Background
I began fishing for shortfin makos (Isurus oxyrinchus)
in 1994 and after learning about their reproductive biology,
I decided that the responsible thing to do was to give back
to the resource rather than to take from it. As my interest
in makos grew I learned about the Department of Fish and
Game's (DFG) volunteer shark tagging program. The program's
objectives are to use the data obtained from the tag and
release of pelagic sharks to estimate the local distribution
and abundance, and to track the shark's long-term migrations
within and beyond the southern California Bight. My involvement
in the tag and release program has grown considerably, as
a result of which during the past four years I have tagged
and released over 1,000 sharks (over 50% makos).
In addition to simply implanting the spaghetti tags on
sharks, we must acquire data on sex and length if we are
to increase our understanding of the local shark population
structure. However, if you have ever tried to handle an
explosive small mako at the side of your boat, you will
know that obtaining accurate length and sex data is not
an easy task. Inaccurate sexing may arise from the fact
that the reproductive organs of male juvenile makos are
not yet fully developed and consequently are very small.
There is also some variation between the common visual guestimation
of length and a more precise direct measurement (see Tagging
section). Striving to come up with a better way to collect
this and other biological information, I designed and created
a shark sling. The original sling was made of plastic ABS
pipes and an old canvas boat cover, however, the sharks
teeth proved more powerful than expected and the canvas
was replaced by thick rubber. The sling was suspended by
an engine hoist, salvaged from the garage, and bolted through
the deck of the 24' Skipjack, "The Shark Tagger". Finally,
to complete my new contraption, I attached a load cell between
the engine hoist and the shark sling. This allowed for a
precise measurement of live weight before the shark was
released.
The first day of weighing sharks off Redondo Beach with
Mike Jones (a professional photographer from Canada) and
David Lopez (a.k.a. "Jaw Man") was very exciting. The first
fish brought to the boat that day was a 6ft. mako, a very
respectable mako for these waters, and a formidable adversary.
After a quick battle we pulled the mako into the sling and
slowly raised the sling out of the water. We anxiously looked
at the digital scale readout as it leveled at 127 pounds,
what an incredible moment. Next, we implanted the tag at
the base of the dorsal fin and collected the makos total
length and sex. Finally we released the hook and lowered
the sling into the water. The mako instantly disappeared
from sight and left us with a vigorous splash.
The idea of weighing the sharks was adopted by John Ugoretz,
from the DFG, and was put to use during their annual long-lining
research cruise off the Southern California Bight. I was
fortunate enough to able to participate in this four-day
research cruise and assisted in many ways. During my many
talks with the investigators aboard the research vessel,
I realized the importance of the bilateral flow of information
between scientists and sport fishermen. For example, to
achieve a clean jaw hook set as opposed to a gill hook set
or deeper stomach set, I showed them my baiting techniques.
In turn the scientists taught me how fragile the sharks
really are, especially the gills where only a paper-thin
layer of tissue separates the water from the bloodstream.
This prompted me to use smaller hooks, and to pay close
attention that if when releasing the fish there was a possibility
of damaging the gills it is better to cut the leader and
leave the hook, rather than taking the chance of deeply
wounding the shark.
During the research cruise I met Diego Bernal, a scientist
on the cruise who was collecting tissue samples for shark
biochemical research. Since then, we have been working together
on various projects. Diego is a graduate student at the
Scripps Institution of Oceanography and is conducting his
Ph.D. research on mako shark physiology. Diego's research
focuses on mako shark swimming energetics, and the use muscle
biochemical capacities as an index of swimming performance.
Another focus on his mako project is to understand how the
relative proportion of swimming muscles, gill surface area
and heart mass change with size, and how these animals utilize
their ability to retain metabolically produced heat to warm
certain muscles and improve sustained locomotor activity.
The combined efforts of my fishing expertise provide Diego's
research with specific tissues, that will in turn offer
a better understanding of mako biology and may ultimately
assist the fishery management in insuring a brighter future
for this very important resource.
