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Southern Gulf Catchments Ltd is a not - for - profit community organisation working through partnerships to implement strategic planning and investment activities that care for our region’s natural and cultural assets.
Coastal Environments and Critical Aquatic Habitats
Our coastal environments and critical aquatic habitats face a range of threats. The Australian Government will deliver outcomes for these important areas - including delivering the Great Barrier Reef Rescue package, protecting and rehabilitating areas for critically endangered and endangered species and migratory shorebirds, improving the quality of water discharged into coastal environments, and protecting Ramsar wetlands.
Project Case Study:
Gulf Fish Passages
Freshwater rivers and streams in the Gulf of Carpenteria region remain in a relatively pristine state, however, fish communities are still under pressure from human activity. For example, roadways can create barriers to migration which affect species that spend some portion of their life-cycle in freshwater or saltwater.
Freshwater rivers and streams in the Gulf of Carpenteria region remain in a relatively pristine state, however, fish communities are still under pressure from human activity. For example, roadways can create barriers to migration which affect species that spend some portion of their life-cycle in freshwater or saltwater.
Map of barriers to fish passage in the Southern Gulf region (denoted by yellow stars) - Marsden and Stewart 2005
Why is fish migration important?
Previous studies have shown that of the 50 species of native fish found in these rivers 24 are migratory species requiring fish passages to maintain healthy population levels. Species such as barramundi, live in freshwater or upper estuaries for portions of their lives, generally entering freshwater as juveniles and leaving as adults to spawn at sea.
Previous studies have shown that of the 50 species of native fish found in these rivers 24 are migratory species requiring fish passages to maintain healthy population levels. Species such as barramundi, live in freshwater or upper estuaries for portions of their lives, generally entering freshwater as juveniles and leaving as adults to spawn at sea.
What we know so far..
A survey of fish passage issues at specifically identified sites in the rivers of the Southern Gulf of Carpentaria was commissioned by the Mount Isa Fish Stocking group in 2005. The aim of the study was to identify any potential barriers to either upstream or downstream migration of fishes in these streams and outline potential options to help reduce the impact that these barriers have on the fish of these streams.
A survey of fish passage issues at specifically identified sites in the rivers of the Southern Gulf of Carpentaria was commissioned by the Mount Isa Fish Stocking group in 2005. The aim of the study was to identify any potential barriers to either upstream or downstream migration of fishes in these streams and outline potential options to help reduce the impact that these barriers have on the fish of these streams.
What are fish passages?
Fish passages or fishways are structures placed on or around man-made barriers (such as dams and weirs) to assist the natural migration of fishes. The fish passages enable fish to either pass around a barrier by swimming up a series of relatively low steps (known as a "fish ladder") into the waters on the other side or create a more swimable path through calvets by slowing the flow of water and creating pools.
Left: Gin Arm causeway, Right: Cones inside Gin Arm causeway
More on why fish passage is important..
Free movement of fish in all freshwater streams is essential to maintain biodiversity and sustain robust breeding populations. Without fish passage significant gaps will appear in up stream fish communities potentially throwing systems out of balance, affecting the environment and fish stocks. Migration is the regular movement of freshwater fish between rivers, floodplains or the sea to breed and grow. Migrations are critical for the survival of native fish populations. It is well recognised that some fish species move during the wet season with flood flows in the rivers any many of the barriers drown out. There are many fish especially juveniles and smaller species that move at the end of the wet season and into the dry season when the flows are lower.
Free movement of fish in all freshwater streams is essential to maintain biodiversity and sustain robust breeding populations. Without fish passage significant gaps will appear in up stream fish communities potentially throwing systems out of balance, affecting the environment and fish stocks. Migration is the regular movement of freshwater fish between rivers, floodplains or the sea to breed and grow. Migrations are critical for the survival of native fish populations. It is well recognised that some fish species move during the wet season with flood flows in the rivers any many of the barriers drown out. There are many fish especially juveniles and smaller species that move at the end of the wet season and into the dry season when the flows are lower.
A fish passage structure in use..
Rock ramp fish ways are used to create fish passages and are designed to reduce the velocity of water flow and create a series of pools that fish can move at low flows. The rocks or cones occurring at intervals up the fish way create slower moving eddy currents where fish can rest before their next burst of vigorous activity. A well-constructed rock ramp fish way will reduce the accumulation of fish below a barrier and allow fish to move up stream and spread out through the river system.
Rock ramp fish ways are used to create fish passages and are designed to reduce the velocity of water flow and create a series of pools that fish can move at low flows. The rocks or cones occurring at intervals up the fish way create slower moving eddy currents where fish can rest before their next burst of vigorous activity. A well-constructed rock ramp fish way will reduce the accumulation of fish below a barrier and allow fish to move up stream and spread out through the river system.
DPI & F in conjunction with Southern Gulf Catchments and Burke Shire Council have now completed three (3) fishways - the Gin Arm Creek crossing, Escott causeway and Burketown Doomadgee road on the Gregory River.
The construction of these three fishways on the Gregory and Nicholson Rivers has opened up 100's of kilometres of stream, ensuring free passage is available on all flows in the river.
Download SGC Factsheet: Improving Fish Passage