Flashbacks to Blackfish: Lachie revisits past lives and reflects on the importance of permanent pools in waterways
What a pleasure a recent week spent in the field was. Not only did I have a chance to repeat a survey that NGT’s Lauren Brown initiated six years ago, I’ve also revisited what feels like a past life.
During my time at Deakin University, I had the pleasure of sharing a lab with Stephen (Bluey) Ryan. He was undertaking his honours and was investigating the population structure of river blackfish. We covered country from northern NSW, all the way over to the Fleurieu Peninsula in SA, but it was the fish in our backyard, the Wannon River, that yielded the biggest surprise. I can’t quite recall the details but something about the fin spines made these fish stand out. It’s funny that I can’t remember the specifics but I can still remember Paul Kelly’s song “Bradman” playing while we were driving around the Grampians, replaying every time we stopped the car to check out a creek. Anyway, Stephen’s work paved the way for further taxonomic investigation and substantiation of the unique status of western Victorian blackfish.
I had a similar flashback to those field trips with Stephen when I moved to the South East of SA again 14 years ago (2008), to work with the then Department for Environment and Heritage. When I first arrived Scott Slater, who was working as a fish ecologist at the time, informed me the blackfish in Mosquito Creek were on the brink of local extinction. I found this hard to believe as Stephen and I had caught dozens near the Naracoorte Caves in the space of about an hour, out of the boot of a Commodore station wagon in 1999. I naively thought Scott probably didn’t know how to catch them, which is funny in hindsight because he is one of the most capable fisherman I’ve ever met.
After the sudden demise of permanent baseflows in Mosquito Creek in the early 2000s due to declining groundwater, sadly, I ended up helping Scott capture the last known blackfish from Mosquito Creek. I’ve always had a hope that they might just be hiding somewhere and magically reappear, but they haven’t. It’s the first time I can pinpoint a realisation that irreversible, environmental decline is real and happening around us.
It’s not hard to become despondent when we experience these declines first hand, but it’s also important that we find gratitude when we experience preservation. And hence this brings me to the point of this lengthy pretext. Our recent follow up surveys of refuge pools on the Wannon River took me back to Jimmy’s Creek campground, where Stephen and I collected specimens over 20 years ago. I’ve camped there a few times over the years and while I’ve often thought about those blackfish, I haven’t actually checked to see if they are still there. I’m now happy to report that they are, and the range of size classes indicates that they are still breeding. So despite the ongoing decline in flows experienced since diversion of the headwaters of the Wannon River to Lake Bellfield, and particularly since a step change in rainfall since the mid-1990s, this section of the river remains a key refuge for the species and, in particular, this distinct taxonomic variety.
Aside from a bit of nostalgia, we also collected some important observations for a range of other species, including little galaxias, obscure galaxiids, pygmy perch and Glenelg spiny freshwater crayfish. Like many Australian waterways, the Wannon River dries down to a chain of ponds and the integrity of these permanent pools is critical refuge habitat for maintaining the integrity of this local and regionally significant fish community. It’s good to see some positive signs in terms of fish numbers and size distribution (they are still breeding) since we last visited.
All of this information is feeding into our documentation of the health of the Wannon River, an important project funded by the Australian Government’s National Heritage Grants.