A silvery fish which represents an important link in the Arctic food chain has been successfully grown in lab conditions, hence giving scientists a chance to learn more about the key but vulnerable species.
Studying Arctic cods is quite a task due to the fact that they spend a lot of time under sea ice. For breeding them in conditions of laboratory, scientists collected young cod off the north coast of Alaska and flew them to a lab in Oregon.
The fish are vulnerable when water temperatures warm.
At 32 degrees, Arctic cod have a relatively high growth rate, Laurel said. At 35.5 degrees, Arctic cod are “rapidly outpaced” by other Bering Sea species such as walleye pollock and Pacific cod.
Arctic cod eggs also are vulnerable. A temperature of 41 degrees is lethal, he said.
Scientists intend to know how Arctic cod will respond to increasing temperatures of ocean. NOAA scientists predict the rise in sea surface temperature in the Chukchi at 1.8 degrees every ten years.
“The concern is, if the Arctic cod are not there, what happens to the ecosystem, or what happens if they’re replaced by something?” Laurel said.
By far, Arctic cod has the most fat content of any cod species and serve as a key middle link in a relatively short Arctic food chain, he said. The cod eats plankton and is hunted by ringed seals, which is the main diet of polar bears.
They also are an important food source for seabirds, narwhals and beluga whales.
An Arctic cod can grow up to 12 inches in a span of four to five years. They can be seen at all depths, Laurel said, and appear to seek out pockets of the coolest water that’s still liquid.
“They’re pretty widely spread, and they seem to be tuned in to their preferred temperature,” he said.
There is no North American commercial fishery for Arctic cod.
Scientists collected young fish from the Beaufort Sea for three summers starting in 2012. They loaded the cod into small, breathable bags and flew them to the Alaska Fisheries Science Center laboratory in Newport, Oregon. The lab is set up to chill natural seawater from the Pacific.
Scientists collected young fish from the Beaufort Sea for three summers starting in the year of 2012.
Initial studies focused on growth of juvenile Arctic cod in response to temperature and food availability.
Scientists followed usual protocols for breeding cold-water fish but were unsuccessful the first year, Laurel said.
“They’re really, really temperature-sensitive as you might imagine, but even more so than we thought,” he said.
They tried again and successfully hatched Arctic cod in colder temperatures. A second set of studies has targeted the effects of temperature and food availability on eggs and larva.
Comparison studies will be carried out next on walleye pollock, Pacific cod and saffron cod for determining which one is most likely to thrive in varying temperatures.