A brief summary of overfishing

Overfishing describes the common practice of harvesting unsustainable levels of fish (or shellfish, crustaceans, etc.).  This has several consequences, some obvious and some less obvious:

First, overfishing robs the future – by taking too much today, we reduce what’s available tomorrow.  As an analogy, consider a bank account accruing interest.  If you deduct more than your earn in interest every year, you’ll soon run out of money.  It’s the same with fish populations – if we continue to harvest too many fish, the population will eventually collapse.

Overfishing isn’t sustainable economically.  Once a local stock has been overharvested, fishers have two options: 1) go further to find an exploitable population or 2) stop fishing.  Going back to the banking analogy, it’s not possible to live off your interest if you keep deducting from the principal. 

Overfishing has unpredictable and harmful indirect impacts.  Consider the example of sharks, rays, and scallops on the Atlantic coast of America.  As Science reported in 2007, worldwide overfishing of shark populations might have helped their prey – smaller rays – grow to much higher levels.  Rays eat scallops, and when ray populations expand, they eat more scallops – bad news for people who make a living harvesting scallops.  So poor management of sharks has impacts throughout the ocean.

Overfishing can change ecosystems dramatically – and this has direct impacts on our economy and diet.  A good example is Atlantic cod in the Canada.  These populations have been closed to fishing or heavily restricted for over a decade, yet many populations have not recovered.  Increasingly, evidence suggests other species are taking the roles cod once played – but they’re not species that provide us with the same benefits.  When invertebrates and plankton replace cod in ecosystems, the people who once ate or sold the cod don’t have a palatable replacement.

 

Here are some ways you can contribute to more sustainable oceans.