I have set my personal standards for responsible mako
fishing. The resource cannot stand the pressure that has
been placed upon it. In the past I have only kept four sharks,
all males over 6 feet in length weighing more than 100 pounds.
The last one, in April of 1998, was 9 feet and weighed over
400 pounds (the largest male mako recorded). If you are
going to take a fish it is best to keep a larger male, leaving
the females to reproduce. A larger male provides more table
faire, as opposed to several pups.
In order to understand the importance of tagging and releasing
makos it is important to review what is known about their
size at first sexual maturity and growth rate. Scientists
have shown that male and female makos sexually mature at
different total lengths, with males maturing at 6ft and
females at between 8 and 9ft. Moreover, the time it takes
makos to reach sexual maturity has not yet been clearly
resolved. For example, some workers have estimated that
males take 3 to 4 years to reach sexual maturity and may
live up to 20 years, while others estimate sexual maturity
at 7 to 8 years and a longevity of 45 years. This is where
the data collected from tagging and recapture become an
extremely important tool for age and growth determinations
of the eastern Pacific makos. In addition, by increasing
the number of tagged makos we augment the probability of
recapturing the fish and thus provide a better perspective
on the distribution and abundance of the regional shark
population.
All sharks fertilize their eggs inside the female and
after an estimated 1 year gestation time, newborn mako pups
are born alive and ready to fend for themselves. The average
mako litter has 14 pups, which measure about 2 1/2ft. total
length. It is important for us as sportfishers to understand
that in difference to bony fish which can produce millions
of larvae every year, makos (and sharks in general) have
a very limited reproductive output. Such a great difference
in the number and frequency of newborns produced by makos
(average of 14/litter), puts them at a substantially greater
degree of danger for overfishing. Moreover, since the average
mako captured in southern California Bight is usually smaller
than 4ft., and large sexually mature makos are a rare find,
the Bight may serve as a nursery ground in which the pups
feed and grow on the abundant prey, such as mackerel and
sardines. In addition, the Bight may offer a safe place
for small makos to avoid becoming prey of larger sharks.
Hunting
Most shark fisherman in Southern California run up to
banks and throw out a bucket of chum, while sitting and
hoping for the best. However, unlike rock cod, pelagic sharks
do not sit and wait for a meal, they spend their entire
life in continuous movement in search of prey. These highly
mobile predators are not going to waste their energy by
hunting in places where water conditions are not adequate.
Pelagic sharks, especially makos, are usually found in a
specific temperature range and in areas where there is an
ample food supply. Even though there are some hypothesis
about some shark species orientating their horizontal movements
with the ocean floor's magnetic anomalies, conclusive evidence
that makos follow such patterns remain unresolved. In addition,
the eastern Pacific makos seem to spend the greatest percentage
of time at depths that are above the thermocline, with only
a limited number of deeper dives. It is important to reiterate
that the large amount of data collected for the northwestern
Atlantic makos may not directly apply to their west coast
counterparts, as the thermocline depth and general bathimetry
are widely different between the east and west coasts. For
example, a mako sonic tracking study off Florida may lead
us to conclude that makos follow the isolume (depth at which
there is no considerable change in light level) and hence
that makos are found in shallow waters during the night.
However, studies of eastern Pacific mako vertical movements
show that they rarely make excursions below the shallow
eastern Pacific thermocline, thus, this mako population
may be limited to an overall shallower depth. In contrast,
the east coast is a completely different situation, as the
thermocline is present at a greater depth allowing for a
potential greater range of vertical movement.
One of the most important reasons why makos are commonly
found around banks and canyons is that there is generally
some associated nutrient rich deep-water upwelling. The
influx of nutrient rich water sparks an increase primary
production, which is the cornerstone of the marine food
chain. Bait schools seek these conditions, and inherently
makos and other apex predators follow. In summary, we are
talking about a specific suite of oceanographic conditions.
These conditions are what you must actively look for, so
don't just sit and wait at any shallow spot for a hookup.
Nevertheless, under the right conditions, I have found makos
in 80 feet of water with no apparently relevant floor structure.
! Remember that you will never become a good fisherman until
you become a great hunter!
