Back to the Future: Bullen Merri Monsters

Fisheries Manager Taylor Hunt talks about how smart stocking is turning back time and re-establishing trophy Chinook salmon in Victoria’s Crater lakes. 

Fish stocking is the mainstay of many impoundment fisheries in Victoria providing excellent recreational fishing for anglers. Many anglers may have heard the fantastic news that the recommencement of stocking of Chinook salmon into the Crater lakes of Bullen Merri and Purrumbete has resulted in the return of trophy Chinook salmon. In 2016, fishers have again caught trophy Chinook salmon to 5.6kg (12lb) and multiple specimens over 4.5kg (9lb). Good numbers of football shaped rainbow trout over 2kg have also been caught.

Trophy Chinook salmon are once again available to fishers at Lake Bullen Merri. Check out Maz Stowlowksi with his 12lb monster!

The returning quality fishery is a result of significant efforts into recovering Chinook salmon fisheries over the past five years, particularly through improved fish production at Fisheries Victoria Snobs Creek Hatchery and science determining optimal numbers for stocking – resulting in smart stocking! Here the journey is shared:

World-class salmonid fisheries

The Crater lakes of Lakes Bullen Merri and Purrumbete, located in south-western Victoria, have a long history of top notch salmon and trout fishing on the back of fish stocking. Particularly in the 1970’s and 80’s, these fisheries were heralded as the best salmonid fisheries in Australia. The dried skin of Henry Rantall’s 23lb 2oz (10.5kg) Chinook salmon caught in 1980 still hangs above the doorway in the Lake Bullen Merri Angling clubrooms, reminding visitors of how good the fishing can be in the Crater lakes. Memories of up to 5,000 anglers lining the banks for the opening of the salmon season in 1978 are testament to how incredibly popular these Chinook salmon fisheries once were.

Chinook salmon of the Lake’s Bullen Merri and Purrumbete were known to reach 12kg and over 87cm in the 1970’s and 80’s.

Tough times

But off the back of the millennium drought (1997-2009), Chinook salmon stocks in Victoria were on their knees. Low rainfall coupled with warm temperatures had resulted in poor broodstock spawning’s at Snobs Creek and resulted in both limited stocking in the Crater Lakes and breeding of future broodstock. Unless something was done, the future of the only Chinook salmon fisheries in Australia was looking bleak. A ban on salmonid importation dating back to 1967 meant that if our broodstock were lost, Chinook salmon fishing in Australia would not be seen again.

The turning point

In 2010, Fisheries Victoria and VRFish met in Ballarat and hatched a plan to return these powerhouse Chinook salmon fisheries to their former glory. A project led by Anthony Forster and funded by recreational fishing licence fee’s conducted three critical steps in the recovery of Chinook salmon:

  • a genetic fitness assessment of Chinook salmon broodstock held at Snobs Creek,
  • a review of Chinook salmon production methods at Snobs Creek,
  • and the purchase of new production equipment including incubators, chilling system, self-cleaning tanks and a filtration unit.

The tasks were a huge success and lead to a major increase in salmon production, fertilisation rates, survival and growth rates and availability of fish for stocking. The final step was to design a stocking program that maximises returns for anglers in both numbers of fish caught and size of those fish. To do this Fisheries Victoria worked closely with the freshwater fishing community to review the stocking and fishery performance history of Chinook salmon.

Angling club records

Fishery performance information was collated from 40 research reports and 25 years of Fisheries Victoria netting surveys and angler creel surveys between 1984 and 2003. This included information such as catch-rate, length, weight and condition of Chinook salmon. All of this fishery performance information was statistically compared against 133 years of stocking records in the crater lakes and assessed for significant trends. But it wasn’t until we also included over 4000 club records collected by the Lake Purrumbete and Camperdown Angling Clubs since 1969 that meaningful trends appeared between fish stocking and fishery performance.

