Originally posted by hazelrah:

they primarily spawn at night, also in storms. they will spawn in the same place, so mark your map. they will despawn at dawn.

them dont despawn , stays there or in the zone until been hunted ( that one that you miss or think that despawn at dawn are just swimming away , can be encountered again in daytime without rains because was already spawned of one of they 3 requeriments to spawn ), and them not spawn in the same place , already test that a lot of time , only have 5% of spawn at night in each 64mx64m squares in the ocean, can spawn too in daytime if there is raining or storming , being night time just adds other 5% to the normal 5% = 10% of spawn if its night time and storm/rains
all that its in the game codes and its true