Gray Whale Tail

Where glaciers have gouged long narrow fiords into British Columbia's coastline, the sea floor may be three times deeper than on the continental shelf. In many cases, the glaciers left large mounds of gravel and rock at the mouths of these fiords, called sills. The currents moving over these sills force nutrients upward, making the fiord mouths productive feeding areas. Behind the sills, the water often lies stagnant and almost lifeless.

The key to survival in the ocean is light. Below about 40 meters, there is too little light for plant life to photosynthesize, and in this surface layer is found the first link of an amazing food chain. These are the tiny organisms known collectively as phytoplankton. Some of the plankton feed on the detritus of dead organisms. Others feed on other phytoplankton. They may all be consumed by larger organisms such as zooplankton, which are for the most part the larval stages of more familiar marine animals such as crabs and shrimp.

Each group of organisms provides food for other larger organisms; from phytoplankton to mussel to Surf Scoter to Bald Eagle; from euphausiid shrimp to herring, to salmon and Harbour Seal, and then to Killer Whale.

Breaching Humpback Whale

The deeper ocean waters are relatively lifeless, but undersea landforms can alter currents to force life-giving nutrients to the surface. The best known of these are the shallower "banks", like the large La Pérouse Bank off Ucluelet. These are productive areas for fish, and important commercial fishing grounds. The abundant food also draws thousands of pelagic seabirds like Sooty Shearwaters and Black-footed Albatross. These species spend most of their lives at sea, coming ashore only to nest. Many of them breed in the southern oceans, and spend their "winter" in British Columbia waters.

The narrow coastal strip produces the greatest abundance and diversity of life in the oceans, and it is here that most people will experience the marine world. Access to this world is made easy by the twice-daily movements of the tides, which conveniently retreat from the shores to expose whole communities of marine organisms.

Many of these organisms occur in the zone between high and low tides, and are well adapted to periods of several hours exposed to the sun and air. A visit to a rocky shoreline will reveal mussels and limpets, anemones and sea urchins, and bright orange and purple sea stars. Tiny crabs and sculpins dart for cover as shadows pass over them. Then the tide comes in again, drawing its liquid curtain across this remarkable performance, until it is time to repeat the cycle again tomorrow.

There are many species that can be harvested from the mud and sand, like tasty clams of several species. Beware, though, that occasionally there is a bloom of algae that produces a toxin. The toxin does not harm shellfish, but when passed to humans, it can cause death by paralytic shellfish poisoning. The bloom is known as Red Tide, and fisheries authorities should be consulted before any shellfish are harvested.