Why a Sustainable Aquaculture is Important

Since the late 20th century wild stocks of popular food fish have been declining around the world.  Much of this have been due to overfishing.  Pollution and habitat destruction have contributed to the problem.

It seems that it is impossible to prevent overfishing or to stop the decline of wild fish stocks.  The open seas are not under the jurisdiction of any particular country.  There are no limits to how many fish ships can take in these waters.  Furthermore, many countries around the world are unwilling or unable to enforce fishing quotas in their waters.

It seems that the collapse of one popular wild fish stock after another is inevitable.  This is why sustainable aquaculture is likely to become the main source of affordable fish and aquatic foodstuffs in the future.

The Collapse of Wild Fisheries:

Wild fish stocks around the world have been declining or disappearing since the middle of the 20th century.  This is happening for a variety of reasons, all of which are related to human activities.

Since the end of the Second World War there has been a dramatic increase in industrial fishing.  Some of the military techniques developed during World War II were put to use by the fishing industry.  Fish and other marine organisms were caught with military precision by an ever increasing number of ships.  This type of industrial fishing inevitably led to a decline in popular wild fish stocks.

Declining Wild Fish Stocks Around the World:

Several popular wild fish stocks around the world have declined significantly due to human activity.  Tuna are a popular food fish that are commonly found canned in supermarkets.  According to observers, wild tuna stocks currently suffer from overfishing.  If this continues it will result in the collapse of stocks.  This will mean that the familiar cheap canned supermarket and corner store tuna may go up significantly in price or disappear altogether.

Shark species are currently being over-fished, often illegally.  Much of the new demand for sharks comes from East Asia where shark fin soup is popular.  Many shark species have declined significantly.  Because many shark species are big in size and high on the food chain, they tend to reproduce and grow slowly.  This makes them more vulnerable to overfishing and slower to recover from it.

Cod fish were once a cheap and abundant food fish.  In 2004 the World Wildlife Fund (WWF) warned that global cod stocks could disappear within 15 years.  Cod fisheries around the world have been declining since the late 20th century.  In the 1990s, for example, the once prolific Canadian cod fishery near Newfoundland collapsed.

On the island of Barbados, flying fish were a popula r, abundant and cheap local fish for  centuries.  Flying fish used to migrate between the South American coast and the waters off Barbados.  Overfishing, however, changed the fishes’ migration pattern.  Today flying fish from South America only migrate as far as the island of Tobago, south of Barbados.  The decline of stocks has driven up the price of the fish.  Many other wild fish stocks are threatened on a regional, or even global, scale. 

Other threatened species include the Chilean Seabass (also known as the Patagonian Toothfish) and the Humphead Wrasse of the Indian and Pacific oceans.

Unsustainable Aquaculture:

The growth of aquaculture has come in part as a response to declining wild fish stocks.  One of the most profitable species of farmed fish is the Atlantic Salmon.  Salmon are one of the more popular food fish in North America.  Wild stocks have declined significantly since the 19th century because of overfishing, pollution and habitat alteration.  Salmon farming has emerged as an alternative to the now scarce wild Atlantic Salmon.

Salmon farming, however, is controversial.  The fish are typically kept in cages in the ocean.  They are fed with feed made from smaller wild fish.  Critics have also argued that farmed salmon negatively impact nearby wild salmon stocks.  In the 1970s, for example, the microscopic parasitic fluke Gyrodactylus salaris was introduced to Norway wild salmon stocks by farmed salmon from infected hatcheries.  Many of Norway’s wild Atlantic salmon stocks were wiped out by the disease (Selina Stead & Lindsay Laird.  Handbook of Salmon Farming.  New York: Springer-Verlag, p. 348).

The crowded cages that farmed salmon are kept in have provided an ideal breeding ground for various salmon parasites like sea lice.  Unnaturally large sea lice populations can then damage nearby wild salmon populations.

Sustainable Aquaculture:

Some species are better suited to aquaculture than others.  Atlantic salmon, for example, are not very well suited to aquaculture.  This is part of the reason why there have been so many problems with salmon farming.  But the aquaculture industry focuses on fish that have a strong demand.  Salmon farming is a profitable industry because salmon is a popular food fish in the lucrative North American market.

The three species of fish that are best suited to sustainable aquaculture are carp, tilapia and some catfish species.  Carp is one of the fish species that is best-suited to aquaculture.  Unfortunately carp are not popular food fish in North America.  In Western Europe, carp used to be common food fish but they are being replaced by other food fish.  Carp are still widely farmed and eaten in Central Europe, Eastern Europe, Israel, South Asia, Southeast Asia and East Asia.

Tilapia are another species that is well-suited to fish farming.  Tilapia are prolific breeders that thrive in warm waters and are now farmed around the world.  Like tilapia, many freshwater catfish species thrive in warm waters.  In the United States channel catfish are farmed in southern States, where catfish are popular food fish.  In Africa and Asia other catfish species are farmed.


With the steady decline of wild fish stocks worldwide, sustainable aquaculture will probably be the main source of fish and marine life protein in future.