The attraction previously tried to offload the whales to Chimelong Ocean Kingdom, a zoo and aquarium in Zhuhai, China.
Thompson barred the transfer because she “could not in good conscience approve an export that would perpetuate the treatment these belugas have endured”.
Her decision was informed by the 2019 “Free Willy” bill, which regulated aquatic animal exploitation, banning whale captivity at aquariums and water parks.
Marineland has been in dire need of financial assistance since the legislation came into force, facing increasing pressure from animal activists and declining visitor numbers.
According to Species Unite, in August last year, the park was fined for the poor conditions in which three black bears were kept, and it was confirmed in November that five whales died last year.
Melissa Matlow, an adviser at World Animal Protection, told the New York Times that “threatening to kill all their animals if they don’t get emergency funding is just repugnant”.
“We need to take comfort that this is the last generation of whales and dolphins that will ever have to suffer again in Canada.”