An unlikely alliance of wealthy yachties, fishers and environmentalists may be about to throw sand in the gears of the mammoth international project to give Australia nuclear-powered submarines after this weekend’s election in Western Australia.

While the national security implications of Australia’s involvement in AUKUS have long been scrutinised, its effect on pink snapper spawning habitat and recreational boating in Cockburn Sound southwest of Perth are emerging as irritants to the progress of the multi-billion dollar defence project.