Sharks in the Arctic: surviving climate change

Sharks are one of the oldest survivors on earth, with fossilized records dating back as much as 400 million years ago.

Many scientists are concerned that with climate change, many of the earth’s species will not be able to adapt and become extinct, including sharks.

However, a new study by researchers in the US show that some shark species likely will be able to adapt.  This is based on analysis of ancient shark teeth found in the western Arctic.

One of the effects of climate change will be reduced salinity in the oceans due to melting of ice and the release of substantial freshwater as ice sheets melt, reducing salt water to brackish water.

The Arctic region is of increasing interest to scientists in all fields as it is warming at roughly twice the rate of more southerly regions of the globe.

Some 40 to 50 million years ago, the Arctic area was a temperate zone and covered with forest.  But while a substantial amount has been learned about the terrestrial conditions through fossils, marine fossils have been much harder to come by.

While studying the fossilized shark teeth of 40-50 million years ago, the American researchers found that these “sand tiger sharks” lived in such brackish oceans.

Sora Kim is the lead author of the June 30 paper in the online journal- Geology.

She is reported in the University of Chicago News saying that when she tested the teeth fossils, “The numbers I got back were really weird,” Kim said. “They looked like fresh water.”

The sand tiger sharks of today prefer warm waters with high salinity, so the study shows that some sharks may be able to adapt to waters with much lower salinity that are expected in the future

The study also gives support to the theory that the Arctic Ocean was at one time cut off from the worlds other oceans.

There are about 20 shark species currently present in Canadian waters, although only a couple are known in the Arctic. One is the deep water and rarely sighted Greenland shark.