For new people struggling, these guys are close to impossible to kill while touching water, never fight them in water, but they do get distracted by fish really easily, if one is too close to your preferred area and your not ready to fight it, drop all your valuables at your hut, have a sleeping bag or preferably a bed in your hut, grab a bow and a few arrows and hit them from far away till they follow you to a different section of river or beach, they might get distracted before they get to you, and if you have a mount you can usually outrun them, they won't get away from water, so if you peg one in the direction away from your area and run up hill once they get close they'll forget you and relocate to the nearest fish. They actually aren't too tough on dry land if you have enough dinos to get them stuck so they can't run back to water, I've taken them out with 5-6 dilos and a few Teranodons. On dry land.