Worldwide, sharks suffer threats from over-fishing, and mercury poisoning. <ref>http://www.ceibahamas.org/shark-ecology.aspx</ref>. Many individual shark species are currently threatened or endangered, often because of human activities such as careless fishing practices and coal fired plants dumping tones of toxic mercury into the oceans. | Worldwide, sharks suffer threats from over-fishing, and mercury poisoning. <ref>http://www.ceibahamas.org/shark-ecology.aspx</ref>. Many individual shark species are currently threatened or endangered, often because of human activities such as careless fishing practices and coal fired plants dumping tones of toxic mercury into the oceans. |