As Gavin Garrison lies half asleep shivering and hungry inside a 4-by-7-foot boat cabin waiting to shoot the next segment of “Whale Wars” in the waters of the Antarctic Ocean, the life of a documentary producer doesn’t seem glamorous.Because voyages stretch for months, the conservation of heating fuel and food is crucial.“I am on call 24/7 because the show takes place on ships that are at sea,” explained Garrison, who works with a crew of six other producers and videographers on one of two ships. The show is broadcast on the Animal Planet network (owned by Discovery Communications, which also owns the Discovery Channel), which leases the footage from the nonprofit Sea Shepherd Conservation Society.“The hardest part is being gone so long and sailing in dangerous waters. There are small icebergs the size of a car called growlers, and they can cut into the hull.”