Big numbers are expected to be on the water this weekend with the opening of trout fishing season today.

The Bay of Plenty Regional Council is reminding boaties and anglers to clean their boats and trailers for weed fragments before taking them into new lakes or rivers in the region.

Trout.

The Bay of Plenty Regional Council land resources (Rotorua) manager, Greg Corbett, says it's all too easy to transfer strands of aquatic weeds from one lake to another.

'We have these damaging weeds in some of our lakes, but don't want them spread any further – and boaties and anglers have a major part to play in that.”

The reminder comes with added strength this year with the newly revised Regional Pest Management Plan 2011-2016, which contains rules on the spreading of pests.

Under the new rules of the Regional Pest Management Plan it is an offence to move or allow to be moved, any machinery, vessel, organism, risk good or others goods contaminated with any contaminant pest plant.

Greg says the emphasis in the short term was to educate boaties and anglers on the serious impacts that aquatic pests can have on our waterways.

'We are fortunate to have some exceptional lakes in our region with very good water quality, and high biodiversity and recreational values worth protecting.

'The rules are really about getting people to be responsible for the lakes and waterways that they use and enjoy.”

Greg says it's important for boaties to inspect their boat including its propeller and anchor chain, as well as the trailer and for anglers to check their gear including waders.

'People need to pick off any weeds and if necessary wash down their boat and gear to ensure the weeds aren't transported to other lakes.”

The new rules are also supported by NIWA and regional council staff who discovered hornwort during surveillance work in the south west bays of Lake Okataina last year.

It is probable that the hornwort was introduced to the lake via a boat's anchor warp due to the boat owner neglecting to check for weed fragments prior to entering the lake.

The lake had been free of two of the most damaging aquatic pest plants, hornwort and egeria.

Known infestation areas in Lake Okataina have been contained and are restricted from access and a weed cordon has been set up at the boat ramp to minimise further incursions.