Not sure why many of the creatures gave different faction hit amounts on different kills but these are my findings.
cauldron shark -3, -4
cauldron hammerhead -3, -5
bull shark -3
impaler swordfish -3
piercer swordfish -2
lancer swordfish -1
spinereef seahorse -3, -4, -5
stingtooth pirana -2
soothebrine seahorse -3, -4, -5
squallsurge seahorse -3, -4, -5
swirlspine seahorse -6
gloomwater mermaid -3, -4, -5
gloomstalker mermaid -3, -4, -5
seahorse patriarch -5
Coralyn Kelpmaiden -5
Shellara Ebbhunter -5
Cauldronboil -10
Cauldronbubble -10
Fabled Estrella of Gloomwater -10
Phinigel Autropos -50