32 % of Tasmania’s east coast rocky reef habitats will be lost to urchin barrens by 2021

Pic: Jon Bryan

Government scientists predict 32 % of Tasmania’s east coast rocky reef habitats will be lost to urchin barrens by 2021

The Australian Newspaper has today published an article titled “Spike in urchin numbers sparks talk of reef disaster”

This article was initiated by the Tasmanian Conservation Trust which released, for the first time, findings from Institute for Marine and Antarctic Studies (IMAS) scientists that predict a 32 % loss of rocky reef habitat on Tasmania’s east coast by 2021 due to expanding urchin barrens caused by an explosion in the numbers of Centrostephanus sea urchins. This disaster is directly related to overfishing of rock lobster, which has removed almost all of the large rock lobsters which are the Centrostephanus sea urchin’s only effective local predator and population control.

The prediction of 32 % loss of reef habitat on the east coast by 2021 was provided in two presentations by IMAS scientists that the TCT attended in March and November 2017.

The TCT’s Marine Spokesperson Jon Bryan said that: ‘If Centrostephanus sea urchin numbers are not controlled by rock lobster, the urchins remove the kelp and other marine plants from the reef, leaving urchin barrens that are an ecological disaster.’

‘These urchin barrens do not normally recover. They have been expanding over the last few decades and we now have the government’s own scientists predicating that nearly one third of our susceptible east coast reefs could be lost by 2021. This would be a disaster for Tasmania’s marine environment and the commercial and recreational fisheries that it supports.’

‘Healthy rocky reef habitats are critical to the survival of rock lobster and abalone. Apart from anything else, urchin barrens reduce abalone and rock lobster numbers to such an extent that both recreational and commercial fisheries are excluded from these damaged reef areas.’

‘While climate change and warming water contributes to this problem, the critical factor, and the only one that Tasmanians can do anything about, is the overfishing of rock lobster that has resulted in the almost total removal of large rock lobster, the only local predator that is able to eat Centrostephanus sea urchins and control the spread of urchin barrens. Areas on the east coast have been overfished to the point where there is only 10 % remaining of the original rock lobster biomass. This is an unacceptable situation for any fishery such as the Tasmanian rock lobster fishery, let alone a fishery where the target species is the only significant remedy for ongoing environmental destruction.’

‘Right now, the most effective solution is to increase numbers of large rock lobster’s able to feed on Centrostephanus sea urchins. That requires urgent changes to the management of the rock lobster fishery.’

During December and January the TCT met and briefed all three major political parties in depth about the IMAS findings and outlined the range of potential actions that could be taken to maintain and increase numbers of very large rock lobsters.

The TCT Director Peter McGlone said that: ‘We ask all political parties to acknowledge the enormity of the threat Centrostephanus poses to our marine biodiversity and the rock lobster and abalone industries that depend on these reef habitats.’

‘We ask all political parties to not use this issue to score political points and urge them to not rule out any measures that can help to maintain and increase numbers of very large rock lobsters.’

‘We ask all parties to commit, if they form government, to bring together all stakeholders to attempt to achieve consensus on how to stop the spread of Centrostephanus.’

‘All effective management measures will have impacts on both the commercial and recreational rock lobster industry and the next government will need to be ready to deal with these impacts. Failure to act now will result in the permanent loss of large areas of reef which will have much greater impacts on both the recreational and commercial fisheries.’

‘Over the last 20 years the TCT has been asking for a stronger management response to slow down the spread of Centrostephanus and all governments, Labor, Labor-Green and Liberal, have failed to take significant action. The predicted 32 % loss of reef to urchin barrens by 2021 shows that the very small steps that have been taken by the last three governments have not been enough to fix this problem. It is vital that all political parties acknowledge the urgent need to find a solution and take actions that will prevent wholesale environmental destruction and the loss of traditional fishing areas to future generations.’
Peter McGlone TCT Director, Jon Bryan TCT Marine Spokesperson