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?
Almost all Australian canned tuna is imported
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 type of catch matters
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.
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.
3. Download seafood guides
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.
To help combat this problem, Coles has partnered with WWF to ensure the seafood it sells is sustainably sourced. Aldi has also introduced an initiative called “Trace Your Tuna” to link tuna to its catch location.
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.
Drought in the Murray River doesn’t just affect the river itself – it also affects the ecosystems that live in the ocean beyond.
In a study published in Marine and Freshwater Research today, we found that the very low flows in the river over the past decade reduced the abundance of microscopic marine plants called phytoplankton, which are ultimately the base of all marine food webs.
This shows that the health of the Murray River has a much bigger influence on the marine environment than we previously realised. With climate change poised to make droughts more frequent and severe in the river, it will be crucial to monitor the health not just of freshwater species, but of the local marine ones too.
Read more: Is the Murray-Darling Basin Plan broken?
Phytoplankton depend on nutrients, which are often delivered to the ocean by rivers. In turn, these tiny plants are a source of food for almost all marine ecosystems. Worldwide, they are responsible for half the production of organic matter on the planet.
In South Australia, a dry period dubbed the Millennium Drought (2001 to 2010) and overallocation of water resources (primarily for agriculture) meant that very little water was delivered from the Murray Mouth to the coastal ocean. Between 2007 and 2010, no water was discharged at all. The water in the river’s lower reaches became much saltier and cloudier.
We used historical flow records and satellite imagery, taken between early 2002 and late 2016, to figure out how much phytoplankton and other organic matter were in the coastal ocean each month. We broke up the area into incremental zones, venturing up to 130km from the river mouth.
We found that during and after high-flow events, Murray River discharge resulted in a huge increase in phytoplankton concentrations – as far as 60km beyond the river’s mouth. Surprisingly, before our research it wasn’t known that the river played such an important role in stimulating phytoplankton growth over such a large area.
Armed with an understanding of how river flows influenced phytoplankton growth, we used historic flow records to estimate phytoplankton concentrations back to 1962. Our results showed that large flows used to occur more often and in greater volumes, and consequently that phytoplankton populations would have gone through more frequent and larger booms.
This in turn would have benefited all of the species that ultimately depend on phytoplankton for food, either directly or indirectly. This food web encompasses almost the whole marine ecosystem.
The past affects the future
Water resource management has greatly altered the volume and timing of freshwater discharges from the Murray. The ocean beyond the Murray mouth now receives small and infrequent deliveries of freshwater.
Rainfall and streamflow are decreasing in this already variable region, while temperatures are rising. This means that South Australia is likely to experience more severe and more frequent droughts, which will cause flows from the Murray mouth to decline still further, ultimately reducing phytoplankton abundance.
Previous research had already established the links between river outflows, phytoplankton and health of marine environments and species. But as far as we can tell, no other research has looked at exactly how extended periods of no or low river outflows affect marine ecosystems. This makes it difficult to predict how these systems will respond to climate change.
We believe that reduced Murray River outflows and reduced phytoplankton concentrations would likely have also placed strain on local mulloway fish and Goolwa cockle populations. Juvenile mulloway use river outflows as habitat and environmental cues, and cockles feed on organic material in the water.
This is why it is so important that the management of the Murray River doesn’t just stop at the river’s mouth, but continues into the ocean beyond. Current plans are focused on restoring flows to support the riparian and wetland ecosystems of the Murray as well as the Lower Lakes and Coorong.
But there has been little recognition of the role of river outflows on the marine environment – let alone in management. Although we might not always think about it, the marine environment is really the end of the river system, and part of a larger global cycle. It would therefore be beneficial if plans extend to monitor the marine ecosystem’s response, both at broad and fine scales, to varying flow events.
It would seem the time is past ripe to call for greater research and consideration on this matter, so that we don’t do further damage to what is actually still a part of the Murray River system, and can improve measures to protect the marine environment.