A trawler in New Zealand prowls for hoki, attracts bluefin for sport fishers. (George Shillinger photo)

A trawler in New Zealand prowls for hoki, attracts bluefin for sport fishers. (George Shillinger photo)

This is how sportfishermen go after southern and Pacific bluefin: they follow the hoki trawlers, giant floating 24-hour fish factories that slowly plow the seas around New Zealand and pull in giant nets filled with hoki. A lot of other animals -- bluefin tuna, sharks, albatross -- go after the fish slipping from the nets. [ed. note: Hoki -- also known as blue grenadier, blue hake, New Zealand whiptail, whiptail or whiptail hake -- are an enormous commercial fishery. They're one of five types of fish used in sandwiches worldwide. McDonald's restaurants in New Zealand alone serve about 300 metric tons (661,500 pounds) in fish sandwiches every year.]