Cold water fisheries moving north
The Gulf of Maine is warming faster than most other patches of sea on Earth, and the process is revealing some of the likely changes to fishery patterns as species such as cod and herring follow the colder water northwards. New species are moving in, such as black sea bass and blue crabs to replace them as the environment changes around them.
Both the eastern USA and Canada have important fishing industries focussed on these species, Maine lobster being particularly famed. Scientists are taking these events as a warning of what might happen as warming takes a stronger hold elsewhere. The seas are also rising fast since the water is less dense and expands as it warms. The pace of warming has been speeding up fast over the last three decades, now being about 10 times faster than back in 1983.
Scientists are unsure as to why this area is warming faster than the rest of the world’s oceans, though changes to the Gulf Stream may be a cause. The changes are likely to be far reaching, as the fragile system of currents that mixes waters and spreads nutrients changes patterns over the coming decades.
Ecological effects observed so far include larger lobster catches (though they may move north too if the warming trend continues as expected), and starving puffin colonies as the herring they eat move away. New fisheries are developing and being licensed to replace the old, but the threat to a billion dollar industry is growing, with no clear certainty of the turn events will take, since many ecological changes act in a non linear pattern. Something that was stable, sometimes for aeons, suddenly changes to a new state when it reaches a tipping point, and the old one might never return.
A similar process struck the cod fishing industry off the Grand Banks. When the fishery collapsed and was protected, hopes were high that cod numbers might rise again, but they have stayed at low levels, since other organisms have effectively replaced them in their old ecosystem. Many such events are expected to cascade through the world’s ecosystems over the coming decades.
Image credit: Laszlo Ilyes