Unusually high water and air temperatures off the US West Coast as climate patterns shift mean bad news for sea lions, sea birds and the fishing industry.
LONDON, 22 March, 2015 – California, currently in the grip of a devastating drought and facing an increasingly parched future, has just been dealt another blow. Not only is the land less productive, but the state’s fisheries could also be about to feel the heat.
A new report warns that the climate seems to be shifting to warmer, less productive conditions. And that’s bad news for seabirds, salmon, sea lions − and sea fishermen.
At play, according to the National Atmospheric and Oceanic Administration Regional Fisheries Science Centres, is the effect of unusually high coastal water and air temperatures over the last year, and changes in the California Current that washes the West Coast of the US.
The consequence is a dip in what ecologists call “primary productivity” – in this case, the tiny copepods and other microscopic creatures that are the first level of the food chain.
Higher death rates
This means less for salmon and other marine species to eat, and higher death rates among sea lion pups in Southern California, and among sea birds on the Washington and Oregon coasts.
Commercial fisheries so far have been good, but California’s fishermen have begun to specialise, and could see catches fluctuate and revenues fall as their target species start to feel the effects.
Toby Garfield, director of environmental research atthe NOAA Southwest Fisheries Science Centre, says: “We are seeing unprecedented changes in the environment.”
John Stein, who directs the Northwest Fisheries Science Centre, adds: “We’re seeing some major environmental shifts taking place that could affect the ecosystem for years to come. We need to understand and consider their implications across the ecosystem, which includes communities and people.”
The changes are partly cyclic: the sea surface temperatures are at record heights, and these have combined with shifts in meteorological cycles, such as the Pacific Decadal Oscillation, and the North Pacific Gyre Oscillation.
“We’re seeing some major environmental shifts taking place that could affect the ecosystem for years to come”
The consequence is that the normal upwelling of deep cold waters has weakened in recent years, and so has the supply of nourishing copepods. Sea lion pups and a species of seabird called Cassin’s auklet have been found dying and emaciated, which suggests problems with the food supply.
Since 2014, blobs of warm water have been observed in the Gulf of Alaska and all the way down the coast, and these conditions tend to be accompanied by lower productivity.
In the past, this has meant poorer catches of salmon, anchovy and squid, although better catches of sardines, tuna and marlin. But lately, both anchovy and sardine hauls have been at lower levels.
Salmon in particular face double jeopardy in California. Not only is the food supply in the sea threatened, but low snowfalls and greater drought mean that the rivers up which the salmon jump to spawn are less hospitable.
The California drought, the worst in the state’s history, has been tentatively linked to global warming. The changes in the California Current may be a coincidence of natural cycles.
Reports such as these are intended to alert communities to changing conditions. They are not so much prescriptions for doom as practical warnings of potential problems ahead. But the tone may well have become more urgent.
“We are in some ways entering a situation we haven’t seen before,” says Cisco Werner, who directs the Southwest Fisheries Science Centre at La Jolla. “That makes it all the more important to look at how these conditions affect the entire ecosystem.” – Climate News Network