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Bags of sorted shellfish shells are deployed at new reef restoration sites.
Bags away! After sorting the discarded shells, these bags are deployed in new reef restoration sites. © Frigatefilms

Stories in Hong Kong

Less Trash and More Reefs

Hong Kong's shell recycling project is turning waste into value for the city's shellfish reefs

The Challenge

Globally, it is estimated that 85 percent of oyster reefs have been lost, making it the most endangered marine habitat on the planet. The cost of losing shellfish reefs is easy to overlook, because oysters, clams and other shellfish are quiet, unsung heroes.

Shellfish reefs provide enormous benefits for water quality by filtering and cleaning the water. Reefs also defend coastal cities like Hong Kong against climate change as they soften the blow of large waves, reduce flooding and prevent erosion caused by rising sea levels.

As a city of seafood lovers, Hong Kong has no shortage of discarded shellfish shells. Most shells end up in overflowing landfills or dumped haphazardly into Deep Bay and along the coastlines. The Nature Conservancy (TNC) in Hong Kong is changing these unsustainable practices by working with the aquaculture communities and hospitality partners to give new value to discarded shellfish shells. 

Did You Know?

Oyster farming in Hong Kong has been an important livelihood for more than 700 years, supporting a local aquaculture industry and cultural heritage. 

Rewilding Our Ocean (3:26) Learn how we are recycling discarded shellfish shells and re-purposing them as subtrate for new reefs.

"Save Our Shells"

TNC has developed the "Save Our Shells" project, an initiative that recycles discarded shellfish shells and repurpose them as substrate for new reefs. Oysters aren't just good for eating—their shells are made of natural materials that are the perfect substrate for new reefs to form and grow. These reefs will provide a boon of benefits, serving as habitats for juvenile fish and other marine life, as natural filter feeders that improve local water quality and as shoreline stabilizers against erosion and storms.

Leaning on TNC's global expertise of oyster recycling and reef restoration projects from the United States to Australia, our goal is to reduce the negative impact of shellfish shell waste, create a more natural environment for native species and increase public awareness around the importance of oysters and shellfish reefs.

Readying the shells
Readying the shells Volunteers sort discarded shellfish shells and place them into bags so they are ready to be used as reef substrate. © Frigatefilms
1, 2, 3!
1, 2, 3! Volunteers and staff deploy bags of recycled oyster shells to be used as substrate for new reefs. © Frigatefilms
Readying the shells Volunteers sort discarded shellfish shells and place them into bags so they are ready to be used as reef substrate. © Frigatefilms
1, 2, 3! Volunteers and staff deploy bags of recycled oyster shells to be used as substrate for new reefs. © Frigatefilms

How It Works

  1. First, we collect used oyster, mussel and scallop shells from restaurants, hotels and also the oyster farming industry across Hong Kong.

  2. Second, the shells are cured to kill off any diseases by laying them out in the sun for a few months.

  3. When they’re ready, they are bagged up and taken to our reef restoration sites.

  4. Finally as part of the reef construction process, the recycled shells are placed into the sea as a ‘settlement substrate’ for juvenile oysters to grow onto.

Shell Recycling

SHELLS ARE COLLECTED from restaurants and hotels in special bins. © Anniqa Law/TNC
PARTNERS ARE CRITICAL to the success of the program like SUEZ who helps with shell collection and transportation. © SUEZ Asia
OYSTER FARMERS also contribute shells that are discarded on shorelines. These shells are often mixed with other debris—such as concrete and plastic nets—creating excess trash . © Anniqa Law/TNC
COLLECTED SHELLS are spread out in the sun to cure before being bagged and placed in the sea. © Anniqa Law/TNC
SHELLS ARE SORTED and placed into natural, biodegradable bags to help form the new reefs. © Anniqa Law/TNC
NUMEROUS BAGS OF SHELLS are strategically placed in the sea to build the new reefs. © Joe Cheung
DEPLOYED OYSTER SHELLS Shells are used to build reefs and quickly become home for many sea creatures like this small crab. © Marine Futures Laboratory, The Swire Institute of Marine Science
× SHELLS ARE COLLECTED from restaurants and hotels in special bins. © Anniqa Law/TNC
× PARTNERS ARE CRITICAL to the success of the program like SUEZ who helps with shell collection and transportation. © SUEZ Asia
× OYSTER FARMERS also contribute shells that are discarded on shorelines. These shells are often mixed with other debris—such as concrete and plastic nets—creating excess trash . © Anniqa Law/TNC
× COLLECTED SHELLS are spread out in the sun to cure before being bagged and placed in the sea. © Anniqa Law/TNC
× SHELLS ARE SORTED and placed into natural, biodegradable bags to help form the new reefs. © Anniqa Law/TNC
× NUMEROUS BAGS OF SHELLS are strategically placed in the sea to build the new reefs. © Joe Cheung
× DEPLOYED OYSTER SHELLS Shells are used to build reefs and quickly become home for many sea creatures like this small crab. © Marine Futures Laboratory, The Swire Institute of Marine Science

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Exposed roots A mangrove forest at low tide in Pak Nai, Hong Kong. © Lori Cheung/TNC

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