Yes one of the joys is keeping it but you agree the rules before you go out.you can pay a reduced fee for the day with the largest/ best going to the captain,a reduced fee and then pay so much per fish ,usually with a limit on the size ,weight and qty you can keep,you can pay an all in fee but again stipulations on what you can keep.Loads of variations.One of the better trips I went on in the Canaries was on a six man boat,Canarian skipper,best fish for Captain,all other fish cleaned,filleted and shared amongst us(I ended up with eight good sized tuna steaks which went on the BBQ)and at lunch time we had fish caught Tuna pasta,crusty bread and a can of beer,pure heaven