Facts About Fish
- It is estimated that there are more than 32,000 different species of fish worldwide.
- A cyprinid fish, the world’s smallest, is only 0.3 inches long.
- The ocean sunfish can grow to 10 feet long.
- In 2016, global fish production reached 171 million tons, with 88% of this amount directed for human consumption.
- 33% of fish species are being fished at biologically unsustainable levels.
- Fishing is big business, with nearly 40 million people working in fishing industries, primarily in Asian and African countries.
- Overfishing is destabilizing marine ecosystems, especially illegal and unreported unregulated (IUU) fishing. IUU fishing involves destructive fishing methods that harm marine environments and species, often killing more fish than are captured.
Why We Need to Protect Fish
- Role in the Ecosystem: Fish play an integral role in ecosystem nutrient cycles. Fish recycle nutrients that are vital in the productivity and survival of organisms at the base of the aquatic food web. The importance of this function suggests that overfishing can be highly detrimental to the proper functioning of the whole ecosystem.
- Ecosystem Services: In addition to providing a myriad of ecosystem services, fisheries play an integral role in both recreational and cultural services around the world, from sport fishing to various religious ceremonies.
- Economic Contribution: Food from fish alone generated $231.6 billion in 2016. Approximately 120 million people are dependent on fish for their incomes, with 97% of these workers living in developing countries.
- Uniqueness: From deep in the ocean to shallow streams, fish have evolved and adapted to their respective habitats in fascinating ways. For instance, some species of fish navigate and hunt through electroreception, a process in which they detect and respond to electrical stimuli, like the speed of the surrounding water current.
Threats to Fish
- Climate Change: Rising ocean temperatures threaten to disrupt the migration and distribution of numerous fish species, from the Pacific Ocean to the Mediterranean Sea. Many species of fish are also decreasing in size as a result of climate change. Rising sea temperatures are also threatening coral reefs, which places additional pressures on fish species that depend on them. For example, the loss of coral reefs in Papa New Guinea has led to a 50% decline in the population of fish species endemic to the islands. Another threat: Roughly a third of all carbon emissions from fossil fuels is absorbed by the ocean, which has made oceans approximately 30% more acidic in the last few decades. As the ocean acidifies, species like coral and oysters face difficulty in forming their shells — or worse, they dissolve, which may cause issues up the food chain for fish. 
- Habitat Loss: Since the 1960s, the amount of water held by dams has quadrupled, impacting populations of freshwater fish. Agricultural development, land clearance, industrial and urban development are all threats to fish populations and habitats.
- Overfishing: Worldwide, fish stocks have significantly declined from overfishing. For example, the Madeiran sardine has seen its population decrease by 30-60% along the coast of western and central Africa, while the Atlantic salmon has seen its population decrease by 90% in North America and Europe.
- Ocean Pollution: Pollution comes in many forms and from different sources — chemicals from production plants, plastic from waste facilities, fertilizers from agriculture, and oil spills — and all can be extremely harmful and cause significant population declines to fish species. For instance, the April 2010 Deepwater Horizon oil spill in the Gulf of Mexico decimated much of the region’s fisheries and inflicted an estimated $3.5 billion in economic losses. This pollution devastates the fish and their ecosystems, and can also contaminate the seafood that people buy and eat.
What You Can Do to Help Protect Fish
- Make safe and sustainable seafood choices. Some species of fish have healthy populations while others are in serious decline from overfishing. Buy sustainable seafood and fish from fisheries and fish farms that support coastal communities and healthy marine ecosystems. To get started, check out a list of organizations that offer sustainable seafood resources across the world.
- Keep our water clean and prevent water pollution. Properly dispose of garbage and waste including recyclable materials; sign Earth Day Network’s Pesticide Pledge and reduce or eliminate lawn and garden fertilizers from your yard; avoid flushing or dumping chemicals or products containing toxic ingredients down the toilet or sink; clean up your pet’s waste using eco-friendly disposable methods; and ditch the plastic for reusable products.
- Test your knowledge about threats to ocean ecosystems with our Oceans Plastic Pollution Quiz.
- Take personal steps to end plastic pollution.
- Learn how to go green, protect the environment and fight global warming with 45 easy-to-follow tips.