NPCs composing that spawngroup :

a_greater_sea_turtle (25%)

a_large_sea_turtle (30%)

a_sea_turtle (25%)

a_young_sea_turtle (10%)

Monstrous_Sea_Turtle (10%)

NPCs spawning around that spawngroup :
(Max range : 100)

powater_a_triloun_water_guardian54, range=83 (-1026,-7,-29)

a_triloun_water_guardian (100%)

powater reef mobs, range=51 (-954,67,-31)

powater front room sharks, range=14 (-957,6,-54)

a_reef_hammerhead_shark (50%)
a_reef_shark (50%)

powater traps, range=10 (-937,22,-61)

a_swarm (10%)
a_swarm (10%)
HatchSpawnPH (90%)
HatchSpawnPH (90%)

powater large mobs, range=46 (-947,62,-41)