The 24 th Annual Tag and Release Tournament (TART) took place in Kailua-Kona, Hawaii, USA on September 1-5, 2014. The televised tournament took viewers along for the week-long voyage as five boats competed to catch and safely release the greatest number of Pacific blue marlin. The concept behind the tournament is to educate viewers about marlin science and to generate appreciation for these majestic and powerful fish. Last year, Ken Corday of Corday Productions and producer of the TART further promoted marlin conservation efforts by sponsoring five minipat satellite tags to place on each boat participating in the tournament for the IGFA Great Marlin Race (IGMR). On September 2, 2014, day two of the TART, Northern Lights Captain Kevin Nakamaru placed the first satellite tag of the race on an estimated 79 kg (175 lb) Pacific blue marlin after a quick fight with angler Brent Nelson. Two days later, Brent hooked a second blue, an estimated 91 kg (200 lb) fish that was tagged by Ihui Nui Captain McGrew Rice. Nearly two months after the TART concluded on October 30, 2014, Kona Blue Captain Dave Crawford deployed the third satellite tag of the race on an estimated 113 kg (250 lb) blue marlin caught by angler Evan Korsh. One week later, on November 7, 2015, Ihui Nui Captain McGrew Rice deployed the fourth satellite tag of the IGMR on an estimated 136 kg (300 lb) blue marlin reeled in by angler Shuzo Aida. When it became evident that the fifth sponsored satellite tag could not be deployed within a reasonable timeframe to the other four tags, the decision was made to deploy the fifth tag in the 2015 Kona, USA IGMR
TART, Kona, USA 2014 Deployments Tag Boat Fish Species Tagged Reported Days at Large Distance (nm) Est. Wt. (lbs) Est. Wt. (kg) Angler Tagger 13P0463 Northern Lights 1 Blue Marlin 9/2/2014 3/3/2015 182 1,773 175 79 Brent Nelson Kevin Nakamaru 13P0465 Ihui Nui 2 Blue Marlin 9/4/2014 Tag Did Not Report 200 91 Brent Nelson McGrew Rice 13P0471 Kona Blue 3 Blue Marlin 10/30/2014 1/18/2015 80 2,124 250 113 Evan Korsh Dave Crawford 13P0467 Ihui Nui 4 Blue Marlin 11/7/2014 5/6/2015 180 2,665 300 136 Shuzo Aida McGrew Rice
On May 6, 2015, the final tag in the 2014 TART Kona, USA IGMR surfaced to win the race after remaining on Fish 4 (Tag 13P0467) for the full programmed duration of 180 days. Fish 4 (Tag 13P0467) traveled east southeast for the entire deployment period and recorded data over a linear distance of 2,665 nautical miles (nm) and a total estimated distance of 3,553 nm* before the tag popped off about 1,300 nm west of the Galapagos! Congratulations to Team Ihui Nui for winning the TART Kona, USA IGMR! Not only is this the longest track and first place in the 2014 TART event, but it is also the second longest track recorded from a Pacific blue marlin tagged out of Kona in the IGMR! Second place in the race belongs to Fish 3 (Tag 13P0471)! Tag 13P0471 popped up southeast of Hawaii and south of the equator on January 18, 2015 after recording data for 80 days on the estimated 113 kg (250 lb) blue marlin. After the fish was released, the marlin swam north briefly before turning east and then south for a point-to-point distance of 2,124 nm and a total estimated distance of 4,587 nm*! As you can see in the plot, Fish 3 (Tag 13P0471) swam across a shoaling region of low temperature and oxygen in the Pacific Gyre in late November early December, which limited its maximum diving depths to around 100 meters. Also reporting due south of Hawaii and south of the equator was the tag on Fish 1 (Tag 13P0463) which surfaced on March 3, 2015 to capture third place in the 2014 TART Kona, USA IGMR. Tag 13P0463 remained on the estimated 79 kg (175 lb) blue marlin for the full scheduled deployment period before it popped up 182 days later- about 586 nm south of the equator and about 400 nm from Bora Bora. After it was tagged, Fish 1 (Tag 13P0463) swam south southeast for about 2 months, turned east briefly, and then swam southwest for the remainder of its track. Although the tag recorded a point-to-point distance of 1,773 nm, you can see by the track that Fish 1 (Tag 13P0463) swam much further a distance we estimate to be approximately 5,111 nm*! Fish 1 (Tag 13P0463) spent the majority of its time (around 70%) in depths less than 50 meters (164 feet), where water temperatures were between 26 and 29.8 C (79 to 85.6 F). The marlin did, however, make several remarkably deep dives in late November, late January, and early February where the water was very cold. The deepest dive was made to a depth of 592 meters (1,942 feet) where the fish experienced 7.8 C waters (46 F)! While it is true that a 600 meter dive isn t unprecedented, we find that most dives are usually between 150 and 250 meters, and dives deeper than 300 meters are rare. Unfortunately, the tag on Fish 2 (Tag 13P0465) failed to report. Although the IGMR has a very high reporting rate of 83% and we hope to hear back from every tag we deploy, there is always a chance that a tag will not report. We can speculate a few reasons this might happen. First, although each tag is painted with anti-fouling paint, biofouling can become an issue, especially
