Mixed feelings about Lake Eildon feeder streams, can we better care for cod?

Eildon has gained a reputation for fast growing slob sized Murray cod

I’m going to declare at the outset that it is not my intended to ruffle feathers however it may in some quarters, but I feel this topic needs to be laid out and discussed. This subject has being going around in the background for years now although never really openly and I think for a good reason; no one wants to publicise it and burn the rivers. The thing is, by never having the conversation or debate, we will never get close to resolving it, so here it goes.

Following the horrendous drought in the late 2000’s, the Victorian Fisheries Authority (VFA) undertook a massive stocking program to recover native fisheries which had been hit hard. The biggest recipient of stocking was Lake Eildon with over a million fish in 3 years and many more since, importantly these fish were all marked with Calcein at the hatchery stage to aid in their identification as stocked fish via otolith (ear bone) analysis. In 2015, the VFA undertook a survey to determine the success of the stocking vs natural recruitment. The results of the survey (Calcein analysis) showed that 99.6% of Murray cod analysed were indeed from stocking, indicating that natural recruitment was very low. The VFA put forward that the lake lacked the zooplankton required to support emerging fry and there was an extremely low survival rate not warranting the protection of a closed season.

The flow on decision for Lake Eildon was that the closed season intended to protect breeding Murray cod, was not relevant as breeding success is minimal. On the upside, by removing the cod closed season at Lake Eildon it created new springtime fishing opportunities. The thought was that fishing participation and associated tourism in the region would increase, consistent with the State Government’s Target One Million plan. This action clearly made the statement that Lake Eildon’s Murray cod fishery was reliant on fish stocking  i.e. it is managed as a stocked ‘put and take’ cod fishery, a bit like your local lake stocked with trout for the school holidays.

In my fishing circles, the most significant improvements to anglers satisfaction with Lake Eildon have come from the improvements in the quality and quantity of the Murray cod catch, there is no doubt that the VFA’s stocking initiatives have been successful and I am a big fan, I want to make that clear. I have fished Lake Eildon for more than 35 years, however over the last ten I have extensively targeted Murray cod there.  In that time, I have observed a steady increase in catch rate and quality to the point I will now seldom fish elsewhere for cod, where as in the past I often drove significant distances to other impoundments, such as the 1600 kilometres to Copeton Dam in New South Wales.  Make no mistake, Eildon has gone past a lake of great potential, and should now be regarded as one of the very best trophy cod fisheries nationwide. This will only get better, barring a natural disaster such as a genetic catastrophe, this is precisely the point of this blog.

This is the bit I have been shy about discussing, the feeder rivers of Lake Eildon like Big River, the Goulburn and the Delatite and the spawning activity that occurs there. I won’t entertain any discussion to the negative that cod spawn in these rivers, I’ve seen them and so have many other anglers in my circles. On one occasion I counted no less than 11 big cod on my sonar in one pool no doubt sorting out who was hooking up with who for the spring. Now the survey conducted by the VFA in 2015 looked at around 200 fish, what is unclear and I can’t seem to get clarity on, was this survey conducted right across the lake or was it confined to easy to access and high population area’s like Jerusalem Creek and the dam wall? This bit about the location is really important, if it did indeed include a wide diversity of locations across the lake including feeder rivers I will sit down and shut up, but the lack of clarity feeds my suspicion that it was done in a concentrated area where a lot of stocking activity occurs. If so, it skews the result in favour of opening the lake up especially the river arms in the closed season.

Right across Victoria the VFA has restrictions in place to protect spawning cod in flowing waters. Well intended, let’s just say that in terms of Eildon they are pretty loose to successfully employ due to the individual interpretation of where flowing water starts and ends in the lake. It can change inside of an hour, damn it can even shift with a wind change in an instant. It’s clear that the rivers are off limits to cod fishers in the closed season, however this grey area of the lake / river confluence point is almost impossible to resolve. We have seen fishing competitions turned to a farce over this exact issue. Aside from mistakes, unethical targeting of the spawaners occurs well upstream in unambiguous flowing water during the close. I say it’s unambiguous however for the up-river fishers perhaps it’s not so clear without a hard and defined geographical seasonal boundary? Enforcement up in the feeder rivers is pretty low, not saying you will never see a fisheries officer there, but certainly don’t bank on it, I never have despite spending many days well up in the arms, but many times I’ve had a visit in the lake itself, resources only go so far.

Why do I care and why am I shining a light on this? Right or wrong, I believe that the Eildon river fish spawn (not many will disagree) but I feel that they are also very successful at it (yes this is a point of contention). Why this matters to me and perhaps should to you, is that the genetic diversity that they give to the lake has to be beneficial to the health of future generations. In a situation where the lake is currently relying on stockers, some wild fish in the gene pool has to be important, it’s a matter of record that fisheries worldwide that rely 100% on stocking is not an ideal situation due to disease and mutations. There are pretty much no signs of this in Eildon to this point, but this is about the long term health of the fishery and not instant gratification.

Our historical practices around building dams and clearing rivers aren’t great for native fish that rely on ability to move upstream at the right water temperatures to spawn in spring. Lots of great habitat work has been conducted however it is a mighty task to undo the presence of a dam mid river. The regular irrigation season high flows that commence in August into the Goulburn River below Eildon can cause a shock of cold water from the bottom of the dam, known as cold water pollution and is not conducive to successful spawning downstream. To me, these difficulties that native fish face, make successful spawning fish wherever they occur something that surely needs more of our focus. I’m throwing it out there that during the recognised breeding season the river fish above Lake Eildon should be better afforded protection, some of these fish may have been there before the dam was built and romanticism aside, their spawn is valuable in a stocker world where the assurances of long term funding to do so can never been seen as guaranteed.

The VFA has announced a two year tracking study in the upper Goulburn to determine if those fish intermingle with the lakes population, this will certainly be interesting and lets hope we get some answers around genetics while they are at it. Now I am no scientist, but I really feel there are some questions that really need answers before action occurs one way or the other. Considerations around temporary access or activity restrictions around the river arms during spawning periods have to be had at some point, we even do it for trout in some locations and to be blunt cod on the whole have to be seen as the priority. Undoubtedly stocking is the reason our fisheries are doing so well, however surely wild spawners deserve our respect too.