Nine convictions for possessing freshwater crayfish were among 56 fisheries convictions handed down in Tasmanian magistrates courts between March and May.
The native crayfish are classified as threatened and fishing for them has been banned for more than 20 years.
"Before the banning of fishing for giant fresh water crayfish in Tasmania in January 1998, records show a wide scale decline in the population, especially in the number of large, reproductive adults," the Inland Fisheries Service's Chris Wisniewski said last year.
"This decline was directly linked to those fishing targeting larger specimens."
Among other matters, the 56 convictions included:
- Four for disturbing spawning fish;
- six for taking protected fish;
- two for abusing an officer;
- one for being in charge of a motorboat without a licence;
- three for taking fish by means other than a rod and line; and
- five for taking acclimatised fish without a licence.
Inland Fisheries' latest quarterly report said the January and February bushfires led to a "marked decrease in angler activity".
"This was chiefly due to travel warnings and road closures, combined with evacuations of key fishing locations during the period.
"This inertia continued through the months of March and April, with decreased numbers of anglers inspected during the Easter-Anzac Day break and weekend marking the closure of the brown trout season."
The IFS said boating safety remained a concern.
Of 633 vessels checked, 23 were found not to have the minimum required safety equipment, while 35 people were failing to wear a require personal flotation device.