Murray Cod is an iconic native fish species that is highly valued by recreational fishers. For many years, Fisheries Victoria and the Department of Environment and Primary Industries, have been conducting research on Murray Cod populations and fisheries. In recent years anglers and researchers alike, have noticed that Murray Cod populations contain relatively few larger fish. To improve the population in the past, fisheries managers have typically increased the minimum size limit. This has improved the numbers of smaller fish in the population, but it has not significantly increased the numbers of large fish in the population, and this means that the best breeders aren't protected.  

The best breeders in fish are the big ones. For Murray Cod these are fish seventy centimetres and above. Big fish are better breeders because they know where to lay their eggs and how to protect them. They pass on their good genes, and they produce large numbers of eggs, and bigger eggs that have a better chance of survival. 
For example in Murray Cod, a fifty centimetre fish will produce around seven thousand eggs, compared to a ninety centimetre fish that produces around sixty thousand eggs.
 
Recent international research dealing with other species has also revealed that setting a minimum, and a maximum size limit, otherwise known as a slot limit, is a better way to sustain a healthy fishery. And by a healthy fishery, I mean a more natural population structure, which includes a large number of fish for breeding, a large number of fish available for harvest, and a large number of trophy fish available for catch and release. 
So the question we had, was do slot limits work for Murray Cod?

To answer this question we used decades of fishery survey information on Murray Cod populations, as well as information provided by recreational anglers, to scientifically test whether slot limits would improve the Murray Cod fishery. 
Previous research conducted by fisheries experts from the Department of Environment and Primary Industries, tested and confirmed that a fifty to seventy centimetre slot limit, offers significant benefits over the existing sixty to one hundred size limit regulation.  The proposed fifty to seventy centimetre slot limit allows anglers to catch more medium sized fish for harvest, whilst protecting the breeding population. 

The research found that over fifteen years, the fifty to seventy centimetre slot limit provided a twelve per cent increase in the number of fish available to harvest, a hundred and forty seven per cent increase in the number of fish over one metre, and a significant improvement to the overall sustainability of the population. 
This research was presented to the Victorian Murray Cod reference group which is a group of twelve experienced Murray Cod fishers from right around Victoria. The group provided their feedback and strong support for implementation of a fifty to seventy centimetre slot limit for Murray Cod. 
Additionally, the Victorian Murray Cod reference group proposed a bag limit reduction for Murray Cod in rivers from two to one fish per day, to protect fish that are naturally breeding, whilst maintaining the bag limit in impoundments and lakes at two fish per day, because these waters are largely sustained by stocking. 
For after sitting in on the Murray Cod reference group which I felt quite privileged to do, it was pretty clear the science behind the slot limits, sustainability and the future wellbeing of Murray Cod, it was pretty obvious that they are taking a step in the right direction, and while it not, might not please everybody, I am sure it is in the fishes best welfare and ah, just one of many steps on the road to improving our fishery as a whole. 
This is definitely the way forward in progressive fisheries management and I fully support these moves. It will protect our larger Murray Cod and in doing so increase the overall population. This will give us better sustainability, a better fishery and in my opinion improve stocks of take size fish. 
To summarise based on this research and support from the Victorian Murray Cod fisher reference group, Fisheries Victoria are proposing the implementation of a fifty to seventy centimetre slot limit state wide for Murray Cod, and a reduction in the bag limit from two to one fish per day in rivers, whilst maintaining the bag limit in lakes and impoundments at two fish per day.  We have always encouraged anglers to let the little ones go so they can grow, now we are encouraging anglers to let the big ones go so then numbers can grow.  For further information, and to provide your comments on this proposal, please visit the DEPI website where you can read a consultation paper, and provide your feedback.