An innovative and exciting fish tracking program is shedding new light on the behaviour of Black Bream and highlights the importance of water quality and complex habitats such as large woody debris.
The Swan Fish Track project is a partnership between the Department of Parks and Wildlife and Murdoch University to understand how Black Bream respond to changes in water quality and use different habitats in the Swan Canning Riverpark, particularly the waters around the oxygenation plants in Guildford and Caversham. The project received funding from the Recreational Fishing Initiatives Fund supported by the Department of Fisheries and Recfishwest.
Swan Fish Track involved tagging and tracking 55 Black Bream and following their movements and behaviour throughout the Riverpark. Local Bream fishers played a key role in the project with competitors at a WA Bream Classic event using their skills to contribute 20 Black Bream, including the majority of large fish over 300mm. The fish were fitted with acoustic transmitter tags, which emit signals to a series of 30 receivers located throughout the Riverpark. As a fish swims past a receiver, information on the tag ID, time, depth and acceleration of the fish is transferred and recorded.
From this data Murdoch University researchers Jake Watsham and Nathan Beerkens were able to analyse the first four months of the Bream’s movement and behaviour. Their results were discussed at the Fishers for Fish Habitat Forum in November and provided some interesting insights into the behaviour of Black Bream.
Bream are capable of travelling….a lot!
Preliminary data from the first four months of the study showed the average distance covered by tagged bream was 33km, with one fish covering a whopping distance of 130km. On another occasion, a fish was recorded travelling 11km in less than 15 hours. When not on the move, fish spent most of their time at receivers in Ascot and Caversham. There was also movement of some fish between the Swan and Canning rivers. Some of the Bream’s movements through the rivers were found to be linked to heavy rainfall events. While Bream are hardy fish that can handle a high salinity range, the tagged fish favoured areas where salinity ranged between 10-20ppt.
Low Oxygen Limits Habitat Availability for Bream
Recent Data from the Swan Fish Track project suggests that Black Bream had a preference for shallow habitat and avoided areas with low dissolved oxygen. Information collected through this project is being used to help inform the operation of the oxygenation plants at Guildford and Caversham to ensure they provide conditions that are optimal for fish in the Upper Swan Estuary.
Bream Need Habitat
The project showed fish favouring areas with complex habitats, such as snags and adds value to the argument that replanting shoreline vegetation and restoring large woody debris may provide a real benefit to the fish in this system. With more than 30km of built-up shoreline there may be potential to improve the fishery by enhancing and restoring this habitat.
The project is ongoing and all fish tagged for the project have a yellow spaghetti tag next to their dorsal fin so if you catch a tagged fish please recorded the details on the tag and your location and release the fish back into the water. After releasing the fish, please call the number on the tag and provide the details to the researchers at Murdoch University.
For more on the importance of healthy waterways and their impact on healthy fisheries, read our article here.