Could underwater farms help fight climate change? - Ayana Johnson and Megan Davis

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For billions of people, seafood provides a significant source of protein and nutrition, but over half the seafood we eat isn't caught in the wild, it's grown through aquaculture. Farmed seafood is one of the fastest-growing food industries, but the farming methods echo the problems we've seen in industrial agriculture. Is there a way to sustainably farm the ocean? Ayana Johnson and Megan Davis investigate.

Lesson by Ayana Johnson and Megan Davis, directed by Biljana Labovic.

For 3 billion people around the world,

seafood provides a significant source
of protein and nutrition.

But recent studies show that 33% of wild
fisheries are overfished,

while another 60% are fished at their
maximum capacity.

In fact, over half the seafood we eat–

from finfish and shellfish to
seaweed and algae–

isn’t caught in the wild.

It’s grown through aquaculture,
or aquatic farming.

Farmed seafood is one of the
fastest-growing food industries,

expanding in volume by 5.8% each year.

But different methods of aquaculture come
with different advantages and issues–

some of which echo the serious problems
we’ve seen in industrial agriculture.

So how can we avoid repeating the mistakes
we’ve made on land, at sea?

What aquaculture approaches are we
currently using,

and what does a sustainable way
to farm the ocean really look like?

One of the most common aquaculture
methods involves large pens made of nets,

where fish are farmed offshore in floating
cages roughly 1000 square meters in size.

Commonly employed off the coast of Chile
and in the fjords of Norway,

these fish, like many industrially
farmed animals,

occupy stressful, overcrowded pens.

They produce massive amounts of waste,

polluting the surrounding areas

and potentially spreading diseases
to wild species.

Worse still, since the antibiotics
employed to fight disease

aren’t fully absorbed by the fish,

they get excreted back
into the environment.

Net pens are also susceptible to escapes,

unleashing huge numbers of fish which
compete for resources

and weaken the local gene pool
with genes adapted for captivity.

Escaped fish can even disrupt local
ecosystems as invasive species.

Other techniques,

such as man-made coastal ponds commonly
used for shrimp farming in Southeast Asia,

create additional environmental problems.

Just like net pens, these ponds are prone
to spreading pollution and disease.

Their construction also frequently
destroys important ecosystems

like mangroves and marshes,

which protect coastal areas from storms,

provide habitats, and absorb tons
of greenhouse gases.

One way to solve these problems is to farm
fish on land

in completely contained systems.

Tanks and raceways can recirculate and
filter water to prevent pollution.

But even fully contained facilities still
contend with another major hurdle:

fishmeal.

About 10% of the seafood caught globally
is used to feed animals,

including carnivorous farmed fish.

Researchers are working on fish feed made
of insects and plant-based proteins,

but for now many inland fish farms
are connected to overfishing.

All these obstacles can make sustainable
aquaculture feel a long way off,

but innovative farmers are finding new
ways to responsibly farm the seas.

The most promising solution of all
may be to look lower on the food chain.

Instead of cramming large, carnivorous
fish into pens,

we can work with natural ocean systems

to produce huge amounts of shellfish
and seaweeds.

These low-maintenance flora and fauna
don’t need to be fed at all.

In fact, they naturally improve
water quality,

filtering it as they feed off of sunlight
and nutrients in the seawater.

By absorbing carbon through
photosynthesis,

these farms help battle climate change,

and reduce local ocean acidification

while creating habitats for other
species to thrive.

Shifting to restorative ocean farming

could provide good jobs for
coastal communities,

and support healthy plant and
shellfish-based diets

that have an incredibly
low carbon footprint.

In just 5 months,

4,000 square meters of ocean can
produce 25 tons of seaweed

and 250,000 of shellfish.

With the right distribution network,

a series of small farms, collectively
the size of Washington State

could feed the planet.

Farms like these are already popping up
around the globe,

and a new generation of farmers is
stepping up

to pursue a more sustainable future.

Done properly,

regenerative ocean farming could play
a vital role in helping our oceans,

our climate, and ourselves.