Fishing for the future

Inmates and researches sorting through the first catch.

There were some great results when seven inmates from the Greenough Regional Prison recently joined NACC and Central Regional TAFE Batavia Coast Maritime Institute (BCMI) to conduct species surveys in the Chapman River.

The seven inmates were all participants of NACC’s NRM Capacity Building for Indigenous Prison Inmates Project – which builds NRM capacity, but also helps inmates work towards achieving a Certificate in Conservation and Land Management over three-and-a-half years.

This particular work contributed to an important invasive species control project aimed at eradicating introduced Tilapia fish from the Chapman River. Read more about how this project was covered by ABC Radio – Mid West and Wheatbelt this week.

Western Australia researchers investigating control strategies for invasive pest fish species. By ABC Mid West and Wheatbelt.

Western Australia’s river systems contain several invasive pest fish species detrimental to the biodiversity of ecosystems.

These include such species as mosquitofish, swordtails, yabby and tilapia, declared one of the International Union for Conservation of Nature’s (IUCN) worst invasive species due to its aggression, wide environmental tolerances, rapid reproduction and ability to alter habitats through nest-building.

Central Regional TAFE Batavia Coast Maritime Institute (BCMI) in Geraldton has been conducting surveys on these species in the Midwest region of WA since 2013.

“Initially we had some support from Recfishwest to develop some survey techniques to look at pest fish in the Chapman River,” Dr Colin Johnson from BCMI told ABC Local Radio.

“After a year of refining our methods for how to ideally survey these rivers, we were then able to get some Federal government funding in partnership with Northern Agricultural Catchments Council (NACC) to expand to look at some of the surrounding rivers as well.”

Researchers are focusing on trying to determine where tilapia, one of the main pest fish in the region, occur and developing control strategies for the species and other aquatic pests.

The rivers that the researchers are studying include the Irwin, Greenough, Chapman and Murchison.

“There’s a lot of life in all of them [but] unfortunately, there are a lot of pests in most of them as well,” Dr Johnson said.

A photo of a flat shell turtle and an oblong turtle from the Chapman River. Dr Johnson said researchers were surprised to see the huge domination of the introduced turtle – the oblong turtle – in the Chapman River. (Supplied: BCMI)

Besides researching aquatic pests, BCMI is also involved in freshwater turtle projects.

Dr Johnson said researchers recently visited an area near Wooleen Station, on the junction of the Roderick and Murchison rivers, where they found native turtles.

“There’s not a great deal of water out there…this ephemeral pool only had water in it for about two weeks,” he said.

“The main thing we found were some of the native turtles, a little desert specialist species.

“They obviously had been buried for a while and once the water came down, they popped out.

“We managed to catch 22 of them in this little pool that was about 100 metres long and included in that were some very small little hatchlings.”

The local native species is Chelodina steindachneri or the dinner plate or flat-shell turtle, Dr Johnson said.

“This species is a desert specialist and gets around the drying of the rivers by burying itself in mud,” he said.

“It can live for at least three years waiting for water and it does that by storing the water in its bladder and going into a kind of hibernation state.

Researchers hope to tag the oblong turtles in the Chapman River so they can compare the population of this turtle with the native flat-shell turtle population. (Supplied: BCMI)

“Overall there seems to be good populations of this species in most of our local rivers, with the exception of the Chapman River.

“In the Chapman we also have another species, Chelodina colliei [or oblong turtle], another native long neck turtle, but this one is from the south-west drainage and it was into the Chapman and now seems to be dominating that river.

“On our surveys we have caught over 2,000 of these colliei species and only four of the local native species.

“Our next step is to do some tagging of the two different species throughout their ranges to try and get an idea of the basic biological information, but also we want to get some decent population estimates for the Chapman River.

“The number I quoted were based on catch rates and we do not know how many of those were re-catches because we release them all.

“So we want to be able to tag them and we can use the tag returns to estimate the populations so we can get a better idea of how these species coexist.”

Dr Johnson said the research work, which was due to finish in the middle of next year, would hopefully continue, depending on funding.

You can read more about the BCMI project here:


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