i've done some heavy customising and come up with a big game fishing setup. for sharks i use a garpoon point on a solid glass shaft. i've made an adapter on the point to accept a glue on broad head.
i use a homemade cable slide system so if this happens i'm still connected to whatever broke it.
on the bow i have a homemade bracket to attach a handline. i incorporated a snap on air fitting for quick detach if needed.
for normal bowfishing i just use the handline setup with IGFA 130# dacron trolling line and AMS slides on the arrow.
for sharks i use just 20 yards of the 130# line to shoot with. the back end of this is tied to my game rod which sits in my gimbal belt while shooting with the drag set light. after the shot i just let them take the line off the spool on the bow, take up pressure on the rod, engage the drag fully and hang on!
works a treat! 8'2" tiger shark
7' 3 3/4" hammerhead
i have used a spincast reel for fish also but i sold it after getting tired of losing arrows because of forgetting to push the button.