In addition to commercial overfishing, climate change, ocean acidification, pollution and plastic waste are all adversely impacting aquaculture. Each of these phenomenon incur considerable costs. The emissions from human activities are causing climate change and ocean acidification. In addition to climate change and ocean acidification, plastic waste is also contributing to the breakdown of our marine ecosystems all of which deplete the world’s fisheries.
Although it may seem counter-intuitive, as sea levels rise fish stocks and by extensions the fishing industry will be adversely impacted. Similarly warming waters will also have a deleterious impact on a wide range of aquatic life forms. For example, salmonids (salmon, trout and whitefish) depend on cold, free-flowing water. As the waters warm and sea levels rise these fish species (and many others) will suffer. In the absence of serious mitigation efforts, habitat loss for salmon and trout could be as high as 17 percent by 2030 and 34 percent by 2060. According to the Natural Resources Defense Council, these two fish species alone are worth between $1.5 and $14 billion a year.
In addition to driving the greenhouse effect which drives global warming, human carbon emissions are also causing ocean acidification. Aquatic food sources and the industries that depend on them are being adversely impacted by ocean acidification. The waters of the ocean are becoming more acidic as a result of absorbing nearly a third of the carbon dioxide released into the atmosphere from human activities.
Increases in ocean water acidity affect a wide range of marine life including mollusks, corals and small creatures at the bottom of the food chain. Mollusks (including shellfish, like clams and oysters) have difficulty growing in more acidic environments.
Alaska’s coastal waters are particularly vulnerable to ocean
acidification because of cold water that can absorb more carbon dioxide,
and unique ocean circulation patterns, which bring naturally acidic
deep ocean waters to the surface. According to research led by the National Oceanic and Atmospheric Administration (NOAA), some of the Alaskan species most at risk are the red king crab and tanner crab. This jeopardizes more than 100,000 jobs and $5 billion in annual revenues. In addition fishery related tourism generates $300 million
Industry, agriculture and other human activities cause a wide range of chemical toxins to enter the oceans. Toxic chemicals adhere to tiny particles which are then taken up by plankton and benthos animals, most of which are either deposit or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically and deplete oxygen causing estuaries to become anoxic.
When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web.
Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behaviour, reproduction, and suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.
The costs to fisheries from pollution are difficult to calculate but they can be conservatively estimated to be tens of billions of dollars per year. A 1988 study indicated that the aggregate economic losses of pollution in New Jersey alone were estimated to range from $379.1 million to more than $1.5 billion. The value of pollution damage on fisheries is hard to quantify but the full scope of those valuations are extensive.
Another major source of pollution is plastic waste. There are five huge collections of plastic waste in the world’s oceans. According to UNEP, at least 267 species worldwide are negatively impacted by plastic debris in the oceans. Conservative estimates of the cost of this debris suggest that it causes at least $13 billion in annual financial damage to marine ecosystems.