First observations of spawning nests in the pouched lamprey (Geotria australis)

Abstract

The pouched lamprey (Geotria australis), one of four Southern Hemisphere lamprey species, is New Zealand’s only freshwater representative of the agnathans. In contrast to that of Northern Hemisphere lampreys, the reproductive ecology of Southern Hemisphere lampreys is poorly understood, with no documented nesting sites or spawning behaviours. In the present study, we utilized passive integrated transponder tags to track migratory adult G. australis to locate spawning sites. Across 2 years, six cryptic nesting sites were discovered, each containing eggs and a single male and female lamprey. The postspawning pairs were all located underneath large boulders, with the eggs forming a coagulated cluster that adhered to the underside of the boulder. Both the male and female lamprey survived spawning for over 105 days. The observed spawning nests highlight a substantial divergence in the reproductive behaviour between Northern and Southern Hemisphere lampreys, as the present observations of G. australis are the first that support clustered cryptic egg deposition and an extended time to mortality postspawning. This study offers the first insights to the long-standing mystery of Southern Hemisphere lamprey reproduction.

Revalidation of the Argentinian pouched lamprey Geotria macrostoma (Burmeister, 1868) with molecular and morphological evidence

“…Unlike most of the Northern Hemisphere lampreys assessed at least as vulnerable, the pouched lamprey has been considered as DD (data deficient) by the IUCN [90]. Currently, the documented ecology of G. australis is based exclusively on Australasian populations [6,11,91], and, therefore, may not be representative of G. macrostoma. Given the genetic and morphological differences found in the present study, it is likely that pouched lamprey from Atlantic and Pacific flowing basins may show different life-history and ecological traits such as spawning habitat selection and timing, migration patterns, and swimming abilities.…”

“…When the young adults are fully grown at sea, they cease feeding and return to freshwater as sub-adults (3 to 4 years), where they become sexually mature, spawn and then die [10]. For most species reaching sexual maturity and spawning occurs within several months upon re-entry to freshwater habitats, but G. australis and Entosphenus tridentatus Pacific lamprey display a protracted maturation phase, where spawning occurs after 12 to 16 months in freshwater [11].…”

Efficacy of 12‐mm Half‐Duplex Passive Integrated Transponder Tags in Monitoring Fish Movements through Stationary Antenna Systems

“…Between August 12 and September 19, 2012, 93 adult Pouched Lampreys (470-628 mm TL) were captured using a combination of fyke nets, purpose built traps, and backpack electrofishing. All fish were sedated with 0.02% 2-phenoxyethanol (Sigma-Aldrich) and 12-mm HDX PIT tags (Texas Instruments, Dallas, Texas) were inserted into the body cavity along the midline approximately half way along their longitudinal axis (Baker et al 2017) using a needle and syringe or tag injector (Oregon RFID, Portland, Oregon). The tags and needle were sterilized using methylated spirits prior to implantation.…”

“…The use of 12-mm PIT tags was required because, despite their length, there is extremely limited space (~2 mm in width) in the visceral cavity of adult Pouched Lampreys (Baker et al 2017). Furthermore, externally mounted tags have been shown to have poor retention rates (Jellyman et al 2002), most likely due to the Pouched Lampreys utilization of habitats within the substrate and under boulders during their upstream migration and spawning (Baker et al 2017).…”

“…This study used four migratory freshwater fish species to test the efficacy of three PIT antenna designs for detecting 12mm HDX tags in small-and medium-sized rivers. The primary aim of the PIT systems that were evaluated was to monitor the movements of the Pouched Lamprey Geotria australis and Giant Kokopu Galaxias argenteus to enhance our understanding of the reproductive ecology of these two threatened species (Franklin et al 2015;Baker et al 2017). As part of these studies, the combined effect of antenna design and single-reader and multiplexor PIT systems on the detection efficiency of 12-mm HDX PIT tags was also evaluated.…”