mmg.com.au

The drawdown of water in Lake Benalla to combat the aquatic pest plant Cabomba will go ahead in early February after a study concluded the planned action posed no significant risk to local platypus breeding success.

Manager of strategic river health for Goulburn Broken Catchment Management Authority, Wayne Tennant said Cabomba was a major looming threat to waterway health in the Broken River catchment and Lake Benalla.

‘‘Draining the main body of the lake so Cabomba dries up in the summer heat is the best way to achieve significant control,’’ Mr Tennant said.

‘‘However, because platypus breed just once a year, with juveniles emerging from their nursery burrows from late January onwards, it is also important to ensure that the timing of the drawdown doesn’t have a negative impact on Lake Benalla’s platypus population.’’

The drawdown of the lake will last 6-8 weeks and is being undertaken with the assistance of Benalla Rural City. At the Goulburn Broken CMA’s request, researchers from the Australian Platypus Conservancy conducted a platypus survey at Benalla just before Australia Day.

Three days of early morning and late evening survey sessions were carried out by two experienced platypus biologists. The study recorded platypus at all of the five sites monitored just upstream of the lake in both the Broken River and Holland Branch, which will continue to hold water after the lake is drained. The only platypus to be seen from any of the 11 survey sites distributed around the main lake was actually feeding at the mouth of Holland Branch.

The survey results indicate it is highly unlikely that any female platypus have established breeding burrows in the main part of the lake this year. Platypus are naturally highly mobile animals and shouldn’t have any trouble shifting their activity patterns for a few weeks to accommodate the lake drawdown.

■For further information about the Platypus survey phone Goulburn Broken CMA on 58201100 or email reception@gbcma.vic.gov.au