On land they are relatively easy to defeat if you have a Bow. When you can use Pikes, Swords, and other stuff, you can defeat a Sarco using melee.

In the water, they will circle around you and make things difficult. Confront on land ONLY (if possible).

Standing on rocks usually does not help, as a Sarco can just lung at you and knock you off you little perch. Shoot the creature with Arrows and keep backing up. You may need to turn around and sprint a bit to stay ahead of it. You CAN outrun a Sarco on land.

If you kill one, make sure you harvest all the useful hide, meat, and Sarco Skin (a trophy).

At level 21 I had over 5 Sarco Skins, many from Sarcos with 10+ levels.

More Sarco Encountering Tips