The Pouched Lamprey, Sniffing out a Place to Spawn

The pouched lamprey, Geotria australis, is one of four Southern Hemisphere lamprey species, and New Zealand's only representative of the agnathans. In contrast to Northern Hemisphere lamprey species, the reproductive ecology of Southern Hemisphere lamprey species is poorly understood. We present results of ongoing studies investigating the cues used in spawning stream selection and the spawning habitat utilised by the pouched lamprey. Using Passive Integrated Transponder (PIT) technology, adult pouched lamprey were successfully tracked over a 15 month period to locate their spawning nests, the first documentation of lamprey spawning sites in the Southern Hemisphere. G. australis appear unique in their spawning behaviour, creating nests beneath boulders with paternal care of eggs during development. Initial investigations of pheromone cues utilising a two choice-chamber apparatus have shown that migratory G. australis are attracted to a mixture of pheromone compounds released by sea lamprey (Petromyzon marinus). These data highlight the divergence in reproductive behaviour between the Petromyzontidae and Geotriidae families, but suggest a commonality may exist in the pheromone cues used during the freshwater migration.