The usual reasons for seamen to leave a ship in a foreign port were 'mutual consent', desertion, hospitalisation and jail.
'Mutual Consent' is genuine enough in most cases, as when the Master and Mates of a ship which has been sold to Canadian owners leave the ship so that the new officers can take over. But in others they look a bit dubious, as a colonial shipping officer implied in the extract below. It's possible that there had been a spot of bother on the ship and the Captain had said to the miscreants, "Right, gentlemen. I want you off my ship. You can either do it the easy way by leaving by M.C. (mutual consent) or I'll take you before the magistrate and give you a bad discharge." Who could refuse such an offer, and why else would they want to be left behind in Bombay?
The back pages of the crew lists hold consular endorsements. Most of these are routine entries, but, occasionally, one adds a bit of colour to the voyage, as with the one below about the fireman breaking his collar bone. Did he fall or was he pushed? is the question that springs to mind.