What’s an Acre of Seagrass Worth? $8,000 in Fish Alone

Healthy seagrass with a jack in the background, Florida Keys National Marine Sanctuary. Credit Heather Dine, NOAA

By Philine zu Ermgassen, postdoctoral fellow at Cambridge University and Dr. Mark Spalding, senior scientist with The Nature Conservancy

For decades, dire tales of collapsing fish stocks were told, only to fall on deaf ears.

Then, in a 2008 report, “Sunken Billions,” the World Bank and the FAO began to couch the problem in entirely new terms – financial terms. They estimated that $50 billion was lost each year due to poor fisheries management. That staggering figure caught the eye of finance ministers, development agencies, and economists around the globe.

At last, the conservation community discovered how to get attention, but it raised a new question: what to do about it? To truly turn the tide, they knew, meant not only taking fewer fish, but also producing more. That’s where seagrass, mangroves, and other habitat come in. These habitats are nurseries to new generations of commercially valuable fish and it is time we recognize the value of those important ocean services on Earth’s balance sheet.

Juvenile fish have it hard from day one. They are at the mercy of the elements and voracious predators. The odds of a microscopic fish larva making it to adulthood are one-in-a-million.  Seagrasses represent the rare safe haven, providing much needed food and shelter. And yet, like the fish, seagrass beds have also been disappearing. Some say the world loses a soccer field worth of seagrass every half-hour, further contributing to the decline in fish.

New fisheries management has to consider the whole life cycle of the fish—where they are born, where they spend their lives, as well as how they die.

In places where habitat loss harms fish, protection and restoration are a very real opportunity. A new study, supported by The Nature Conservancy, tells us just how real. The report tells us that each square meter of seagrass habitat we save in southern Australia could add nearly one kilogram of fish each year. Said in a different way, every acre of seagrass could add US$8,000 of commercially important fish to the oceans every year.

No one is blind to the fact that seagrass restoration is both technically challenging and financially expensive, but these figures show that the benefits far outweigh the costs. Some restoration efforts could pay for themselves in just five years. In these terms, seagrass restoration is a no brainer.

A volunteer examines a clam during a massive seagrass restoration effort at The Nature Conservancy’s Virginia Coast Reserve, volunteers gather reproductive shoots containing ripe seeds from the underwater plants. Mark Godfrey, Nature Conservancy
A volunteer examines a clam during a massive seagrass restoration effort at The Nature Conservancy’s Virginia Coast Reserve, where volunteers gather reproductive shoots containing ripe seeds from the underwater plants. Mark Godfrey, Nature Conservancy

And yet, as with so many projects where the costs are large and the benefits are shared, money can impede getting seeds in the ground. If such benefits went on the balance sheet of a company, a champion would certainly appear, but these benefits go to many—to commercial and recreational fishermen, to local economies, and to seafood fans—and thus no champion is forthcoming.

On an encouraging note, however, the story of the financial impact of a small patch of seagrass in a small part of the world is but one among the many that our ocean has to tell. Valuing ocean wealth stands to change everything. It represents a fundamentally new model for the global conservation conversation. It has been reviewed and tested by the scientific community.

We can use it to build a complete accounting of coastal wealth that includes jobs, food security, and tourism income into an honest and compelling bottom line figure. Suddenly, that little patch of seagrass in South Australia is no longer “dead space” able to be snuffed out by a change in shipping lanes, run-off or pollution, but rather a storehouse of wealth.

Humans crave quantification. Numbers turn heads. Numbers change policies. Numbers are compelling. But, we must act fast. Seagrasses are being lost every minute we wait. And, it’s costing us untold billions.

We can start by mapping our ocean wealth, like a pirate would plot his hidden treasure. We can start understanding things like how valuable mangroves are at filtering out pollution, or coral reefs in generating tourism, or oyster beds are at protecting coastal erosion. We must build these systems into our economic models in the realest, most compelling financial, engineering, and policy terms we can find. Tabulating the value of services is essential if we are ever to truly comprehend the vast wealth of the ocean and maximize investment and development dollars.

Correction: On September 24, editors revised the potential value of fish protected by an acre of seagrass from $US80K per year to $US8K per year, due to a conversion error in the published manuscript. Values for the increase in biomass and the estimated payback time remain unchanged.



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