Our team was engaged to undertake aquatic ecology surveys and assessments to support environmental planning and approvals requirements for Queensland Rail’s Timber Bridge Replacement Program. The objective of this program is to upgrade and replace old timber bridging with concrete and steel bridges which will require minimal maintenance, be flood resilient, and be resistant to fire or insects.
Communities need to move around to flourish, as do fish
Replacement of timber bridges on the North Coast Line will enhance access for local communities and facilitate higher productivity vehicle access.
However, the program also has environmental considerations. Many instream structures such as culverts, dams, and weirs are built on Queensland waterways, presenting potential barriers to fish moving into waters upstream or downstream.
Allowing fish passage is essential for the survival and health of fish populations. Fish need to be able to move freely through rivers and streams to access different habitats, find food and reproduce. Without the ability to move freely, fish populations can become isolated and depleted, and declines in many native fish species are thought to be due to the impacts of barriers to fish movement.
Additionally, allowing fish passage helps to maintain the overall health of the ecosystem. Fish play a vital role in many aquatic environments, serving as both predators and prey. By allowing fish to move freely, it is possible to maintain the balance of the ecosystem and support the health of other species that depend on fish for food.
Waterways for waterway barrier works are those that are identified by the government as being waterways for fish passage. The development of new, or existing waterway barriers, must provide adequate fish passage.
Safeguarding our living waterways
Our team was engaged to assess 18 crossings between Cardwell and Tully to determine whether they were defined and classified as waterway barrier works.
Of the 18, nine were identified as waterway barrier works that required waterway barrier works assessments addressing the requirements of Queensland’s development assessment provisions under the Planning Act 2016 (Qld) (Planning Act).
A substantial part of this engagement involved undertaking aquatic ecology surveys examining the biology, population, and diversity of fish species at each site to work out how they may be impacted by variations caused by the bridge works. Fieldwork is essential to carry out aquatic ecology surveys but can be quite perilous.
One survey method was to deploy overnight traps in several locations, returning the following morning to study the trapped fish, plus electrofishing in some streams. Crocodiles are a real danger in the Tully area, so we must be very mindful of the methods we use to conduct our research.
NGH North Queensland
Threats to our native fish come in all shapes and sizes
During fieldwork, our aquatic ecology team discovered that the proposed waterway barrier works were not the only threat to our native fish in the area.
We discovered and identified an invasive species, the Mangrove Tilapia, 100km outside of its known range. This is a very resilient fish species that out-competes and out-survives our native species because they can breed prolifically in our tropical waters.
Having reported the find to the Department of Agriculture and Fisheries, as the biosecurity regulator, there are controls and measures they can put in place with this knowledge.
Helping to keep the project on track
Our aquatic ecology surveys and fieldwork observations, coupled with extensive desktop research and interpretation of engineering design and hydrology reports, informed the development assessments which were lodged with the Council and the State Government.
Prior to us being engaged, work on this project had already begun and was edging closer to the waterways in question, so our client required urgent approvals.
To support our client and maintain the project’s momentum, we liaised early and frequently with the Council’s development assessor to secure expedited approvals which would normally take a minimum of 12 weeks to process.
The bridges are now complete on the drive north from Cardwell along the western side of the Bruce highway.