Im not sure about the seaway but around 10 years ago in the Coomera river where the fresh and salt water meet, there used to be swarms of herring, jacks, mullet, bream, tailor and to many other fish to list. Most afternoons after school and on the weekends my dad and i used to fish there. You would get dozens of fish in as many minutes until a concrete plant was built upstream.
Within a few months there was hardly any fish in the area and i beleive something from the plant was to blame .
