Complex sentence: The effects of this course of action by fishery departments has been stark, and catastrophic events such as drought or bushfire, after which introduced trout species were restocked but upland native fish were not restocked, have shifted the balance further.
Split into simpler sentences: The effects of this course of action by fishery departments has been stark. Catastrophic events such as drought or bushfire, after which introduced trout species were restocked but upland native fish were not restocked, have shifted the balance further.