Penguins are not only found around Antarctica. In fact, half of all species live beyond Antarctica and also migrate to temperate areas when their offspring are adults. Magellanic penguins on the coast of Argentina also follow this cycle. A study has now shown that there are differences between the sexes in where they move to and that this has some potential for conflict with fisheries.
According to the research team, female penguins generally migrate further north in winter than males, especially between May and August. Towards the end of the winter, both sexes move for it rather in direction of the south, into Patagonian waters, before returning to their breeding grounds. The researchers also discovered a difference in the depth of the dives: Female penguins generally dove less deeply than their male counterparts, the researchers write in their paper, in which the well-known German researcher Klemens Pütz was also involved. It recently appeared in the journal PLoS ONE. Both sexes, however, according to the results of the study, move to regions where fishermen are also frequently on the move in winter. In the regions, fishing is mainly for shrimp, squid and bottom trawling. This puts them in competition with both sexes, who seem to have different eating habits. For male penguins, squid and deep-dwelling fish seem more likely to be at the top of the list. In contrast, females prefer more shrimp and smaller fish in the upper part of the water column.
The authors of the study examined Magellanic penguins in the province of Tierra del Fuego and used geologgers to attach on a total of 26 animals. With these devices they were able to calculate the movements of the animals, their diving depths and duration. The loggers stayed on the transmittered animals throughout the winter. This allowed them to match the movement patterns of the penguins with the ship movements of the fishing boats. The researchers also collected blood samples from the penguins to study evidence of their diet during the winter period. But the researchers were only able to analyze nine data sets in total, which the research team says somewhat reduces the study’s power. Still, they believe their data is an approximation of a potential risk to the animals and can help create protective measures for the penguins. They also point out that Argentina already has a national seabird conservation action plan in place since 2010 to protect the animals from bycatch.
Magellanic penguins are not among the most endangered penguin species and their population is estimated at 2 -3 million individuals. But more and more fishing vessels are moving into the areas where the penguins and many other marine animals also spend the winter. These are not even national fishing ships only. Increasingly, Argentine authorities are discovering Chinese trawlers fishing close to Argentina’s maritime borders and not shying away from illegal activities within Argentine waters. On several occasions, conflicts arose between the navy and the fishing vessels. In 2016, an Argentine coast guard vessel sank an illegal fishing trawler from China after it tried to resist inspection and had tried to ram the coast guard vessel several times. No people were harmed in the process.
Dr Michael Wenger, PolarJournal
Link to the study: Dodino S, Lois NA, Riccialdelli L, Polito MJ, Pütz K, et al. (2021) Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal. PLOS ONE 16(8): e0256339. https://doi.org/10.1371/journal.pone.0256339
