There is a major problem in our oceans. Once seemingly inexhaustible in number, the fish in our seas are somehow vanishing. It sounds crazy, but it’s true. Once giant schools of mackerel and sardine, shoals of tuna, magnificent sailfish and marlin, even sharks; all of these and more are disappearing fast. What could have such a major impact on an environment that covers over 75% of the surface of the Earth? The simple answer? Us. Fish are disappearing and they’re disappearing right into our mouths.

I recently watched “The End of the Line” an award winning documentary about the overfishing crisis. In it, the opposing claims of two respected scientists were debated. The first, Dr. Boris Worm of Dalhousie University conducted a study with results that indicate a 90% decline in populations of virtually all commonly targeted fish. That’s species like tuna, swordfish, marlin, cod, all the fish you see in the supermarket, all of them with populations barely 10% of what they were just a hundred or so years ago. A conflicting view was proposed by Professor Ray Wilborn of the University of Washington who took exception to Worm’s methods and results. “Totally wrong,” he rebutted. “There’s just no question, that’s totally wrong.”

If you’re like me this all sounds pretty familiar. Over the last decade or two, we’ve seen countless debates play out between climate scientists and climate change deniers. Before that, it was between lung cancer specialists and the scientists employed by tobacco companies. It seems as though any scientific whistle-blowing has its contingent of ardent opposition. I assumed that once Prof. Wilborn finished picking apart the work of Dr. Worm he’d move on to explain how fish stocks remain healthy and abundant. I was wrong. His argument was simply that a more accurate measure of global decline would be 70%.

I was stunned. When it comes to fish, the argument isn’t about whether or not there’s a problem. The debate among academics is merely about exactly how catastrophic the problem is. As it turns out, global overfishing may be the most pressing conservation issue facing us today. It is for this reason that Safari West recently became a Conservation Partner of the Monterey Bay Aquarium Seafood Watch. As a facility specializing in terrestrial mammals and birds, it might seem like Seafood Watch is a bit outside our wheelhouse. The truth, however, is that the situation faced by species like bluefin tuna is eerily similar to that faced by our own white rhinos.

Like rhinos, bluefins have been hunted by humans for centuries. Also like rhinos, advances in technology, staggering increases in human population and demand, and economic pressures valuing short-term gain over long-term sustainability has lead to nearly insurmountable devastation within the population. The northern white rhino, in particular, serves as a poignant example as there are now only three left in existence.

The plight of fish in our seas has many variables—climate change, ocean acidification, pollution—but Seafood Watch is specifically concerned with overfishing. How on earth could human beings in boats have overfished something as massive as the ocean?

First of all, bear in mind that for most of our history the seas have been like the vending machines that stand in many of our offices and break rooms. We usually can’t see into the office Coke machine, but we take for granted that if we drop in some change, we’ll be rewarded with a refreshing beverage. The sea has always been the same. We’ve generally been unable to tell how many fish are swimming off our shores but we could safely assume that if we dropped in a hook, we’d eventually pull out a fish.

For much of human history that technique has served us beautifully. In pre-industrial times the ocean kept us supplied with nutrition and our take was insignificant enough to not overly disrupt the system. Even as we took to the seas in boats designed for fishing, our impact remained relatively unchanged. We’d drop in hooks and pull out fish, but at a rate that went seemingly unnoticed by the oceans at large. It wasn’t until fishing became a large-scale commercial venture that our efforts began to have a significant impact.

A good example of this is Georges Bank, one of the most famous fisheries in the world. Situated off the northeast coast of the United States, the bank used to teem with cod and halibut. It was such a profoundly fertile source of fish that in the 16th century, over half the fish consumed in Europe originated from Georges Bank. New England’s history as a commercial fishing center is based on its proximity to the bounty of Georges Bank. For hundreds of years, the Bank was fished by ships dropping hooks. Even with this simple technique, the scale of the of Georges Bank catch was such that by 1850 halibut populations were nearing collapse.

But the worst was yet to come as technology improved and new gear revolutionized the fishing industry. Single hooks developed into long lines, which are literally miles-long lines of filament dangling thousands of baited hooks. With the advent of steam power, drag nets came into play. Eventually, we saw the invention of the bottom-trawler; a tremendous net dragged behind a boat and scraping against the sea floor. Bottom-trawlers made it to Georges Bank by the 1920’s and were able to catch in an hour or two what the old hand-reel fishermen could catch in a month. The impact was devastating.

Bottom-trawlers—with their unfortunate side effect of demolishing the sea floor—were the worst offenders, but other commercial fishing devices were devastating as well. Gill nets and longlines are exponentially more efficient at bringing in fish that single hooks but at the cost of being completely nondiscriminatory. A ship trawling for cod will inevitably haul aboard a lot more than the fish of choice including other fish species, sea birds, dolphins, sea turtles, and even sharks and rays. All this extra stuff is called “bycatch” and generally speaking, it goes right over the side and is usually dead or dying when it happens.

Let’s compare this style of fishing to some of our terrestrial hunting techniques. A single human fishing with a single baited hook or harpoon is roughly analogous to a single human hunting with a bow or spear. The take is minimal and relatively non-disruptive.

