Claws

Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage and the target is grappled (escape DC 14). Until this grapple ends the merrow can't attack a different creature with its claws.

Harpoon

Melee or Ranged Weapon Attack: +6 to hit, reach 10 ft. or range 20/60 ft., one target. Hit: 11 (2d6 + 4) piercing damage. The target makes a DC 14 Strength saving throw. On a failure the merrow pulls the target up to 20 feet toward the merrow.