An underwater remote controlled camera assisted survey has raised concerns about a persistent sea pest that is coming to the Australian harbor from the New Zealand. The pest is known as New Zealand screwshell and had emerged 70 years ago in the Tasmania because of ballast water. It has been found in a survey by scientists that the same has spread till Sydney Harbor.

The main point of concern is that this research, for the first time, has noted the intensity of the invasion. According to the scientists, the pests are spread to portion equivalent to Tasmania, as it broadens from southern Tasmania to Sydney Harbour.

Showing concerns about the dramatically increasing number of the screwshells, The Dr. Neville Barrett, of the Tasmanian Aquaculture and Fisheries Institute, said that in order to acquire more space on the ocean floor, screwshells are growing at a pace even faster than any other species. Dr. Neville also said that having an extremely thick shell just like the one found cane toad, the screwshell is growing endlessly. It is being predicted that the pets will replace many other species.

He also said that probably due to the hard skin possessed by the shell fish, other marine creature that can reduce the growth of the same, are not being able to penetrate to the skin to eat screwshell.

He said, "In the long run it may definitely impact on things like scallop trawl fisheries and even fisheries for things like flathead".