Record numbers of dead leopard sharks are washing up on the shores of northern California since mid-March.
They mate and have pups in shallow waters, so sometimes they get stuck in man-made lagoons when tide gates close.
According to the San Francisco Chronicle, toxic fungal blooms combined with man-made chemical waste poison the water in these waterways.
Additionally, sharks swim in schools, so if one washes up on the shore, many others are likely to follow.
Scientists at the Pelagic Shark Research Center believe that thousands of sharks may have died in the area.