Glass sponge reefs

British Columbia’s prehistoric glass sponge reefs are an international treasure. Found in Hecate Strait, the Southern Strait of Georgia, Chatham Sound, and Howe Sound, these fragile reefs provide vital habitat to a wide range of marine animals including endangered rockfish, but are very vulnerable to damage.

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Show your support for the protection of BC’s Sea of Glass! Send a letter of thanks to the Minister of Fisheries and Oceans Canada for establishing the Hecate Strait and Queen Charlotte Sound glass sponge reefs,
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British Columbia’s glass sponge reefs are one of the great wonders of the world’s ocean. Although individual glass sponges are found across the world, glass sponge reefs were thought to have gone extinct 40 million years ago until living glass sponge reefs were discovered in Hecate Strait in 1987.  Scientists have likened this discovery to finding a herd of dinosaurs on land.

The Hecate Strait and Queen Charlotte Sound Reefs are by far the largest and most pristine reefs. They are 9000 years old, cover 1,000 sq. kms and reach the height of an eight-storey building. Since it’s discovery several smaller reefs have been discovered in the Strait of Georgia, Howe Sound and Chatham Sound. One small reef has been discovered in Alaska but other than that they are found nowhere else in the world.

Glass sponge reefs provide important habitat for other marine life, including spot prawns, rockfish and sharks. They feed on bacteria and are very efficient filter feeders. A single small reef can filter enough water to fill an Olympic-sized swimming pool in less than 60 seconds!

To find out more about BC’s amazing glass sponge reefs visit


The threat

The glass sponge reefs’ are incredibly fragile and over half of the reefs in Hecate Strait were destroyed by bottom trawling before fishing closures were put in place in 2002. Heavy bottom fishing gear like trawl nets, traps and long-lines can easily damage and crush the reefs.  Unfortunately the large

Glass sponges are also vulnerable to sedimentation. Large sediment plumes kicked up as fishing gear, anchors or cables are dragged along the seafloor can smother and choke the reefs. Glass sponges will stop filtering oxygen and food from water if there is too much sediment

What CPAWS is doing

Our goal is to get all of BC’s glass sponge reefs designated as marine protected areas (MPAs). Like parks on land, MPAs are designed address all known threats to species and ecosystems within a given area, and provide permanent protection. 

  • After more than 16 years of work, CPAWS is celebrating the final designation of the Hecate Strait and Queen Charlotte Sound glass sponge reefs! 
    The Hecate Strait and Queen Charlotte Sound glass sponge reef MPA was designated on 16th February 2017. The MPA will prohibit bottom contact fishing activities from occurring within at least 1 kilometre of the reefs, until it can be proven that the activities are not harmful to the reefs. This is a significant improvement from the weak protecton measures initially proposed. In 2015 we asked Canadian’s for help in demanding better protection for the reefs and thousands of you responded. CPAWS has nominated the Hecate Strait and Queen Charlotte Sound glass sponge reefs for UNESCO World Heritage Site status to provide global recognition of the importance of the reefs.

  • In June 2015 fishing closures were established around 9 reefs in the Strait of Georgia to protect them from accidental damage.
    The Strait of Georgia fishing closures prohibit all bottom contact fishing within 150 metres of the reefs. We are currently working with Fisheries and Oceans Canada to educate recreational fishers and other marine users about the reefs and the fishing closures. We will continue to push for MPAs status for the reefs in order to protect them from other threats, including anchor damage and under-sea cables.   

  • We are working to secure immediate protection of the Howe Sound and Chatham Sound reefs from bottom contact fishing activities and undersea piplelines that pose an imminent threat to these reefs.

To see a timeline of the glass sponge reefs, including discovery and protection, click here!


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