Saint-Fur Zoo is a huge place that some would dare call a theme park. The monday and tuesday is like a weekend were most activities are closed. The indentured servants are then send to the school, at their expense of course, to get some education. The first april is the day the physical Ed. classes do their swimming exams. To help them get a good score this hoax was made. The teacher tell the swimmers that she will send a shark or a orca after they swim the first meters and the one that doesn't swim fast and well enough will end in her belly. The predator get to eat something else but the swimmer get to make real good time. Motivation is the key and this joke always rise up the morale of the wardens.
P.S.= The school of Saint-Fur only use female swimsuits for the students and no the pool isn't warmed artificially. Cold water is good for the body anyway.