Cane toads have been reported 17 times in Perth since 2009, when the department assumed responsibility for their control.
The Perth tally includes 18 live and nine dead toads.
In four instances, cane toads were found in the suburb of Perth Airport, the most recent of which involved two dead and seven live toads discovered in a mango plant consignment from Kununurra at the Toll Express truck depot.
Cane toads have also been spotted in Belmont and Kewdale in recent years.
Toads are collected by department staff and humanely destroyed by vets at Perth Zoo, a department spokeswoman said.
She said the department had a new detector dog in Kununurra to inspect high-risk freight on its way south.
‘Reggie’ replaced the original detector dog, Nifty, which retired in 2011, in the wake of a cane toad sighting in East Perth earlier this year.
‘Toll Express is a responsible operator and has a positive working relationship with Parks and Wildlife,’ a department spokeswoman said.
She said the department was working with the freight company to establish how cane toads were able to get into the consignment.
‘Parks and Wildlife, with the detector dog, will inspect any further shipments from this nursery prior to leaving Kununurra.’
She urged people who find a suspected toad to isolate, but not kill the animal, and immediately report it to the cane toad hotline on 1800 44 WILD (9453).
‘Some native frogs look similar to a cane toad, so it is important to have the animal correctly identified,’ she said.