Bycatch Loggerhead Satellite Tagged

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7/18/2025

A new capture and note from Dr. Tomomi Saito (Usa Marine Biological Institute):

"We are pleased to report that we relealsed a female loggerhead turtle fitted with a transmitter today from Kochi Beach (33°27'59.2"N 133°29'48.5"E).

By the way, while patrolling Kochi Beach this morning, we discovered this female got caught in a wave dissipating block and was unable to lay eggs. We released her today, so we hope she will lay eggs from tomorrow onwards."

Turtle specific data:

17/7/2025 discovered at Kochi Beach

SCL: 87.8 cm, SCW: 68.5 cm, BM: 84 kg

Left hindlimb tag: 56189; right: 56188

PTT Transmitter ID: 286997

PIT Tag ID: 392145000243138

Below are some pictures from the Usa team of the loggerhead:

Kochi female loggerhead shortly after capture on Kochi Beach.

Kochi female loggerhead after the Spot 6 satellite tag was attached.

Headed back to the water after a successful tag attachment.  We are hoping to be able to track her movements near the nesting beach and when she comes out to nest once again.

7/2/2025

Kochi turtles continue to transmit and remain in the same areas as they were more than a month ago.  

The video above shows the tracks of turtle 581 from 3/26 to 7/2/25 and turtle 583 from 4/8 to 7/2/25.

5/25/2025

Kochi by-catch loggerheads 581 & 583 continue to trasmit good location data and remain in the coastal waters where the water depth is ~140 meters (turtle 581) and <50 meters for turtle 583.  Both turtles have ventured into the Seto Inland Sea area where the water temperature has risen to ~18 degrees C.

Dr. Saito (Usa Marine Biological Institute, Kochi University & PI) wrote:  "ID581 is hanging around at the eastern entrance of the Seto Inland Sea. Nearby, in the largest loggerhead nesting site in Honshu, Senrihama-Beach in Minabe Town, Wakayama Prefecture, nesting was confirmed for the first time this year last weekend."

Below is a video of their tracks/movements since late March up through 5/25/2025.

4/27/2025

Below is a video clip of turtles 581 and 583 showing their travels since they have arrived in shallow waters.  Their track is overlayed on sea surface temperature to show that they are in waters that are 15-16 degrees C (583) and 17 degrees C (581).  The water depth is around 50-100 meters for turtle 583 and 50-200 m for turtle 581.

It is also interesting to note that their rate of travel has lowered to 0.4 km/hr for turtle 583 and 1.1 km/hr for turtle 581.  My guess is that they have found a plentiful forage ground and I also suggest that they both are back in an area they have visited in years past.. Just a guess on my part.  As the water warms, they may move up into the embayments that are now still too cold for them.

Dr. Tomomi Saito, Director of Usa Marine Biological Institute, commented:  "The Seto Inland Sea is still too cold to enter, but the water temperature in the southern points of the Kii Peninsula or Shikoku Island has reached 20°C, so loggerheads will soon start laying eggs in southern Japan. 

Our team at Kochi Beach will start our survey on the 7th of next month."

4/13/2025

I haven't posted about our two loggerheads that are still transmitting 98 days post-release for several weeks-my bad!!!  They have not been idle and we find that turtle 581 has traveled 4,952 km and 583 has traveled 4,127 km.  They have both "returned" to near where they were released and are probably in relatively shallow waters  where there is, hopefully, lots of food.

Below is a video animation of their tracks and current locations.

3/24/2025

Update of tracks for 581 and 583 after 78 days at sea.

581 has become entrained in the strong north-northwest flowing Kuroshio current running and ~3 kts/h.  Turtle 583 is just about to enter the Kuroshio current also... we will see if 583 begins to move northwest also.

3/6/2025

Loggerhead turtles 381 and 583 continue to transmit after 60 days.  They have moved into the same general area (see map).  Below are two graphs showing the SST that the turtles have experienced during their travels.

I have created an overlay of Chlorophyll a concentrations on the tracks of 581 and 583 and note that they are in relatively productive waters at this time.

SST for turtle number 581.

SST for turtle 583

2/13/2025

Turtles 581 and 583 continue to transmit after 39 days at sea.  581 has followed the meandering Kuroshio current to the north while 583 has broken out of the Kuroshio current and headed to the south.  Both remain in waters that are 19 to 22 degrees C.

Turtles 581 and 583 are following a similar path moving along the main Kuroshio currents.

Above are tracks for turtles 581 and 583 up through 1/24/2025 on the general current pattern off of the coast of Japan.

Below is a chart showing the track and locations of turtles 571, 580, 581 & 583 since their release.  This map is automatically updated daily.

  

1/6/2025

Tomomi Saito and his research team from Usa Marine 'Biological Institute, Kochi University have release 2 more loggerheads captured as by-catch at Moroto Point in Japan.  

About noon of 06 Jan. 2025, released them off Tosa Bay (33°13'00.0"N 133°40'00.0"E). 

13/12/2024 Bycatch at Shiina Fishing Port, Muroto-shi, Kochi Pref.

SCL: 82.7 cm, SCW: 67.0 cm, BM: 78.5 kg

Left forelimb tag: JP30791-A, left hindlimb tag: JP40193-A 

PTT Transmitter ID: 265581

PIT Tag ID: 392145000262151

27/12/2024 Bycatch at Shiina Fishing Port, Muroto-shi, Kochi Pref.

SCL: 73.1 cm, SCW: 59.8 cm, BM: 55.5 kg

Left hindlimb tag: JP40196-A

PTT Transmitter ID: 265583

PIT Tag ID: 392145000261239

1/2/2025

Below is a short clip of the location of turtle 580 as of Jan 2, 2025.

12/31/2024

Below is a short clip of the location of turtle 580 on New Year's Eve.

12/28/2024

12/19/2024

Turtle number 580 has become entrained in the easterly flow of the Kuroshio Current and is moving southeasterly in waters that are 21-23 degrees C.  Below is an animation of the current flow that 580 is currently in.

12/13/2024

Turtle 580 continues to move to the southeast in waters that are approximately 22 degrees C.  Based on the track for the couple of days, 580 may have found an area where there is some forage items.. it is wandering in a localized area.

Above is a chart of 580's track since release showing that 580 may have found some forage as it is remaining in a small area.

12/08/2024

Dr. Tomomi Saito and his team from the Usa Marine Biological Institute, Kochi University have tagged and released a sub-adult loggerhead turtle that was caught by fishermen at Shiina Fishing Port.  The turtle was healthy and in good condition as it was released off of a fishing boat in Usa Bay.  Below are the specifics and biometrics for the turtle.

Congratulations to the Usa Research Team!

Information about turtle 580.

6/12/2024 Bycatch at Shiina Fishing Port, Muroto-shi, Kochi Pref.

SCL: 70.1 cm, SCW: 57.7 cm, BM: 54.5 kg

Left forelimb tag: JP40191A, left hindlimb tag: JP40192A 

PTT Transmitter ID: 265580 

PIT Tag ID: 392145000261749

 

Turtle 580's track post release on 12/08/2024. Map is updated daily.

 Satellite tag is attached and protected on the front by a "bumper".

Turtle 580 is ready for release and is about to go over the side of the fishing vessel.

Waving goodby and wishing good luck to 580!