Where does seafood come from?
Wild fisheries are a complex and fascinating natural resource—they are extractive yet renewable, vulnerable yet resilient. They contain unique human dimensions that tie directly to food security, nutrition, and livelihood. About half of the world’s seafood is wild-caught and about half is raised in farms (i.e. aquaculture).
An understanding of seafood and its complexities must start with the question: where do fish come from?
Looking at Earth’s colors from space is a good way to see the diversity of life on land. The bright gold of Northern Africa’s desert contrasts with the green grasslands of Central Africa. The reddish Australian Outback differs from the white Antarctic just south. The contrasting colors show that species are not evenly distributed across land—different environmental conditions create an unequal spread of biodiversity around the terrestrial world.
But from space, the ocean looks uniformly the same from, making it impossible to tell what is below the surface.
However, like the land it surrounds, “The Ocean” is not a continuous, singular entity. Currents, temperature, and geologic barriers separate the ocean ecologically much like climate and topography do on land.
Fish concentrate in areas of high primary productivity. Primary productivity in the ocean is the same as on land: photosynthetic organisms like plants, algae, and phytoplankton turn sunlight into organic matter. Photosynthesizing organisms are then eaten by larger organisms, which are then eaten by larger organisms, et cetera, et cetera.
To find out where fish live, we can look at where photosynthesizing organisms live. Modern satellites make this easy: this map shows productivity in the ocean as measured by chlorophyll concentrations in the water. You can mouse over to see how these areas correlate with fish catch.
As you can see, the most productive region in the world is near Alaska—sure enough, the North Pacific Ocean provides more wild-caught fish than any other region. The world’s most-eaten fish, pollock, comes from this area.
What about the biodiversity of tropical coral reefs?
Coral reefs make up less than 1% of ocean habitat but contain roughly 25% of ocean species, an incredible display of concentrated biodiversity. However, biodiversity is not the same as biomass. One common measure of biodiversity, species richness, is the total number of different species, whereas biomass is the total weight of living things. Coral reefs support high biodiversity: there are tens of thousands of different types of coral reef fish. But the biomass (the total weight of all those fish) is limited by low productivity, stemming from a lack of available nutrients. In highly productive areas like the North Pacific and North Atlantic, there are far more fish (together forming a greater biomass), but relatively few species.
To sum up, the ocean is not uniform and most fish generally come from more productive areas in the ocean.
A note on freshwater fisheries:
Fishing is the act of catching wild fish.
There are three different kinds of fishing defined by the scale and purpose of the fishing being done: recreational fishing, subsistence & small-scale fishing, and commercial fishing.
Recreational fishing is for fun.
People enjoy fishing in many ways: fly fishing creeks, lakes, and rivers can be peaceful meditation; an afternoon spent fishing from a local pier can be important family time; diving and spearing fast-moving fish is an exhilarating challenge for many, and there is no better feeling than cooking and eating your catch with loved ones. Enjoyment and hobbies are individual choices and fishing plays an important role in the well-being of many.
Subsistence & small-scale fishing is for necessity.
In many parts of world, especially in coastal and island communities, where industry, trade, and wealth are not yet developed, fishing can be one of the only sources of food and money and therefore plays an important part in food security, nutrition, and development. 90% of all people who fish for livelihood do so in small-scale fisheries. Many of these fisheries have significant cultural and traditional value as well.
Commercial fishing is for feeding billions of people.
Modern society evolved from the most basic human need: to eat. Early humans stopped migratory hunting & gathering when they realized they could stay in one place if they grew their own food. Agriculture allowed permanent communities, and civilization was born. Population growth, technology, and taste have brought us to a modern system of large, industrial farming and processing that makes food more accessible than ever in human history. It is a grand and amazing feat to provide food for billions of people; and that’s what commercial fishing contributes to: food and protein accessibility—and typically without the environmental costs of land-based food production!
Here at Sustainable Fisheries UW we focus on fish as food and the science & policies that contribute to sustainability.
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This post is part of Sustainable Seafood 101.
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