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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.
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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.
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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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.
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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