Full list of all 44 Maneater achievements worth 1,350 gamerscore. It takes around 10-12 hours to unlock all of the achievements in the base game on Xbox One.
The base game contains 32 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 12 achievements worth 350 Gamerscore.
Completed all objectives in The Gulf
Reached 100% objective completion in all regions
Destroyed Scaly Pete once and for all
Destroyed all Apex Predators
Acquired 100% of available evolutions
Defeated the Apex Sperm Whale
Completed all objectives in Sapphire Bay
Found all nutrient caches
Found all license plates
Found all landmarks
Defeated the Apex Killer Whale
Completed all objectives in Caviar Key
Completed all objectives in Golden Shores
Completed all objectives in Dead Horse Lake
Reached Infamy Level 10
Completed all objectives in Fawtick Bayou
Completed all objectives in Prosperity Sands
Defeated the Apex Great White Shark
Reached Mega Growth
Acquired 50% of available evolutions
Reached Elder Growth
Defeated Scaly Pete's second encounter
Defeated the Apex Hammer Head
Defeated the Apex Alligator
Defeated the Apex Mako shark
Defeated the Apex Barracuda
Reached Adult Growth
Reached Infamy Level 1
Reached Teen Growth
Evolved for the first time
Survived Birth
Completed the tutorial
Completed all available objectives in Truth Quest
Defeated the Atomic Leviathan
Completed 100% of the Time Trials
Acquired 100% of the Atomic evolution set
Completed all objectives in the Plover Island Complex
Ate all the Questers
Defeated Terranova
Defeated the Bone Sperm Whale
Reached Level 40
Defeated the Shadow Orca
Defeated the Electric Great White
Began the quest for the truth