By Dipika Chawla, Rainforest Alliance
“Our big problem here is that we’re harvesting and consuming wild animals on a global commercial scale… We need to allow the ocean to rebuild, to figure out how to do aquaculture right, and to be a lot more careful than we have in the past.”
Tuna play an incredibly important role in marine ecosystems, our diet, and the fishing industry. Bluefin tuna (Thunnus spp), a highly prized commodity in the sushi industry, are an especially remarkable group of species. They are gigantic – Atlantic bluefins can weigh up to 1,500 pounds – and built for speed, reaching up to 40 miles per hour. Skipjack tuna (Katsuwonus pelamis) are smaller and serve as the main species used in canned tuna.
As a popular source of protein for humans around the world, tuna plays a vital role in the global fishing economy, affecting the livelihoods of workers in the commercial fishing industry as well as those of local fishermen living in coastal areas. Unfortunately, the profitability of tuna has led to massive overfishing, pushing some tuna populations to the point of collapse.
For more than a decade, The Ocean Foundation has been working to conserve tuna populations around the globe. We spoke with the organization’s president, Mark J. Spalding, and its Global Tuna Conservation Project director, Shana Miller, about the current state of the world’s tuna species and what can be done to mitigate the harm caused by overfishing, climate change, and more.
Question: Why should tuna conservation be a priority?
Spalding: Tunas are high trophic level species. I like to think of them as the lions of the ocean. As top predators, they are very important to ecosystem function. Tuna, especially bluefin, is also a human consumption product that is in very high demand. As a result, they fetch high prices at fish markets, which in turn motivates fisherman to find more of them or to at least keep catching them. Overfishing has put tuna populations around the world in danger, which threatens ocean health as well as our food security.
Management of fisheries in the past was based on under-informed science. We’ve been investing in improving our science, which has unfortunately led us to the conclusion that things are worse than we thought due to interconnectivity and the long migratory pathways of this animal, particularly between both sides of Atlantic.
Question: What are the threats facing tuna species today?
Miller: Overfishing is far and away the biggest threat to tuna species. Tuna is a heavily exploited commercial species and one of the most sought-after fish in the food industry. Bluefin tunas are the most threatened of all tuna species. They live relatively long, up to 40 years, and mature late, with some species reaching sexual maturity as late as 16 years old. A population with this type of life history gets depleted very quickly and takes much longer to recover.
Skipjacks are much smaller fish, topping off at about 40 pounds — they grow and mature faster and don’t live nearly as long. Consequently, they are more resilient to fishing pressure and are not classified as overfished anywhere. However, fishing pressure is increasing and we’re getting to the point where the risk of overfishing is more of a concern. Currently more than 50% of tuna caught in fisheries are skipjacks. We work with skipjack in the Pacific, where the world’s biggest tuna fishery is located.
Spalding: In addition to overfishing, the Deepwater Horizon oil spill in 2010 and the Fukushima nuclear meltdown in 2011 posed serious habitat threats to tuna. The BP oil spill happened during height of bluefin spawning, near the only known western Atlantic bluefin spawning grounds, and was a severe blow to the population. As for Fukushima, there have been some reports that almost every bluefin that’s been caught in Pacific, either for scientific research or for consumption, has had contamination that is directly traceable to the nuclear power plant meltdown.
A lot of scientific verification is necessary in both disasters before we can know the extent of the damage. But both of them really tell us how interconnected the ocean is. In both of these cases, what we’ve seen is probably just the tip of the iceberg in terms of what suffering has occurred as a result of these human-caused accidents. Bluefin tuna just happen to be important to humans and are also dramatically fast and beautiful, both of which make it a charismatic species.
Tuna’s high price has also spurred investment in what is called “tuna ranching,” in which juveniles are gathered in a net and towed to a location where they are “finished”, or fattened and readied for sale, and can be supplied on demand to Asian fish markets and the like. All of this means that there is tremendous pressure on these species, which concerns us at The Ocean Foundation. Consequently, we have hosted a couple of projects that work with tuna and have also provided grants to other organizations that are doing so.
Question: What are the problems with tuna ranching?
