For millions of years, fish species in the
Pacific and Atlantic oceans have stuck resolutely to where they
belong, kept from venturing between oceans by the cold water of the
But new research suggests a warming Arctic could
soon see fish putting aside their differences and bridging this
chilly divide. And this could have implications for native species
and commercial fisheries, the researchers say.
A natural barrier
For most of the last 2.6 million years, the cold
temperatures and low nutrient levels of the Arctic have deterred
fish species from crossing between the Pacific and Atlantic
The cold conditions mean at present only 135 of
more than 800 known fish species are found in latitudes north of
where the UK sits, in either the Atlantic or Pacific
But a new study, published in Nature
Climate Change, finds that with Arctic
temperatures increasing almost
twice as fast as the global average, this
natural barrier is set to weaken.
Melting sea ice will mean ocean currents can
carry warmer water and nutrients into Arctic water, taking fish
further north and potentially allowing them to mix
'Rapid explosion in fish
The researchers use computer models to forecast future ocean
conditions such as surface temperatures, salinity, and currents,
and project how the distribution of different fish species could
respond to climate change.
They analysed how suitable the Arctic seas would
be for over 500 fish species during this century if greenhouse gas
emissions continue at current rates.
The maps below show that many species will gradually
progress north, eventually reaching the northern coasts of Canada
and Russia, where fish from each ocean can mix. Their modelling
shows that by 2100, 44 species could enter the Atlantic from the
Pacific, with 41 species potentially crossing back the other
Projected number of fish species in high latitudes
under business-as-usual greenhouse gas emissions. Results shown for
2015, 2050 and 2100. The dark blue show areas with the most species
present. Source: Wisz et al. (2015).