Marine reserves have been found to be effective tools in conservation. They act as fish nurseries, where babies can grow up and endangered species can hide. This protected area, roughly the size of Great Britian, will apparently still allow some fishing at a sustainable level. It is funded largely by The Nature Conservancy and Leonardo DiCaprio Foundation.
Ocean Refuge the Size of Great Britain Announced - National Geographic https://apple.news/AUKcqqeIFTt6Bq7-JufOJmg