Miller: Tuna ranching, as it’s practiced now, poses problems for tuna conservation and ocean conservation in general. Bluefin tuna are large animals that require a lot of forage—that is, fish for their own diet. You need up to 15-20 pounds of sardines, mackerel, or whatever you’re using as feed, to produce every one pound of bluefin tuna. So it is really inefficient in terms of the feed conversion ratio. There’s concern that local sardine populations are being depleted in order to feed the bluefin in the ranches off of Baja California in Mexico.
The tuna ranches have open ocean pens with high population densities of tuna, are located in coastal areas, and produce a lot of wastewater. There are concerns about water pollution, as contaminants can seep into drinking water sources. Tuna ranching also disrupts tunas’ normal migratory patterns, since they are trapped in one relatively small area.
Spalding: Some of the environmental problems with tuna ranching include degrading the gene pool; removing the species from the predator-prey relationship; and putting nutrients, defecation, and wastes from the facility all in one concentrated location.
Typically in tuna ranches, they’ll remove the tunas and take them to the market as they’re needed. But occasionally, they will transport a live animal to the market, as that’s incredibly popular in Japan. For example, they’ll put a single bluefin on a jet in Tijuana and fly it nonstop to Tokyo, where they can sell it for a huge amount of money—the record price is nearly $1.8 million for just one tuna. The carbon footprint of sending a single fish on a jet plane across the Pacific is just another environmental cost of this practice.
Question: Are there any regions of particular concern for tuna conservation?
Spalding: These are highly migratory species that can travel extremely long distances at high speeds. We know that tuna found in Gulf of Mexico one day can be found off the coast of Maine not long after. So the simple answer is, no! Tuna are everywhere.
Miller: Tuna are found in 91% of the world’s ocean. They have a huge range and impact most coastal countries. In almost all waters where tuna are found, there are at least artisanal fisheries, if not large industrial fishing fleets.
Question: What role do governments play in protecting tuna stocks?
Spalding: The United States, Canada, Mexico, Europe, and Asia all have commercial tuna fishing fleets. The United States is one of only three countries, in addition to New Zealand and Iceland, that is actively trying to put the brakes on overfishing. Our federal government is involved in species monitoring activities and is doing a relatively good job in setting catch limits.
The Magnuson-Stevens Fishery Conservation and Management Act, the primary law dealing with fishing in the US, was originally passed in 1976 and included some conservation language. Each time it’s been reauthorized, that language has been substantially strengthened. When the Act was most recently reauthorized a few years ago, we finally got regulations that are designed to prevent any overfishing at all.
That law is up for reauthorization this year, and there’s a tremendous amount of push back from the fishing industry. The government needs to maintain its commitment to stopping overfishing and not allow the law to be watered down. Thus far, this Act has been a major conservation success—a well implemented piece of legislation that appears to be effectively protecting our oceans. Though it benefits everyone in the long term, we are concerned that the law will be watered down because it hurts some people economically in the short term.
Miller: Because tunas are so highly migratory, tuna fisheries are managed by Regional Fishery Management Organizations (RFMOs). The International Commission for the Conservation of Atlantic Tunas (ICCAT) works in the Atlantic, and the Indian Ocean Tuna Commission works in the Indian Ocean. The Pacific is much bigger and so there are three RFMOs: the Inter-American Tropical Tuna Commission (IATTC), the Western and Central Pacific Fisheries Commission (WCFPC), and the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). For this project, we are working directly with ICCAT in the Atlantic and IATTC and WCFPC in the Pacific to promote science-based catch limits, size limits, and more.
Question: How is climate change affecting tuna conservation?
Miller: Western Atlantic bluefin spawn only in the Gulf of Mexico. Bluefin tuna are cold-water fish, and when they’re in the Gulf of Mexico, they’re at the upper limit of their temperature range. Any warmer, and they can develop cardiac problems and even experience heart attacks. As surface waters heat up due to climate change, there’s concern that the Gulf of Mexico will become too warm for bluefin tuna.
Ocean acidification is also likely to cause problems for most fish species, including tuna. Changes in habitat ranges and decreased oxygen in the water column are also concerns.
Spalding: Put very simply, the main thing we want to do with any species in the face of climate change is make it as resilient as possible. A resilient species is more likely to survive the habitat fluctuations caused by climate change. More resilience can be assured if we seek higher genetic diversity, large population counts, and habitat protection. We can accomplish these things by stopping overfishing and harmful tuna ranching practices.
