The Bering Sea, bordered by Alaska and Russia, is known for its challenging conditions and abundant marine life. It supports one of the world’s most lucrative and hazardous fisheries: crab fishing. The sea’s underwater landscape significantly influences where these valuable crustaceans reside.
The Bering Sea’s Diverse Depths
The Bering Sea features a varied seafloor topography, broadly divided into two regions: the extensive continental shelf and the deeper abyssal basin. The continental shelf, in the northern and eastern parts, is a relatively shallow plain, typically less than 500 feet (about 150 meters) deep. In contrast, the southwestern portion plunges into an abyssal plain, with depths commonly ranging from 12,000 to 13,000 feet (approximately 3,700 to 4,000 meters). The deepest point reaches about 13,442 feet (4,097 meters) in the Bowers Basin.
Where Crab Fishing Occurs
Commercial crab fishing in the Bering Sea primarily occurs on the relatively shallow continental shelf, which provides specific conditions for various crab species. Fishing operations generally target depths from 100 to 600 feet (30 to 180 meters) for species like red and blue king crab. Golden king crab, however, can be found in deeper waters, between 600 and 2,400 feet (180 to 720 meters).
These shelf areas are favored due to their flat bottom topography, conducive to deploying and retrieving crab pots. The eastern Bering Sea shelf is a significant fishing ground. Fishermen use large, heavy steel pots, typically 7 feet by 7 feet and weighing over 700 pounds, designed to withstand harsh conditions and settle on the seafloor where crabs live. These pots are baited with fish like herring or cod and lowered to the bottom, remaining there before retrieval.
How Depth Influences Crab Habitats
Depth is an important environmental factor for crab populations in the Bering Sea, influencing parameters that define their habitats. Water temperature, pressure, light penetration, and food availability all vary significantly with depth. Many crab species, such as snow crab, prefer cold water conditions. Juvenile snow crabs, in particular, concentrate in colder, shallower waters, with temperatures between 0 to 1°C being optimal for their development.
Crabs also have specific substrate preferences tied to depth. Snow crabs often inhabit muddy bottoms, where they can burrow for protection. Red and blue king crabs tend to prefer sandy bottoms. Food availability, influenced by light penetration and nutrient upwelling, also dictates where crabs congregate. These environmental conditions create distinct zones at different depths, making certain areas more productive for specific crab species.
Primary Crab Species and Their Depth Preferences
Several crab species are commercially fished in the Bering Sea, each exhibiting distinct depth preferences influenced by their biological needs. Red King Crab ( Paralithodes camtschaticus ) and Blue King Crab ( Paralithodes platypus ) are generally found in shallower waters, from the intertidal zone down to about 600 feet (180 meters). Red king crabs are particularly abundant in areas like Bristol Bay. Blue king crabs, with a more limited distribution, are often located around islands such as St. Matthew and the Pribilofs.
Golden King Crab ( Lithodes aequispinus ) typically inhabits deeper waters, ranging from 600 to 2,400 feet (180 to 720 meters), along continental slopes and in the Aleutian Islands. Snow Crab ( Chionoecetes opilio ) and Bairdi Crab ( Chionoecetes bairdi ), often marketed together, are widely distributed across the eastern Bering Sea shelf. Snow crabs are commonly found at depths less than 984 feet (300 meters), with an average depth around 300 feet (91 meters). Bairdi crabs also prefer similar depths, often found around 300 feet (91 meters), and both species prefer soft, muddy bottoms.