GMR: The Great Marlin Race
By Dr. Randy Kochevar, Hopkins Marine Station
Anglers from around the world gathered in Kona, Hawaii for the 51st annual Hawaiian International Billfish Tournament and the launch of the 2010 Great Marlin Race (GMR). The GMR program was initiated in 2009 to commemorate the 50th anniversary of the HIBT and its long history of collaboration with cutting-edge billfish conservation research. The Great Marlin Race is a “competition within a competition,” where angling teams have the opportunity to sponsor an electronic satellite tag that is deployed on a Pacific blue marlin during the tournament.
The objective of the research is to discover where blue marlin go in the Pacific after deployment in the summertime marlin fishery off Kona, Hawaii. When the tags pop off the fish – after 120 days – the fish that has traveled the farthest “wins.” The sponsor of the tag (usually a team) gets a free entry into the 2011 tournament. The first Great Marlin Race was coordinated by Stanford University Professor of Marine Science Dr. Barbara Block, who in the 1980’s pioneered the development of electronic tags to follow the migrations of open ocean fish. Dr. Block and her colleagues Peter Davie, Charles Daxboeck and Julian Pepperrel did much of their early work in collaboration with the HIBT as part of the Pacific Ocean Research Foundation. Dr. Block and former PORF director Mr. Bob Kurz, along with Stanford University marine biologists Dr. George Shillinger and Dr. Randy Kochevar, created and launched the first Great Marlin Race in 2009.
In the first Great Marlin Race, a total of ten tags were deployed – seven during the tournament itself, plus three others that were put out in the weeks following the tournament’s end. A website was built (www.greatmarlinrace.org
), where anglers could check in to see the progress of their marlin within the race. The tags came off gradually over the course of their programmed six-month deployment, and after 180 days a total of five tags had reported in. Four of these tags revealed remarkable journeys, ranging from 1,036 to 2,651 nautical miles. These are among the longest tracks ever recorded for Pacific blue marlin, three of which swam all the way to the Southern Hemisphere, winding up in the vicinity of the Marquesas Islands in French Polynesia.
Dr. Block observed, “For me it was fascinating to see how far the blue marlin went so quickly across a portion of the ocean that is very hot - the equator. I had just been to the Marquesas in 2009 with Stanford@SEA
so it was extra special to see the linkage of blue marlin of Kona and this remarkable archipelago.”
By analyzing the transmitted data from the first Great Marlin Race, the Stanford team learned the Kona blue marlin led dual lives – spending their days diving at depths ranging from 25-100 meters, with occasional deep dives of 250 meters or more; and spending the nights in the top five meters of the water column.
This is a common behavior pattern in the open ocean among a wide variety of different animals, and suggests that the marlin may be searching more at depth during the day following along with the smaller squid and fish on which they feed.
The research plan for the 2010 race built on the findings of its predecessor. Instead of 180 day deployments, the 2010 tags were programmed to surface after 120 days to keep things moving along, and to help achieve higher rates of return. Using this approach, the Great Marlin Race team hopes to learn even more about where these magnificent animals go and what they do in their journeys across the vast Pacific Ocean basin. Drs. Block and Kochevar hope the race concept can be picked up by other tournaments around the globe. They’ve created a website called GTOPP.org that utilizes sophisticated computer codes to quickly display the data from electronic tags on open ocean animals around the world. If you’re interested in creating your own GMR for your tournament, please contact:
Findings from the First Race
One of the most interesting findings from the first race is the diversity of migratory behaviors, the Stanford team observed. Although three of the marlin traveled to the same general region – around the Marquesas – the routes they took and the timeline of their travels differed greatly: two of them made the journey in 89 and 93 days respectively, while the third spent much more time in the Northern Hemisphere, not even crossing the equator until well after the first two marlin had already arrived in the Marquesas. And the fourth marlin did something completely different than the other three - traveling mostly east of the Hawaiian Islands rather than south, remaining in the subtropical convergence zone – a very dynamic region which supports a wide variety of open ocean animals.
Pop-up satellite archival TAG (PAT)
The pop-up satellite archival (PAT) tags used in the race are built by Wildlife Computers of Redmond Washington. Block and her team, along with many other scientists around the world, are using these tags to reveal the secrets of numerous pelagic species. They are essentially micro-computers attached to a swimming animal, designed to withstand the rigors of life at sea. Each tag has sensors which measure depth, temperature and light, along with a very accurate clock. The combination of time, light and temperature are used to estimate the animal’s location, and to document its behavior and the environmental conditions around it. Every 30 seconds the microprocessor “wakes up,” takes a reading from each sensor on the tag, then processes and stores this information.
After a programmed length of time (typically 30-360 days), a metal pin on the tag receives a current and corrodes in less than an hour. The tag is then released from its tether and floats to the surface, where its precise global position is established and it begins relaying its stored data through Earth-orbiting ARGOS satellites. For the 7-10 days that follow, the data stored on the tag are transmitted via satellite back to the Block laboratory where they can be analyzed.