Overview: The bull shark and greenland shark are examined. These sharks are believed to have swam upriver hundreds of miles.
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First Air Date: Oct 31, 2007Last Air date: Mar 24, 2010Season: 4 SeasonEpisode: 68 EpisodeRuntime: 45 minutesQuality: HDIMDb: 7.40 / 10 by 13 usersPopularity: 5.328Language: English