Read this excerpt from a passage.

"Unfortunately, one response to these regulations has been pirate fishing: fishing done without regard to national or international laws. Motivated by both need and greed, individual and commercial fishers alike have violated fishing regulations and laws the world over. As the World Wildlife Foundation reports on its website, 'Pirate fishing accounts for an estimated 20% of the world’s catch and as much as 50% in some fisheries. The costs of illegal fishing are significant, with the value of pirate fish products estimated at between $10–$23.5 billion annually.' Not only is this a noteworthy illegal profit, these pirate fishers are difficult to stop."

Which sentence from the passage is a major supporting detail?