All four dolphins are in Bahia San Blas, moving through the main channel. At some point during the tracking window, each pair was intact, but it is unclear who was together most recently because the times of most recent positions (red dots) are different for each animal.
Friday, March 21, 2008
Thursday, March 20, 2008
Franciscana Dolphins - Tracking Day #17 (March 20)
Dolphins Near Mouth of Bay
Tunken and Kure have returned to Bahia San Blas, and as of early this morning they were off the mouth of the bay, with Nahuel not too far away. It is likely that Kona was also there, but we did not get a signal from her during the same satellite pass as the others. David Douglas, the USGS scientist who developed the filtering program to determine which satellite fixes are reasonable to use for analyses, has also developed a program to evaluate social associations between our dolphins based on separation distance. When considering only those signals from different animals received within 10 minutes of each other, a clear pattern of consistent, close association is apparent for each pair of dolphins caught and tagged together. Evaluation of photos obtained by the Argentinean photo-ID team confirmed that the orcas they observed earlier this week were in fact the same two whales seen in the same areea a year ago, and different from the pair seen last week. The team will remain in the field through Sunday.
Tunken and Kure have returned to Bahia San Blas, and as of early this morning they were off the mouth of the bay, with Nahuel not too far away. It is likely that Kona was also there, but we did not get a signal from her during the same satellite pass as the others. David Douglas, the USGS scientist who developed the filtering program to determine which satellite fixes are reasonable to use for analyses, has also developed a program to evaluate social associations between our dolphins based on separation distance. When considering only those signals from different animals received within 10 minutes of each other, a clear pattern of consistent, close association is apparent for each pair of dolphins caught and tagged together. Evaluation of photos obtained by the Argentinean photo-ID team confirmed that the orcas they observed earlier this week were in fact the same two whales seen in the same areea a year ago, and different from the pair seen last week. The team will remain in the field through Sunday.
Wednesday, March 19, 2008
Franciscana Dolphins - Tracking Day #16 (March 19)
Kona and Nahuel are together to the northeast of the banks north of San Blas, but they may be returning to Bahia San Blas. Kure and Tunken were together earlier in the tracking window inside the bay, but it is unclear if they are still together as Nahuel moved to the mouth of the bay (his most recent positions are several hours more recent than Kona's). Martin Mendez will have all of the genetic samples from the tagging efforts over the past four years in-hand by May, and will be proceeding with analyses to determine relationships of the tagged animals as well as those caught in fishing nets. The photo-ID team found orcas yesterday, and it is believed that they were the same ones seen by our team in 2007 in Bahia San Blas.
Tuesday, March 18, 2008
Franciscana Dolphins - Tracking Day #15 (March 18)
Dolphins Remain Inside Protected Area
Nahuel and Kona remain to the northeast of San Blas, and appear to continue to move together. Kure and Tunken remain in Bahia San Blas. Early this morning they appeared to be together, but Kure does not have a position from the same time as Tunken's most recent position at the mouth of the bay, so I can't say if they remain together. According to Pablo, the movements of both sets of animals remain inside the marine protected area. The photo-ID team photographed dolphins yesterday, including a resighting of one seen earlier in this session, but did not find any of the tagged dolphins. They will remain in San Blas for several more days.
Monday, March 17, 2008
Franciscana Dolphins - Tracking Day #14 (March 17)
Dolphins Remain Outside of Bay
The two pairs of dolphins are near banks outside of the bay, with Kure and Tunken NE off Banco Nordeste for the third day, and Kona and Nahuel off the mouth of Bahia San Blas. Both sets of animals were together during the tracking window. The photo-ID team saw many dolphins yesterday, but it was too rough to take photos.
The two pairs of dolphins are near banks outside of the bay, with Kure and Tunken NE off Banco Nordeste for the third day, and Kona and Nahuel off the mouth of Bahia San Blas. Both sets of animals were together during the tracking window. The photo-ID team saw many dolphins yesterday, but it was too rough to take photos.
Sunday, March 16, 2008
Franciscana Dolphins - Tracking Day #13 (March 16)
Dolphin Pairs Remain Together
For a second day, Tunken and Kure have remained to the northeast of the range described for the dolphins tracked during 2007, and they appeared to be together for much of the overnight tracking period. Kona and
Nahuel remained within the previously-described range. They appeared to be together through much of the period, but the red dots for their most recent positions, outside the mouth of the bay, were separated in time
by several hours.
These positions, near sandbanks outside of the bay, will make it difficult or the photo-ID team to work with the animals today unless it is unusually calm. Rough seas over the banks create difficulties for safe boat operations, and the tiny dorsal fins of the dolphins (less than 6 inches tall) are obscured by waves. Note that the banks where Kona and Nahuel were located are called "Hellcat Banks."
For a second day, Tunken and Kure have remained to the northeast of the range described for the dolphins tracked during 2007, and they appeared to be together for much of the overnight tracking period. Kona and
Nahuel remained within the previously-described range. They appeared to be together through much of the period, but the red dots for their most recent positions, outside the mouth of the bay, were separated in time
by several hours.
These positions, near sandbanks outside of the bay, will make it difficult or the photo-ID team to work with the animals today unless it is unusually calm. Rough seas over the banks create difficulties for safe boat operations, and the tiny dorsal fins of the dolphins (less than 6 inches tall) are obscured by waves. Note that the banks where Kona and Nahuel were located are called "Hellcat Banks."
Franciscana Dolphins - Tracking Day #12 (March 15)
Tunken and Kure Ranging Farther
Tunken and Kure have moved to the northeast of the banks to the north of San Blas, ranging a bit farther than any of the dolphins we tracked last year. They appeared to be together much of the time, but were not together at the end of the daily tracking period. Kona and Nahuel were paralleling each other's movements inside the bay, if they were not indeed together, through much of the period.
Tunken and Kure have moved to the northeast of the banks to the north of San Blas, ranging a bit farther than any of the dolphins we tracked last year. They appeared to be together much of the time, but were not together at the end of the daily tracking period. Kona and Nahuel were paralleling each other's movements inside the bay, if they were not indeed together, through much of the period.
Franciscana Dolphins - Tracking Day #11 (March 14)
Dolphins Diving Deep
The dolphins continue their expected patterns of movement in the bay. Although the first pair appeared to be together yesterday, they all appeared to be moving independently this morning. It wil be great when, in several months, the genetics data should be available to allow us to determine if animals caught together are related. Dive data from the three dolphins with TDRs indicate some dives to 30-35 meters (the deepest water available in the bay), and for more than three minutes in some cases.
The dolphins continue their expected patterns of movement in the bay. Although the first pair appeared to be together yesterday, they all appeared to be moving independently this morning. It wil be great when, in several months, the genetics data should be available to allow us to determine if animals caught together are related. Dive data from the three dolphins with TDRs indicate some dives to 30-35 meters (the deepest water available in the bay), and for more than three minutes in some cases.
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