At least when it comes to the macrofauna. Every year, Boston builds a fish weir:

A fishweir is basically a large fence that is used to trap fish, which are then caught (usually scooped out of the water)…

During the excavation and construction of Back Bay, a fishweir, thought to be about 3,700-5,200 years old, was discovered at what would today be Clarendon and Boylston streets–which then would have been a shallow marine intertidal zone. I bring up fishweirs because it’s important to realize what makes the large investment in building them useful: lots and lots of fish. You’re basically trapping fish against a fence and either spearing them or grabbing them.

For anyone who is familiar with New England salt marshes and seashores, this strategy seems ridiculous. When is the last time, in those habitats, you have seen enough fish (and minnow-sized fish don’t count) to justify this strategy? What many people don’t realize is that these habitats, until a couple of centuries ago were teeming with wildlife; in terms of productivity, these habitats are marine equivalent of Iowa farm soil. In Maine, lobster, in shallow habitats, were so plentiful, they were used to fertilize soil–and feeding lobster to servants, slaves or orphans in the 1600s was illegal (it was considered feeding people cockroaches). Ditto the fish.

That’s right, intertidal marine life a few centuries ago was so plentiful, you could basically scoop it out of the water with baskets.

Today, in deeper parts of the ocean, the effects of trawling has been awful:

Clear-cutting doesn’t really do trawling justice. Trawling is more like hunting for deer by lining up bulldozers and flamerthrowers on one side of a forest, and then smashing through the forest in order to flush deer out the other side. It is that destructive.

I realize food is a very personal thing, but I would rather have factory farming any day than the annihilation of the oceans. But unlike tropical rainforests, this occurs far from sight, so we don’t even realize what we’ve lost.

Which brings us to this article about the depopulation of the oceans (boldface mine):

It is difficult for us to imagine the oceans before humans transformed them, and how they teemed with life. In Anna Clark’s history of fishing in Australia, The Catch, she describes the “fishing Eden” that greeted early Europeans: “the sea floor off the west coast of Tasmania carpeted red with crayfish; fish so thick that nets could be set at any time of the day; an ‘astonishing magnitude’ of Australian salmon; and mountains of mullet that migrated annually up the east coast”. This accords with James Cook’s and Joseph Banks’ descriptions of the density of marine life they found in Botany Bay, where the crew speared stingrays weighing as much as 152 kilograms and reported catching “about 300 pounds weight of fish” in just “3 or 4 hauls” of the net. In Tasmania, whales congregated in the Derwent River in such numbers they were a hazard to shipping, while on the other side of the globe, off the coast of Cornwall, a shoal of sardines was spotted in 1836 that stretched for well over 100 kilometres. Today there are approximately 90,000 nesting female green turtles left worldwide, but studies suggest that when Europeans arrived in the Americas there were more than 50 million in the Caribbean alone. Reports describe them filling the ocean from horizon to horizon as they grazed upon the seagrass that surrounded the Cayman Islands; as late as the 18th century, ships en route to the Caymans could navigate through darkness by the sound of the turtles’ shells knocking together as they fed. Further back again the Roman writer Oppian describes a Mediterranean so full of fish it was possible to catch tuna by simply dropping a log with a spike on it into the water.

More often than not, these descriptions of astonishing abundance were merely the prelude to their destruction. Despite Indigenous Australians having fished along coastlines for tens of thousands of years without adverse effect, Australian fisheries began to collapse within a few generations of European colonisation. The bays around Sydney were denuded of oysters by the 1860s; by 1880 Sydney Harbour, once brimming with fish, was described as “scarcely … a source of supply at all”; and by the 1920s stocks of Sydney’s tiger flathead had collapsed due to the introduction of ocean trawling. The decline in numbers also brought reductions in size, as fish were caught and killed before they could reach adulthood: where once sturgeon up to 5 metres long were common in the bays and estuaries of North America, now they are gone, while the immense rays that glided across the sandy bottom of Botany Bay in Cook and Banks’ time would be exceptional today. Even Oppian’s teeming Mediterranean is now so devoid of fish that many marine biologists call it the Deaditerranean.

No one alive truly understands what we have done to oceans–that they could be so teeming with life is completely alien. There simply isn’t any place where one can find this concentration of marine organisms (unless you’re in the middle of a school of fish). We have created a barren desert.