Purse seine fisheries use a large net to surround a school of fish. In recent years purse seiners have increasingly used fish aggregating devices (FAD) to attract tuna and increase their efficiency. However, FADs also attract bycatch and juvenile tuna and are poorly regulated. Therefore, only purse seine fisheries that set on free-swimming schools of tuna are considered sustainable.
Quick guide to better tuna
What can you do?
1. Read the label
Examine the details on the back of the can for tuna species, fishing method and catch location. There are sustainable options for each of these categories.
The best approach is to opt for skipjack before yellowfin or other tuna varieties. Next, choose tuna caught using “pole-and-line” or “FAD-free purse seine” before “longline” or “purse seine”. Then, check for tuna caught in the Western Central Pacific Ocean – this may appear on the can as FAO Nr. 71. If the can doesn’t at least identify the species or fishing method, it’s probably not worth your time.
2. Consider eco-labels over unverified self-claims
Eco-labels and eco-claims often feature prominently on tuna cans. Eco-labels are market-based tools used to promote sustainable practices. Decoding them can seem challenging, but it doesn’t have to be.
First, it is important to recognise that a dolphin-safe label is not a sustainability label. It focuses only on the impacts of fishing on dolphins. Dolphin-safe doesn’t consider tuna catch levels or other socio-environmental impacts. Most importantly, it doesn’t require independent third-party verification.
In contrast, some newer eco-labels consider a wider set of impacts including target species stock levels, impact on other species and even the social impact on fishers – such as fair pay and work conditions.
So far, MSC is the only label to be recognised by the Global Sustainable Seafood Initiative (GSSI), but keep in mind this label is not without criticism.
In recent months, the MSC-certified Pasifical brand has been criticised because its FAD-free purse seine sourced tuna are transported on vessels that can also catch FAD-caught purse seine tuna. Some commentators argue that this enables unsustainable FAD-caught fisheries to continue operating.
On the other hand, MSC has the strongest chain of custody. It can trace every can of tuna from the supermarket shelf all the way back to the fishery. It’s not clear whether the original criticism was driven by competition for supermarket shelf space, as some industry insiders have claimed.
Various online guides are also available to help consumers choose sustainable seafood options. These guides rank and recommend seafood using a stoplight system. The recommendations are based on available scientific research or a defined set of criteria.
4. Future technologies, supply chains and transparency
While the steps above assist with making sustainable seafood choices, it doesn’t help if the fish you’re buying has been mislabelled. There is still uncertainty related to transparency and traceability in the supply chain.
New applications that use tracking data are also developing. Apps are available that scan QR codes and barcodes to provide consumers with extra information about the origins of lots of different products including seafood. These include Oziris in Australia, ThisFish in Canada and the Seafood Traceability System offered by the Korean government.
Simultaneously, new initiatives such as Global Fishing Watch are providing open access to vessel movement data, providing tremendous opportunities for transparency and traceability.
In short, the easiest way to make a sustainable choice when buying canned tuna is to check the contents label and look for a credible eco-label. If you have a little more time, it might be worthwhile to check out seafood recommendation guides or to download a product tracking app on your smartphone.
Fishing nets pose a serious risk to the survival of penguin species, according to a new global review of the toll taken by “bycatch” from commercial fishing. Fourteen of the world’s 18 penguin species have been recorded as fishing bycatch.
The review shows the level of bycatch is of greatest concern for three species: Humboldt and Magellanic penguins, both found in South America, and the endangered New Zealand yellow-eyed penguins.
On New Zealand’s South Island, yellow-eyed penguins are down to fewer than 250 nests. Previous population strongholds have declined by more than 75%. Conservative population models predict local extinction of yellow-eyed penguins by 2060, if not earlier.
Penguins are among the world’s most iconic and loved birds, despite the fact that many people never get to see one in the wild. Indeed, the opportunities to do so are diminishing, with ten of the 18 penguin species threatened with extinction. After albatrosses, penguins are the most threatened group of seabirds. And, like albatrosses, bycatch is thought to be a serious issue for some species.
On land, many penguins are now well protected, thanks to the efforts of conservation researchers, government agencies, community groups and tourism operators. Where many penguins were once vulnerable to attack from introduced predators, or to habitat loss from farming or development, today the biggest worry for many penguin chicks is how to get more food out of their parents.
But below the waves it’s a different story. Over thousands of years, these keen-eyed seabirds have evolved to catch food in the depths, while avoiding natural predators such as seals and sharks. But they cannot see the superfine nylon fishing nets invented in the 1950s which fishers now set in penguin foraging areas.
Little penguins, whose scientific name Eudyptula minor literally means “good little diver”, typically forage in the upper 20 metres of the ocean, with each dive lasting about 90 seconds. The larger yellow-eyed penguin – Megadyptes antipodes, the “big diver of the south” – prefers to hunt on the seafloor some 80-90m down, holding their breath for 2-3 minutes before coming up for air. If they do not encounter a fishing net, that is.
Gillnets (also called set nets) in particular are very dangerous for penguins. These nets are set in a stationary position rather than being dragged through the water. They are designed to catch fish around their gills, but can just as easily snare a penguin around its neck.
