A Crew Trip is when a member of your Crew (ie. Facebook friend) goes fishing and takes you with them. As with any other Trip you take, there's no guarantee of a catch, but any fish you DO catch are added to your points and gold total. You are also awarded 50 points per person for every crew member you take when you lead a Crew Trip. Crew Trip notifications show in your Captain's Log in the same way your other Trips show. Here's an example of each;