If you are planning to specifically target makos you must
spend countless hours reading fish reports and analyzing
sea-surface temperature maps, which in conjunction provide
the best way to select the appropriate water conditions.
These optimum conditions have proven to be: 70BAF surface
water, lots of bait (preferably mackerel), and a good strong
drift approximately 1-3 knots (best if parallel to the shelf).
To increase the chances of catching a mako, you should preselect
at least 4 different spots that meet you water condition
criteria. Upon reaching the first spot it is important to
use your fish-finder to locate a school of baitfish, in
addition, look for signs of birds and jumpers. Next, determine
the direction and strength of the drift and reposition yourself
BC to BD mile updrift (a greater distance may be necessary
if the drift is very fast). The objective is to lay a good
chum slick that will pass directly over the preselected
spot. The best chum slick is created using 2 square 4 BD
gallon buckets of New Fishall Chum and dumping them into
5 gallon round buckets with 40 1" drilled holes. I have
baptized this as "choke chumming". I have found New Fishall
Chum to be the best bait mix available. When I start my
drift and am trolling the buckets, I drop over a Top Gun
Deep Diver made by Ballyhood Big Game International Trolling
Lures. The Ballyhood has a 2lb mackerel inserted in it.
When trolling, I usually use a Penn International 80 STW
spooled with 130 LB Dacron with the drag set to 38lbs. It
is important to keep the mackerel at the thermocline depth.
Using this method I can attribute about half of my catch
to the Ballyhood and have found that usually the bigger
makos hit it first! To give your chum slick that "special
quality", have a one gallon dispenser of Menhaden Fish Oil
from Bordner Offshore Products, dispensing oil in the fully
open position. It has proven extremely effective to continuously
submerge a Mako Magnet over the side of the boat. Since
your slick only distributes its smell along your drift path,
the Mako Magnet expands you effective range of fish attraction
by projecting a 360BA low frequency sound up to a distance
of 1 mile. Scientists have long taken advantage of the shark's
incredibly sensitive hearing and pressure wave perception
and used low frequency sounds to attract them. If there
is no activity for about an hour at the first preselected
spot around move to the next one. Remember that this is
the reason you have 4 preselected spots.
Tagging
Fishing alone over 90% of the time has obligated me to
devise some unique techniques for safely capturing and tagging
sharks. I use a Penn International 50SW reel spooled with
100 LB Dacron, and attach a wind on leader made of Burns
Saltwater Outfitter's Soft Steel monofilament. Practical
experience has taught me that Dacron is far superior to
monofilament because it does not stretch and you can get
a higher test line with the same capacity of line on the
reel. One of the advantages of using the Soft Steel wind
on leader is that you only need to attach a maximum of 5ft
of 360lb single strand stainless steel leader. To estimate
the length of the leader that will best work for you, place
the rod into the rod-holder and let the leader hang over
the side of the boat until it touches the surface of the
water, measure this distance and then subtract 12 inches.
I have found that following this procedure allows the bend
of the rod to assist in an effective hook release. The 300
LB Soft Steel that I have setup enables me to max out the
drag so that I can easily drop the rod in the rod-holder.
This is the best and safest way to handle sharks at the
side of the boat.
Releasing the sharks is as important as catching them.
To release the sharks and minimize the damage to the their
soft tissues, I use the Burns Saltwater Outfitters release
stick. I have found that Burns has the best design available
as it does not have any sharp edges, and has a smaller head
which is easier to work with. Slide the release stick down
the leader until you reach the arch of the hook, then patiently
wait for the fish to position itself correctly, this will
considerably reduce the chance of post-catch mortality.
The predetermined length of the steel leader (see previous
paragraph) bends the rod and creates the perfect spring
action to help release the hook. Neonatal makos (under 3ft
in length) are very fragile, in a sense like newborn babies,
so I will not force a release stick into their mouth as
the gills lie dangerously close. To decrease the damage
done to small makos by the releasing process, I have found
that if the hook is not clearly visible in the jaw, it best
to cut the leader as close to the hook as possible. It is
very important to avoid letting the sharks run with the
bait as they can easily swallow the hook and become injured
during the fight. To avoid such an outcome, I do not put
the line more than 100 feet off of the back of the boat
and I set the hook immediately to insure a proper jaw hook
set. Remember that if you are going to go out and catch
makos, there is no room for error and the job should be
done right the first time.
