In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.

Let me give you an example: Article: There are a lot of public libraries in Britain. These libraries have more than one hundred and fifteen million books, not including those libraries of public schools. Public libraries not only lend books, music records but also help children, patients in hospitals and others to get special play readings, film shows and so on. The first public libraries were founded in about the year 1850. Today's public libraries usually have a reading-room, a lending room and a reference room. The greatest and most famous library in Britain is that of the British Library in London. It was founded in 1973 and has over 10, 000, 000 books. It has nearly every magazine, newspaper and book published in Britain and other parts across the world.
Answer: 10,000,000 or less.
The answer to this example can be: How many books are there in the British Library?
Here is why: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.

OK. solve this:
Article: December usually marks the start of humpback whale season in Hawaii. But experts say the animals have been slow to return. The giant whales are an iconic part of winter on the islands and a source of income for tour operators. But officials at the Hawaiian Islands Humpback Whale National Marine Sanctuary said they've been getting reports that the whales have been difficult to spot so far. "This isn't a concern. But it's of interest. One theory was that something like this happened as whales increased. It's a product of their success," said Ed Lyman. He is a Maui-based resource protection manager and response coordinator for the sanctuary. "What I'm seeing out there right now is what I expected a month ago," said Lyman. He said he was surprised by how few of the animals he saw while responding to a call about a distressed calf on Christmas Eve. "We've just seen a handful of whales." It will be a while before officials have hard numbers. That is because the annual whale counts don't take place until the last Saturday of January, February and March. This is according to former sanctuary co-manager Jeff Walters. "They don't necessarily show up in the same place at the same time every year," Walters said. More than 10,000 humpback whales make the winter journey from Alaska to the warm waters off Hawaii. There, they mate and give birth. Lyman said the whales' absence could just mean they're spending more time feeding in northern waters. That's possibly because of El Nino disruptions. Or it may be because their population has gone up. "With more animals, they're competing against each other for that food resource, and it takes huge energy reserves to make that long migration over 2,000 miles," he explained.
Answer: They are largely hunted by humans.
Answer:
Which isn't the reason why humpback whales are slow to return according to Lyman?