STRETCH UPDATES - COHORT IV
Map: Cohort II Current Locations & Map: Cohort III Current Locations
Map: Cohort II and III Combined
RECENT 'STRETCH' PUBLICATIONS
SHIPBOARD NOTES (from Koki Sagiura)
Nov. 2, 2026
As of today there are 34 STRETCH loggerhead
October 30, 2026
Below is a map of the locations for the three Cohort 4 loggerheads that are outfitted with Splash10 tags. Their tracks are indicative of Cohort 4 as a group in that they have all turned south as the water temperature has begun to decline. All three of them began to move to the south in late September/early October and all three are at approximately the same latitude (~42.7degrees N)
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| Tracks of Splash10 tagged loggerheads Vladi, Helena and Solimar of Cohort 4 showing the release point as well as their location as of 10/30/2026. |
October 24, 2026
As of today, there are 46 STRETCH loggerheads still transmitting and providing good location data. With the exception of three turtles that are in the east off of the coast of North America, 43 loggerheads are arrayed between 38 and 45 degrees north and 135 and 179 degrees West. They are all "clustered" around the 18 degree C isotherm with a low of 16 and a high of 20 degrees C.
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| Sea surface temperature as of 10/24/26 overlain on the locations of the 46 STRETCH loggerheads still transmitting. |
October 21, 2026
The video below shows the tracks of the STRETCH loggerhead turtles in Cohorts 1 through 4 that have migrated to the south east from their point of release to the area off of the Baja California Peninsula. This area is considered a "new" area for loggerheads and was previously not considered as important loggerhead habitat. In the case of Cohort 1 (C1) there were 7/25 turtles that took this path (28%); C2 there were 19/30 turtles that took this path (63%); C3 there were 3/30 turtles that took this path (10%); C4 (still very early in the tracking) shows maybe 2/30 individuals that are "trending" in that directions (7%). The analysis of the oceanic parameters (SST, salinity, currents, productivity, etc.) at the time the various cohorts were released may well give us a clue about what caused or allowed the turtles to make these migratory choices.
October 18, 2026
There are 4 STRETCH loggerheads still transmitting from the region off of the Baja California Peninsula. They are Cruz (Cohort II, 833 days post release), Abreojos, Squirt and Cedros (Cohort III, 466 days post release). None of the Cohort IV STRETCH loggerheads seem inclined to head east and remain in the central north Pacific area. Below is an animation of the track of the 4 "BCP" STRETCH loggerheads.
Above is a video animation of the 4 STRETCH loggerheads that continue to transmit locations and are off of the Baja California Peninsula.
October 13, 2026
As of today it appears that there are 3 Cohort II, 17 Cohort III and 25 Cohort IV still transmitting locations. There are three loggerheads still transmitting near the Baja California Peninsula (1- CII and 2-CIII turtles). All the rest, including all of CIV are in the northeast central Pacific. Below is a SST overlay showing the general temp where most of the loggerheads are located.
Below the SST overlay is a Chlorophyll a overlay.
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| The black numbers represent the tag temperatures reported by these three turtles to give you some idea of the color scale for the temperature. The warmest is 21 and the coldest is 16 degrees C. The three loggeheads near the BCP are in waters between 21 and 23 degrees C. |
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| The color map above represents the concentration of Chlorophyll a and the locations of the CI, CII and CIII loggerheads. They are generally in the Chlorophyll transition front where the concentration of Ca is ~1 mg/m-3 indicating high productivity and likely good forage for our little loggerheads. (color map Chlorophyll-a gap filled DINEOF 9km (NRT, daily, VIIRS. https://coastwatch.noaa.gov/cw_html/cwViewer.html?lat=33.36&lon=-222.56&z=1&layer0=chlmixedVIIRSd#) |
September 26, 2026
A BRIEF LOOK AT THE 5 REMAINING SPLASH 10 TAGGED TURTLES' DIVING BEHAVIOR
Sora, Seiran (Cohort III), Vladi, Helena and Solimar (Cohort IV) continue to transmit location and diving data. Below is a summary of their diving to depth bins of 1, 5, 10, 15, 20, 25, 30, 40 and 50 meters at time intervals 0900-1459 (daytime), 1500-2059 (late afternoon/evening), 2100-0259 (night) and 0300-0859 (pre-dawn/morning).
The five turtles show a remarkably clear difference in the magnitude of their diel vertical movements.
Sora has the strongest vertical redistribution, followed by Seiran. Vladi and Helena showing intermediate changes, while Solimar remains predominantly near the surface throughout the day and night.
