Why We Need Protected Areas
On my trip I’ll be moving through a lot of terrestrial (land) ecosystems as well as marine and freshwater. When we think of parks, we typically think of areas of land set aside for preserving ecosystems or landforms, or good camping spots, but it turns out that protecting the ocean in parks is just as important as it is on land.
Why do we need Marine Protected Areas (MPA’s)? In a nutshell, because fish don’t have babies until they grow to a certain size, but fisheries are happy to target fish that are below the minimum breeding size. Therefore, without protection from fishing pressure, entire populations can be wiped out very easily. A classic example of this was the Atlantic cod fishery in the Maritimes. Today, over ten years after its collapse, and it still hasn’t shown significant signs of recovery.
Certain species are more resilient to fishing pressure, while others are very sensitive. This all depends on their particular biology. Humans dragging the oceans for fish is a relatively new concept for the ocean, so some species just don’t happen to be well adapted to it, while others conveniently are. Dungeness crabs seem to rebound fairly well, but conversely, rockfishes don’t. There are 35 species of rockfishes on BC’s coast. They are related to the tropical lionfishes with the venomous spines. Some species don’t produce eggs until they reach 15 years old. It is very easy to overfish these species. Black rockfish used to be common around Vancouver and Howe Sound but they have been extirpated. Another problem with rockfishes is that they usually live fairly deep and when they are pulled to the surface their swim bladders expand out their mouths and they usually die unless the person knows what to do to get them negatively buoyant again.
If you live in Canada and you eat “red snapper”, there is a very good chance it is a rockfish. You may think that our fisheries are, or at least can be, sustainable for rockfishes. But you may be quite surprised by the reality. Yelloweye rockfish are now a prohibited species. Why? Because they may grow up to two centuries old, and the populations may only successfully spawn once every 30 years! Look at this amazing list of statistics from the Vancouver Aquarium. Other species of rockfishes are more resilient, like coppers.
What MPA’s do is establish a safe zone where fishes can grow up to breeding size. The spawn from these breeders serves to seed the surrounding areas with baby fish. It’s not quite this simple for many species because the fry don’t migrate very far, but in principle it generally works.
Another reason for MPA’s is to protect the structure of undersea ecosystems. It is easy to not notice destructive fishing practices because we can’t see below the surface but they are even more sensitive to this than land based ecosystems are. Coral reefs are routinely despoiled with dynamite fishing and cyanide. This reduces the productivity of the reef since the base organisms, corals, don’t thrive anymore. In BC we have similar structures, glass sponge reefs which inhabit deeper waters in certain areas beginning in about 100 feet of water. These grow very slowly and can get quite large. Unfortunately, trawling destroys them. This is another case where the ocean is totally ill-equipped to handle our destructive harvesting practices. Land based ecosystems are better adapted to this because wind storms and forest fires routinely level forests. And trees grow much faster than sponge reefs do.
Still another important reason for MPA’s is to protect large congregations of sea animals like sea lions or birds which congregate in certain coastal areas in high numbers. This is a little different than terrestrial ecosystems where the animals tend to disperse more evenly throughout the landscape, or if they do congregate together in herds then they move around.
In BC we are starting to see more MPA’s being established, but we need many more. Great Britain recently set aside very large areas of its coastal waters as protected areas.