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74 - 2012 World Record Game Fishes The IGFA Great Marlin Race (IGMR) is a partnership between IGFA and Stanford University that pairs recreational anglers with cutting‐edge science to learn more about the basic biology of marlin and how they utilize the open ocean habitat. The goal of the program is to deploy 50 pop up archival tags (PAT) in marlin at billfish tournaments around the world each year. Follow the Pop Up Archival Tags at http://igmr.igfa.org Photo by www.sportfishimages.com

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74 - 2012 World Record Game Fishes

The IGFA Great Marlin Race (IGMR) is apartnership between IGFA and StanfordUniversity that pairs recreational anglerswith cutting‐edge science to learn moreabout the basic biology of marlin and howthey utilize the open ocean habitat. The goalof the program is to deploy 50 pop uparchival tags (PAT) in marlin at billfishtournaments around the world each year.

Follow the Pop Up Archival Tags at http://igmr.igfa.org

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o matter the species ‐‐‐‐‐blue, black, striped or white‐ marlin are revered byanglers around the world. Their elusiveness, speed and strength makethem one of the world’s premier game fish.

Unfortunately, the very same qualities that enamor recreationalanglers also make marlin exceedingly difficult to study. Obtaining move‐

ment data on game fish is vital for proper management, as it can provide evidence ofspawning locations, habitat utilization and stock structure. Historically, much of ourdata for billfish came from conventional tagging. Conventional tags have several advan‐tages in that they are inexpensive to manufacture and are not reliant on a source of elec‐tricity, which means you can easily deploy many and they are viable as long as the tagisn’t shed. Conventional tags have documented maximum linear travel distances of upto 14,893 kilometers in blue marlin and a maximum time at large for sailfish of 17.9years.

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PAT Tags VersusConventional Tags

Like most things in life however, there are also disad-

vantages to conventional tagging. They are dependent on

being recaptured and reported, and recapture rates are typi-

cally less than 2%. The movement data garnered from these

tags are also limited; they can only show a linear distance

from point of capture to point of recapture and they also are

unable to record any information on vertical movements and

how billfish utilize the water column.

In the last few decades, pop-up archival tags (PATs) have

become a popular alternative method of tagging because

they have broadened our ability to collect an incredible

amount of high quality data on billfish movements. These

electronic tags use sophisticated technology that allows them

to collect information on depth, water temperature and light

as often as every 10 seconds for periods up to one year. PATs

have a distinct advantage over conventional tags: they do

not need to be physically recovered. Instead, at a pre-pro-

grammed date, a pin at the bottom of the tag that connects it

to its tether corrodes away, setting the tag free from the fish.

Once the tag floats to the surface it transmits archived infor-

mation to an orbiting ARGOS satellite, which is subsequent-

ly transmitted to the researcher. A light-based geolocation

algorithm is then used to reconstruct the migration track of

the animal. As a result we can not only see actual migration

tracks but also how the fish vertically utilized the water col-

umn and the temperatures associated with it.

Where a PAT tag shows the intricate path traveled by a billfish, theconventional tags only show distance traveled from point A to pointB. The information garnered from the PAT tags has broadened ourability to collect an incredible amount of high quality data on billfishmovements.

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Conventional tag

PAT tag

2012 World Record Game Fishes- 77

The PAT tags show a broader range of migratory paths, from south‐south‐west to almost due east, and distances of 2,281 nautical miles so far.

Graph A: Depth preference as a function of time –showing that this marlin spent 60‐70% of the time inthe top 5 m of the water column, and the remainder ina deeper layer, ranging from 25‐50 or 50‐100 m.

Graph C: This collection of graphs shows longitude, mini‐mum and maximum depth, and minimum and maximumtemperatures all as a function of date.

Graph B: Temperature preference as a function of time –showing that this marlin spent the vast majority of time(>80%) in water from 26‐28oC.

Graph D: Daily maximum depth as a function of date,with colors indicating environmental temperature.