As fishing gear advanced from hooks and lines to shrimp boats and trawling nets, so too did our bows and arrows give way to high powered rifles. When it comes to the mass-capture capabilities of fishing nets, however, there are few terrestrial analogs. Possibly the closest comparison we can make between hunting and our current fishing capabilities is the method of driving stampeding animals off cliffs once employed to hunt herds of American bison. By panicking an entire herd and driving them toward a precipice, hunters were able to save tremendous amounts of time and effort and kill hundreds of bison in one go. The trade-off to this bounty was an incredible waste since the method usually killed more animals than could be effectively used. The simultaneous annihilation of entire herds—young and old alike—had major ramifications for the long-term stability of the bison population as well.

The American bison is now the national mammal of the United States and yet relatively few Americans have ever seen one because their range is so drastically reduced. Marked declines like that of the bison have been instructive to us on land and their complete extinction was avoided in part because we were occupying the same space and could see the decline in real time. The opposite is true of our aquatic prey species. We are generally much less aware of what is happening beneath the surface of the sea. Fishing records have long suggested a decline in returns as well as a general shrinking in the size of specimens caught, but this data has gone largely unrecognized and ignored. As a species, we’ve simply been unable to imagine that there won’t always be plenty of fish in the sea.

Here’s the other piece of it; just like bison, tuna, marlin, and other large fish species aren’t born large. They’re born tiny and vulnerable and during this stage in their lives, they need a place to hide. Kelp stands, beds of seagrass, coral reefs; all of these seafloor environments act as nurseries for fish fry that may one day grow to become our sashimi. When a bottom-trawler scrapes across them, these nursery habitats are heavily damaged or completely destroyed. I the most fecund of commercial fisheries, the same areas can be trawled over and over again within a single year, leaving the seafloor a sterilized wasteland.

Another misconception about how sea life works is a widespread belief that fish breed readily and often. We ate nearly all of the orange roughy before someone discovered that it takes them two decades to reach sexual maturity. We gobbled them like Thanksgiving dinner without ever realizing how long it would be before the next generation came along. In another spectacular blunder, we developed an incredibly efficient method of catching salmon as they struggled upstream by the thousands. They practically threw themselves into our nets and it wasn’t until the population completely collapsed that we realized we were catching them just before they laid the eggs that would’ve replaced them. So our practices have been ignorantly short-sighted for a long time, and now the oceans are emptying.

This is not an issue of luxury. It’s not just that we won’t be able to enjoy sushi or blackened halibut as much. Over one billion humans (that’s a full seventh of the global population) depend on fish to survive. Beyond strict necessity, fish make up over 20% of the animal protein intake for half the humans on the planet. Currently, as a species, we’re consuming at least 95 million tons of wild-caught fish each year (plus an addition 75-80 million tons of farmed fish). That’s approximately 375-Billion pounds of fish! Meanwhile the bycatch—the dead and dying bystander organisms we catch by accident—we throw about 7-million tons of them back into the sea every year. Calling that amount of waste colossal doesn’t even come close.

Luckily there’s quite a lot that can be done, and from what we’ve seen the ocean appears to be both strikingly resilient and quick to rebound when given a chance. The best first step, which it seems most every scientist agrees on, is a massive scaling up of our establishment of marine protected areas (MPAs). These are essentially our national parks but in the ocean. Protected areas free of fishing are as effective than preserves on land. Without us netting them, many fish populations recover quickly.

Unlike our national parks which are usually bordered by urban development, MPAs are usually bordered by nothing but open ocean. This means that as fish populations expand, they naturally spill out of protected reserves. Many MPA advocates describe them like banks. The reserve is the initial investment and the overflow fish are the compounding interest. This methodology already has proven results. Blue Ventures (please link to www.blueventures.org), has already recorded tremendous successes with this system in Madagascar.

Over a decade ago, Blue Ventures teamed up with the people of a fishing village in southern Madagascar to close off a portion of the offshore reef in which the locals fished for octopus. After a relatively short period of time, the area was reopened with staggering results. As news of this techniques spread, other villages mimicked the technique. Eventually, this leads to the first locally managed marine area (LMMA). Today there are 64 LMMAs in Madagascar which combine to protect a full 11% of the Madagascar sea floor.

In 2010, over 200 nations gathered in Japan and set a goal of protecting 10% of the entire ocean by 2020. This is an important first step toward the 30% protection determined by scientists to be a requirement for comprehensive, ocean-wide sustainability. Progress is being made but it is unnervingly slow. Numbers vary depending on the source but we’re currently only at 3-4% protection. There’s a lot of work left to be done.

There are a number of things us average citizens can do to help with this situation. Support the creation of more MPAs and pressure your leaders to that end. Another thing you can do that’s more immediate and ongoing is to join us on the Seafood Watch. The Monterey Bay Aquarium has built a useful downloadable app that highlights seafood that’s caught sustainably and that which clearly isn’t. It’s a simple to use feature on any phone and it can help you avoid buying fish that are endangered or caught in a destructive way. Pausing to check if the salmon at your store is a good buy or not may add a minute or two to your trip, but this truly is the most impactful thing we can do to help. Ever heard of dolphin safe tuna? Dolphins had been dying in droves as a form of bycatch and public pressure on retailers and suppliers from consumers like us changed the industry. Regulations, MPAs, and policing are important, but consumer demand shapes the market. Help us and help the seas. Pay attention to what you buy and let your grocers and restaurants know that you’re paying attention. If we each do that, we change the tide.