Archives for April 2022

Breaking down barriers to help increase the fish population

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Almost half of the fish species in the Mackay Whitsunday region can live in both freshwater and
saltwater environments. They move between these habitats for a variety of reasons including to
feed, reproduce and avoid predators. Ideally, fish should be able to move freely and easily between
different habitats. Unfortunately, barriers like dams, weirs, road crossings and other man-made
structures can prevent or inhibit the movement of fish throughout the catchment.

This is a concern for the fish population, and locally important species such as barramundi, sea
mullet, mangrove jack, jungle perch, tarpon and long-finned eels, which are significantly affected if
they’re unable to access breeding and feeding habitats. In many cases the fish are unable to
complete their life cycle and sustain a healthy and resilient population.

Reef Catchments, with funding from the Australian Government’s Reef Trust, contracted local fish
experts at Catchment Solutions to update a fish barrier prioritisation report from 2015. The current
study identifies 9,738 potential fish barriers, more than doubling the number found in 2015 (3974).
Only a small fraction of the increase was attributed to new barriers, with the bulk resulting from the
use of better satellite imagery, improved stream mapping and addition of wetlands to the study
area.

Identification of barriers

This study not only identifies the locations of barriers, but also includes an analysis to rank the
barriers in order of importance for fish passage. The barrier ranking process determined the extent
to which barriers affected the sustainability of fish communities, with barriers top ranked having the
worst impact on fish communities.

Fish barriers.Key criteria included:

  • the available habitat upstream from the barrier
  • the size of streams
  • the proportion of intensive land use in the sub-catchment
  • the number of barriers downstream
  • the distance from the estuary, stream flow, habitat condition
  • the physical characteristics of the barrier

Priority for remediation

Reef Catchments Conservation and Communities Officer Carlos Bueno, said that the purpose of the
prioritisation was to identify key sites for investment, which is an ongoing priority for Reef
Catchments and local governments.

The updated report identifies Stafford’s Crossing (O’Connell River), Vitanza Road (Saltwater Creek),
Marklands Wetlands, Flaggy Rock and Andromache Weirs, and many others, as top priority for
remediation. The next step is to fix the highly ranked barriers to improve fish movement and habitat
availability.

Catchment Solutions Fisheries Ecologist Trent Power, said that the current prioritisation took a big
leap forward in terms of being able to remotely identify barriers to fish passage. This will help Reef
Catchments, Mackay and Whitsunday Regional Council and other catchment groups focus their
funding on sites which will deliver the greatest benefit to local fish stocks.

Full report

Long reach excavator targets wetland weeds

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Reef Catchments is working to protect and restore wetlands south of Mackay, assisting
landholders in the Sandringham Wetland Complex to manage their land and improve grazing
practices.

As part of this project, which is funded by the Australian Government’s Reef Trust, a
long reach excavator has been brought in for a trial to mechanically remove water hyacinth
and put it into the adjacent fallow cane paddocks as mulch, as an alternative to spraying vast
amounts of herbicides to control this localised infestation.

Reef Catchments and the landholder are investigating if the mulch layer of aquatic weeds in
the paddock will improve soil conditions and benefit the next cane crop, optimising the balance
between production and ecosystem protection, promoting a health environment for the native
birds and fish species, and reducing pollutants running off to the Great Barrier Reef lagoon. The
potential for biocontrol releases is also being investigated, which could deal with the infestation
long-term, since the seed bank can be viable for up to 25 years.

The Plane Creek catchment, in which the Sandringham Wetland Complex is located, covers
2,539 square kilometres, and 28% of the Mackay Whitsunday Isaac (MWI) region. Reef
Catchments is partnering with landholders in the Sandringham Wetland Complex to improve fish
habitat, restore native vegetation and improve water quality.

Assisting landholders

Reef Catchments has already assisted local landholders to implement over 6.5km of new wildlife
friendly fencing and 11 additional off-stream watering points to manage stock access in sensitive
ecological areas. Wetland habitats are an important part of many grazing properties in
Queensland. Most wetlands in Queensland are on private land, and many are on properties that
run grazing businesses.

Reef Catchments Project Officer – Conservation and Communities, Carlos Bueno, said, “The
Sandringham Wetland Complex provides many vital functions to the local coastal area due to its
unique soil types and water holding capacity.

“Improvements and adoption of best management
practices on these critical ecosystems can enhance the ecosystem and improve grazing
productivity.

“Graziers value the Sandringham Wetland Complex for providing water and feed for stock, and
reserves during the dry season or droughts. The impacts of grazing on wetlands can include
reduced water quality from additional nutrient inputs, increased soil compaction and reduced
native vegetation.”

Wetlands are the boundary between two different ecosystems, dry and wet, which means they
have a unique role in nutrient exchange and water supply to surrounding lands. They also provide
habitat, food, and shelter to many different plants and animals including endangered, vulnerable,
and migratory species.