Even though it is tempting to use big hooks so that the
big one does not get away, I have found that 9/0 Mustad
hooks are more than adequate. These small hooks are inexpensive
and reduce the risk of damage to the fish. Not long ago,
I tagged and released a 7ft. mako that was over 200 lbs,
an 8ft 2inch mako over 300 lbs, and many pups on the same
Mustad hook without any evidence of material stress. Shark
skin and mandibular cartilage is very tough, so the hooks
need to be razor sharp and it is wise to use a dremel tool
as a sharpening instrument.
As far as tagging, I have found that the Aftco tag stick
is the best. The best time to take a shot at the fish with
the tag stick is when he is positioned dorsal up. Find the
correct spot at the base of the dorsal fin, stare exactly
at point where you intend to insert the tag and give it
a shot. Tagging the fish while it is rolling on its side
increases the chance of lacerating the great lateral vessels,
which may result in death. The National Marine Fishery Service
and the California Department of Fish and Game have successfully
adapted a spear gun to insert the tags. This innovative
device allows the tagger to accurately place the tag at
the base of the dorsal fin while minimizing the fish handling
time. It would be very wise to make this device available
to all the taggers, and thus minimize post-catch mortality
associated with bad tag insertion.
It is very important to obtain reliable length measurements,
and here are some of the methods commonly employed by taggers:
a. marks on the side of the boat that have a
known distance between them
b. marks on your tag and release stick that have known distance
between them
c. different colored ribbons attached to the release stick
that have a known distance between them
d. a stiff tape measure
Measuring techniques will vary depending on the size of
shark that you are dealing with and the relative state of
stress that the shark demonstrates. If the captured mako
is under 5ft., has a clean jaw set hook, and it is not thrashing
like mad at the surface, I like to gently hold the fish
by the tail and roll it ventral side up. I immediately extend
the tape measure next to it while checking its sex. If the
mako is very small and I conclude that a visual determination
of sex will not be accurate, I hold the leader with one
hand and feel underneath the shark looking to find claspers
if it is a male.
To minimize the shock associated with capture I like to
beat the fish on heavy tackle, measure, sex, tag and release
it as quickly as possible (usually less than 2 minutes).
Occasionally I have recaptured a mako that I had tagged
earlier that day, and I have also recaptured the same fish
the next day. After all the time that I have spent fishing
for makos, I have gotten better at minimizing capture related
stress and I usually give the makos a few pets before sending
them on their way.
Importance of tagging
Recent fishery studies conducted by the National Marine
Fisheries Services (NMFS) off the western Atlantic and the
Gulf of Mexico have concluded that the depletion of up to
eighty five percent of the regional shark resource is attributed
to overfishing. The eastern Pacific is by no means exempt
from such poor management, and we must therefore learn from
the East Coast example and prevent such devastating decreases
in local shark populations. It is important to understand
that the research conducted by scientists on East Coast
makos, does not necessarily apply to the fishery in Southern
California Bight. The ecology of eastern Pacific makos appears
to be very different from their east coast counterparts,
for example, they differ in food source, diving patterns,
average depths (see Hunting sections for more details),
temporal and spatial migrations, and overall length. So
when it comes time to apply a management plan for the eastern
Pacific mako population, decision makers should take caution
in only using the information available from the east coast
studies to infer a west coast management plan.
In 1983 the Department of Fish and Game started the volunteer
pelagic shark tagging program. Out of the 21,000 shortfin
makos that have been tagged and released to date, there
have only been 84 reported recaptures. Most of the recaptures
have occurred within thirty days from the original date
of capture, and within fifty miles of the initial site.
It is extremely difficult for policy makers to rely on such
a small data set to dictate future management decisions.
