What are the threats to our oceans?

Fishing

Giant ships, using the latest equipment, can find schools of fish quickly and accurately. Modern fishing practices are incredibly wasteful. When fishers target particular species that they want to catch, they also catch other species accidentally. These non-target species are called bycatch and can include fish, marine mammals, seabirds or invertebrates such as crabs and shells.

Most modern fishing practices are incredibly wasteful. Every year, fishing nets kill up to 300,000 whales, dolphins and porpoises globally. Entanglement in lines and nets is the greatest threat to the survival of many species including some birds. As larger fish species decline in numbers, the next smaller fish species are targeted and so on.

More on bycatch

As fisheries in the northern hemisphere in particular have become depleted in stock more fish are being illegally caught around Africa and the Pacific depriving local inhabitants of major resources - food and income.

Habitats can also be altered by fishing. For example, bottom trawling, can destroy many fragile ecosystems.

Also see "So what's wrong with fish?". This an excellent detailed article covering a wide range of issues related to fishing. Highly recommended.

Part of a fishing fleet

Yellow fin tuna

Fish farming

Like agriculture, fish farming or aquaculture is not just one industry. A large number of aquatic species, from seaweeds to scallops to salmon, are framed using a variety of techniques in locations all over the globe. The framing of each species has its own particular benefits and risks.

For example, in Thailand, and many other tropical nations, coastal mangrove forests have been cut down replaced with prawn farms.A benefit of fish farming is that over one billion people rely on fish as a main source of protein, many of them in developing countries. Fish farming provides a significant amount of this fish.

More about environmental effects of fish farming.

A fish farm producing salmon and
ocean trout in Tasmania