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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 cuttingedge 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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  • 2012 World Record Game Fishes- 75

    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 worlds 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 advantages in that they are inexpensive to manufacture and are not reliant on a source of electricity, which means you can easily deploy many and they are viable as long as the tagisnt 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.

    76 - 2012 World Record Game Fishes

    Conventional tag

    PAT tag

  • 2012 World Record Game Fishes- 77

    The PAT tags show a broader range of migratory paths, from southsouthwest 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 6070% of the time inthe top 5 m of the water column, and the remainder ina deeper layer, ranging from 2550 or 50100 m.

    Graph C: This collection of graphs shows longitude, minimum 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 2628oC.

    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 representing lower utilization. So in this we see that, throughout the duration of the track, the marlin spent the majority of time 6070% in the upper 5 metersof the water column. The blue band lower in Graph A shows that it also spent some portion of time (1030%) in the depths from 10100 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 2628 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 illustrate 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 years 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 Blocks 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 preprogrammed 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 lightbasedgeolocation 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.

    78 - 2012 World Record Game Fishes

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    Continued on page 80

  • 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

    p