Mean calculated depth by local-time interval:
DAY DUSK NIGHT DAWN
Turtle 09-15h 15-21h 21-03h 3-09h
Sora 3.62m 5.29m 10.58m 7.82
Seiran 2.51m 4.51m 7.22m 3.89
Vladi 1.11m 3.13m 4.12m 2.15m
Helena 1.12 1.77m 3.51m 2.05m
Solimar 1.08 1.51m 2.54m 1.34
September 23, 2026
UPDATE: COHORTS II, III AND IV
Eight Cohort II loggerheads (807 days post release) continue to transmit locations. Of the 30 Cohort III released, 18 are still transmitting (441 days post release) and 27 of the Cohort IV loggerheads have transmitting locations in the last 10 days (82 days post release).
Below are images of the Cohort members current locations and the combined map of all three Cohorts.
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| Cohort II locations after 807 days post release. |
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| Cohort III locations 441 days post rlease. |
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| Cohort IV locations 82 days post release. |
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| All Cohort turtles' current locations as of 9/23/2026. |
September 4, 2026
As the Eastern and Central North Pacific Ocean churns under the onslaught of major tropical storms and hurricanes we see that our STRETCH loggerheads are doing well. Below is the accounting for the three Cohorts that are currently transmitting.
Cohort II seems to have only 7 turtles still transmitting after 787 days at sea. All of them are expected to lose power very soon. It has been an amazing group of turtles and they have provided our team with a "mountain" of data. Cohort III has 19 loggerheads reporting in out of a total of 30 that were released after 421 days. Cohort IV shows 26 individuals who have "checked in" in the last 4 days. That is 26 out of a total of 30 56 days after release.
COHORTS II, III AND IV
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| This image shows the locations of Cohorts II, III and IV and the location of the eye of hurricanes, Lowell, Karina and Marie as of 9/4/2026. |
Cohort II
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| Seven Cohort II turtles are still transmitting after 787 days at sea. |
Cohort III
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| 19 members of Cohort III are still transmitting after 421 days at sea. |
Cohort IV
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| Twenty Six members of Cohort IV are still transmitting after 56 days at sea. |
August 25, 2026
Summary Diving Behavior of Sora, Ai and Seiran After 415 Days at Sea
The graphs shown below compare the average percent of time spent by Ai, Seiran and Sora at depth bins 1 meter to 50 meters for the last 415 days. The interpretation of these graphs is that all three of them are showing similar diel diving behavior with some individual variation. The generalized look is that the turtles remain on the surface during the Daytime, transition to diving during the Afternoon-Early Evening, Spend the majority of their time during the Night time between 10 and 20 meters depths and transition back to less diving to depth and more time spent on the surface during the Night time Early Morning period. Next I will next take a look at any seasonal variation that might be present.
August 19, 2026
August 11, 2026
Uzuki
For roughly two months now, Uzuki has been traveling in a clockwise direction within a current eddy and the question has been, is Uzuki simply caught in this eddy and is going along with the flow of the current or is there are reason for this circular path... i.e., is Uzuki staying in the eddy because there is a higher concentration of food items available. The latter has been highlighted in the literature as being the reason loggerheads often are seen within these types of anticyclonic current eddies - its is where the food is.
Some of our Colleagues in France (Philippe Gaspar and Julien Temple-Boyer) have created some animations tracking Uzuki and plankton concentrations and it's track relative to 50 passive drift particles. Below are two animations created by Julien.
Philippe writes: "The particles appear to perform smaller loops inside the eddy while Uzuki performs longer loops closer to the eddy’s edge. It might indicate that Uzuki is moving (swimming) to remain at the eddy’s edge which is richer than the eddy’s core
However, the animation of Uzuki’s trajectory in relation with simulated zooplankton concentration suggests that Uzuki does not really get into the richest area…a behavior not that obvious to understand."
"We shall also be careful with any interpretation acknowledging that both simulated current and zooplankton fields contain errors !"
The mystery remains... what is Uzuki up to.
Uzuki's path relative to plankton concentrations. (animation by Julien Temple-Boyer)
Uzuki's track relative to the tracks of 50 passive particles. (animation by Julien Temple-Boyer)
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| Uzuki's track from June 11 until August 11. |
August 3, 2026
How do the the three cohorts compare after 27 days at sea?
Below are maps of the locations of Cohorts II, III and IV after ~25 days at sea.