Central to the trends was the idea that there is only limited food in the Crater Lakes to support fish growth. Stocking more fish over the years had resulted in higher catch rates but smaller sized fish due to competition for the same food resources. Stocking less fish over the years had resulted in lower catch rates but larger fish due to less competition. Stocking other species alongside Chinook salmon also impacted their performance. To get the best out of our restocking of Chinook salmon, it was clear that the balance of numbers and species needed to be carefully considered.

Smart stocking

Informed by the science and in a bold move at the time, fisheries managers proposed a four-year stocking plan to restore trophy Chinook salmon fisheries to the Crater lakes. The stocking plan included the short-term suspension of stocking of brown trout for two years and only modest numbers of rainbow trout were released alongside Chinook salmon. The key rationale for this stocking plan was:

  • Anglers wanted the return of trophy Chinook salmon to the Crater lakes and the science told us to get there we needed to limit overall numbers of fish to be stocked,
  • Brown trout are long lived salmonid species and by competing for the forage fish population with Chinook salmon, they impact their growth and condition,
  • Brown trout are widely available in other waters throughout Victoria, whereas Chinook salmon, have only ever reliably performed well in the Crater lakes,

The four-year stocking plan was discussed with and endorsed by recreational fishing representative groups at a meeting held at the Lake Purrumbete Angling Club rooms in August 2012. In November 2012, the first Chinook salmon fingerlings were released into Lake Bullen Merri. This was the first time Chinook salmon had been stocked into Victorian waters for five-years.

A Snobs Creek Hatchery Chinook salmon about to be stocked into the Crater lakes.

Monitoring results

Thanks to the commitment of Rob Hems and the Lake Purrumbete and Camperdown Angling Clubs, a detailed monitoring program funded by Recreational Fishing Licences fees was established in 2013 to track the performance of the stocking plan.

The monitoring has since collected valuable information on the fishery through an angler creel survey interviewing more than 1,100 anglers at Lake Purrumbete, and over three years of catch and effort statistics collected by members of the Lake Purrumbete and Camperdown Angling Clubs across both Crater lakes.

Results from the monitoring project found Chinook salmon have performed very well in Lake Bullen Merri, with high catch rates by anglers and some specimens reaching impressive sizes over 5kg. In nearby Lake Purrumbete, Chinook salmon had also delivered high catch rates for anglers, but have not grown as large as hoped with the largest fish being 2-3kg.

Adaptive management and the future

Fisheries managers and anglers met in 2015 to discuss the monitoring results and consequently stocking plans were adjusted for the Crater lakes to optimise what each can deliver for freshwater anglers. To provide a range of high quality trout and salmon fishing opportunities across both lakes, stocking plans were to focus on high quality Chinook salmon and rainbow trout for Lake Bullen Merri, whereas stocking plans were prioritised towards brown trout in Lake Purrumbete. Chinook salmon likely haven’t performed well in Lake Purrumbete due to the redfin population and this issue is being assessed through a separate project.

Fisheries Victoria are delighted with the exceptional fishing at Bullen Merri as a result of smart stocking in strong partnership with anglers. Fisheries managers will continue to work on ways to maintain and continue to improve fishing at the Crater lakes and other waters around the state. Considering some of the larger Chinook salmon caught this year were not in full spawning colours, we are optimistic bigger fish are yet to be caught by anglers. Furthermore, another strategy currently being trialled for the Crater lakes is to on-grow Chinook salmon quickly using temperature controlled recirculation technology and stock them after five, rather than 13 months after hatching. These fish may grow faster and consequently bigger for anglers to catch in the future. Stay tuned for results of the trial.

With 10 pounders readily available, the next target are the 15-20 pounders of the past and I’m optimistic that smart stocking may get us there yet!

Since stocking recommenced in 2011, anglers have seen the size of Chinook salmon rapidly grow in the Bullen Merri fishery. Photo source: Ben Bremer.

This article appeared in our Winter 2016 edition of our Fishing Lines magazine.

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