Sentence:  They like to spend their time in freshwater rivers in coastal waters. Saltwater crocodiles are fiercely territorial and fully mature male <WSD>salties</WSD> force younger and smaller <WSD>salties</WSD> into the ocean where they have to search for river systems. 
Meaning of the word marked with <WSD> tags:  A salt-water crocodile (or estuarine crocodile).