Answer One: I would be worried if the amount of albatrosses and crabs decreased every time I do the quest, which would indicate a depletion in their numbers. Yet the amount of predators remains steadily constant. Don't worry, there's plenty of 'em to go.
Answer Two: I'm getting 175 reputation (+10% with human racial) per quest. Albatrosses and crabs can go extinct for all I care. Tortollans, you're going to love me!!!