38 million tonnes. That’s not an accident; that’s a catastrophe. A staggering figure, likely underestimated, that represents an oceanic massacre on an unimaginable scale. Deemed collateral damage by the commercial fishing industry, this isn’t just about numbers; it’s about dolphins, whales, turtles, seabirds, sharks, and countless fish. Sentient beings swept aside like they don’t matter. These are the ‘unintended’ victims of bycatch, a term the industry uses to soften the brutal reality. Their lives are nothing more than incidental losses in the pursuit of profit because some lives are deemed less valuable.
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The most common definition of bycatch is the incidental capture of non-target species. Bycatch — a word that sounds almost harmless, like a minor mishap. Just the “incidental” capture of non-target species. But let’s strip away the euphemisms and confront the brutal reality. Picture this: if 38 million tonnes of terrestrial wildlife were wiped out each year, slaughtered in the pursuit of a single species, would we still dismiss it so easily? Imagine lions, wildebeest, leopards, birds, monkeys, and elephants all dying needlessly just to capture antelope. The outrage would be deafening. So why is it any different when it happens in our ocean? Why do we turn a blind eye?
Using deliberately vague terms and hiding behind a smokescreen of technicalities and loopholes is standard practise for the fishing industry. Making the mass slaughter of wildlife a grey area, which shifts and bends to suit how a fishery is run is a scandal. This isn’t just a debate over definitions; it’s a deliberate strategy to blur the lines, to mask the true scale of destruction happening beneath the surface. Bycatch isn’t a technical issue — it’s an ethical one, and until we stop playing word games, the ocean will keep paying the price.
The lack of a clear standard leaves room for harmful practices, and can be summarised in Dr. Steven Murawski’s, renowned ocean scientist, quote in which he talked about this issue over thirty years ago: “yesterday’s bycatch may be tomorrow’s target catch”.
According to the 2009 article ‘Defining and estimating global marine fisheries bycatch’ by WWF, inconsistencies of what is and isn’t a target species leads to confusion in measurement and data. Therefore, it presents a new definition for bycatch as “catch that is either unused or unmanaged”, where ‘unused’ includes discards and wasted catch that is neither sold nor directly consumed, and ‘unmanaged’ refers to catch that doesn’t have specific management to ensure its sustainability. This new definition, focusing on fisheries sustainability and management, aims to clarify the term and set a clear, global standard that’s easier to understand and monitor.
Image credit: common dolphin washed ashore, via CSIP, ZSL and MCGA.
While it’s true that wherever there’s fishing, there’s bycatch, some types of gear pose greater dangers to marine lives than others, especially ones that are highly unselective and cover large areas at one time. Longlining is one of these. This fishing technique uses single lines that can extend for up to 80 miles long, with several baited hooks branching off the main line. The bait attracts not only target species, which are usually swordfish, tuna and halibut, but also seabirds, sharks, rays, and turtles. The average bycatch rate for longline fishing is more than 20% of the total catch. Not to mention that longlines are often lost in the ocean, continuing to kill marine life due to entanglement.
Gillnets are another example of extremely harmful gear. These mesh nets can be either anchored to the bottom or left to drift, forming a wall that catches fish and other marine life by getting them stuck in the holes around their gills. Like longlining, gillnets are highly unselective, covering several miles up to 100 feet deep. They are most common in the Indian Ocean and pose a threat especially to sharks, with 64% of shark catches recorded by the Indian Ocean Tuna Commission being caught in gillnets. These are also the highest gear category globally for cetacean bycatch. Due to their impact in wildlife, these have been banned in the high seas since 1991 by the United Nations.
We can’t forget bottom trawling, a practice as destructive as it is indiscriminate. Enormous, heavy nets dragged mercilessly across the ocean floor, ripping apart coral reefs and marine habitats that have taken centuries to form. This is more than just an unsustainable fishing technique; it’s a full-scale assault on marine life. Everything in the path of these nets is caught, crushed, or killed, leaving behind a barren, lifeless seafloor in their wake. Entire ecosystems are destroyed in a matter of hours, and the damage they leave behind can be permanent or take decades to recover. According to marine scientist Juan Mayorga, at least 437 million tons of non-target species have been unintentionally caught in these nets.
National Observer Program, NMFS/SEFSC, Public domain, via Wikimedia Commons
Bycatch has devastating impacts in marine wildlife populations. In some fisheries, the percentage of bycatch outweighs the amount of target catch: a shocking rate of four to one has been recorded in the Gulf of Mexico shrimp trawl fishery, meaning that for every pound of shrimp caught, four pounds of other species also had to be caught. Unfortunately, some species are at the brink of collapsing due to these destructive fishing practices and bycatch.
One of the most well-known examples is the vaquita, the world’s smallest and most endangered cetacean in the world. This species, which lives in the Gulf of California in Mexico, has seen its population decimated, going from 567 in 1999 to an estimate of nine in 2019, due to illegal fishing for totoaba. The totoaba fish has a high value in Asian markets as it’s believed that its swim bladder has medicinal properties. Despite being illegal since 1975, illegal totoaba trade persists. The most common gear used to catch totoaba are gillnets, which are the key driver behind the vaquita’s near extinction.
