Extinctions in the sea: Myths and realities

It is a fact that humans have caused several extinctions, particularly in the terrestrial realm. In the marine realm, however assessing the complete disappearance of a species from the face of the earth beyond any reasonable doubt, is a formidable task. In this contribution, the main results of an extensive review on the marine extinctions documented during the last 200 years are presented. It seems that similar to 50% of the recent documented marine extinctions may be over-estimated because there is no explicit consideration of critical uncertainties such as species' spatial distribution, or the evidence used to support some cases is misinterpreted or unconvincing. It is concluded that 1) humans are fully capable of eliminating marine species, particularly those that are naturally extinction-prone; 2) marine extinctions are less frequent than those in the terrestrial realm, and despite that the average number of documented extinctions per year shows a positive trend since the XIX century, the trend during the last 100 years is negative; 3) before declaring an extinction, all available supporting evidence must be scientifically evaluated; and 4) when declaration of extinctions are premature or improperly supported by all available scientific evidence, they can negatively affect the very efforts dedicated to species conservation.