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| Tracks for Cohort II turtles after 26 days at sea. |
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| Tracks for Cohort III turtles after 26 days at sea. |
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| Tracks for Cohort IV turtles after 27 days at sea. |
July 30, 2026
As we near the end of July, we find that 21 Cohort III turtles are still transmitting after 385 days at sea and 13 Cohort II turtles are still going after 752 days at sea. Twenty-eight of the 30 Cohort IV turtles have reported in the last 5 days... 18 days after their release. CIV is a little difficult to track because of the requirements of the Kineis and ARGOS satellite systems.
NOTE: MOL, the shipping company that has been instrumental in the transport and release of all four Cohorts of STRETCH turtles has posted a story about their participation in the project.
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| Composite location map of all three Cohorts (II, III, IV) as of 7/30/26. |
July 27, 2026
Uzuki Swimming in Circles???
STRETCH Co-PI, Jeff Polovina pointed out recently that it appears that Uzuki is swimming around inside of a current eddy- he writes "It sure looks like cohort 2 Uzuki, in the west near the emperor seamounts, has made 2 trips around an eddy." To be able to visualize this behavior better, I took Uzuki's track since June 3, 2026 through today and overlaid it on the current eddy that is present... NOTE: this is the location of this eddy as of 7/27/26 and it has undoubtedly varied over the last 50-60 days....it does confirm Jeff's observation that Uzuki is indeed swimming around in a large/strong current eddy.
Below is Uzuki's track during June and July showing its movement around the current eddy.
July 25, 2026
Our Turtle Guardians in California
Having successfully released all Cohort IV loggerheads on July 9th, our two turtle guardians (Koki-san and Taka-san) disembarked from the Liberty Ace in Panama and transited to Los Angeles and Montery Bay where they were hosted by STRETCH colleagues Cali and Larry. They got to see the unusual green turtles that travel up the San Gabriel River and visited the world famous Montery Bay Aquarium. Below is a picture of Taka-san, Larry-san and Koki-san in Monterey, California.
July 23, 2026
SST for Combined Chart
Cohort III is spread out from nearly -178 to -125 longitude but most are in the "green" SST which is from 17-20 degrees C. Cohort II has the BCP contingent that is down south and in waters that are a bit warmer- ~ 24 degrees C. So far, CIV are all moving in a northerly direction as expected and as seen in C I, II and III shortly after their release. With El Nino coming on it will be interesting to see how all of these wonderful loggerheads react... Where will they go???
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| The SST overlay has CII, CIII and CIV locations with color coded SST. |
July 20, 2026
CII, CIII, CIV and COMBINED UPDATE
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| 13 Cohort II loggerheads are reporting locations as of 7/20/26. These turtles have been at sea for 742 days since their release! |
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| 21 Cohort III loggerheads are reporting locations as of 7/20/26. |
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| 30 Cohort IV loggerheads are reporting locations as of 7/18/26. |
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| CII, CIII AND CIV combined locations as of 7/20/26. |
July 17, 2026
MOL- STRETCH TURTLE RELEASE PHOTOS
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| Koki-san and Taka-san on the deck of the Liberty Ace with one of the Cohort IV loggerheads. |
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| Liberty Ace crew members are seen lowering one of the CIV turtles. |
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| Liberty Ace crew members are seen getting ready to lower one of the CIV turtles. |
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| The Liberty Ace release team. |
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| Koki-san with dinner on board the Liberty Ace. |
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| Taka-san replacing the water in the containers for the CIV turtles. This whole process was done daily. |
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| A little daily "deck exercise" that each CIV turtle got while its container was clean and fresh sea water added. |
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| Taka-san with a CIV loggerhead. |
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| Basket is turned over and the loggerhead is released. |
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| Free at last.... a CIV loggerhead swims away from the Liberty Ace and into the vast North Pacific ocean. |
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| Ready to be lowered to the ocean and released. |
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| Ready to go! |
July 16, 2026
Below is an image of the current location of all 62 loggerhead STRETCH turtles
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| Above is the current location of 62 STRETCH loggerhead turtles as of 7/16/26. |
July 13, 2026
Update of CIV
All 30 Cohort IV loggerheads released on July 9, 2026 are "reporting in" and we have positions. Interestingly they are located in the same area as many of the Cohort III loggerheads and the majority of them have moved to the north as expected. Below are two images (CIV and CIII) to show their relative positions.
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| Cohorts III and IV locations as of 7/13/26. |
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| Cohort IV locations on 7/13/26. |
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| Cohort III locations on 7/13/26. |
July 10, 2026
Taka-san and Koki-san reported from the MOL ship Liberty Ace that all 30 Cohort IV loggerheads were safely released and swam away on the beginning of their great adventure.
