Inland Waterway's work to increase the native fish carrying capacity of the Macquarie River ramped up last week, with $60,000 worth of snags going in the Macquarie River. This took the group's total breeding snags placed in the water to 336, or $166,750 worth of work, with funds generated through the Easter Lake Burrendong Fishing Classic, and Habitat Action Grants.
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Many fishers know that anglers will catch 9 out of 10 murray cod right next to, or near some form of snag or structure, however within the scientific community a debate has been raging for many years about the effectiveness of introducing new habitat into large rivers- until now!
As reported by Fishing World, scientists have been arguing about the effectiveness of what is sometimes referred to as the "honeypot effect", when new habitat is introduced for fish in a large river, the question is does the number of fish increase, or do the fish already present simply move to the new habitat?
A team of scientists from the Arthur Rylah Institute, University of Melbourne, University of Canberra, the Federal Government, and Flinders University have finally answered this question, but it wasn't simple, quick, or easy.
In a publication just released in the scientific journal Ecological Applications, Dr Jarod Lyon and his team describe how they took a large-scale approach, in terms of time, effort and space. They studied 110 km of the Murray River over seven years, and with partners at NSW Department of Primary Industries installed more than 4450 "snags" (mainly large pieces of wood), recorded more than 10 thousand fish, and analysed more than six million records of tagged fish.
This work shows that providing woody habitat ("snags") for fish in the Murray River did indeed result in an increase in the population size of native fish.
"We found a three-fold increase in the abundance of Murray cod, and a doubling of abundance of golden perch, in the reach of river where habitat restoration was done, compared to sites where habitat remained constant," Dr Lyon said.
"This was certainly an encouraging finding", he continued. 'In addition, abundances of the target species in the adjacent reference sites remained stable, indicating that the numbers of fish across the whole study area had increased, rather than just the same fishes just moving around'.
'These results give great confidence to river managers that installing woody habitat really does help native fish populations thrive and delivers substantial benefits to the communities using them."