Twenty bottlenose dolphins were found dead on beaches in Galveston and Jefferson counties on Monday, rekindling a mystery officials said may never be solved.

Monday’s discovery on the Bolivar Peninsula follows an unusually high number of dolphin deaths about the same time last year but may provide just as little in the way of answers.

Almost 70 dolphins washed up on Galveston County shores between Feb. 27 and March 23, 2007.

Those dolphins were badly decomposed, hampering efforts to test tissue samples. Of those tested, the results were either inconclusive or showed no abnormalities, said Blair Mase, who coordinates regional efforts involving stranded marine animals for the National Oceanographic and Atmospheric Administration.

The dolphins found Monday are also badly decomposed, so drawing conclusions from tissue samples could again prove difficult, Mase said. Members of the Texas Marine Mammal Stranding Network were collecting samples Monday.

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