There are only so many fish in the sea, and they are sensitive to changing habitat conditions and fishing. Some of the biggest challenges facing responsibly harvested seafood include climate change, overfishing, illegal fishing, and environmental impacts of the fishery. Conscious efforts by fishermen, effective and enforced management, and collaboration between the seafood industry, fishery managers, scientists and conservation NGOs address these issues, securing a sustainable source of food for the world. By choosing responsibly sourced seafood, you support groups and fisheries working to protect the oceans for future generations.
According to a 2014 United Nations Food and Agriculture Organization report, one-quarter of the world's fish stocks are overexploited, depleted or recovering from depletion. They have been under excess fishing pressure, which has reduced their capacity. There is no possibility of increasing fishing activity, and in some cases the stocks may decline further.
The Effect of Climate Change and Ocean Acidification on Fish
As global temperatures rise in our oceans, fish stocks and the communities that depend on them may be threatened by changes to their environments. In fact, according to a 2015 study by the WWF, one of the main reasons for declines of marine species in the last 30 years is climate change. No one knows the full impact of climate change and ocean acidification, but it is expected that:
- Fish will move to different areas as temperatures change.
- Some species will not be able to adapt to the rapid changes and become extinct.
- Food chains will be disrupted as predators move into new territories.
- Wetlands and other reproduction areas will be covered by rising sea levels.
All ocean life is connected through the food chain, so fishing of one stock can have far-reaching and unexpected consequences. The habitat can be further impacted by the use of certain fishing methods in sensitive habitats and the amount of bycatch (the unwanted catch of fish and other species not targeted by the fishery). Strong management, regulations and conscientious efforts by fishermen can reduce these impacts and make seafood, wild and farm-raised, environmentally responsible.
According to the UN Food and Agriculture Organization’s “The State of the World Fisheries and Aquaculture 2014,” 28.8 percent of the world’s fisheries are overfished, depleted or recovering.
There are two different issues associated with fishing intensity: overfishing and overfished. Overfishing means that the rate of fishing is too high – too many fish are being removed from the population for it to remain healthy. Overfished means that the population of the fish is too low – too many fish have been removed from the population (by fishing, disease, habitat lose, etc) for it to remain healthy. Stopping overfishing quickly can prevent fish populations from becoming overfished and reducing the level of fishing activity can help overfished populations recover.
Since the second half of the twentieth century, there has been immense growth in commercial fishing. Between 1950 and 2000, the harvest levels increased from 19 million tons of seafood to about 90-100 million tons. This increase disproportionately impacted large, predatory fish such as swordfish, shark and tuna, that are popular food fish. With help and effective fisheries management these populations may be able to recover to healthy levels, but for many species this is a long-term solution. Eating a variety of seafood, especially underutilized species can help reduce pressure on overfished stocks.
No one knows the full impact changes to the climate will have on the oceans. As scientists continue to research the effects of temperature change, sea rise and ocean acidification, a better understanding is emerging.
As the global temperature increases, fish habitats are changing. Scientists note that fish are moving away from their usual areas and migration patterns, following their needed water temperatures. This disrupts food chains as predators and prey move to different territories. In addition, it is anticipated that some species will not be able to adapt to the rapid changes in their environment and start disappearing. Further, as temperatures in the oceans increase, global sea levels are expected to rise, by 2.5 to 6.5 feet by 2100. Wetlands, mangroves and other important reproduction and nursery areas will be covered by the rising seas.
Let’s start with a quick science lesson about ocean acidification. Ocean acidification refers to the fact that the oceans are become more acidic. Liquids fall somewhere on the pH scale of 0 to 14 which measures its acidity (the lower the number the more acidic). Learn more about the science of ocean acidification from NOAA: http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F
Ecosystems in the oceans were built over time based on a relatively steady environment. However, since the Industrial Revolution began in the early 1800s, the oceans have been absorbing more and more carbon dioxide from the air. Carbon dioxide causes chemical reactions in the oceans making the oceans more acidic. The increased acidity weakens the shells of animals like shellfish, corals and plankton. As it threatens the base of the food chain and habitats, ocean acidification threatens the health of entire ecosystems, fisheries, and communities dependent on the oceans.