Sportfishermen offer an important link between scientist
and policy makers, as our combined fishing effort can provide
an adequate number of tagged sharks which in turn will ensure
a more comprehensive picture of the eastern Pacific mako
population. There are currently only 52 active taggers on
the West Coast and most of these taggers only tag a few
sharks (5-10) per year. There is a desperate need for more
fishermen to pick up the phone and call (562) 590-4801,
to get their free tagging kit, the future of our resource
depends on this.
I have personally concentrated my efforts and made it
my goal to increase the number of taggers in our local program.
Not only have I learned a great deal about sharks, but I
have found some great avenues for teaching the general public
about our decreasing shark population and how they can influence
its future. Chuck Myers and I have been able to increase
awareness through our television show the West Coast Sport
Fishing Show by filming conservation minded shows, and focusing
on the tagging program. Last May I started my own web site
(www.sharktagger.com) with the assistance from my engineer
and designer Jamie Wilkinson. It has been people like Jamie,
who have helped increase awareness on this issue without
expecting anything in return, that emphasize the good nature
sportfishermen have. The web site provides a lot of exciting
information for fishermen. We have a very active message
board with Live Fish Reports and have focused in offering
the public a number of scientific studies that will provide
the visitor with an in depth review of some aspects of mako
ecology and biology. In addition, the site provides all
the information you need to know about the tagging program,
and even has the capability of downloading an application
form for tags. The site also has an impressive image gallery,
which is constantly being updated with current photos. Through
my website and in conjunction with Don and Mel from Allcoast
(www.sport-fish-info.com), who have added a shark message
board to their site, I have been able to expand my area
of work and now have a much stronger voice that can reach
out to many more fishermen.
Conclusion
Sport fishermen and commercial fishermen on the West Coast
seem to be over fishing the local shark populations. Without
adequate scientific studies, it is not possible to impose
new laws to protect the shark fishery. I would like to see
sport fishermen get together and set a standard of responsible
fishing for the mako fishery. The guidelines that I feel we
should follow are:
a. Set size limits (nothing taken under six feet).
b. No females taken.
c. One fish per angler per season.
d. All fisherman must tag.
If all sport fishermen tagged sharks, we would gather sufficient
data to influence changes in the laws that would result in
a regulation of the commercial fishery. In contrast to the
6500+ taggers that NMFS has in the East Coast, the West Coast
only has 52 active taggers. If we collect enough tagging information,
we will be able to make changes like the ones accomplished
in the East Coast fishery, for example we could:
a. Impose size limits on commercial and sport fishermen.
b. Improve monitoring of recreational and commercial landings.
c. Prohibit finning of all cartilaginous fish in both
state and federal waters.
d. Close the state waters to direct shark fishing during
the pupping season.
e. Close some or all nursery areas to other fisheries
that take large numbers of juvenile and adult sharks in
their bycatch.
f. Prohibit the use of gear with high bycatch and or require
the use of devices that cause such unnecessary mortality.
g. Require commercial fisherman to tag bycatch and undersized
fish.
h. Develop tag and release training programs.
Although I have created a strong voice in conservation
to increase further awareness and help develop future studies,
I need to acquire more support and sponsorship. I am looking
to large corporations, both marine and non-marine related,
to expand awareness to all the fishing related public and
the general public. To reach some of my goals, I need to
have a larger, safer, and more dependable vessel in which
more accurate data can be collected using the shark sling,
and in which I can educate new taggers and collaborate with
scientists. To continue my mission I need a boat sponsor,
this will enable me to collect DNA samples from which scientists
can build a spatio-temporal database of local shark populations,
and will permit me to assist with the ongoing studies by
scientists at Scripps Institution of Oceanography. In turn,
I am able to provide my sponsors with advertising on my
web site, television show, through media attention and via
public speaking at seminars. If anyone is interested in
learning more about tagging, information on sponsorship,
or would like to go out fishing, please contact me at (310)
371-4401 or email me at sharktgr@gte.net, and please don't
forget to check out the web site at www.sharktagger.com.