Going from Mexico to the UK, cetaceans are also highly impacted by bycatch in British waters. Estimates indicate that over 1,000 cetaceans are killed every year in UK fisheries, with the most impacted species being the harbour porpoise, common dolphin, minke and humpback whales. Gillnets again pose the biggest problem. Despite being a very small proportion of UK fisheries (around 2%), they are the biggest cause of cetacean bycatch. Trawling in the Bay of Biscay causes the death of up to 9,000 common dolphins per year, and creels (pots and traps) designed to catch shellfish species in many locations also present an entanglement risk to large whales, such as minke and humpback.
Iakov Kalinin iStock
Reducing bycatch is no easy task. As mentioned previously, monitoring and gathering data is extremely difficult, and multi-stakeholder action is needed to make any kind of progress. While the UK Fisheries Act 2020 was an important recognition of the problem as it meant the government committed to minimise and eliminate bycatch of sensitive species, it failed to provide an outline of measures and actions necessary to achieve this goal. Two years later, in 2022, the Marine Wildlife Bycatch Mitigation Initiative was published. Another step in the right direction, however, the lack of effective action and direction garnered criticism amongst conservationists. The document highlighted actions that authorities could take, with no measurable objectives or timescales for implementing and enforcing such actions.
The current bycatch numbers in the UK are only estimates. Despite the legal requirement since November 2021 for all vessels licensed to fish in UK waters to report marine mammal bycatch to the Marine Management Organisation (MMO), in 2022, fishers have voluntarily reported only 19 incidents, far below what’s estimated by experts. As less than 5% of UK fisheries have targeted monitoring for protected species bycatch, these numbers are likely to be higher than the 1,000 cetaceans mentioned and the projection of 1,800 to 3,300 guillemots that are killed every year due to fishing activity.
Despite being a complex issue, bycatch can and should be minimised and ideally eliminated. Where there’s a will and effective management, this can be achieved. A great example comes from Namibia, where the Albatross Task Force helped reduce seabird bycatch by 98% through engagement actions and government regulation.
There are plenty of bycatch mitigation measures that can be used, one of these being fishing gear modification, such as ‘circle’ hooks, which are less likely to be swallowed by turtles than the common J-shaped ones. In a 2013 study published by ZSL, researchers found that circle hooks reduced bycatch rates of leatherback turtles by 91% in the Portuguese swordfish pelagic longline fishery. Gear modifications such as weighted lines and side-setting in the Hawaiian longline tuna fishery not only decreased bycatch rates of black-footed-Laysan albatross in 67% but also presented several operational benefits, according to this same study.
Measures such as these tend to be well-received by fishermen, as they allow them to keep fishing and avoid potential fishery closures.
Pingers, or acoustic deterrent devices (ADD), can also be implemented as a cetacean bycatch mitigation initiative. These may alert marine mammals of fishing gear and drive them away. They have been widely adopted in gillnet fisheries but also trialled in trawls, longlines, and creels. Pingers are required by law in some countries, including the UK, where vessels over 12m which use gillnets or entangling nets in the Celtic Sea and North Sea must be equipped with those. Its effectiveness, however, is still being discussed and studied. Pingers and acoustic deterrent devices are best suited to static gear and are not as effective on towed gear. It’s important to mention that some gear is not fit for purpose and should be removed.
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On a policy level, a requirement for Remote Electronic Monitoring (REM) on industrial fishing vessels could be extremely effective for data collection, which can lead to better fisheries management, as a reporting tool and to ensure best practice. It’s a cost-effective and reliable tool that’s been recommended as the best method for monitoring large pelagic vessels by an ASCOBANS report.
Closely linked to effective monitoring, introducing bycatch limits to fisheries is also an option. However, this requires having observers on vessels, which might not be feasible in small-scale fisheries and in countries that can’t afford such observer programmes.
While the ultimate goal should always be to eliminate bycatch, it’s also important to provide training to those involved in fisheries on how to handle bycatch and safely release animals caught in fishing gear when this happens. WWF in partnership with CMS (Convention for Migratory Species) and IWC (International Whaling Commission) developed guidelines to safely handle and release small cetaceans from fishing gear. It’s an important initiative that can be replicated to other species and help save many marine lives.
Given the lack of data and monitoring, the scale of bycatch globally is likely to be higher than the numbers presented above, which are already extremely concerning. It’s hard to imagine another industry that would accept and look the opposite way to a 40% wastage rate and to such levels of unsustainable management. We can’t forget that this wastage isn’t merely a number. It refers to an alarming rate at which wildlife has been killed year after year for the sake of profit.
Imagine any other industry “accidentally” wiping out 38 million tonnes of wildlife each year and getting away with it. Bycatch is unthinkable. Yet, it’s happening right in front of us, and the commercial fishing industry is somehow shrugging it off as business as usual. Remember, the global fishing industry receives $35 billion in subsidies annually. This is government-funded ocean destruction, the systematic removal of marine species, all for profit and an unsustainable food source. It is nothing short of a global scandal. The trade-off is unacceptable, and the time for complacency is over. Bycatch mitigation isn’t a choice; it’s a responsibility — for businesses, governments, policymakers, and law enforcement.
The brutal truth is that the bycatch epidemic thrives on a mindset of “out of sight, out of mind,” a convenient disregard for the suffering of marine life. We’ve ignored these silent victims for far too long, but ignorance is no longer an excuse. We must do better. Our ocean demands it, and the future of our planet depends on it.
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