Anchovy are an important prey item of Little Penguins and numerous fish species in Port Phillip Bay. They’re also great on pizza!
So Channel Deepening through their spawning habitat in Hobsons Bay and the Yarra is cause for concern, as is disposal of contaminated dredged sediments in the Bay. In response to these concerns, a Baywide Anchovy Survey is being conducted over several years.
Anchovy larvae comprised 74.5% of total fish larvae sampled in PPB during November to January of 2007-08. Curiously, just 6 months later, the Baywide Anchovy Study Sub-Program conducted during June-July 2008 recorded no Anchovy in the 0+ (first year) age class.
The Goomai grab-dredge in the Yarra
Explanations cited for the failure to find first year Anchovy are:
1. Anchovy of 0+ years of age occur in regions of PPB not sampled;
2. Fish of this size may not have been sampled due to loss through the net;
3. A recruitment failure may have occurred beyond the larval stage.
If anchovy recruitment from the 2007- 2008 season has failed, the effects on penguin foraging would initially be absorbed by the presence of the 1+, 2+, and 3+ year classes. Increased penguin preying on older age class Anchovy is likely to reduce the mature (reproductive) Anchovy population. Combined with the absence of the 0+ age class Anchovy, this is likely to impact on Anchovy recruitment in subsequent seasons.
The degree of impact of the dredging program on penguin prey species such as Anchovy, like many other aspects of the project, will often take more than a year or two to show up. The results of the 2009 Anchovy surveys are sure to be really interesting.
