-1 echoes of the beast: electroreceptive sense
-1 claws
-1 diminutive size
-1 aquatic
+0 truly aquatic - being a shark out of water is a good reason to shift to a different form.
-2 inhuman speed
-4 supernatural recovery
+3 catch
-1 ventral photophores: can use stealth skill in open water, even without anything to hide behind; this reduces penalties for lack of cover by two.  When viewed from above, a dark topside matches the view of the ocean depths, while from below, an adjustable bioluminescence matches the light filtering down from the surface.  This ability can also be used as a light source in particularly dark aquatic environments.
-1 snapping lunge: +2 fists when striking from ambush
-1 refresh deliberately not spent

(unspent: +1)
+5: athletics, alertness, stealth
+4: empathy, investigation, lore
+3: conviction, endurance, rapport, fists
+2: scholarship, deceit, discipline, might
+1: performance, contacts, presence, survival

details on individual forms:
One each male & female of the following four species:
http://en.wikipedia.org/wiki/Centroscymnus_coelolepis -- selected for maximum diving depth; can reach over two miles underwater.
http://en.wikipedia.org/wiki/Brachaelurus_waddi -- can survive out of water for up to 18 hours.
http://en.wikipedia.org/wiki/Heterodontus_japonicus -- because it just looks neat
http://en.wikipedia.org/wiki/File:Mustelus_aterias.jpg -- ditto