Bycatch: A Hidden Problem in Commercial Fishing
Commercial fishing is one of the oldest and most widespread economic activities in the world, vital to the livelihood of millions of people living along the coasts of all oceans. However, behind the targeted capture of commercially valuable fish species lies a phenomenon often overlooked but extremely damaging: bycatch.
The term “bycatch” refers to all marine species that are caught during fishing operations but are not the fisherman’s intended target. These species can include fish, sea turtles, seabirds, sharks, cetaceans, and other forms of marine life not destined for the market.
Examples of bycatch include sea turtles and sharks, which are often caught during swordfish or tuna fishing with longlines, as they share the same habitat and feed on the same bait as these targeted predators.
Main Causes of Bycatch
Non-selective fishing techniques are the primary cause of bycatch. Among the most problematic are trawl nets, gillnets, and longlines. These gears are designed to capture large quantities of fish but are incapable of distinguishing between species. As a result, many non-target organisms are accidentally trapped and killed.
The Impact of Bycatch on Marine Ecosystems
Bycatch has devastating consequences for marine ecosystems. Populations of non-target species can decline sharply, especially when they are already vulnerable or endangered, such as sea turtles.
This ecological imbalance can threaten marine biodiversity and disrupt the food chain. Additionally, bycatch represents a significant waste of marine resources, as many of the accidentally captured species are discarded back into the sea already dead or fatally injured.
Strategies to Reduce Bycatch
Addressing the bycatch issue is essential to ensure high levels of marine biodiversity. Over the years, various strategies have been developed to mitigate this problem, some more effective than others.
Selective Fishing Gear
The adoption of more selective fishing gear can help reduce bycatch. For example, using nets with larger mesh sizes allows smaller fish and other non-target species to escape.
One of the most effective strategies is the establishment of Fishing Exclusion Zones. The creation of marine protected areas, where fishing is prohibited, provides refuge for vulnerable species and can virtually eliminate bycatch. Implementing stricter regulations and improving the monitoring of fishing activities can also significantly contribute to reducing bycatch.
Modifying fishing techniques — such as changing the methods, depths, or times when nets are deployed — has also proven to be an effective way to reduce bycatch.
Exclusion Devices
In the past, devices such as TEDs (Turtle Excluder Devices) were developed. These are tools installed in trawl nets designed to allow sea turtles to escape after being caught.
Circle hooks were also studied for a long time but failed to produce significant results. Although they were intended to reduce accidental captures of sea turtles, it was later found that they proportionally increased the capture of sharks and blue sharks.
Despite millions of euros invested by the European Community to develop these technologies, most of these systems have now been shelved or even abandoned due to the significant loss of target catch, making their use economically unviable for fishermen.
Conclusions
Bycatch represents a major challenge for marine conservation. Reducing this phenomenon is crucial to protecting biodiversity and ensuring the proper functioning of marine ecosystems.
At Blue Conservancy, we believe that in order to truly combat bycatch, it is necessary to significantly reduce fish consumption, particularly of top predators such as tuna and swordfish, which are among the most sought-after species on the market.
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