Oceans and coastal ecosystems are key contributors to human lives, livelihoods, and economic development. Fisheries are an important component of the global economy, and nearly 3.2 billion people rely on fisheries for almost 20 percent of their protein intake. The sector plays a crucial role in securing food, nutrition, employment, and income for millions of people, especially in developing countries. In addition, fisheries are a crucial part of the cultural and traditional heritage of many countries.

At the same time, oceans and coastal areas are facing significant challenges related to climate change impacts such as rising seas or storm surges, illegal fishing, and inefficient resource use, which place a burden on marine ecosystems and exacerbate existing policy and governance challenges.

1. Threats to the fisheries sector

1. Overexploitation

As human populations continue to grow across the globe, ensuring food security is the principal driver for the long-standing fisheries as well as the fast-growing aquaculture sector. The ultimate objective is to provide safe, nutritious, and cruelty-free food sources to humans in a way that is sustainable and does not damage the marine environment or harm ecosystems.

However, half the world's marine and coastal ecosystems currently experience overfishing. The State of World Fisheries and Aquaculture report published by FAO predicts that total annual fish production will increase to 204 million metric tonnes in 2030. This not only would inflict pressure on the fisheries sector itself but could also lead to ecosystem deterioration. The direct impacts of overfishing can reduce fish biomass, affect biodiversity and the sustainability of fisheries, and exacerbate the impacts of destructive fishing gear on marine ecosystems (e.g. bottom trawls). Indirect pressures of overfishing include habitat degradation from destructive fishing gear and pollution such as microplastics or oil.

In addition to the disastrous effects of over-exploitation on fish stocks, illegal, unreported, and unregulated fishing (IUU) hinders national and global conservation efforts and inhibits progress in achieving ‘sustainability’ in the fisheries sector. Studies have revealed that globally, at least 7.3 million tonnes of dead or dying fish are thought to be discarded from marine fisheries annually by employing large-scale industrial fishing. According to the FAO, the approximately 60 million metric tons of fish caught annually for human consumption have typical edible yields of between 50 and 60 percent, leaving an estimated 25 million metric tons of available byproducts. At the same time, the estimated production of byproducts from aquaculture is in excess of 60 million metric tons. The majority of this discarded fish and other marine fauna could be used as starters for other industrial production, for example animal feed, fertilizer, fish oil, fish-skin leather, gelatine, or chitin/chitosan from crab shells/shrimp waste. If the existing catch would be utilized more fully, this could increase the sustainability of the sector as well and provide additional livelihood opportunities. Further, by-catch per annum is nearly 40.4% of the total catch. In addition to that, national catch records do not consider recreational catching as well. As open oceans and the coast are widely becoming or have become popular for tourism and tourism-related activities, an increase in recreation fishing might further affect the sustainability of fisheries stocks.   

There has been much debate about the degree to which ocean ecosystems are impacted by (over)fishing, and IUU, which is also termed as "top-down forcing" because such changes occur when predators at the top of the food web are removed, versus the availability of nutrients and other resources in an ecosystem, termed "bottom-up forcing". It is vital to find a point where humanity could benefit from aquatic biodiversity and ecosystems without compromising their sustainability. 

2. Pollution impacts

The degree of pollution stress on marine ecosystems is different for developed and developing countries, but it creates considerable pressure on the fisheries sector. Primary effects are from the effluents from industries, agricultural lands, and sewer lines releasing into the open ocean without treatments, which has wide and various effects on fish populations.

Fertilizer remains from the agricultural runoff causes eutrophication (enrichment of nutrients specifically nitrate and phosphates), reducing the water quality and preventing oxygen dissolution which could cause massive death of various sea creatures. 

Chemical components, particularly heavy metal traces from the industrial effluents, can accumulate in fish bodies causing alterations in their metabolism, and will pass through the food chain (to end up with humans.

Apart from these impacts, coral reef and mangrove ecosystems degradation and disruption of fresh/marine water bodies will affect their reproduction, hence leading to a drastic reduction in fisheries stock. Further, ocean-borne sources of marine litter and oil pollution have a potential influence on fisheries decline while questioning ocean health as well. 

Finally, plastic pollution, especially micro- and nano-plastics, present the biggest threat to the survival and sustainability of fisheries stock. The scientists heavily report plastic pellet ingestion, entanglement, and suffocation caused by microplastics and marine litter across the globe and the issue tend to be increasing day by day. Their impacts not only affects the species longevity but also deteriorate the ecosystem's health. 

