Three cowcod rockfish recently went on display at the Monterey Bay Aquarium—the first time these rare and beautiful fish have been exhibited in any public aquarium.
There are close to 100 rockfish species worldwide, but the cowcod (Sebastes levis) is one of the largest. It can reach 39 inches in length, and live up to 55 years. You’ll find our new arrivals in the Monterey Bay Habitats exhibit, and can recognize them by their large heads and faint, vertical bars—resembling ribs—on the sides of their bodies. They also have spiky dorsal fins that have earned them the playful name, “roosterfish.”
Life Down Deep
Like most rockfishes, cowcod prefer life down deep. They’re rarely seen at depths shallower than 300 feet, and can be found all the way down to 1,600 feet. (View a NOAA video of cowcod taken at 290 feet by a remotely operated vehicle.) If a rockfish comes up too quickly—for instance, on a fishing line—rapid decompression of the air bladder causes it to inflate and die.
But just as scuba divers decompress, it’s possible for fish to avoid the harmful effects of rapid pressure changes. Hubbs-SeaWorld Research Institute in San Diego (HRSWI), which captured our three cowcod, built a pressurized chamber that allows the fish to slowly decompress over the course of a week before they emerge healthy and intact. Our cowcod underwent this procedure at HSWRI and are thriving. The Aquarium—working in partnership with Hubbs-SeaWorld—has created its own compression chambers to help fishes survive when brought to the surface. One such chamber, resembling a scuba tank, is small enough to keep onboard a collecting boat. Having these devices mean that fishes can be safely transferred to research facilities like Hubbs-SeaWorld—or to other aquariums, where they can serve as ambassadors and promote awareness of the conservation issues that rockfishes face in the wild.
Cowcod Conservation
Because of their large size, cowcod were prized by recreational and commercial fishermen. Through the 1960s, California fisherman could pull up a longline with dozens of fish attached. But, as with many long-lived fishes that reproduce slowly, cowcod couldn’t take the pressure.
By the 1980s they had become increasingly rare, and were declared over-fished by the Pacific Fishery Management Council in 2000. A recovery plan was adopted in 2001, and the California Department of Fish & Game established a conservation area devoted entirely to cowcod in southern California waters. Still, it may take a century to rebuild the cowcod population to sustainable levels, even with limited fishing.
Raising awareness of these issues is one reason these fish are being studied at Hubbs-SeaWorld and displayed at the Aquarium. In an ambitious project sponsored by Chevron Corporation, Hubbs-SeaWorld is trying to rear cowcod and other vulnerable species, and to release their captive-bred offspring to replenish wild populations. Our three cowcod have been at the research institute for several years, and were transferred to the Aquarium in hopes that they will reproduce in our large, cold-water exhibit.
“Cowcod have never been on public display anywhere,” says Aquarium Senior Collector Joe Welsh. “We’re lucky that Hubbs-SeaWorld chose us.”
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