Key socio-economic species such as barramundi, sea mullet, mangrove jack, jungle perch, tarpon and long-finned eels are significantly affected by a large number of anthropogenic barriers that prevent, delay or obstruct fish migration in the Mackay Whitsundays (MW) region.
Barriers in the MW region impact freshwater fish communities, affect aquatic ecosystem resilience and reduce the vicarious values the local community places on waterways flowing into the Great Barrier Reef Marine Park.
This report has been commissioned by Reef Catchments Limited (RCL) Natural Resource Management (NRM) group to identify and prioritise regional barriers. The Report comprises a three-stage fish barrier prioritisation process (FBPP) that comprehensively ranks barriers to fish passage based on a number of key biological, geographic and economic considerations.
The prioritisation process initially utilised Geographic Information System (GIS) software to rapidly assess thousands of potential barriers before undertaking a collective optimisation and rank-and-score approach. Importantly, key socio-economic ‘flow on’ benefits of improving aquatic ecosystem connectivity have been considered i.e. increasing fisheries productivity and conserving vulnerable fish species.
Fish migration is an essential life history adaptation utilised by many MW fish species. Migration strategies between key habitats have evolved for a variety of reasons, including for feeding and reproduction purposes, to avoid predators, to utilise nursery areas and maintain genetic diversity.
Barriers preventing connectivity in the MW region impact fisheries’ productivity and create environmental conditions favourable for invasive fish species. Significantly, approximately 48% of MW region fish species undertake ontogenetic shifts in habitat use between near-shore marine and freshwater environments. Low transparency barriers located on high ordered streams close to the tidal interface have the greatest impact, preventing and impeding juvenile diadromous species from undertaking important longitudinal and lateral life-cycle dependant migrations into critical nursery habitats.
In many parts of the world remediation of barriers with appropriately designed fishways is one of the most successful management tools utilised by government agencies and natural resource management groups to help reduce the impacts of barriers. However, objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. The following MW barrier prioritisation process achieves this by investigating the cumulative impacts barriers have on the environment, fishery, economy and local community. The resulting priority ranked list will assist natural resource managers and decision makers in determining where best to allocate limited funding opportunities to ensure the greatest environmental and socio-economic outcomes for the MW region.