3. Climate change and global warming

Adding to the anthropogenic influence on the decline and disruption of fish stocks, climate change plays a major role in deciding the sustainability of marine and coastal fisheries. Changes in temperature can affect an organism's physicochemical and biological processes, which could influence their growth, reproduction, and survival. Ecologically, these effects on a certain species can spread across various taxonomic groups through the trophic levels to alter population dynamics, compromise ecosystem functions, and cause loss of biodiversity. The warming climate also affects food availability and relocation and breeding habits for a number of species. The adverse effects of ocean warming could end up in species migration, invasion, and extinction.

Climate-assisted factors such as sea-level rise, temperature fluctuations, disturbances in water cycle and altered precipitation patterns, increased heat, expansion of minimum oxygen levels, increased intensity and frequency of storms, freshwater flow and rainfall, ocean acidification, and salinity changes could affect fish production, biology, size and reproductive efficiency. This in turn could potentially affect the faunal biodiversity and ocean-based economy leading to unemployment and poverty. 

Apart from these, climate change-induced natural disasters could cause extensive damages to the ecosystems including mangroves or coral reefs that are vital for fish reproduction, while destroying fishery-based economies through property damage or by causing death of fishermen. Globally, more than 850 million people live within 100 km of the coast and are being impacted by changing coastal systems. People have always taken autonomous actions to adapt to change but with the extremity of the issue, extensive preparedness is needed to manage climate-related risks, especially with respect to vulnerable fishing populations. The concepts of climate change adaptation and resilience are becoming core concerns in international development with many donors advocating for the mainstreaming of climate change adaptation and resilience into development policy. 

The impact of climate change on the fisheries sector has substantial economic consequences, including the loss of fishery-related jobs and losses in returns. The social and environmental stakes surrounding the future of fisheries management are high. Thus, applications of conventional techniques centralized only to protect fish population have repeatedly failed across both social and environmental dimensions. 

2. A shift towards sustainability

1. Sustainability fact check

In 1971, oceanographer Jacque-Yves Cousteau spoke of the need for us to "plant the sea and herd its animals using the sea as farmers instead of hunters.” Almost 50 years later, the world is still struggling to adopt the ‘sea farmer’ lifestyle as we continue to search for the elusive ‘sustainable’ equation that allows for thriving marine ecosystems and a thriving fishing industry in parallel. Once more, it is clear that this equation differs from location to location and depends on numerous biological, ecological, social, and economic factors. There are huge discrepancies in the implementation of sustainable fisheries management practices in different parts of the world and ambiguities in defining the term 'sustainable fishing.' Therefore, it is an easy practice but a complicated reality. 

There are several aspects that are essential to achieving sustainable fisheries management: scientifically based stock assessment and management advice, regulation and enforcement of access to fisheries and catch restrictions, and enforcement of regulations. Drawing the line between sustainable use and overuse in the fisheries sector is a complex undertaking. However, countries with fishing waters are responsible for maintaining and sustainably managing their fishing stocks and marine ecosystems. Legal control of IUU and overfishing can reduce overexploitation but must be supported by a continuous monitoring system to achieve long-term sustainability. Resource partition, economic benefits, and livelihood support should be carried out in an unbiased manner prioritizing the fisher families. 

2. Responsible aquaculture 

The demand for seafood is expected to increase significantly by 2050 if historic trends in income and population growth, urbanization, and diets are maintained. This has prompted researchers to contemplate the future role of aquaculture in meeting demand and supporting nutrition needs. For aquaculture, this means a food system that supports public health through the production of diverse seafood, provides multiple, rich sources of essential nutrients, and supports equitable access to nutritious, safe, and culturally acceptable diets that meet food preferences for all populations, without compromising ecosystem functions, other food systems, and livelihoods. In addition to that, mariculture, the farming of other marine organisms, currently accounts for 36% of global aquaculture, of which nearly 60% are mollusks. While maximization of benefits other than provisioning services is often considered a prerequisite, in other cases the maximization of fisheries yields is prioritized. 

Besides food production, rearing endangered marine faunal populations has also become increasingly important for these culturing practices. Conservation of their genetic stock, regeneration, and enriched rearing has popularly become a part of aquaculture. Seafood can also be locally grown to cut down on our carbon footprint. If done right, ocean farming can be accomplished without the consumption of electricity, fresh water, or the use of antibiotics, utilizing the ocean's natural energy. We can see a better and brighter tomorrow, as we responsibly cultivate seafood in the open ocean for the economic and physical health of our society.

