Aquatic Ecologist, Keen Lure Fisher
Matt is a fisheries biologist with a specialist focus on aquatic ecosystems, including GIS stream network analysis and ordering, in-stream habitat rehabilitation, and fishway construction and engineering. He also leads the design and construction of wetlands to improve water quality and aquatic ecosystem habitat.
Connecting Estuaries With Wetlands
- In terms of migratory habits, Australian fish species are the opposite of most northern hemisphere species. Rather than powerful, mature fish migrating upstream against the current to spawn, almost all Australian migratory species need to move downstream into the estuaries or coastal areas for spawning. This includes iconic sport fish such as barramundi, tarpon, mangrove jack and jungle perch, as well as dozens of small native species.
- The small size and weaker swimming ability of our fish makes it difficult to get past physical and flow velocity barriers. Migrating barramundi, for example are 25-30mm long and struggle to get over an 8cm waterfall. In the northern hemisphere, salmon ids are large and powerful and can leap over quite large barriers.
- This leaves Australia’s native fish vulnerable as the juveniles are exposed to predation if they remain in the estuaries, but even relatively small barriers such as pipes, culverts, road crossings etc can prevent them moving to the safety of upstream areas to grow out. With high predation and low recruitment to the upstream areas, fish stocks suffer.
- There are literally tens of thousands of potential fish barriers in Queensland alone and the cost and labour associated with fixing them all is enourmous. Matt’s group works on prioritisation plans and implements fishways where possible and where they are likely to be most beneficial.
- While fishways have the potential to make the spread of some exotic pest species easier, this needs to be weighed up against the loss of native species from those areas due to lack of connectivity. Apex species (ie most of the sport fishing species) also play a big role in predation on exotic species, so their absence from freshwater habitats aids the exotics to get a foothold.
- Fish stocking is a useful tool and can go some way toward restoring the numbers of iconic species in upper areas of the freshwater systems but could become unnecessary in All but landlocked impoundments if there was good connectivity and quality habitat.