No pictures yet but the on-board team reported that every thing went smoothly and profusely thanked the Liberty Ace crew and officers for their help in a successful release!
The Tags are on a transmission schedule of one hour on and 23 hours off so we will not see them all at the same time as they may have started their one hour transmission at different times. The restricted transmission windows are programmed to extend battery life with the expectation that the batteries will last up to 4 years (in theory). Below is a map showing some of them at the deployment site where they were released.
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| The two groups of turtles transmitting are shown at their approximate release locations. As the days pass they will all come online and we will be able to trace their paths. The location at the release point is 39°59.2032'N, 149°02.9923'W and the SST was 19 degrees C. |
Also of note, is the fact that we now have a total of 63 turtles (13 CII-721 days, 20 CIII- 366 and 30 CIV-1 day) transmitting locations.
Cohort II Map
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| Cohort II locations as of 6/10/26. |
Cohort III Map
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| Cohort III locations as of 6/10/26. |
July 9, 2026
Today, July 9, 2026 is the proposed release day for Cohort IV. Koki Sagiura said that the turtles will be released at about 1500 hours local time so we will cover their release when we get the report from Koki on the Liberty Ace. IN THE MEANTIME::: Cohort II has reached a chonological milestone with 12 individuals still transmitting at 730 days or TWO YEARS!!! That these tags have continued to transmit for a full two years is a major accomplishment and provides data over a very significant time range which covers major changing environmental conditions (from seasonal variations to major climatic variations). The amount of data provided is massive and will keep our STRETCH Team busy for a long time!
Hopefully, pictures of the upcoming release will be available soon.
July 8, 2026
Below is a map of the proposed release point from Cohort IV at 40.27 N and 150.00 W.
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| Release point is planned to be at the encirdled white dot. |
July 6, 2026 - Update on Cohorts II & III
Thirteen Cohort II turtles continue to transmit solid locations after 726 days at sea. Sixteen Cohort III are still transmitting after 360 days at sea... we have lost contact with a few of them in the last couple of weeks. The loss of contact may be the result of tag malfunction, tag detachment and sinking, predation or a combination of these. We will likely never know what the cause is.
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| Cohort III locations as of 7/4/2026 after 360 days at sea. |
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| Locations of Cohort II turtles still transmitting on 7/4/2026 (726 days at sea). |
Cohort IV is on Board the Liberty Ace
The fourth cohort (C IV) of STRETCH loggerheads was loaded onto the RoRo ship Liberty Ace (TRACK THE SHIP) on July 29th by staff from the Port of Nagoya Public Aquarium. They were successfully put on the ship on the upper deck where they will be cared for by Kochi University graduate student Koki Sagiura (his second STRETCH cohort deployment) and Takahiro Hoshino from the Port of Nagoya Public Aquarium (Taka-san has worked at PNPA for over 20 years and is currently curator of the Aquarium's penguin exhibit). The C IV loggerheads are kept in individual containers and the two caretakers (Noa and Taka) take them out on deck and change their water and clean their containers once every day. They feed the turtles a specially prepared diet in their containers each day.
Today the ship left Nagoya for Yokahama and, after a short stay in Yokohama, the ship will begin its voyage across the Pacific to North America. Part way across, at a point very close to where Cohorts I through III were released, the ship will "stop" and each turtle will be carefully lowered by basket and released into the ocean, just as the three other cohorts were released. Please see a video of the release operation of Cohort I. It will pretty much be the same process this year.
Photos below taken by Takahiro Hoshino
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| The PNPA turtle group and the crew of the Liberty Ace. |
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| Liberty Ace crew member transporting a couple of loggerheads to their "cabin." |
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| The stern of the RoRo ship Liberty Ace. |
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| PNPA director Dr. Kurita and the Liberty Ace Captain. |
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| Out two STRETCH turtle guardians, Taka and Koki. |
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| STREETCH loggerheads being placed in their "Cabin" on board the Liberty Ace. |
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| Bow of the Liberty Ace. |
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| STRETCH loggerheads taking the elevator up to their "cabin." |
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| Thirty STREETCH loggerheads safely in their "Cabin" at the beginning of their voyage the release point in the northeast central Pacific. |
Latest Positions - Cohorts II & III
As of June 22, 13 Cohort II turtles continue to show their locations after 713 days at sea and 20 Cohort III turtles' locations are known after 349 days at sea.
