Have you ever gone fishing? Depending on where you live, you may have gone fly fishing for trout, ocean fishing for marlin, or diving for abalone. If you have, then you've been part of a fishery--the human activity of hunting an aquatic animal. Most likely it was a sport fishery, the kind of fishing that's done as a hobby.
Have you ever eaten seafood? If you've had fish sticks, a lobster dinner, or sushi and you didn't catch it yourself, then you were the consumer of a commercial fishery--the kind of fishing where fishermen earn a living and make a business by selling what they catch.
The word "fishery" refers to the whole operation, including the people who catch the animals (fishermen, boat captains), the equipment they use (boats, rods and reels, traps, scuba diving gear), the people who deal with the catch (purchasers and processors), and the billions of humans around the world who eat seafood. There are many different kinds of fisheries, from small-scale artisanal fisheries on remote islands, where children walk on the beach collecting sea cucumbers in a bucket, to huge industrial fishing fleets that use airplanes to spot fish schools and machinery to drop thousands and thousands of nets and hooks into the middle of the ocean. Many fisheries are managed, which means that governments make rules about the number of fishermen, the type of equipment they can use, the places and times they can fish, and how many fish they can catch.
Squid have been fished around the world for a very long time. The ancient Chinese and Greeks caught them, along with the squid's cousins, cuttlefish and octopuses. But in just the last few decades, squid fisheries have been growing and growing. The explanation may be related to two ideas that are already familiar to a lot of people: "the tragedy of the commons" and "fishing down the food web."
The tragedy of the commons was first described by an ecologist named Garrett Hardin. Since some resources, such as fish in the sea, are owned by nobody and yet used by everybody, they can be very quickly depleted when everyone looks out only for their own interests. Ocean resources have long been considered a "commons" in this sense, and historically people have raced to use as much of the resource as possible before anyone else gets to it.
An additional problem with the ocean is that for a long time people thought it was an inexhaustible resource--that there was no limit to the number of fish in the sea. But there are not infinite fish, so fishery after fishery has crashed. You've probably heard "fish stories" from old fishermen who claim that when they were young, there were more fish in the sea and they were bigger. In some cases, that's true.
When one fishery crashes, people naturally started looking for another one. In some cases, this can lead to fishing down the food web, an idea proposed by marine scientist Daniel Pauly. At first, humans had a tendency to catch the biggest animals, like cod and tuna and whales. But once we caught most of those, we had to move to smaller animals, then smaller still, and so on. In some places, this seems to explain the historical progression of fisheries, while in other places it doesn't.
Squid tend to be mid-size predators, smaller than dolphins, sharks, and tuna--so, from that perspective, fishing down the food web could explain the recent increased in squid fisheries. On the other hand, many squid prey on smaller species, like sardines, that have actually been fished for much longer than the squid have. In the immortal words of Facebook relationships, it's complicated.
Squid fishermen often shine very bright lights on the water to attract the squid to the surface--although no one has really taken the time to study how well this technique works. The lights are so bright, and there are now so many of them, that you can see squid fishing fleets on satellite images from space!
The Humboldt squid is currently the biggest squid fishery in the world. Not only that, it's even the biggest invertebrate fishery in the world--bigger than lobsters, shrimps, clams, any of that stuff. And it's still growing.
Many squid fisheries aren't very strongly managed--that means there aren't many rules about who can catch how many squid and where they can do it--because we don't know much about squid biology. Some squid fisheries aren't managed at all. Squid have very short lifespans, often only 6 to 18 months, and their populations are so unpredictable that scientists don't have enough time to calculate how many squid are in a single generation before those squid have spawned a new generation and then died. A scientist named Bob Leos once compared trying to count the number of squid in the ocean to trying to measure a fog bank.
Even so, no squid fishery has crashed yet, which leads some people to think that they might be intrinsically sustainable. Those very short lifespans, and the fact that squid makes lots of babies, set them apart from animals like whales or sharks that live for a long time and only have a few babies. If seafood were lumber, squid would be more like bamboo than like redwood: they grow fast and replace themselves quickly, under the right conditions. It is possible that squid fisheries are more sustainable than many other fisheries--but that doesn't mean they're immune to the tragedy of the commons.
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