Shapechanger. The wereshark can use its action to polymorph into a Large shark-humanoid hybrid or into a Large shark, or back into its true form, which is humanoid. Its statistics, other than its size and AC, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Keen Smell. The wereshark has advantage on Wisdom (Perception) checks that rely on smell.

Blood Frenzy: The shark has advantage on melee Attack rolls against any creature that doesn't have all its hit points.

Water Breathing The wereshark can breathe only Underwater while in shark form.

Amphibious(Hybrid form only). The wereshark  can breathe air and water while in hybrid form.

Multiattack. In shark form, the wereshark makes two claw attacks. In humanoid form, it makes two trident attacks. In hybrid form, it can attack like a shark or a humanoid.

Bite (Shark or Hybrid Form Only). Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) piercing damage. If the target is a humanoid, it must succeed on a DC 15 Constitution saving throw or be cursed with wereshark lycanthropy.

Trident (Humanoid or Hybrid Form Only). Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 12 (2d6 + 5) piercing damage, or 14 (2d8 + 5) piercing damage if used with two hands to make a melee attack.