Today’s oceans remain vastly more wild places than land. You can take a couple turns off of Hollywood Boulevard, don snorkel gear, and swim among three-hundred-pound giant sea bass and see families of grey whales – all of this within sight of the skyscrapers of Los Angeles. Swimming with whale sharks in Yucatan, diving the cathedral kelp forests of Monterey, watching thousands of sea turtles lumber up on Costa Rican beaches – by and large wildlife in the oceans is in much better shape today than wildlife on land. Yet, at the same time the majority of large tunas and sharks are gone, cod stocks have collapsed, and whales are just now climbing back from near extinction. A new paper in this week’s journal Science explores these seemingly contradictory views of the ocean as both wild and heavily impacted. Authors of this report find that the same patterns that led to the collapse of wildlife populations on land are now occurring in the sea, but ocean exploitation remains centuries or even millennia behind in the oceans. But the study shows that industrial use of the oceans is increasing quickly. The next one hundred years, they caution, promises to present major challenges to the health of marine wildlife.
We officially recognize about 500 human-caused animal extinctions on land in the last 500 years, so many that the current terrestrial extinction rate is one of the biggest mass extinctions recorded since our planet’s birth. But this new study points out there have only been about 15 animal extinctions caused by humans in ocean habitats. Contractions in the range of wildlife species have also been less severe in the oceans. Asian tigers, for example, have lost approximately 93% of their historic range and face eminent extinction, but tiger sharks still range across the world’s oceans.
Authors of the report suggest, however, that what is masked in these comparisons are major shifts in the ways that we are now using the oceans and what that means for the future of marine wildlife. As lead author Douglas McCauley, an ecologist at the University of California, Santa Barbara, points out “Increasing industrial use of the oceans and the globalization of ocean exploitation threaten to damage the health of marine wildlife populations making the situation in the oceans more similar to the degraded state of life on land.” The hunting of sharks, the wolves of the ocean, has increased dramatically because their fins are used in expensive soup. As a result, 100 million sharks a year are now killed across the globe. And even if we haven’t driven any shark species totally extinct, we have reduced their numbers to such low levels that, in many cases, they might as well be extinct.
McCauley explains: “Imagine if the global population of garbage collectors crashed to only 100 individuals. It would really be no comfort to us, as we waded through streets full of trash, to know that somewhere in the world garbage collectors still existed – because the critically important services that they provide would have gone functionally extinct. It is the same for marine animals. They do things that are important to humans and are important to their own ecosystems.”
Have ocean extinctions been minimized by uncertainty? “It’s hard to detect when a marine species goes extinct.” says McCauley. “It took science 73 years to find the Titanic after it sank – and that was a 50 thousand ton ship. You can only imagine how hard it is to be certain a rare fish or shrimp has been driven globally extinct.”
The new paper compares the march of the Industrial Revolution on land and in the oceans. During the 1800’s vast tracts of farmland and factories beat back forests, drove many terrestrial species extinct, and sucked up resources that were mined and drilled out of the ground. But at the same time in the ocean, fishing still used sailing ships and was clustered in a small sliver of nearshore ocean. A lot has changed in the last 200 years. Our tackle box has industrialized. Now we fish with helicopters, satellite guided super trawlers, robot fish killers, and long lines that can stretch from New York to Philadelphia. McCauley says, “All signs indicate that we may be initiating a Marine Industrial Revolution. We are setting ourselves up in the oceans to replay the process of wildlife Armageddon that we engineered on land.”
Co-author Steve Palumbi at Stanford University lists the emerging threats to the oceans: “There are factory farms in the sea, and cattle-ranch style feed lots for tuna. Shrimp farms are eating up mangroves with the same appetite with which terrestrial farming consumed native prairies and forest. Stakes for seafloor mining claims are being pursued with gold rush-like fervor. 300-ton ocean mining machines and 750 foot fishing boats are now rolling off the assembly line to do this work.”
On top of all of this, climate change is also severely degrading remaining habitat for marine wildlife. If anything, these researchers conclude that marine animals are even more at risk to climate change than terrestrial fauna.
The authors of this study highlight three major areas where action will be needed to slow losses of marine wildlife.
First, we can’t let ourselves be blindsided by the Marine Industrial Revolution. McCauley soberly reflects that, “Some of this marine development will be necessary in an overcrowded world” but we need to proactively monitor and plan it out carefully.
Second, we need to set aside more and larger places in the ocean without industrial development or fishing and design these protected areas specifically with climate change in mind. Co-author Robert Warner (UC Santa Barbara) cautions, “Reserves alone, however, are not enough. We need creative and effective policy to manage damage inflicted upon ocean wildlife in the vast spaces between marine protected areas.”
Third, we need to slow rates of climate change to avoid turning the oceans into a place that is increasingly hostile to many types of marine wildlife. “Anyone that has ever kept a fish tank knows that that if you crank up your aquarium heater and dump acid into the water – your fish are in trouble,” reminds co-author Malin Pinsky an ecologist at Rutgers University. “This is what climate change is doing now to the oceans.”
The message in this report is one of tenuous optimism: things are bad in the oceans but not as bad as they have been on land. And this difference is significant. “Because there have been so many fewer extinctions in the oceans,” says McCauley, “We still have the raw ingredients we need for recovery. There is hope for sharks and tunas, but there is not that same hope for the dodos, mammoths, moas, passenger pigeons, and hundreds of other terrestrial wildlife species that have crossed over the extinction threshold.”
Nature doesn’t always give us second chances to behave more responsibly, but as Warner remarks “The sustained health of the oceans presents a unique opportunity – we can blunder forward and make the same mistakes in the sea that we made on land, or we can collectively chart a different and better future for our oceans.”
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