Question: How can the tuna fishing industry change in order to become sustainable?
Spalding: Aquaculture can be a viable solution if implemented correctly. Today more than 50% of all fish production comes from aquaculture, and it’s growing at the rate of about 6% every year. It can be a solution to food security issues, and it may reduce pressure on the ocean if we do it right.
A few years ago, the prevailing attitude was that all aquaculture was bad. This opinion formed as a result of poorly managed open-pen salmon and shrimp farms, the latter primarily existing in mangroves. But when you look at all types of aquaculture, it’s far more nuanced. There are forms of aquaculture that are thousands of years old, located in riverine systems and coastal shore areas. These appear to be sustainable just because they’ve lasted for so long. The modern, closed systems, on the other hand, don’t allow animals or pollution to escape and prevent nutrient growth, genetic intermixing, and disease spread. We need to search for the best way to manage aquaculture so we can use it as a sustainable alternative.
Miller: Tuna can be a very prolific species. There’s no reason for people to stop eating tuna altogether. They’re a great source of protein for the world. Species like Pacific bluefin tuna that are at less than 4% of their historic levels are probably not the best fish to be eating. But other species, if managed properly with catch and size limits and spawning grounds protection where necessary, can be sustainably fished. That is what we’re working to promote.
There’s also a need for better management of industrial fishing gears–longlines and purse seines, in particular. Longlines can be dozens of miles long with a thousand hooks, and they’re just floated in the open ocean. While they are targeting tunas and swordfish, these baited hooks also attract sea turtles, sharks, marine mammals, and other endangered species. These animals are then trapped on a line for up to 18 hours before they’re retrieved. Air-breathers like turtles can drown. At this stage, we’re looking for more observer coverage and better monitoring of longline fisheries to get a better idea of their impacts on marine life.
Purse-seine fisheries use Fish Aggregating Devices (FADs)–floating objects that are tracked by satellites and attract schools of skipjack, bigeye, and yellowfin tuna. When the tuna are present, fishing vessels will come and wrap big nets around entire schools of tuna, indiscriminately catching juveniles and adults alike. Some FADs, called entangling FADs, have nets that hang down in the water and entangle sharks and sea turtles. Research suggests that this type of fishing changes the natural behavior of tunas, which swarm to the FADs instead of following their normal migratory patterns. High residency has been noted, meaning that once tuna find the FADs, they tend to stay.
There’s not nearly enough information about all of the FADs in existence. Fishing companies lose them or let them float away when they’re no longer useful, and they will continue to attract fish. This creates a marine debris issue, as there are tens of thousands of these objects floating in the ocean. We’re asking for better management and tracking of FADs and FAD fisheries.
Question: What are the best strategies for preventing overexploitation of tuna?
Miller: Our top line objectives for this project are to end overfishing of bluefin and bigeye tuna and to get science-based, hard catch limits for all species. For more vulnerable species like bluefins, we’re also calling for minimum size limits to protect the juveniles so that more of them can reach maturity, spawn, and contribute to the next generation. Bluefins would also benefit from spawning ground protection. A tropical fish like a skipjack will spawn throughout the year when conditions are appropriate, whereas the bluefin species spawn seasonally. For example, western Atlantic bluefin are present in the Gulf of Mexico from January to June, but peak spawning takes place only from March to May, so we’re working on protecting that area and trying to restrict fishing activity during that time period.
Spalding: If we know a fish stock has been overfished, then we need to cut back on fishing until rebuilding can occur. If we think a fish stock is healthy, then we can take only enough out of the system so that reproduction can keep up with consumption. Our big problem here is that we’re harvesting and consuming wild animals on a global commercial scale — this is not a livestock situation where we’re in control of population and breeding.
The human population is growing. We’re going to grow from 7 billion to 9 billion people in the near future. Currently one out of seven people rely on fish for protein every day. If we reach 9 billion people and that ratio stays the same, we will need enough fish every day to feed the entire population of the United States. We need to allow the ocean to rebuild, to figure out how to do aquaculture right, and to be a lot more careful than we have in the past.