Complex sentence: Subject to a chronic, progressive and lethal disease: the Withering Syndrome or Abalone waisting disease, leading to mass mortality.This has caused the closure in California of the fishery of the black abalones in 1993.
Split into simpler sentences: Subject to a chronic, progressive and lethal disease: the Withering Syndrome or Abalone wasting disease, leading to mass mortality. This caused the closure in California of fishing for black abalones in 1993.