As Captain Paul Watson once said, “If the oceans die, we all die,” and if that’s true, then humans are doing a darn good job at plotting their own demise. Around half of the planet’s oxygen supply comes from the sea, which also plays a huge role in regulating global temperatures, weather patterns, and climate.
Its inhabitants, too, are among our greatest allies in the fight against climate change because their excrements absorb carbon dioxide and help balance ocean acidity. And yet, here we are treating our planet’s oceans like inexhaustible resources and depleting their waters of fish and other marine life at a ridiculous rate that ventures into the area of billions per year. Unless we stop, and soon, scientists predict that every species of wild-caught seafood will collapse by the year 2048.
Large-scale commercial fishing operations are to blame, and for many decades, conservation scientists have been pushing for more sustainable fishing methods across the globe. But is that even good enough anymore, given the general consensus of what those methods entail and the level of damage that we’ve already inflicted upon these seas?
In the book Marine Conservation Biology: The Science of Maintaining the Sea’s Biodiversity, Marine biologist and fisheries scientist Ray Hilborn explains that there are three primary ways to define sustainable fishery: (1) long-term constant yield, (2) preserving intergenerational equity, and (3) maintaining a biological, social and economic system. But there are some shortfalls of each of those definitions and here we’ll dive into why truly sustainable fisheries may not be remotely achievable in today’s world.
The Problem With Long-Term Constant Yield
“Long-term constant yield” supports the idea that fish will continue to reproduce and replenish their numbers when fishing is allowed only up to the maximum sustainable yield – that is, the largest possible harvest in alignment with the fishes’ reproduction rates so that mostly “surplus” fish are removed. The theory assumes that nature, when left undisturbed, establishes a steady state of existence and that this calculated rate of extraction allows the local fish populations to naturally adjust to new steady states so that equal numbers of fish can continue to be harvested season after season.
What this fails to recognize is that the only real constant in nature is, in fact, change, and that fish populations naturally fluctuate, so that what may have been a sustainable harvest in one year could quickly deplete local fish stocks in another. It also doesn’t take into account the age, size, or reproductive status of the fish that are caught, all of which play a key role in population replenishment and growth rates.
In addition, this approach looks at each individual fish species in isolation without paying proper tribute to the ecological linkages that exist between various marine species and their habitats. As such, it can support devastating commercial fishing practices, such as bottom trawling, which involves dragging huge, heavy nets along the ocean floor. These nets destroy deep-sea coral, sponges, and fauna while scooping up everything in their paths that isn’t attached to the seafloor. As Les Watling, a professor in biology and oceanography, explains, “virtually all of the world’s continental shelves, and increasingly on continental slopes, ridges, and seamounts” have been repeatedly dredged by these bottom trawlers, and deep-water communities have been radically altered to include far less diversity as a result.
Bottom trawling also results in a despicable amount of by-catch, to the tune of 7.3 million tons of marine life – including non-target fish species, sea turtles, dolphins, whales, sharks, albatrosses and other seabirds – caught as unintentional victims each year. In the United States alone, by-catch is estimated to weigh in between 17-22 percent of total catch, or two billion pounds every year. And worldwide, this practice is greatly contributing to the deaths of endangered species and dwindling numbers of important predatory species, which is causing a trophic…