These graphs illustrate the environmental preferences of the marlin. In Graph A, we see depth preferences plotted as a function of time (date). The colorson the graph represent the percentage of time the marlin spent at different depths – with warmer colors representing higher utilization and cooler colors rep‐resenting lower utilization. So in this we see that, throughout the duration of the track, the marlin spent the majority of time – 60‐70% ‐ in the upper 5 metersof the water column. The blue band lower in Graph A shows that it also spent some portion of time (10‐30%) in the depths from 10‐100 meters – althoughthe preferred lower depth appears to have become somewhat shallower with time. Graph B uses exactly the same approach, only with temperature insteadof depth. So here we see that, for the most part, the marlin spent most of the time (80%+) in water from 26‐28 oC.

These graphs show a few things simultaneously. The bottom extent of the colored bars in Graph C shows the deepest depth reached for each day, and thecolors along that bar show the water temperatures as a function of depth. One of the most interesting things about these figures is that they tend to illus‐trate that these fish are diving just to the top of the thermocline, where the temperature begins to fall quickly. In regions of the ocean where the mixed layeris very deep, they dive deep. In regions where the mixed layer is shallow, they make more shallow dives. In Graph D we see that there is only one notableexception, near the end of the track – when the marlin makes a dive to about 100 m into water around 15oC

INFORMATION GARNEREDFROM PAT TAGS

Satellite tags have been used to

investigate a number of questions

with billfish including commercial

and recreational post-release survival

rates, vertical movements and their

interaction with pelagic longline gear

as well as how low oxygen levels

compress habitat. The “Achilles

heel” to PATs is their cost. Even

though the data they collect is nearly

second to none, at upwards of $4,000

per tag they are anything but inexpen-

sive. Fortunately, recreational

anglers are stepping up to the plate to

help cover the costs of these incredi-

ble data gathering tools.

In 2009, IGFA Trustee Peter

Fithian, IGFA Representative Bob

Kurz and Stanford University biolo-

gist Dr. Barbara Block hatched a plan

to pair tournament anglers with cut-

ting-edge PAT technology. The con-

cept was to have anglers/teams spon-

sor PATs at the 50th Hawaiian

International Billfish Tournament

(HIBT). In essence, they created “a

tournament within a tournament”

where anglers competed to see whose

tagged fish traveled the farthest.

Anglers would be able to view the

tracks of tagged marlin on a website

and the winner would receive a free

entry for a team of up to six anglers at

next year’s HIBT. Dubbed the

“Great Marlin Race” (GMR), the first

year was an instant success with

seven tags deployed during the HIBT.

In 2010, the second GMR took

place at the HIBT and 10 tags

deployed. Present that year were

IGFA Chairman Packy Offield and

IGFA President Rob Kramer. After

attending the HIBT, both decided that

IGFA should work with Stanford to

expand the great work of the GMR at

other tournaments and venues.

In early 2011, IGFA started dis-

cussions with Barbara Block’s lab at

Stanford to expand the GMR concept

globally. The result of this exciting

partnership is the IGFA Great Marlin

Race (IGMR). Working in close col-

laboration with anglers, boat captains

and crews fishing before, during and

after billfish tournaments around the

world, the IGFA Great Marlin Race

plans to deploy 50 PATs on a variety

of marlin species in the Pacific,

Atlantic and Indian Oceans each year.

PAT TAGSDid You Know?• These electronic tags use sophisticated technology that allows them to collectinformation on depth, water temperature and light as often as every 10 seconds forperiods of up to one year.

• PATs have a distinct advantage over conventional tags: they do not need to bephysically recovered. Instead, at a pre‐programmed date, a pin at the bottom of thetag that connects it to its tether corrodes away, setting the tag free from the fish.

• Once the tag floats to the surface it transmits archived information to an orbitingARGOS satellite, which is subsequently transmitted to the researcher. A light‐basedgeolocation algorithm is then used to reconstruct the migration track of the animal.As a result we cannot only see actual migration tracks but also how the fish verticallyutilized the water column and the temperatures associated with it.

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Data generated from the IGMR will

increase our knowledge of distribution, popu-

lation structure and biology of marlin and

engage anglers and the general public in the

research process. By better understanding

where these animals go and how they use the

pelagic ecosystem, we will provide valuable

information to the resource managers and pol-

icy makers responsible for ensuring their long-

term conservation. Two other unique qualities

about the IGMR are that it includes a very

interactive website where participating anglers

can monitor the results of the efforts, and all

IGMR tag data will be available to scientists

and managers in an open access system.

