Researchers are alarmed by the notable decline of Port Jackson sharks in the waters of Adelaide, as efforts have yielded no discovery of any eggs from the recent breeding season. This raises serious concerns regarding the local population's survival, as the sharks had previously been a common sight for snorkellers and swimmers in shallow reef areas off Christies Beach.

Ecologists speculate that an extensive algal bloom could be responsible for either the death of these sharks or their migration away from the region. The Department of Environment and Water is considering strategies such as repopulating affected areas, however, their specific plans for Port Jackson sharks remain uncertain. The implications of this situation are significant, as these sharks play an integral role in the marine ecosystem's balance.

The sudden absence of this species raises questions about the broader ecological health of the Adelaide coastal waters. The Port Jackson shark is known for its harmlessness to humans, making its retreat from popular marine areas a troubling signal of environmental degradation and a potential warning about the effects of algal blooms on local biodiversity.