This is a summary. To read the whole story subscribe to BostonGlobe.com
CHATHAM — The 50 pound severed tuna head drifted in the water off the back of the M/V OCEARCH like a decaying chew toy, dripping blood and oil, begging for a great white shark to come up out of the ocean and give it a taste.
Standing on the back deck, Captain Bob Yates bangs a clever down on a small herring, splitting it in two. He collects a handful of fish bits with his hands and throws them into a stained plastic bucket.
Mike McCallister, a 28-year-old research biologist from the University of North Florida , takes the bucket from Yates and pounds the fish into a thick paste with a shovel.
It is just after 10 a.m. and the two men, one a seasoned fisherman, the other a young scientist from Florida, are building a chum trail, hoping to coax a great white shark out of the deep.
“You get one person back here, it gets boring and tedious after a while,” McCallister said, throwing another clump of mush out. “I enjoy doing it. It helps pass the time.”
Full story for BostonGlobe.com subscribers.
Get the full story with unlimited access to BostonGlobe.com.
Just 99 cents for four weeks.