A Tasmanian salmon farmer is considering expanding its fish farms to reduce disease loads and minimise the need to feed its stock antibiotics.

Fisheries officers say tip-offs from the public have led to another eight people being caught trying to illegally take crayfish from south-east South Australian waters.

Volunteers say more injured turtles will continue to be washed up in 'ghost nets' on western Cape York, in far north Queensland, in the coming weeks.