Their locations are shown in the images below:
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| June 22, 2026 locations of 13 Cohort II turtles. |
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June 22, 2026 locations of 20 Cohort III turtles. Note that Squirt (white circle) has move east southeast and is very near the cluster of Cohort II turtles some 500-600 km off the west coast of North America/Baja. See map below. |
Satellite Tag Attachment - Day 4
The STRETCH team finished up the satellite tag attachment on Day 4 (June 20, 2026) by attaching three Splash tags to the remaining Cohort IV loggerheads. The SPLASH tags are a little larger and record dive data, temperature, maximum depth, etc. so the three loggerheads they are attached to are larger that those that received Spot 6 tags. In all, there are 30 satellite tagged loggerheads in Cohort IV. These 30 loggerheads will be kept at the aquarium until the ship comes to Nagoya to pick them up in early July. The ship will transport them to the northeast Pacific where they will be released, just as Cohorts I, II and III were.
See the loggerhead Stretch Post for images.
Satellite Tag Attachment - Day 3
After a successful day 1 & 2 (18 tags attached), the team will assemble again at PNPA to begin the second day of attachment of satellite tags.
UPDATE: Nine more tags attached successfully and there are three more to do on Saturday in Japan.
Below are a few pictures of the process...
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| The STRETCH tagging team (missing HPA student Taiga) after completing the attachment of 27 tags on 27 juvenile loggerhead turtles. Three more tomorrow monring. |
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| After the completion of the attachment of 27 satellite tags to juvenile loggerheads, the STRETCH team does a traditional Japanese toast to the safe transport and release of the loggerheads in early July. |
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| Larry and Dana cleaning and drying the carapace of our little loggerheads. |
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| Rella, Noa and Rino with a loggerhead they have just gotten ready for satellite tag attachment. |
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| Scrubbing the carapace. |
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| Must get the carapace very clean so the resin will "stick" properly. |
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| A view of the worik area and the workers at the Port of Nagoya Public Aquarium. |
The STRETCH Team has Arrived
June 17, 2026 Nagoya, Japan
The STRETCH team has arrived at the Port of Nagoya Public Aquarium (PNPA) to attach 30 Wildlife Computers satellite tags to Cohort IV loggerhead turtles. The team assembled this morning in Kanayama and traveled to PNPA at 0900 to begin the process. Today they are planning on attaching 9 satellite tags. Below are a few pictures and videos to show the beginning of the process.
From left to right: Rowan, Drew, Taiga and Dana are covering vulnerable tag connections so that there is no resin covering them.
George talking to the TV crew filming the attachment procedure.
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| The team is scrubbing the carapaces of the loggerheads so that they are clean for the attachment process. |
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| The attachment team working hard on the attachment process. |
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| STRETCH elder supervising the process. |
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| Head supervisor Larry. |
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| TV crew interviewing Larry Crowder as HPA student translates from English to Japanese. |
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| HPA student NOA is translating the interview with Larry Crowder. |
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| Hawaii Preparatory Academy Student cutting the fiberglass cloth to be used in the attachment of the attachment of the tags- Larry Crowder taking pictures on the left. PNPA Turtle Curator Masanori Mori shows HPA students turtle eggs that are developing in incubators. What we were seeing was a group of hatchlings from a nest with only about 25 viable eggs. Since there were so few eggs, they wouldn't able to work together to move enough sand to reach the surface on their own. They were being incubated and monitored, so they could safely make it out. (video by Rella) |
On June 17, Members of the Stretch Team will assemble at the Port of Nagoya Public Aquarium to begin the process of attaching satellite tags to 30 juvenile loggerhead turtles that have been raised at the aquarium. This post will feature the attachment process and the activities associated with process. I will interject information about Cohorts II and III loggerheads that are still transmitting.
Stay tuned as the team accomplishes this last bit of work and Cohort IV loggerheads are transported by ship out to an area where the other three cohorts have been released.
For past information on Cohort II and III go to the Post "Streetch Updates - Cohort III" below.
JUNE 15, 2026
As members of the STRETCH Team start their trip to the Port of Nagoya Public Aquarium to attach 30 Wildlife Computer satellite tags to juvenile loggerhead turtles as the fourth Cohort of turtles in the STRETCH experiment. Cohort IV turtles will be released from a MOL car carrier transport ship in early July somewhere near where the other three cohorts were released. It will be interesting to see how the coming Godzilla El Nino will affect the migration patters of this last Cohort of loggerheads.
As of today, 13 Cohort II turtles continue to show their locations after 707 days at sea and 22 Cohort III turtles locations are known after 341 days at sea.
Their locations are shown in the images below:
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| Locations of Cohort II on 6/15/26 after 707 days at sea. |
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| Locations of Cohort III on 6/15/26 after 341 days at sea. |
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