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.
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
| Year | Month | Grade |
|---|---|---|
| 2024 | A | |
| 2023 | A | |
| 2022 | A | |
| 2021 | June | E |
| 2020 | A | |
| 2019 | May and December | E |
| 2018 | A | |
| 2017 | A |