OWLSHARK

Init +0

Melee Atk • bite +4 (1d10)
 • tail slap +3 (1d6, only in water)
 • wing-rasp +2 (1d8)
AC 16HD 4d7+4
MV fly 30, swim 45
Act 2d20
SP drag down
Fort +6
Ref +3
Will +1
AL C

The owlshark can be sighted from coastlines or at sea, distinguished by its dorsal fin and it's wing tips breaking the water's surface.

It will attack small watercraft as well as individuals or small groups of people on beaches.

If its bite attack exceeds the target's AC by 5 or more, it has gotten enough of a bite to maintain a grip on the individual (Str 18) and will attempt to dive back into the ocean to devour them, thrashing them for additional bite damage each round when under water (no need to roll to hit).

BONUS!

BASIC STATS!

OWLSHARK
Move: 120 feet/turn flying; 180 feet swimming
Hit Dice: 4 +1
Armor Class: 5
Treasure Type: nil (see notes)
Alignment: neutral
Attacks: 2
Damage: 2-12 bite, 1-6 for the others 

Reference the above for the monster's behavior. While it has no treasure of its own, if it has been actively preying upon humanoids in an area, there may be much those folks had upon them which may now be scattered along the beach, just off shore...