Skates are mysterious creatures, and scientists still know little about them. We often catch skates when we sportfish for halibut. The angler usually thinks he has a halibut when the heavy fish hits the lure, but we soon know it’s a skate when the animal exerts long, steady pulls instead of the head-jerking motions of a halibut.
“What is it?” The angler asks when he reels the strange creature up to the side of the boat.
“It’s a skate,” I say.
“What’s a skate? Is it like a stingray?” He asks.
“It’s related,” I reply, “but skates and rays belong to different families.”
Skates in the family Rajidae differ from rays in the family Myliobatidae mainly because skates lay eggs, while rays give birth to live young. Both skates and rays are cartilaginous fish (they have no bones) and are related to sharks.
Biologists have identified 14 species of skates in Alaska, and eight of these species are considered common in the Gulf of Alaska and the Bering Sea. Two of the most abundant species in Kodiak Island’s waters are the Alaska Skate and the Big Skate.
The Alaska Skate ranges from the Gulf of Alaska to the Bering Sea and the Aleutian Islands and west to Japan. They live at depths from 56 to 1286 ft. (17-392 m) and prefer soft bottoms of sand, silt, or mud. They grow to 53 inches (135 cm) in length.
Alaska skates are long-lived and do not reach sexual maturity until they are ten years old. A female lays 20 to 40 eggs per year, and each egg is enclosed in a tough case to protect the embryo as it grows. Since a female skate has dual uteri and shell glands, she can form two single encased embryos at a time. The embryo grows for an average of 3.7 years before it emerges from its case as a fully developed young skate. In certain areas, skate egg cases litter the ocean floor, and beachcombers who find them on the shore call them mermaids’ purses or devils’ purses. Biologists have identified several skate nursery areas in Alaska’s waters. Some of these nursery areas have egg densities of over 100,000 eggs per square kilometer.
A skate’s exceptionally long gestation period and its prolonged maturation until it can reproduce concern biologists. Skate populations are potentially fragile, and if targeted by commercial or sport fisheries, they could easily be overfished. Once considered a trash fish, skate wing is now presented as gourmet food in some regions. The Monterey Bay Aquarium lists skate as seafood to avoid because several North Atlantic species are now in decline from overfishing.
Juvenile Alaska skates eat mainly crustaceans such as amphipods and hermit crabs. As they grow, they begin to eat fish. While enclosed in their tough egg casing, skates remain protected from most predators, but hairy triton snails can prey upon a developing embryo by drilling through the case. Once they hatch, young skates are vulnerable to predation by any larger fish. Steller sea lions and other sea mammals sometimes feed on adult skates.
In my next post, I will profile the big skate, the largest species of skate in the waters off of North America.
Robin Barefield is the author of four Alaska wilderness mystery novels: Big Game, Murder Over Kodiak, The Fisherman’s Daughter, and Karluk Bones. Sign up below to subscribe to her free, monthly newsletter on true crime and mystery in Alaska, and listen to her podcast, Murder
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