FISH MONITORING ON THE ANGLESEA RIVER

This month scientists from the Arthur Rylah Institute (ARI) conducted a fish monitoring survey
in the Anglesea River estuary. They surveyed both the number and species of fish currently living in the river.

The survey found four species of fish, Black bream, Smooth toadfish, Yellow-eyed mullet, and
Australian Salmon.

Most of the fish surveyed were small juveniles, with only a small number of large fish collected.
The majority of fish currently living in the Anglesea River estuary are small (under 60mm)
juvenile Black Bream.

Corangamite CMA will continue to monitor water quality conditions in the river and keep the
community updated about actions underway in the Anglesea River estuary.

BACKGROUND

Since mid-2019 the Anglesea River has been persistently acidic with very little fish life.
In late 2022, after persistent heavy rain, the Anglesea River reconnected with the ocean,
allowing for free passage of water between the ocean and the river. This provided an
opportunity for fish migration into the river and improved water quality.

Flows from the upper catchment tributaries of Salt and Marshy creeks have since reduced, and
the river mouth has recently closed. This is likely to result in increasing acidity into the future,
especially if rainfall mobilizes acid sulfate soils in the upper catchment wetlands.

With estuary closure, the river level has also dropped, creating a significant risk of activating
acid sulfate soils at Coogoorah Park and releasing metals and acids into the river system.

Releases of stored water have commenced into the Anglesea River to reduce the risk of
activating acid sulfate soils in Coogoorah Park. The stored water having been harvested from
the Anglesea River during winter has a low pH and may contribute to increasing the acidity of

the river. However, the risk of continued low water levels in the estuary activating additional
areas of acid sulphate soils has been identified as a more significant and irreversible overall risk
to the Anglesea River.

The Corangamite CMA has been working with other agencies, including Surf Coast Shire Council
and the EPA, to try to mitigate the effects of acid water on the fish population. To this end we
have been monitoring acid levels, dissolved oxygen levels and river height levels.

The Anglesea River is enjoyed by the Surf Coast communities and remains a popular holiday
destination for many Victorians. The river remains safe for local and visitor communities to
enjoy water-based recreation.