shanksmare

The Bridge Net that Sirsnookalot speaks of is probably the best solution to your problem. An alternative solution could be constructing the following fish retriever:
 
1). about 15' of parachute chord
2). an 8 ounce (or thereabouts) Bank Sinker
3). a couple of very large hooks (about 8/0 to 10/0) the eyes on the hooks must be large enough for the bolt to fit through
4). a 1/8" bolt about 1" long with 2 washers with a nut
5). a very large snap swivel
 
Take a drill with a 1/8" bit and open up the loop on the sinker so the bolt will fit through. Drill another hole near the oppossite end of the sinker.
 
Put a washer on the bolt then a hook. Insert the bolt through the enlarged loop of the sinker. Put the other hook on the bolt, followed by the washer and the nut. Tighten the nut with the hooks pointing away from the sinker.
 
Insert the parachute chord through the hole in the fat end of the sinker. Insert the parachute chord through the swivel porrtion of the snap swivel. Slide it to within a couple of inches of the sinker and secure with an overhand knot.
 
To use you just clip the snap to your line and lower the sinker with hooks on it into the fishes mouth. A quick jerk will hook the fish and it can be lifted up the wall or to the pier using the parachute chord.
 
You can wrap the line around the sinker and carry it in your pocket (carefully, it may be prudent to crimp the barbs on the hooks down) until needed. It worked off of peirs and bridges for large striped bass and bluefish.