Habitat Damage - Along the Coast and Under the Water

February 2003
Fish and shellfish need habitat—places to hide, feed and breed. As human numbers grow, it becomes more and more important for us to take care of ocean habitats. Only then can the sea continue to feed us.

The coasts need our care
Healthy coastal wetlands are a fertile habitat for fish and shellfish. But half of the world's people live near a sea coast; most large cities are next to the ocean. Coastal waters suffer from having so many people living and working nearby. Wetlands have been paved or plowed under. Bay waters are polluted by sewage, oil, chemicals and agricultural fertilizer. When we damage these coastal habitats, we destroy the homes of many of the fish we eat.

The seafloor shelters fish and shellfish
Many kinds of fish and shellfish live and breed along the ocean floor. Scallops burrow into the sandy seafloor. Young cod find shelter in rough rocky reefs among delicate underwater communities of sea fans, tubeworms and anemones. Kelp forests, rooted among rocks, are lush habitat for Pacific rockfish. Flatfish, like sole and halibut, hide on sand and gravel.

Dragging damages the living seafloor
Bottom trawlers catch fish by dragging nets across the seafloor. Some trawlers put rockhopper gear, including old tires, along the base of their nets to roll over rocky reefs so they can catch fish hiding between the rocks. Dredges drag nets with a chain mesh base through soft sand or mud to catch scallops and sea urchins. These types of fishing gear crush life on the seafloor and damage the places where fish feed and breed. Some scientists believe that fishing with rockhoppers and dredges harms the ocean more than any other human activity.

The seafloor never gets a break
Once the living seafloor is damaged, it can take centuries to grow back. Near Australia, bottom trawlers have pulled up and destroyed six-foot-tall gorgonians (coldwater coral) that were at least 700 years old. And with trawl fleets fishing all over the world, the seafloor in popular spots never gets a chance to recover. Parts of the North Sea off Denmark are trawled up to 400 times a year.

Fishing's future depends on habitat
What to do? Protect certain critical areas from fishing of any kind, marine scientists suggest, and fish others more carefully. Fishing is allowed in most marine protected areas, including National Marine Sanctuaries. But wherever possible, the scientists suggest, we should favor fishing methods that spare the seafloor. Longlining, hook-and-line fishing and trap fishing are all habitat-friendly methods.