3. Maintaining ocean health

While many parts of the ocean and the coast have been highly degraded due to human actions such as coastal development and urbanization, by acting right now and becoming 'ocean-responsible,' humanity can reverse the course. Improving aspects of ocean health such as the condition of marine habitats including corals, seamounts, mangroves, and seagrass beds can benefit other components of the ocean ecosystem including fish stocks and increase resilience to other pressures—in particular, climate change. While pressures and stressors will decrease fish stock abundance and marine ecosystem health, resilience counteracts these negative effects. 

There is also a need to vastly improve monitoring to discover the true state of fisheries around the globe and better enforce management and regulations that prevent overfishing or illegal activities. Current ocean governance recognizes economic and ecologic objectives, but more attention needs to be given to social objectives and the benefits that fisheries could provide. The socio-economical and livelihoods of fishing communities should be properly addressed in the conservation agenda, and their perspectives should be included in the decision-making progresses as well. Simultaneously, fishers should be educated and guided on the negative impacts due to various malpractices in fishing and make them understand their roles and responsibilities in ocean conservation. 

The fisheries sector does not operate in isolation. With its key stakeholders widespread, finding a point for inclusive participation is critical. This poses a challenge for governments in terms of policy coherence, institutional coordination, and collaboration, to ensure that issues such as decent catch and social protection to the fishers and protection of the ocean. All partners and actors should therefore strive to seize those opportunities and rethink fisheries, with the full participation of fisheries actors, and with an approach that cuts across sectors to ensure social, economic, and environmental sustainability. 

4. Legal protection for conservation

According to the conservationists, while efforts to curtail overfishing and promote ocean biodiversity through the establishment of marine reserves have generally had positive results, the period leading up to implementation of policy can be a particularly vulnerable one. For vast swaths of the ocean, no single owner has exclusive rights and so must compete against others for extraction. This raises an important unanswered question: Does the announcement of a future conservation policy lead to preemptive extraction, even in a commons?

Globally, an estimated 7% of the world’s ocean is now designated as marine protected areas (MPAs), a marine spatial management approach that restricts human activities. Many of these areas are further designated as marine reserves, a special type of “strict” MPA that prohibits all extractive fishing. The last few decades have witnessed growth in MPA numbers and coverage. While the trend towards increasing MPA declaration has tapered off recently, this requires complex negotiations between multiple stakeholders ranging from fishermen to respective government officials. The many and varied motivations for implementing MPAs and specifically no-take marine reserves include conserving habitats, increasing abundance of fish inside the marine reserve, and increasing the production and spillover of fish outside the marine reserve. Proponents of MPAs argue that marine reserves are a critical tool in modern conservation efforts and that sealing off large parts of the world’s oceans from commercial fishing pressure will enable threatened fish stocks and entire marine ecosystems to rebuild and replenish. Yet, it can often be a challenge to draw the boundaries for an MPA without compromising fisher livelihood. 

The importance of marine conservation and sustainable use of its fisheries resources has been recognized as a central component of sustainable development as it contributes to poverty alleviation, food security, and sustainable livelihoods. This notion was reinstated by the adoption of a stand-alone Sustainable Development Goal (SDG) on the conservation and sustainable use of oceans, seas, and marine resources for sustainable development (SDG 14) as part of the UN 2030 Agenda for Sustainable Development. The fisheries and aquaculture sector has much to contribute to securing all the SDGs but is at the core of SDG 14. While on the other hand the Convention on Biological Diversity (CBD) was mainstreamed into implementing SDG 14 by integrating biodiversity and ecosystem services into the fisheries sector, including as part of the ecosystem approach. The intended outcomes of this synergy are mainly focused on the establishing of additional MPAs. 

Restricting access to marine resources which provide food or income without consideration of alternatives or transitional livelihood arrangements contributes to conflict over use of contested marine space Failure to achieve participation of people in management decisions can build a growing divergence between those prioritizing marine conservation goals and others prioritizing, for example, food security resilience from the same marine resources. This call for new mechanisms to support the effective implementation of policy and management regulations for sustainable fisheries and ecosystems where conservation of economy as well as people, as the only solution to ensure fisheries around the world are sustainable. 

