Are sea lampreys disappearing before our eyes? – Decline repeats itself in Portugal, Spain, France and Sweden.
Foto: Jenny Berntson Djurvall/Sveriges Radio
T
he situation is worse in Sweden, but sea lampreys are declining in several European countries, including Portugal, says Inês de Castro da Silva Oliveira, a PhD student from MARE - University of Évora, to the Swedish radio Sveriges Radio.
As part of a collaboration with Swedish researchers for sampling directed at sea lamprey species (i.e., techniques for sampling and identification of larvae of this species using electrofishing), MARE researcher Inês de Castro Oliveira participated in an interview with Swedish radio Sveriges Radio (starting at minute 9), alongside the Swedish researchers responsible for coordinating this fieldwork, Mikael Svensson and Elisabeth Thysell.
Sea lamprey is considered a rare species in Sweden, and the researchers are trying to understand its distribution in the country by identifying suitable habitats and assessing the number of larvae in those locations. Collecting this information is crucial for potential habitat restoration actions in Sweden, to increasing the number of sea lampreys reproducing in Swedish rivers.
As happens in Portugal, where declining sea lamprey numbers in the last two years even led to the cancellation of the Lamprey Festival in Penacova in February 2024, Sweden is also experiencing decreases. This summer, the lowest ever numbers of observed adult sea lampreys was recorded, says Elisabeth Thysell, fisheries consultant for the Swedish regional authority in Halland. This scenario is repeated in Spain and France. The theory is that, without larger fish in the oceans, adult sea lampreys struggle to find food, ultimately failing to complete their life cycle and not returning to rivers to reproduce.
Inês de Castro Oliveira traveled from Portugal to Sweden to share MARE's knowledge about this species. Knowledge acquired through the work that MARE's research group "Fish Biology, Conservation, and Management," to which she belongs, develops focusing on these species, particularly in the Mondego River.
Her PhD thesis, supervised by MARE researchers Catarina Mateus and Pedro Raposo de Almeida, focuses on learning more about the sea lamprey's life cycle, with an emphasis on the marine phase of this cycle, about which there is still little scientific knowledge.