Tuna fisheries involve the commercial catching of various tuna species across the world’s oceans. These operations are globally significant, providing a major source of protein and contributing substantially to the economy of many nations. Tuna, known for their migratory nature and firm flesh, are consumed in diverse forms, from fresh sushi to canned products. The industry’s reach extends from small-scale coastal communities to large industrial fleets operating in international waters.
The Global Landscape of Tuna Fisheries
Tuna species, found in tropical and temperate regions of all oceans, are highly migratory. The primary species targeted by global fisheries include Skipjack, Yellowfin, Bigeye, Albacore, and various Bluefin tunas.
Skipjack tuna (Katsuwonus pelamis) is the most frequently caught species, making up about 60% of the global tuna catch, found in surface waters. Yellowfin tuna (Thunnus albacares) and Bigeye tuna (Thunnus obesus) inhabit tropical and subtropical waters, with Bigeye preferring deeper, cooler environments. Albacore tuna (Thunnus alalunga) is found in temperate waters, prized for its lighter meat. The three Bluefin tuna species—Atlantic (Thunnus thynnus), Pacific (Thunnus orientalis), and Southern (Thunnus maccoyii)—are the largest and most valuable, found in cooler zones.
The global tuna industry is a significant economic driver, generating over US$40 billion annually. More than 70 countries participate in tuna fishing, with the Pacific Ocean accounting for approximately 68% of the total global tuna catch, followed by the Indian Ocean at 22%, and the Atlantic Ocean and Mediterranean Sea at 10%. The industry directly employs over 6 million in the Asia-Pacific region. Tuna’s widespread availability and versatility make it an important component of global food security, providing an affordable and nutritious protein source. Around 70% of tuna consumed globally is sold in canned form.
Fishing Practices and Their Consequences
Commercial tuna fishing employs several methods, each with distinct operational characteristics and environmental consequences. Purse seining is the most common method, accounting for approximately 66% of the global tuna catch. This technique deploys a large net around a school of surface-dwelling tuna, like skipjack and yellowfin, drawing the bottom closed to encircle them. While highly efficient, purse seining can result in significant bycatch, including sharks, marine mammals, and juvenile tuna. This issue is exacerbated when fishing around Fish Aggregating Devices (FADs), floating objects that attract marine life, leading to increased incidental catch of vulnerable species.
Longlining is another prevalent method, especially for larger, deeper-dwelling tuna like bigeye and bluefin, accounting for about 9% of the global catch. This technique uses a main fishing line, extending for miles, with thousands of baited hooks at various depths. The extensive nature of longlines often leads to high rates of bycatch, including seabirds, sea turtles, and sharks, which become accidentally hooked.
Longline bycatch can exceed 28% of the total catch, threatening non-target species. Gillnets, which comprise about 4% of the global tuna catch, are vertical panels of netting that entangle fish by their gills. Though used for tuna, they are indiscriminate, leading to incidental capture of marine mammals and other non-target species.
Pole-and-line fishing, which represents about 7% of the global tuna catch, is considered a more selective method. This technique uses a pole, line, and baited hook to catch tuna individually. Individual capture allows unwanted species to be released alive, resulting in significantly lower bycatch rates. However, less selective methods contribute to overfishing, as tuna populations are harvested faster than they can reproduce. This pressure depletes target stocks and disrupts marine food webs by removing key predators and non-target species.
Safeguarding Tuna Populations
Ensuring the sustainability of tuna fisheries requires robust management and conservation efforts. Regional Fisheries Management Organizations (RFMOs) are international bodies tasked with setting quotas, regulations, and conservation measures for migratory fish stocks like tuna across vast ocean areas. These organizations, such as the International Commission for the Conservation of Atlantic Tunas (ICCAT) and the Western and Central Pacific Fisheries Commission (WCPFC), coordinate management among member countries to prevent overfishing and promote responsible harvesting. They also develop harvest strategies that set fishing targets based on scientific assessments of stock health.
Conservation strategies extend to improving traceability within the supply chain to combat illegal, unreported, and unregulated (IUU) fishing by ensuring tuna is legally sourced. Scientific research is essential, providing data for accurate stock assessments, informing management decisions and sustainable catch limits. Efforts to reduce bycatch include developing more selective fishing gear and practices, and using observers on vessels to monitor catches. Marine protected areas (MPAs) can offer sanctuary for tuna and other marine life, allowing populations to recover and ecosystems to thrive.
Consumer awareness and market-based initiatives also contribute significantly to sustainability. Certifications from organizations like the Marine Stewardship Council (MSC) indicate that tuna has been sourced from fisheries that meet rigorous environmental standards. These certifications empower consumers to make informed choices, incentivizing the industry to adopt more sustainable practices. While progress has been made, continuous efforts are needed from all stakeholders—governments, industry, and consumers—to ensure the long-term health and productivity of global tuna populations.