River Blackfish population in the Snowy River catchment
Scientific name
Gadopsis marmoratus
Status in NSW
Endangered population
Characteristics
- Rounded tail;
- A long, slender body with a slightly mottled appearance. They can vary from green or brown to almost black;
- A single dorsal fin that extents almost the length of the body;
- The pelvic fins are on the underside of the body, below the gills, and consist of one or two rays;
- Large mouth with the upper jaw longer than the lower jaw.
Size
River Blackfish have been recorded at a maximum of 333mm in length in the Snowy River catchment in NSW.
Distribution
The River Blackfish is a medium-sized native fish that occurs in the Snowy River catchment of the eastern (coastal) flowing drainages and the Murray-Darling basin in NSW. Studies have shown that the two populations are genetically distinct and may in fact be separate species.
The River Blackfish was once abundant in the Snowy River catchment, being caught right throughout the mid and upper reaches. This population has suffered a serious decline and is now found only along about 50km of waterways of the Delegate River and some of its tributaries.
- Freshwater threatened species distribution maps in NSW
- Report a River Blackfish sighting from the Snowy River catchment
Habitat
The River Blackfish from the Snowy River Catchment is a secretive, bottom-dwelling fish, inhabiting a wide range of habitats from upland and lowland small creeks, fast flowing rivers to murky streams. It is generally nocturnal, utilising different habitat types at different times of the day e.g. undercut banks during the day for protection and open water at night to search for food.
The River Blackfish is a non-migratory species, each fish spending its entire life within a 20-30 metre home range. Observation of captive fish suggests that they are highly territorial.
Why is the River Blackfish population in the Snowy River Catchment threatened?
- Soil erosion and land clearing degrade habitat and spawning sites;
- Cold water released from large dams may disrupt temperature spawning cues, metabolic functioning, growth rates or feeding
- Removal of large woody debris removes essential spawning sites and reduces reproductive success
- Interspecies competition with introduced species of trout and redfin, as well as predation of juveniles
- Accidental capture by recreational fishers;
- Altered water flow in the Snowy River has disrupted the habitat and ecosystem of River Blackfish as the species prefers flowing water.
