KALISPELL, Mont. (AP) — Officials are proposing a "mandatory kill" regulation for walleyes in Swan Lake after two of the invasive fish were found to have been illegally introduced into the fishery.

Daily Inter Lake reports (http://bit.ly/1QbHeSb ) the Montana Fish and Wildlife Commission is set to decide Thursday whether to implement the proposed ruling.

The two walleyes were discovered in October, causing concern among state biologists who believe the large predatory fish may take over and displace other species in the lake.

The mandatory kill regulation requires anglers who catch a walleye to kill the fish, report the catch within 24 hours and turn it into the state agency within 10 days.

A $25,000 reward is being offered for information that leads to a conviction of those responsible for the walleye introduction.