Wednesday, May 6, 2015

Studies Look at Climate Impact on Arctic Cod, Northern Rock Sole

New research studies on Arctic cod and northern rock sole are offering federal regulators insight into how climate change may affect some Arctic marine species.

NOAA Fisheries scientists say that hatching and growing Arctic cod in captivity is shedding light on the influence of temperature and competition from more southern cod species on Arctic cod survival.

A second study is providing information about the ability of northern rock sole to withstand changes due to lower pH levels in the ocean, or an increasingly more acidic ocean.

Growing Arctic cod in the Alaska Fisheries Science Center laboratory is helping scientists understand how these “bellwether” fish in the arctic marine ecosystem may fare in a warming ocean and climate change. It also allows for new studies in a laboratory setting of Arctic cod, who are a key component of the Arctic marine ecosystem, providing an important food source for seabirds, ringed seals, narwhals, belugas and other fish.

The new research is also showing that Arctic cod may be the most vulnerable to warming ocean waters.

In general, NOAA scientists said, Arctic marine species require colder water to survive than populations further south, but determining just how cold is tricky and requires specialized laboratory space to simulate the Arctic environment.

Young Arctic cod were collected during the summer months of 2012, 2013 and 2014 in the Beaufort Sea, and live-shipped to the Alaska Fisheries Science Center laboratory in Newport, Oregon, where facilities allow for simulation of Arctic environments to grow fish by mass chilling natural seawater pumped from the Pacific Ocean.

The first series of experiments focused on growth of juvenile Arctic cod in response to temperature and food availability, while the second series of experiments, which is still ongoing, focuses on the same factors during the egg and larval stages. At the same time tests were being conducted on Arctic cod, comparative studies were done on walleye pollock, Pacific cod and saffron cod.

In waters bordering northern Alaska, coastal surface temperatures can already exceed 14 degrees Celsius in the summer, and NOAA predicts temperatures in these regions will increase by one half degree Celsius per decade.

If these northern waters get warmer, beyond the range that Arctic cod eggs and juvenile fish can compete and survive, we could see cascading effects in the marine food chain, according to NOAA. Top predators may be forced to feed on other fish that are lower in fat content, like saffron cod, Pacific cod or pollock. Loss of high quality prey like Arctic cod may make it especially difficult for ringed seals already dealing with the loss of nursery habitat with shrinking sea ice, they said.

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