Dead sharks and rays are washing up along the lagoon in Aquatic Park — a grisly, sad and curious sight for walkers, bikers, runners and others discovering the carcasses. Numerous people contacted Berkeleyside over the past week saying they’d seen the dead marine life at Aquatic Park, many sending pictures. Naturalists and marine experts are also tracking and documenting the reports, a whirlwind of investigation that consumed some over the weekend, despite the Superbowl, sources said. Reports of the small, spotted leopard shark carcasses, as well as those of bat rays, related species in a class of fish called elasmobranchii, have also come in from Redwood Shores, in the South Bay. Dead rays were also sighted in Novato.