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The fate of the skate and the future of the ocean

Posted on 5 July 2012

The Common skate might seem like an unlikely conservation cause. Its close-set eyes and pointed nose lend it a sinister look, while its flattened, spreading wings seem almost devilish.

The Common skate might seem like an unlikely conservation cause. Its close-set eyes and pointed nose lend it a sinister look, while its flattened, spreading wings seem almost devilish. Then there is the name: ‘common’ implies ‘nothing to worry about’. But this fish has suffered greatly from the spread of industrial fishing in European seas, its abundance diminished a thousand times over since pre-fishing days. Common skate now cling to existence in a few places where rugged terrain or fierce currents have kept out bottom trawlers.

If we turn back the leaves of time to the early 19th century, we find a very different world in which Common skate rule the ocean floor. They are not just common but abundant, in places gathering in groups of tens or hundreds strong. Many are of prodigious size, with wingspans two to three metres across. When measured from nose to the tip of their long tails, some giants might top four metres. Common skate were one of the fishes referred to by Olaus Magnus the Goth in his account of northern seas when he said, “It is no trivial danger that looms over these fishermen as they pull with their hooks at fish of gigantic strength and bulk, twelve feet long, such as halibut, skate and other winged fish.” Photographs from the 19th century show catches of skate so large several strong men were required to life them.

The realm these skates inhabited was very different from that of today. Where now we find vast expanses of mobile gravel, sand and mud, the seabed of old was crusted with life. Seen from a skate’s perspective, the delicate fronds of hydroids and waving arms of brittle stars would have seemed like fields of long grass swaying in the wind. Every pebble and rock sustained its own little microcosm of red seaweed, orange and yellow sponge, or lucent goblets of sea squirts. How different from the comparative sterility of today’s restless sands.

The skates’ kingdom came under attack as bottom trawling spread. The trawlers dragged their nets across the seabed gathering up all before them. By the mid 19th century, there was a noticeable decline. In the 1860s, one fisherman from the tiny Yorkshire port of Staithes recalled how the town would send a couple of boatloads of skate to market every day a decade before, but there was hardly a skate to be seen now.

Since those long-ago days, fishing has continued its relentless transformation of the undersea world. Many other creatures have joined the dethroned skates. Their habitats changed beyond recognition, they now live in obscurity at the margins of existence. Today it is not just fishing that is changing their world. As the planetary dominion of humanity has surged onward, our influence has spread to the limits of the oceans and into their darkest depths. We have long fretted over a growing list of pollutants in the sea: oil, toxic chemicals, agricultural fertilisers, sewage, plastics, even noise, each is exerting its insidious stresses on marine life. Added to these alterations, the oceans are heating up as greenhouse gas emissions build. They have spared us much worse warming than we have today by absorbing roughly a third of our carbon dioxide emissions to date. But this may be a poor bargain in the long run since dissolved carbon dioxide has increased ocean acidity 30% since pre-industrial times. That rise is making life harder for all the shellfish, corals and plankton that secrete chalky skeletons. A rise in acidity of 150% is expected by century’s end if we fail to curtail emissions. Such a change could blow a huge hole in oceanic productivity, not to mention spelling the end for coral reefs as we know and love them.

It will take time to control the major drivers of change in the sea: the growth in human population, our insatiable appetite for worldly goods and the carbon-emitting economy upon which it all rests. Conditions in the sea will get worse for life, perhaps much worse, before they get better. We must prepare.

This is why saving the Common skate is so important. If we want to give the oceans the resilience to weather these added stresses, we have to reinvent ocean management. Instead of knocking populations down to their bare minimum and flattening complex habitats in the process, we must manage to maintain vibrant ecosystems in which life abounds. That means creating many, many more marine protected areas that are beyond the reach of fishing. We need to surpass the target set by the UN Convention on Biological Diversity of 10% of the sea protected by 2020 and head on toward 30%. We need to cut fishing by half in much of the rest of the world and phase out or greatly restrict the most destructive methods like trawls and dredges. We should completely abandon fishing in the deep sea (> 800m down); life there is too fragile to sustain fishing. And we should redouble efforts to reduce pollution of all varieties.

In such a world, animals like the Common skate would once again thrive. At its heart, saving the skate isn’t about extinction prevention or increasing seafood supplies. It is about protecting our own future. The oceans take up over 95% of the living space on this planet. They play an overwhelming role in maintaining the habitability of our world. We ignore this simple fact at our peril.