Nearly all 97% of the world's listed migratory fish species are threatened with extinction, according to the first-ever report on the State of the World's Migratory Species.
That report finds the populations are dwindling for nearly half 44% of the planet's listed migratory species, while more than one-in-five of them are threatened with extinction.
The report says each year, billions of individual animals traverse distant continents, countries and habitats, performing crucial functions, such as the large-scale transfer of nutrients between environments.
University of Auckland institute of marine science professor Rochelle Constantine spoke to Corin Dann.
