Police assisted Primary Industries and Regions SA officers in testing people on commercial and recreational boats off Port Lincoln on Friday with one alleged positive result.
Officers from Police Water Operations supported PIRSA Fisheries officers in conducting a compliance operation off Port Lincoln from the Fisheries Patrol vessel 'Southern Ranger'.
The Water Operations Unit tested 25 people on commercial vessels for alcohol and drugs and were pleased with the return of no positive results.
All commercial vessels were involved in the pilchard/sardine catch, prawn and tuna feed fisheries.
Unit members also tested one recreational boat operator and as a result a 45-year-old man allegedly tested positive of cannabis.
Under South Australian law anyone operating a vessel or is a member of the vessel's crew may be required by a police officer ot submit to a drug or alcohol screening test.
This includes for motorboat operators, essential crew members, waterskiers, observers and those towed in any manner behind a boat.
Anyone found to have drugs in their system or over the blood alcohol limit of 0.05 can face large fines and/or imprisonment.