Apart from common sense and dont shoot game fish (trout salmon) none really, have a look at the minimum sizes copied from
http://www.nwsa.ukf.net/
Dab...................boat 8" shore 8"
Flounder............boat 10" shore 10"
Sole...................boat 10" shore 10"
Plaice.................boat 11" shore 11"
Mullet.................boat 13" shore 13"
Mackeral............boat 12" shore 12"
Pollack................boat 12" shore 12"
Garfish.................boat 15" shore 15"
Coalfish................boat 14" shore 14"
Ballan Wrasse.......boat 9" shore 9"
Bass.....................boat 16" shore 16"
Cod......................boat 14" shore 14"
Poor Cod..............boat 7.25" shore 7.25"
Whiting..................boat 10.6" shore 10.6"
Haddock...............boat 14" shore 12"
L/Spotted Dogfish..boat 18" shore 15"
Bull Huss...............boat 23" shore 23"
Spurdog................boat 23" shore 23"
Smoothhound........boat 20" shore 20"
Rays.....................boat 16" shore 16"
Conger Eel ...........boat 48" shore 36"
Silver Eel...............boat 15" shore 15"
John Dory..............boat 13" shore 10"
Tub Gurnard..........boat 11" shore 11"
Ling.......................boat 28" shore 28"
Rockling................boat 7.25" shore 7.25"
Pouting..................boat 10" shore 7.25"
Red Bream............boat 10" shore 10"
Black Bream..........boat 9.5" shore 9.5"
Brill........................boat 14" shore 14"