If it gets tangled in a net, a penguin will panic and drown in minutes. In Tasmania, nets with more than 50 drowned little penguins have been found washed ashore. Other penguins are found on beaches with characteristic bruising from net entanglement around their necks.
When a penguin is killed at sea, this has knock-on effects back at the nest. The chicks will die of hunger or fledge underweight, with little chance of surviving their first year at sea.
The breeding partner left behind will probably skip a breeding season; some penguins never find another partner after losing their mate. I have seen them calling plaintively from their nest, or even going down to the shore in the evening to look out to sea, before returning to their nest all alone.
In New Zealand, the endangered yellow-eyed penguin is declining. Current population models predict their extinction on the New Zealand mainland by 2060, or potentially even earlier. Yellow-eyed penguins are facing many threats mostly because they are simply living too close to humans.
Whereas threats on land are reasonably well managed, threats at sea need urgent attention. Marine habitat degradation by industries that damage the seafloor will take decades to recover. Similarly, pressures from climate change will not have a quick enough fix to save yellow-eyed penguins from local extinction.
There is one thing, however, we can change immediately: the needless death of penguins in fishing nets. This will give already struggling penguin populations a bit of a breather and maybe even the resilience required to deal with the many threats they face in their daily fight for survival.
Judging by the number of penguins washed ashore with net injuries, many fishers simply discard penguins’ carcasses at sea rather than reporting bycatch or working towards solutions to mitigate it.
Do we really want penguins to drown for our treat of fish and chips? Less destructive fishing methods are available that do not cause penguin bycatch and the death of other protected species.
But these more selective fishing methods would require fishers to change gear, which costs money. Currently, there is very little legal or commercial incentive for fishers to do anything about penguin bycatch.
But there are a couple of things you can do. Please do not just buy any fish with your chips – ask which species it is and how it has been caught. You can use a sustainable seafood guide, such as New Zealand’s Best Fish Guide or Australia’s Sustainable Seafood Guide. That way you can help the penguins snag a safe fish supper of their own.
Unfortunately, we’re probably underestimating the impact that fishing is having on ray populations. Although some will survive capture, we know little about the non-lethal and long-term effects of that stressful experience.
Included in those unknowns are questions relating to reproduction. In particular, what if the captured ray was pregnant? Would she still give birth? If she did, would her offspring survive?
Beyond just this species, our results suggest it’s possible that other ray and shark species that have live-birth (including most large sharks) could be similarly affected.
All rays give birth to live young. For many species pregnancy lasts about a year, making them more likely to be captured during reproduction compared to egg-laying species.
A makeshift maternity ward
Pregnant southern fiddler rays were collected by hand in Swan Bay, Victoria, Australia, using SCUBA to minimise stress during collection. They were transported and housed in our “maternity ward” – a large outdoor research facility located nearby.
Our maternity ward included a large tank equipped with a giant paddle that pushed water past stationary nets, thereby simulating a trawl net being dragged by a boat. Rays were placed in these nets and trawled, followed immediately by 30 minutes of air exposure to replicate the process of sorting the catch on board a boat. A similar number of control females were kept in a separate tank and were not subjected to trawling or air-exposure.
Over the next three months, pregnancy and the health of each mother was regularly monitored via ultrasounds, blood-sampling and weighing. At birth, their pups were also measured for length, weight and had their blood sampled. Mothers carried and gave birth to an average of two pups.
It’s tough out there for the little guy
Pups from trawled mothers were 12% shorter and 27% lighter than those from untrawled mothers.
Lower body mass may mean pups have fewer energy reserves – in the form of an internal yolk sac – to rely on. An increased risk of starvation is possible during the early stages of life when inexperience can make catching prey difficult.
Pups from trawled mothers also showed signs of a stress response in their immune system, and increased vulnerability to infection and disease is possible. The increased energy needed to maintain a healthy immune system may also limit growth rates. This is important for female fertility because larger females tend to carry more offspring.
Mum feels the stress too
Trawled mothers showed indicators of stress for 28 days after trawling, exhibiting elevated immune responses and 9-15% lower body weights compared to their unstressed counterparts.
Reduced body condition after giving birth could mean that the next mating event may be delayed or missed in order to rebuild sufficient energy stores for a successful pregnancy.
By examining the non-lethal responses to capture stress, we’re working towards more efficient fishing practices that improve conservation outcomes for marine species.
Regarding reproduction, it may mean that we can better assess and manage fishing practices in areas where sharks and rays are known to congregate and breed. Fishing techniques that reduce the amount of accidental capture of rays and sharks will benefit both fishermen and conservation efforts, especially during vulnerable breeding periods.
For example, “turtle exclusion devices” in trawl nets (originally designed to prevent the capture of sea turtles) allow animals that are much bigger than the target catch to escape through a chute. Such a device may be suitable for reducing shark and ray bycatch too.
Our study into how capture affected pregnancy in rays is part of a larger research program led by Monash University in collaboration with Flinders University, University of Tasmania and the Victorian Marine Science Consortium. The research program’s results on both lethal and non-lethal outcomes of capture have helped inform the Australian Fisheries Management Authority (AFMA) how to fish for the future and improve the conservation of sharks and rays.