The North East zone, Central East zone, the area between Whale Head and Tasman Island and the area in Bass Strait from Port Sorell to Stony Head have been opened to both recreational and commercial fishers.

Testing in the remaining zones has shown that paralytic shellfish toxin levels remain in excess of the 0.8mg/kg level, and the Department of Primary Industries, Parks, Water and the Environment has advised that it is unsure when the status of those zones may change.

A spokeswoman for DPIPWE said monitoring results indicated that rock lobster fishing was safe in the opened zones.

"It is not clear when the closed biotoxin zones may open, as rock lobsters are much slower at eliminating the biotoxins from their bodies than bivalve shellfish," she said.

"The encouraging news is that diminishing PST levels in bivalve shellfish suggest that the toxic algal bloom is dissipating.

"Sampling and analysis of rock lobster from these closed zones is being undertaken in accordance with the rock lobster biotoxin management plan, and they will be open as soon as sample results return acceptable levels of PST."

The spokeswoman said bivalve shellfish bought from shops remained safe to eat due to close monitoring of the industry.

Wild harvested shellfish remains under a public health alert and should not be eaten.

Updates on the PST situation are available from the DPIPWE website.