5. Upgrading research strategies

Historically, fisheries studies were conducted via single-stock assessments and were only required to provide substantial data. But, with increased demands and potential pressure on fishing ecosystems and climate change issues in the way, research trends in fisheries should take several diversions. While addressing the planet's protein needs, protecting the fish stock (specifically genetic stock) has paved the way to tremendous variations in fisheries research propaganda. Every day researchers are working on understanding fish ecology, migrations, invasions, and thermal responses due to ocean warming, fish dynamics, and other factors. In addition, research initiatives which look at the contributions, impacts, and drivers of changes for small-scale fisheries are critical to providing policy-relevant understandings to decision-makers and empowering advocates with key data. 

The ocean is a three-dimensional volume that changes over space and time (as the fourth dimension). An interdisciplinary research program on ocean connectivity is required, including more knowledge of the functional links that connect components of the marine system, i.e., physics, chemistry, biology, geology, ecology, and humans. Hence, fisheries sciences must look at the fisheries management with a holistic approach, joining the visions of many disciplines that so far have worked independently of each other. Simulation-based ocean technologies, modeling, local data managers, and artificial intelligence are needed to understand, observe, predict and manage multiple stressors, extreme events, and a safe operating space for our use of the four-dimensional ocean.

6. Awareness creation and capacity-building

Monitoring and managing fisheries status throughout the global/regional/national level is essential in maintaining their sustainability, or, in the case of depleted fisheries, facilitating their recovery. Such monitoring and gathered knowledge would help educate the fishermen and parties involved in fishing, with the consequences of overfishing and IUU fishing. Adequate knowledge can be provided by the government authorities on using the proper fishing gears and maintaining less/no ecosystem damage. They should be well-educated with the impacts of plastics and toxic chemical pollution and how they cause biological disintegration which might later affect the fish catch quality, quantity, the value chain, and human health. Training and education should be undertaken in their native languages for them to be a part of the solution. Assistances on choosing community-based fishery management, altered livelihood development, women and youth motivation, and community mobilization should also be provided whenever necessary. 

If conservation scientists collaboratively work together with local fishermen and harness their experiences into scientific methodologies, this could create synergies and result in better management outcomes. Researchers have experienced positive outcomes by applying methods combining conventional scientific knowledge and local fisher experiences, especially in developing countries. In addition, fishers, exposed to multiple habitats, and who fish with multiple gears have a greater knowledge of connectivity patterns within the seascapes. Incorporating their insights that have accumulated with ecological observations and hands-on experiences would assist in achieving sustainability goals faster. 

It is vital to understand what makes the fisheries sector unique in each community or country and encourage users to look beyond economic factors alone.

3. Looking ahead

Getting the balance right for all ocean users requires taking into account the social, cultural, environmental, and economic aspects of fisheries. The pressure to sustainably feed ever-growing populations and the need to maintain this economically significant sector will continue to grow. Additionally, the impacts of climate change on fisheries and aquaculture still need to be understood in more detail and more broadly. But these pressures are jeopardizing the substantial food, nutrition, livelihood, and biodiversity benefits provided by the ocean and coastal ecosystems.

Even though global fishery stocks are at stake, issues pertaining to fisheries management often have to be addressed from a local or regional perspective. Lack of insights, financial resources, and support, weak governance, and absence of stakeholder engagement can hinder the adoption of best practices to achieve sustainability in fisheries. The interactions between these different components determine the dynamics at play within and between systems and their degrees of influence on fisheries. This creates a 'wicked problem' for marine policy, that is, a challenge that is not only complex and difficult to define, but dynamic, ambiguous, interconnected, and systemic.

Therefore, a holistic and multidisciplinary approach is required to shift towards 'sustainable' fisheries where sustainability and proper balance of resource utilization with nature being the key factors. There must be changes, and even transformations, to ocean governance and the fisheries sector to improve economic, environmental, and human well-being outcomes.

1. Fishing for the future

The world has a long way ahead. Overcoming the barriers outlined above and rebuilding depleted fish populations and ecosystems is a serious challenge for governments, the fishing industry, local communities, and other stakeholders. It is crucial to find the right equilibrium that allows humans to benefit from fisheries resources without damaging ocean ecosystems and affecting aquatic biodiversity. Already, there are pockets of excellence that showcase the achievability of “sustainable fisheries.” The need to understand multiple interactions, dynamics, and complexities requires participatory processes across systems and sectors to facilitate policies that are more adaptive and to support integrative and dynamic management.

A truly sustainable fishery and aquaculture sector will be able to support the world’s increasing population with food security and economic stability not just for the next decades but for as long as humanity exists. With proper knowledge, appropriate tools, a willingness to adopt novel approaches, and adequate support, today's motivation can become tomorrow's reality.