Here’s how the IGMR works. Satellite

tags are sponsored by tournament teams, indi-

viduals or clubs at the price of $4,000 each.

Each tag is programmed to pop off the fish 120

days after it is deployed. Once the tag pops

off, information is transmitted to a satellite

and then to scientists at Stanford University.

Then the data are processed so that anglers can

see graphical representations of the tracks of

each individual fish on the IGFA Great Marlin

Race website. In a given tournament, the tag

What have welearned from satellite tags?

Perhaps some of the most interesting data thatPATs collect is how billfish move vertically in thewater column. A study published in 2006 byrenowned billfish experts Eric Prince and PhillipGoodyear compared vertical habitat utilization inbillfish in the western North Atlantic and the east‐ern tropical Pacific. Using PATs, they monitored 19billfish in the western North Atlantic for a total of801 days and 13 billfish in the eastern tropicalPacific for a total of 429 days.

Their study conclusively showed that billfish inthe western Atlantic spend more time deeper in thewater column than those in the eastern tropicalPacific. Atlantic billfish spent 25‐35% of their timedeeper than 50 meters, while their Pacific counterparts only spent 1‐5% of their time at that depth.

But why the difference in behavior? The authors attributed it to the different oceanographic features that characterize the twoareas. The eastern tropical Pacific is an area of nutrient upwelling marked by a cool and very shallow thermocline at roughly 25 metersin depth. In addition the water becomes hypoxic, or very low in dissolve oxygen, directly below the thermocline. In contrast, the west‐ern North Atlantic’s thermocline is roughly 75 meters deep and has sufficient dissolved oxygen down to several hundred meters. As aresult, it appears that billfish are constrained to the upper layers of the water column in the eastern Pacific due to low dissolved oxy‐gen, while in the Atlantic they are not.

This “vertical habitat compression” has several potential effects on billfish and those that pursue them. In the eastern Pacific it isthought that this narrow vertical niche not only applies to billfish but their prey as well. As a result, billfish in this area not only huntin very productive waters but also have their prey confined to relatively shallow depth, which may help increase encounter rates. Thismay partially explain why billfish, such as sailfish, are consistently bigger in the eastern Pacific than in the western Atlantic. Since theyare more confined to the upper portions of the water column they may also may be more available to billfish anglers. The downside isthat this may also make them more prone to interactions with commercial longline and purse seine gear as well.

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80 - 2012 World Record Game Fishes

that surfaces farthest from where it was initially deployed wins the race for that tournament. The overall winner of the annu-

al IGMR is the fish that travels the furthest in all the participating individual IGMR events for that year.

Each annual IGMR will run from October 1st to September 31st (based upon when tags pop off). The 2011/2012 IGFA

Great Marlin Race officially got underway at the Club Nautico de San Juan’s 58th Annual International Billfish Tournament

(IBT) that was held in San Juan, Puerto Rico on September 5-11, 2011. As the inaugural event for the IGMR, the IBT was

a resounding success with all 10 tags being sponsored by individuals or teams by the first day of fishing! Additional tour-

naments and locations for the 2011/2012 IGMR include:

• February 2012: South African Deep Sea Angling Association Classic; South Africa

• March 2012: Australian International Billfish Tournament/

Gamex Billfish Tournament; Australia

• August 2012: Madeira, Portugal

• August 2012:Hawaiian International Billfish Tournament; Hawaii

• September 2012: San Juan International Billfish Tournament; Puerto Rico

If you are interested in hosting anIGMR event or sponsoring tags, con‐tact IGFA Conservation DirectorJason Schratwieser:[email protected]

To follow real‐time tag pop ups formarlin visit the IGMR maps athttp://igmr.igfa.org/latestmap.aspx

Satellite tags are sponsored by tournament teams, individuals or clubs at a price of $4,000 each. Each tag is programmed to pop off the fish120 days after it is deployed. Once the tag pops off, information is transmitted to the ARGOS satellite and then to scientists at StanfordUniversity. At the 2011 San Juan International Billfish Tournament in Puerto Rico, 10 PAT tags were purchased by tournament teams and sixof the tags were placed. To see the latest IGMR map with tag pop ups visit http://igmr.igfa.org/latestmap.aspx.

2012 World Record Game Fishes- 81