When I sat down to read John Steinbeck’s classic, Cannery Row, I was expecting it to be about fish; naturally, this is why I chose it for the Book Club. I like to think I’m not the only person who would have thought this, given that the book takes place in Monterey, CA, one of North America’s most iconic fishing towns. Or at least it was until the 1950s, when it became apparent that the local sardine population had been overfished to the point of collapse. To put my mistake in context, it would be akin to thinking that Star Wars is about space. In truth, Cannery Row—like Star Wars—has very little to do with where it is set; it is actually about the people who call that setting home and the relationships they form.

Prior to the collapse of the sardine stock, Monterey, CA was once a bustling cannery town.

Prior to the collapse of the sardine stock, Monterey, CA was once a bustling cannery town.

Normally I’d be content writing about the lives of the people in the book—they do live in a fishing town after all— but I feel like this is a good opportunity to get into a little fisheries science. (Nothing too intense!) At Ocean Wise, we often use terms like sustainable, overfishing and overfished—all of which seem intuitive in layman’s terms. However, these all have very specific meanings in ecology. In fact, one of the four criteria that determine whether a type of seafood is recommended as a sustainable Ocean Wise option is the health of the stock. This criterion specifically looks at the abundance of the fish (i.e., whether the stock is overfished) and the fishing pressure from the fleets targeting those fish (i.e., whether overfishing is occurring).

So let’s break down the terminology.

Firstly: sustainable. In fisheries ecology, this word has a fairly straightforward definition.

Overfishing occurs when more fish are being taken from a population than it is producing naturally.

Overfishing occurs when more fish are being taken from a population than it is producing naturally.

Every fish stock, be it sardines or tuna, has a carrying capacity. This is the maximum number of fish that can live in a given habitat given the constraints of the environment (e.g., food availability or spawning ground size). In the absence of fishing, a stock will remain near this population size, which means that every year the number of fish that die from natural causes (old age, predation, disease) is roughly equivalent to the number that are born. When a population is reduced below carrying capacity, it has an ability to recover (i.e., more births than deaths are occurring) to carrying capacity. This could be a result of less competition for food or space to hide from predators when the population size is smaller. So, as long as a fishery is catching only the surplus fish produced (i.e., new fish produced in excess to those needed to replace the natural deaths), the population size will remain stable and fishery can be considered sustainable.

Based on this, overfishing is the state when a fishery is catching more than this difference (i.e., the total number of fish deaths as a result of natural causes and those caught by fishing is greater than the total number of births). Above, when I said that the sardine stock had been overfished, in a biological sense, this means that the population size of sardines is below a given reference point that has been determined by management. There are many different ways of determining a reference point, but in general, it is usually about half of the population size at carrying capacity. Given these definitions, to get to an overfished state, at some point overfishing had to occur.

Typically, smaller species of fish are more resilient to fishing pressure than larger species.

Typically, smaller species of fish are more resilient to fishing pressure than larger species.

Once overfished, a stock can persist in that state under very little fishing pressure. Such is the case with the Atlantic cod stock off the east coast of Canada, where fishing effort has been greatly reduced since the early 1990s, but the stock still remains a fraction of its original size.

Despite that whirlwind tour, hopefully these terms now make a little bit more sense. Although Cannery Row didn’t get much into fishing or the issues surrounding the collapse of the sardine fishery and how the region was rebuilt, a book called The Death and Life of Monterey is a great choice for those interested in learning about what actually happened to the town’s fishery and people. In the meantime, keep an eye out for the Ocean Wise symbol on menus around the country and feel free to impress your friends by explaining some of the science behind it.

Blog post by Laurenne Schiller, Ocean Wise research analyst and book club curator at the Vancouver Aquarium Marine Science Centre. 

Overfishing is the single biggest threat our oceans face today. With more than 650 partners across Canada, Ocean Wise makes it easy for consumers to make sustainable seafood choices that ensure the health of our oceans for generations to come. The Ocean Wise symbol next to a seafood item is the Vancouver Aquarium’s assurance of an ocean-friendly seafood choice. www.oceanwise.ca

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