After spending all of May in Golfo de Penas conducting a followup investigation to the expedition that took place earlier in the year, Saoirse returned to Puerto Eden on the tail end of a stupendous stretch of good weather.
Similar to the previous expedition, the workflow generally was divided between an oceanography and taphonomy team. While a group in the dinghy surveyed the coastline searching for new whales or conducting measurements on carcasses, Saoirse shadowed while repeating a total of 40 oceanographic stations throughout the Golfo and surrounding fjords.
Repeating stations completed in February, Erika Sagardía managed CTD casts and nutrient and gas sampling from water samples collected with a Niskin bottle at 5m. Katie McConnell conducted sampling for quantitative and qualitative phytoplankton community research using vertical plankton net tows and Niskin samples from the surface and 15m depth. Katie also completed a series of Paralytic Shellfish Poisoning (PSP) tests using Scotia Kits, primarily with phytoplankton and some mussel samples. From the 10 PSP tests conducted in the field, 9 showed a negative presence of the biotoxin and 1 test showed an ambiguously positive result. Interestingly, this ambiguous result came from the head of Seno Newman, in the same site where the only positive PSP test was registered during the February expedition. Extra samples of shellfish and munida were frozen and sent to Dr. David Cassis at the Universidad de Santo Tomás in Santiago for further analysis of PSP.
This May we were happy to have with us Valentina Molinos, a researcher from Fundación MERI, who conducted new zooplankton tows which complimented the oceanographic stations’ CTD casts and Phytoplankton sampling. Using a large round net, Valentina and Greg would go out in the dinghy each night, towing the net for 20 minutes and capturing all sorts of krill, ctenophores and other small, drifting animals. With this registry, we are able to describe one more step in the dynamic food web in Golfo de Penas’s marine ecosystem.
Most thrilling, during our first day crossing the Golfo de Penas, Valentina also was able to deploy a hydrophone as we drifted and observed a small group of 4-5 Sei whales swimming and circling right next to Saoirse. During this encounter, we were able to capture some faint, low-decibel underwater trumpeting from the whales! As Sei whales are notorious for being extremely shy and elusive, this recording is a great step forward in the knowledge of this endangered species!
While at anchor each night, Valentina deployed the hydrophone for 8-10 hours, and we hope to have captured more calls from marine mammals in the region in these recordings.
Although it is extremely difficult to extract detailed samples from long-deceased whales, we are happy to report that we did not see hardly any newly dead whales during the trip.
This May we were able to add to the sample set taken in February with a large quantity of baleen and bone samples from 99 whales, and, when possible, skin and tissue was also taken.
Also, 4 time lapse cameras installed in February showed the immense range of movement of carcasses because of large tide swings. As the tide rises, relatively in-tact carcasses with large amounts of fat begin to float, and their physical orientation, or even location on the beach can change dramatically within a matter of hours. Furthermore, some of the largest tide swings of the year occurred in early March, and some carcasses disappeared completely. See two shots below:
The cause of the nearly 400 whales’ death will remain a mystery until samples are further analyzed in laboratories in Chile and Germany, and we anxiously await results for biotoxin, virus and parasite presence, and the detailed analysis of the trace elements in the baleens and the genetic content of collected bone fragments. In the furture, we are planning our return to download data from the newly installed Bushnell cameras, and hope to be able to reinstall them for more monitoring.