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Fish Kills Report Card

Aquatic Plants

B

Aquatic Plants

Macroinvertebrates

C

Black Bream

A

Waterbirds

C

Fish Kills

A

Water Quality

C

Major fish kills have been recorded in the Vasse Estuary since 1905 with large fish kills reported every 5-10 years. Fish kills are usually caused by low dissolved oxygen and/or phytoplankton species that are toxic to fish. Fish kills grades are outlined below.

2024 Fish Kills Grade

A

Key Findings 2024

  • No fish deaths have been recorded in the Vasse Wonnerup wetlands in the last 3 years.
  • Fish deaths in the Vasse Wonnerup wetlands in the past have occurred most often in the Vasse Channel, and upstream of the floodgates.
  • Low dissolved oxygen has been the cause of most recent fish kills in the Vasse Wonnerup Estuary, often associated with an algal bloom.
  • The most recent fish kill in June 2021 killed an estimated 20,000 black bream and 5,000 mullet and was caused by a late season algal bloom causing low dissolved oxygen levels in the Vasse Estuary Channel.

Fish Kills Grades Over Time

A

Excellent

0

B

Very Good

<100

C

Fair

100-999

D

Poor

1,000-5,000

E

Very Poor

>5,000

Estimated number of fish deaths

YearMonthGrade
2024A
2023A
2022A
2021JuneE
2020A
2019May and DecemberE
2018A
2017A

View other report cards

Aquatic Plants

B

Aquatic Plants

Macroinvertebrates

C

Black Bream

A

Waterbirds

C

Water Quality

C