What clues does Dickens give about Jerry Cruncher's other job?

Jerry Cruncher Sr.'s other job is initially referred to as 'fishing', but when Jerry's son (Jerry Jr.) follows his father and his father's partners to observe what they were doing, it's hinted at that the men pull up a dead body rather than a fish. Jerry Jr. runs home quite afraid, and later asks his dad what a "Ressurection-Man" is. Jerry Sr. is much more knowledgeable about it than he initially puts on to his son, and when Jerry Jr. suggests that it might be something that he wants to do someday, his dad becomes very proud. (i.e. A Ressurection-Man was someone who would dig up corpses and give them over for scientific research)