Novel method for quantifying lamprey migratory pheromone in NZ streams

Kanakana (lamprey) is a taonga species that is in serious decline in New Zealand. Their secretive nature adds to the difficulties in understanding their distribution and ecology in freshwater environments. Certain pheromones (or chemical smells) are released by New Zealand larval lamprey. Adult lamprey have been shown to select spawning streams based on a migratory pheromone mixture released by larvae living upstream, while mature female lampreys will also select streams based on the sex pheromone released by mature males. There is significant potential for use of these pheromones to further understand the ecology of these secretive animals.
While at NIWA Dr Stewart, in conjunction with Dr Cindy Baker, developed a novel method for quantifying the lamprey pheromone petromyzonol sulphate (PS). PS is released by stream resident larvae and, as it is unique to this species, is an ideal surrogate for detecting the presence and estimating size of populations. The method uses a selective passive sampling device (PSD) called POCIS to accumulate PS from streams and rivers and advanced mass spectrometry to quantify the amount of PS in the water. From this an average time integrated water concentration can be calculated, and populations of stream resident larvae estimated. Since moving to SEL in 2015, Dr Stewart has continued his collaboration with Dr Baker.
To date, the methodology has been utilised within NZ by NIWA (as a complementary technique to eDNA) as part of an MBIE-funded programme on lamprey restoration, Auckland Council, Department of Conservation, Horizons Regional Council, Environment Canterbury, Tasman District Council. The method has also gained international interest with a study completed in Argentina and one currently underway in Oregon (US).