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A recent international documentary, panned universally by fisheries scientists, claimed there was no such thing as sustainable fishing or sustainable seafood. This, and other misinformation about overfishing, is easy to refute with science but it still prevails around the summer barbeque as you throw your 3 kg line-caught snapper on the hotplate. 

In this Mythbusters, we will address some of the claims made about the state of global fisheries, offer some home truths about where there really is an overfishing problem, and offer up enough science that you will be happy to be eating commercially-caught fish out of New Zealand waters. 

Myth: There is no such thing as sustainable fishing 

Of course, there is: If the rate of natural mortality of the fishery PLUS what you are catching is less than the rate they reproduce, the fishery’s biomass will not decrease.  So, as long as you know how many fish are there, you can ensure the fish stock will not get below a healthy level. This is where fisheries management comes into play.  

Myth: Fisheries management is flawed

Simply speaking, you count the adult fish, or in more scientific terms, you assess the status of the fish stock to determine the current stock size in relation to the management target and from that set and manage conservative catch limits across all harvesters (commercial, recreational and customary non-commercial). That means taking into account the number of fish, their reproduction rate, their natural mortality rate, and the level of extraction or fishing impact. The maximum available catch for everyone depends on the type of fish, and the catch will likely range from 4 percent to 10 percent of the adult biomass in any year – meaning there is always a very large majority of the fish still in the water and breeding. Around the world, where countries have good fisheries management systems, fisheries assessments are done by scientists on a regular basis. In New Zealand, the Ministry for Primary Industries (MPI), contracts independent scientists, including the National Institute of Water and Atmospheric Research (NIWA), to do this every year. Assessing stocks means the Minister can reduce the number of fish that can be taken out of the water by fishers, including the commercial sector, if it looks like their numbers are getting below a sustainable point.  

Fisheries management in NZ is built around three targets. There is the “management target” where the fish stocks are healthy. This is what we manage to, but like all natural systems, the biomass varies from year to year in response to the broader environment. Below that there is a “soft limit” where some caution needs to be had. If a stock is assessed as being below the soft limit, mechanisms are put into place to rebuild that fishery, usually reducing the number of fish allowed to be caught for a rebuild period. And then there is the “hard limit”, which is where all fishing may stop completely to allow the stock to rebuild as fast as possible. Fish stocks in New Zealand are managed so that they fluctuate around management targets and have a high probability that the soft and hard limits are avoided. 

Myth: All the world’s oceans are overfished

Unfortunately, not all. According to the United Nations Food and Agriculture Organization (FAO), the world’s authority on fisheries, 34.2 percent of all the world’s fisheries are overfished, and these are mostly in countries that do not have good data on their fish stocks. Underdeveloped parts of Asia and Africa probably have significant amounts of overfishing and depleted stocks. Country of origin is generally the best general indicator of seafood sustainability. What gets measured, gets managed. If a country monitors their fisheries well, as New Zealand does, its seafood is probably sustainable. Luckily, there is very little seafood imported into New Zealand so the fish you buy is highly unlikely to be from an unsustainable source. 

Myth: Our fisheries are not being regularly assessed, because I haven’t seen the data

MPI tell us whether a fish population is in one of three categories each year. The annual data on New Zealand’s fish stocks is publicly available on the MPI website and in 2021, 152 fish stocks were analysed, with most of them in good shape. The 152 stocks account for 67 percent of the total NZ QMS catch and 85 percent of the value of that catch. The MPI analysis tells us that 84.9 percent of the fish stocks assessed are above the soft limit which equates to 94.3 percent of the catch volume. Almost 80 percent of the assessed stocks were doing even better than that and were above the management target. 

Corrective management action has been put in place or is being considered for stocks that are below their management targets, or the soft or hard limit, or where overfishing is occurring. While assessments are not routinely undertaken for the remainder of our stocks, their status is monitored less rigorously through trawl surveys and catch analyses. In the event a sustainability problem is suspected, MPI will put in place an appropriate management response, often focused on becoming better informed on the status of the stock.  

Myth: The oceans will be empty of fish by 2048

This often cited “fact” about the oceans being empty by 2048 has been proven wrong over and over since it first emerged in a 2006 press release. Even the authors of the original projection have admitted their analysis was flawed. The University of Washington School of Fisheries points out that criticism of the paper was quick. The authors of the original paper worked with a number of fishery scientists that had criticized them to take a closer look at the abundance trends in fish stocks. This analysis was published in 2009 and showed that, on average, stocks were not on a path to total collapse and were stable over the previous 20 years. In 2020, the data was updated again, and the new analysis showed that fish populations around the world are generally healthy or increasing in abundance. So, to clear up any confusion: the UN (FAO) estimates that 66 percent of fisheries are sustainable and contribute 78.7 percent of the seafood the world consumes. The 2048 projection has been scientifically rejected and should stop being cited. 

Myth: All the world’s oceans are in trouble

It is great that two thirds of all the world’s fisheries are being monitored and are increasing in abundance. But there should be concern about the remaining third not being managed well. Everyone wants sustainable, healthy fisheries. An overexploited fishery may end up collapsing – and with it the revenue, jobs, and food it supplies. Science tells us that countries where fish populations are not assessed and monitored are much more likely to be overfished and unsustainable. The United Nations, in their FAO annual report, The State of World Fisheries and Aquaculture, unequivocally state that; “the solution for fisheries sustainability around the world is clear: implement effective fisheries management.” The 2020 report says that it is mostly developed countries that manage their fisheries and that means global fisheries sustainability has not improved evenly. And developing countries are facing a worsening situation when compared to regions that intensively manage their fisheries. With less effective fisheries management, many have stocks with only half the abundance of assessed stocks in well managed fisheries. Unfortunately, good science takes a lot of resources, and many developing countries do not have the financial or technical capacity to manage their fisheries sustainably.  

Myth: Nothing is being done about overfishing 

In countries where fisheries are not well managed, improved government policy around fisheries management would be good for the oceans and good for food production. Well managed fisheries are critical to feed the world and the FAO has a vested interest in keeping stocks healthy. That’s reinforced by a report which says global consumption of seafood is growing faster than for any other protein. Seafood consumption is growing at an average of 3.1 percent each year while other protein like meat and dairy are growing at 2.1 percent. Fish provides 3.3 billion people (more than 40% of total world population) with 20 percent of their animal protein each year and in countries such as Sri Lanka, Bangladesh, Cambodia and Indonesia that rises to 50 percent. Unfortunately, the latest FAO report states that because of poor management of fisheries in developing countries, the percentage of unsustainable fisheries has increased from 33.1 percent to 34.2 percent.  

The waters of the Pacific southwest, eastern central and northeast are leading the sustainability charge. Those are the waters off New Zealand, and the United States, both of which have robust fisheries management regimes in place. However, the Mediterranean and the waters off South America are in dire straits. The good results in countries like New Zealand and the United States are not sufficient to reverse the damage being done elsewhere. The FAO says this highlights the need to urgently replicate successful management systems, such as New Zealand’s Quota Management System, in poorly performing fisheries.