There is also evidence that increased UV exposure could hurt Antarctic krill, which live in the upper part of the water column, making them vulnerable to UV exposure. Krill eggs, which float on the surface, are even more vulnerable. If Antarctic ice continues to melt as a result of global warming, whale habitats could change dramatically. And that's very worrisome. But the biggest problem is simply that low numbers make recovery a slow process.
Fish can bounce back in a couple of years.
Whales take longer than that. Whales reproduce more slowly than humans. In 1993 the Soviet Union stunned the world with the revelation that, throughout the 1960s and 1970s, they had killed perhaps as many as 20 times the number of the most endangered species than they had previously reported. The blue whale in particular offers an irresistible lure for whalers who might be tempted to cheat. At 60 to 80 tons and more than 100 feet long, a blue whale could fetch as much as half a million dollars on the Japanese market.