Happy Biodiversity Birthday Chagos!

'Imagine commuting to work with a dolphin leaping next to you. Imagine entering crystal clear, warm water and being surrounded by more fish than you thought possible against a backdrop of stunning corals.' 

Five years ago, on the 1st April 2010, the government designated the Chagos marine reserve in the British Indian Ocean Territory. In one commitment, 640,000km2 of ocean became fully protected and the largest marine reserve in the world was born. As with any birthday, it’s good to take a moment to reflect on and celebrate what’s happened in the lifetime of the marine reserve.

Heather Koldewey and a Coconut Crab, Chagos
ZSL's Heather Koldewey and a coconut crab

Scientific linchpin for study of our oceans

Since 2010, 14 scientific expeditions have taken place involving 82 scientists from 37 organisations and 11 countries. The first of these was supported by Project Ocean and enabled a group of scientists led by Chagos expert Professor Charles Sheppard to start setting important baseline data early in the establishment of the reserve.

I was one of those lucky scientists and how best to describe that experience? Well, imagine commuting to work with a dolphin leaping next to you. Imagine entering crystal clear, warm water and being surrounded by more fish than you thought possible against a backdrop of stunning corals. Imagine reef sharks cruising by, huge groupers looking vaguely interested at you and elegant manta rays gliding off into the deep blue. Chagos is amazing! It’s like living in the highlights of a nature documentary and a stark reminder of what our ocean should look like. This is one reason scientists are attracted to Chagos - it provides a vital reference site as elsewhere we grapple to understand, protect and restore a damaged ocean. 

The value of science here cannot be underestimated. Thanks to the Darwin Initiative, we’ve been able to establish a series of regular monitoring sites for the reserve. In the last three years, we’ve added 50 new fish species to the records, bringing the total to 821 fish species documented in Chagos. We’ve added 32 new coral species records, bringing the total to 310 species. We’ve monitored the only place in the world where populations are increasing of the Red foot and Brown boobies and discovered a wintering population of Matsudaira’s storm petrel. We’ve even counted coconut crabs for the first time at night on the outer islands. The Darwin expedition team are there right now, looking at everything from coral diseases (very low in Chagos) to cryptofauna, and will return in a couple of weeks with many more discoveries and insights.   

Pioneering new technology

BIOT Science Expedition Crew, ChagosWhen the marine reserve was designated, fishing stopped, ending a commercial tuna fishery. One big question was how the reserve would help mobile species like tuna and sharks that can swim beyond the reserve boundaries. The first challenge was how to find this out without just doing more fishing. The second was that no-one had ever done any research in the open ocean around Chagos.

ZSL worked with the University of Western Australia and developed a new ‘mid-water camera trap’ which uses longline fishing methods, but with cameras instead of hooks. Since then, 390 of these cameras have been deployed to document species, numbers and biomass of the open ocean marine life.

On their first deployment in Chagos, a false killer whale was recorded, a species previously unknown to occur there! In a complementary research programme led by Stanford University, 152 sharks and 25 manta rays have been tagged so far in Chagos to find out their movements inside and outside the reserve. On top of this, fisheries and environmental data modelling (by ZSL PhD student David Curnick), oceanography and acoustic studies are helping us answer this question. 

45,000 fewer sharks caught

We still have a lot to do to prove the benefits of the reserve to mobile species, but we do know that following closure of the fishery there are 2.7 million fewer fishing hooks deployed in Chagos every year by the longline fishery. That equates to a total of 13.5 million fewer fishing hooks since the marine reserve was established in 2010. The bycatch from this fishery was mainly sharks and rays. With no fishing in the reserve, an estimated 9,000 sharks and rays are no longer fished out of Chagos waters each year, or more than 45,000 sharks and rays since the marine reserve was established. 

Connect Chagos

With a difficult political history and ongoing controversy, we have worked with the Chagos Conservation Trust (CCT) to establish an environmental training programme for the Chagossian community. The engagement in the open days, training courses and advanced training has made ‘Connect Chagos’ very inspiring. Most importantly, to date it has given seven Chagossians the opportunity to join expeditions to Chagos as trainee scientists, connecting them with both their heritage and the marine reserve.

False killer whale picture on mid-water cameras. Picture: ZSL/Tom Letessier
False killer whale picture on mid-water cameras. Picture: ZSL/Tom Letessier

Future of our seas

The Chagos marine reserve is an amazing legacy and a major contribution to securing the amazing wealth of biodiversity that exists in the UK Overseas Territories. Recently the UK government stated its intention to declare the Pitcairn Islands as the next marine reserve, which would protect 840,000 km2 of ocean. It would be very exciting to think that Chagos could become the 2nd largest marine reserve by its 6th birthday! 

Chagos in pictures

Our infographic highlights some key discoveries since the MPA in Chagos was established. 

You can also see some of the key species we've been researching in our Chagos Facebook gallery.

Read more about our work in the Chagos Archipelago

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