during long deployments. It s also possible for the antenna to become encrusted with organisms or physically damaged which can impede the tag s ability to transmit data or it s possible the tag could malfunction (although a very rare occurrence). Another possibility is the tag was crushed when it reached very deep depths. In very deep ocean basins like the Pacific, it is possible that the blue marlin died and when it sank to the ocean floor, the tag may have been crushed before it was able to release from the carcass. Marlin are very temperature sensitive and the depth range of Pacific blue marlin are likely constrained by the thermocline (the boundary between warm surface waters and colder deeper waters). In the IGMR, we have found that that 60% of the time, they occur in the top five to ten meters of the water column and when they are not near the surface, they primarily occur between 50-100 meters. We have seen this bimodal depth distribution since the project began which likely represents a diel (day/night) pattern where fish dive deeper during the day and remain near surface waters at night. One theory is that because marlin are visual predators, by diving deeper during the day, they can better see their prey (silhouetted at surface) while remaining invisible to them below. So, if they see a school of prey, they are able to swim from beneath them at high speeds. In addition to these behavioral factors (i.e., how Pacific blue marlin hunt), there are likely to also be physiological factors at work, which are related to the effects of both temperature and oxygen availability to the marlin. For example, there are extensive regions of the Central Pacific where oxygen concentrations are very low in deeper water. The IGMR dataset suggests that this clearly influences diving behavior, limiting marlin in these regions to shallower portions of the water column. Despite initially traveling in different directions following release, it is noteworthy that all three fish behaved as expected by remaining above the 15 C thermocline (with occasional deeper dives into colder water) and primarily using water temperatures between 26 28 C (79 82 F). Fish 3 (Tag 13P0471) initially headed north whereas Fish 1 (Tag 13P0463) and Fish 4 (Tag 13P0467) headed south and east respectively. Both Fish 1 (Tag 13P0463) and Fish 3 (Tag 13P0471) crossed the equator into the southern hemisphere, whereas Fish 4 (Tag 13P0467) stayed north of the equator and experienced the warmest maximum temperature (31 C). These different yet similar patterns may be due to the unusually warm water throughout the Central Pacific in the fall and winter of 2014. Of particular interest will be the influences of an even warmer Pacific basin developing in 2015. Our thanks and gratitude goes out to tag sponsor Ken Corday as well as the captains, anglers, crew, and participants in the 2014 TART Kona, USA IGMR for contributing to the growing number of data sets for this species collected through the IGMR. The greatest insights from
animal telemetry data usually come when we can amass large datasets from multiple animals, over long periods of time. These kind of data and we are just getting to the point where we have a critical mass of data for Pacific blue marlin allow us to discern the broader patterns of behavior, both in terms of migratory cycles and diving behaviors like discussed in this report. So while three of the tags that reported provided great datasets, their significance is that they add valuable pixels to a larger image that we are assembling to understand how these animals function in the wild. Thanks for helping us continue to learn about billfish behavior which enables their conservation and protection of the sport we love for future generations of fishing!
Tag 13P0463 Fish 1 Tag number: 13P0463 Sponsor: Ken Corday Angler: Brent Nelson Tagger: Kevin Nakamaru Boat: Northern Lights Species: Blue marlin Estimated weight: 79 kg Deployed: 9/2/2014 Reported: 3/3/2015 Days at large: 182 Distance traveled: 1,773 nm Maximum depth: 592 m Minimum temp: 7.8 C Maximum temp: 29.8 C
Tag 13P0471 Fish 3 Tag number: 13P0471 Sponsor: Ken Corday Angler: Evan Korsh Tagger: Dave Crawford Boat: Kona Blue Species: Blue marlin Estimated weight: 113 kg Deployed: 10/30/2014 Reported: 1/18/2015 Days at large: 80 Distance traveled: 2,124 nm Maximum depth: 376 m Minimum temp: 9.2 C Maximum temp: 29.4 C
Tag 13P0467 Fish 4 Tag number: 13P0467 Sponsor: Ken Corday Angler: Shuzo Aida Tagger: McGrew Rice Boat: Ihui Nui Species: Blue marlin Estimated weight: 136 kg Deployed: 11/7/2014 Reported: 5/6/2015 Days at large: 180 Distance traveled: 2,665 nm Maximum depth: 368 m Minimum temp: 9 C Maximum temp: 31 C