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| Conservation
Issues |
Conservation Update
[December 7, 2004 - By Jim Summers, WVBF Conservation Director]
As you all are aware of, we are constantly looking for new and better ways to conduct our weigh-ins and to protect
the resources we cherish so much. I have been reading about the Shimano water weigh-in system and would like to
share that with you.
Did you know that fish weigh the same in the water as they do out? Apparently it is a fact.
Shimano initially partnered with the research team at Queen's University because of their determination to minimize
the impact of live -release tournaments on fish. Researchers from the University examined the physiological condition
of bass after many different tournament events, carefully monitoring the environmental conditions to which fish
are exposed during every aspect of a tournament. In addition to real tournaments, numerous experiments under highly
controlled conditions helped to determine the impact of specific tournament procedures on the physiology of the
bass. Important scientific findings show that the weigh-in process is the most critical time for fish caught in
a live release tournament, the traditional weigh-in procedure contributes to a large metabolic disturbance in fish,
which can lead to increased stress levels and mortality. Based on these findings, Shimano has developed the new
Shimano Water Weigh-in System" that improves the physiological condition and the survival of fish in live
release tournaments.
The main cause of this metabolic disturbance is a shortage of oxygen. Similar to humans, fish can tolerate reduced
levels for very short periods of time, but the period of oxygen deprivation last longer than a few seconds it begins
to have very significant consequences. Most tournament organizers make a significant effort to maintain water oxygen
levels during the weigh-in, but this can be a very challenging task without the proper equipment and because large
numbers of fish are weighed water oxygen levels change very rapidly at certain steps of the weigh-in, especially
in hot weather. Water oxygen levels are not the only factor that contributes to a shortage of oxygen within the
fish. Whenever a fish is removed from the water, the regions of the fish's gill used to take up oxygen (the lamellae)
will collapse and the exchange of respiratory gases (oxygen and carbon dioxide) will be restricted. During the
traditional weigh-in process, which involves weighing the fish in the air, they will experience a significant bout
of oxygen deprivation.
What have we learned so far? You got it, OXYGEN is the most important issue for fish during the weigh-in process
and we need to look at how difficulties arise and what we can do, remembering that not just one aspect of the weigh-in
is causing oxygen shortages for the fish, but a combination of low oxygen conditions that can be created during
the weigh-in. Each step of the weigh-in process has been found to be a potential oxygen problem for the fish. Because
large masses of fish are places in transfer bags with very little water, oxygen levels fall extremely fast in the
bags. The problems are further complicated because some anglers bag their fish while waiting in their boats way
ahead of their weigh-in time. Weighing fish in the air exposes them to another round of oxygen deprivation, if
fish are not placed into the water after weighing this exposes them to even more deprivation of oxygen. As the
weigh-in continues, fish may be exposed to low oxygen conditions in the live-release vessel, or holding tanks,
because the metabolic requirements of a large mass of fish can exceed the capacity for aeration. These are common
situations that can occur during a traditional weigh-in process. The important point is that there is not a single
incident of oxygen deprivation in a typical weigh-in that fish could not handle for a short period of time, but
when these bouts of oxygen deprivation are combined the situation quickly becomes very dangerous for the fish.
In many cases, they are still alive when released, but in relatively poor physiological condition.
This is why Shimano recommends weighing fish in water to eliminate areas of oxygen deprivation during the weigh-in
procedure. The type of transfer bags are also critical, bags with slots or ventilated, that will not hold water
should not be used. Shimano recommends fish should always remain in the water and anglers are advised not to place
the fish from the boat to the transfer bags until it is time to weigh in. As all of you are aware we only put out
ten bags at a time and this is one of the reasons, the other is we only have 8 drop line hoses with compressed
air to put in the bags while you are waiting in line. This lets us control the weigh-in and we don't have long
lines of anglers with bags of oxygen-deprived fish. This is why we will not weigh fish that are not in Federation
bags. The biggest change to the weigh-in procedure has been to weigh the fish in water. This eliminates one of
the most serious bouts of oxygen deprivation for the fish and further reduces the deadly sequence of low oxygen
conditions that arise using traditional weigh-in methods. This system therefore provides measurable physiological
benefits for the fish. The muscle energy reserves in fish weighed in water are much greater than those weighed
in air. The concept of weighing objects in water has been around for a very long time in scientific circles. Anglers
can rest assured that the weights of fish obtained in water are as accurate as those obtained in air.
Tournament organizers will also be pleased to know that there is little need for specialized equipment, making
it easier (and less costly) to switch to water weigh-ins. The first piece of equipment necessary is a modified
weigh-in basket. This can be done by; drilling holes around the base of the basket it is also critical that these
baskets all weigh the same after being drilled. Next we need a container that will serve as a water basin on top
of the scales. It must be large enough to accommodate the baskets being used and hold 6 to 8 inches of water; the
height of the water is not critical but must be enough to cover the fish in the basket. The most important item
is the scales they must be able to weigh 100 lbs the reason for this is they must be able to weigh 60 to 80 lbs
of water plus 6 fish limits. So now we are ready to weigh the fish. We first put the water basin on the scale and
add he proper amount of water, then put a basket on the top of the basin, then tare the scale. It should go to
zero, we now have the weight of the basin and the basket removed from the scale, add a nice limit of 3lbs smallmouth
from the River and it should give you 15 lbs for your five fish. The fish are in water and not deprived of oxygen.
Well as far as I can tell our weigh-in procedure is pretty good. We have three oxygen pumps for the tubs and the
tank, pure oxygen for emergencies. The only thing we don't do to help the survival of the fish is weigh them in
water. This may be in our future.
Weighmaster Steve Jackson may be getting wet.
May God bless you all and your families and have a safe and happy holiday season.
Jim |
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