The ocean has been slightly basic for the past 300 million years, averaging a pH of about 8.2. Today the pH stands at about 8.1. That drop of 0.1pH units may not seem like much, but it means the oceans became 25% more acidic in the last 2 centuries. That rate of increase is 100 times faster than any change in acidity in the oceans for the last 65 million years.
The carbon dioxide came from and continues to come from the burning of fossil fuels. The more fossil fuels we burn, the more carbon dioxide is absorbed by the oceans. The more carbon dioxide absorbed by the oceans the more acidic they become.
Ocean acidification is increasing faster than anyone anticipated. Oyster and shellfish in the Pacific Northwest are already being affected, with weakening shells and increased susceptibility to disease. Various species of plankton are also being affected, reducing the base of the food chain for entire ecosystems. Other effects of acidification will continue to emerge, impacting not only fish and shellfish but also the communities that depend on the oceans.
Fishing and aquaculture have numerous impacts on the environment. Since all species in the ocean are connected to each other, overfishing of one specie affects the entire ecosystem. The habitat can be further impacted by the use of certain fishing methods in sensitive habitats and the amount of bycatch (the unwanted catch of fish and other species not targeted by the fishery). Strong management, regulations and conscientious efforts by fishermen can reduce these impacts and make seafood, wild and farm-raised, environmentally responsible.
Habitats provide homes, reproduction areas and nurseries for fish and shellfish. They can be impacted by poorly and irresponsibly conducted fishing and aquaculture. Areas such as coral reefs, kelp forests, mangroves and wetlands are particularly important for the health of a wide variety of organisms and are very sensitive to damage.
Some types of fishing gear and aquaculture are more likely to cause habitat damage than others. Dredges and bottom trawling, which scrape the ocean floor, can cause damage. However, by making changes in the gear and limiting the time of year of the fishery, the number of fishing trips in a particular area and the fishing areas to more resilient habitats (those with muddy and sandy bottoms that change with ocean currents) the habitat effects may be reduced.
Poorly managed aquaculture can also cause habitat damage through pollution, destruction of critical habitats, escapes of fish from the farm, and the spread of disease to wild populations. Aquaculture, when done correctly, may be a solution to reducing pressure on wild stocks and can be sustainable. In the last few years, farmers have made significant improvements to their farms and new environmental standards are being developed to guide these developments.
Bycatch is a major issue that responsible fishermen and managers are working to reduce. Bycatch is the unintended catch of a fishery. It can include undersized fish, endangered species and unmarketable species. Much of this is discarded either alive or dead. Some fishing gears, including certain types of longlines, dredges and trawls, are associated with higher levels of bycatch. Fishing methods known to have low levels of bycatch include hook-and-line, pot and traps and trolling.
Improvements in fishing gear, including turtle excluder devices and bycatch reduction devices, have reduced the amount of bycatch and increased the amount that is returned to the water unharmed. Management regulations such as limiting the fishing area and deploying fishing gears in areas known to have low levels of sensitive marine organisms further reduce bycatch. Additionally, creating markets for abundant species that are caught as bycatch provides incentives for fishermen to keep those fish and helps reduce pressure on other fish stocks.
Fish Feed in Aquaculture
Aquaculture can have an additional impact on the environment. Often fish that are farm-raised, such as salmon, eat other fish and the feed used in these farms can include large amounts of wild caught fish. Alternative feeds are being developed that use fish byproducts or reduce the amount of wild fish protein used, replacing it with land animal or plant based proteins, which can themselves have other environmental impacts (pollution, pesticides, fertilizer runoff into the watersheds). By sourcing from sustainable protein sources from land or sea to provide protein to these fish, dependence on at risk fish populations is reduced. Another solution is raising non-fish eaters such as tilapia and catfish, or filter-feeding shellfish, which actually help improve the water quality of the area in which they are farmed.