As Rich sails across the world’s oceans he will not see the thousands of fish species living in the waters far beneath his boat or the smaller prey species and plankton that they eat. Fish is a growing source of food for people around the world, but as more people eat fish and the technology to locate and catch them improves, many species have been depleted (or are being depleted) by overfishing, climate change, and other factors. Satellites and advanced sonars or fish finders are making it easier to locate schools of fish, and new nets equipped with sensors are catching more of the available fish. Bycatch, or catching fish you aren’t trying to catch, is a problem because it doesn’t allow those species to reach reproductive age to replenish their population.

Warming ocean waters are causing many fish populations, which prefer certain temperatures to grow and survive, to move to more preferable habitats which could be farther offshore and away from current locations. The same is happening to the prey fish eat, and as the source of food moves so do the fish that eat them.

Another increasing problem in the world has been illegal, unreported and unregulated (IUU) fishing, which makes it very difficult to manage fisheries. It is a global problem that threatens ocean ecosystems and sustainable fisheries. Many governments, international organizations and private industry groups are working together to combat IUU fishing.

We want to be able to keep eating fish, but we won’t have enough for the future unless we allow depleted fish populations to rebuild and grow, and unless we keep other populations at healthy levels.
The good news is that fish are a renewable resource, and they can naturally replenish their populations if the right management measures are put in place.

As scientists we try to understand basic biological questions like how does each species of
fish grow and reproduce, but we also need to know how the environment or ecosystem in which the fish live affects its behavior and life cycle. This way of looking at the whole picture (and not just the fish) is called ecosystem-based management, and it is being put into practice in many parts of the world. A number of depleted fish populations are recovering, but we have a lot more work to do.

As students, there are many ways you can become involved in helping to sustain fisheries around the world and especially in your local area. You can help track ocean currents through surface drifter programs (check out oceanographer Jim Manning’s drifter tracks), learning more about fish species that live in your area and catching only those fish that are not in danger of depletion.