Fionn,
It comes down to the style of fishing that suits the competitors. The normal basic boat competition sees anglers fishing for points per fish and maybe even points per cm lenght. The points are set up to give a fair chance to all anglers. Many comps limit the amount of particular species that can be caught.
There is a boat score card template on the SAI SAC section.
Many small-boat anglers fish species hunts or specimen hunts. You can get some idea from here:
www.skuaangling.netGive me a shout if there is anything else.