Sometimes serendipity leads you to be in the right place at the right time!
Yesterday I was working at Birrong, a south-western Sydney suburb. I decided to check out a green patch on the street map called Maluga Passive Park. As I neared the duck pond, I saw a boat on the other side. One of the fellows waved at me, and I waved back. They headed over to where I was standing. I asked them what they were doing, and they told me to lift the lid on one of the bins by the side (Picture 2), and it turned out they are contracted to clear the pond of the noxious fish, European and Koi carp (Cyprinus carpio), and goldfish (Carassius auratus). Koi carp, which are an ornamental strain, revert to their natural colour in the wild.
They then demonstrated their technique, and held up the "victim" for me (Picture 1). Then they headed out again (Pics 3 & 4)
Home to Google, and I found out from the council website that introduced noxious fish can severely impact the health of aquatic ecosystems by increasing water turbidity and nutrient concentrations, destroying aquatic plants, and potentially causing the recurrence of toxic blue-green algae blooms. They also breed rapidly, eliminating native fish, tadpoles and other small lifeforms. They use electrofishing, which involves passing a small electric current through the water to stun fish. Native fish are released unharmed and exotic fish are euthanased. Electrofishing took place in in 2003 and 2005. In November 2003, native Australian Bass (Macquaria novemaculeata) fry - they are native to the local area - were introduced to re-establish a healthy breeding population that are predators of introduced fish - they eat nuisance algae and carp eggs.
European Carp are mainly bottom feeders and tend to stir up sediments, increasing turbidity and releasing nutrients such as nitrogen and phosphorus into the water. In this way, carp contribute to toxic blue-green algal blooms in freshwater.
European Carp are mainly bottom feeders and tend to stir up sediments, increasing turbidity and releasing nutrients such as nitrogen and phosphorus into the water. In this way, carp contribute to toxic blue-green algal blooms in freshwater.
Bankstown Council continues to monitor and remove carp to ensure that the Bass survive and water quality is not further degraded. And that's what these blokes were doing!
