Myers fizzing san angelo 2010

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  • Several names have been given to this condition in fish----fish bends, depressurization illness, etc. In the scientific realm, its most commonly called Barotrauma. What causes barotrauma and what are symptoms of the condition? It results when fish are removed from the high-depth, high-pressure zone to the surface which causes the volume of air within a fish to increase, thereby affecting fish buoyancy. Barotrauma is to fish what the bends are to human divers. External symptoms include swollen belly due to an over-inflated air bladder, floating upside down, inability to resubmerge. In more severe cases symptoms include bulging eyes, everted stomach, Barotrauma can be fatal to both marine and freshwater species that inhabit deeper depths including black basses.
  • What is the function of a fish’s air bladder? Its very important in that helps fish compensate for pressure- depth relationship in water. Ambient pressure doubles for every 33 feet of water depth. The air bladder allows for fish to achieve neutral buoyancy at any water depth. Neutral buoyancy is a very important mechanism in that it allows fish to conserve energy and rest more air is required in the air bladder at deep depths to achieve neutral buoyancy less air is needed in the air bladder at a shallow depth to achieve neutral buoyancy In advanced species like black basses, air is exchanged in and out of the air bladder via the circulatory system. This exchange is accomplished by the rete mirebele, the front area of the air bladder which contains a high density of blood vessels. The rate at which fish can transfer air to and from the air bladder is very, very slow. Studies of bass using hyperbaric chambers found that it takes 1 hour for a fish to fully regain neutral buoyancy after a depth change of 6 inches. Reeling a fish in slow does is not a practical way to alleviate barotrauma because of how slow a bass’s air bladder acclimates to depth changes.
  • . I would bet that many of you have caught fish from a depth of 10-12 feet and that fish ends up with barotrauma.
  • There are three common treatments used to alleviate barotrauma in tournament bass.
  • Specific objectives addressed by our study were: Determine the incidence, that is frequency of occurrence, of barotrauma in Amistad tournament bass and the current incidence of barotrauma treatment by Amistad tournament anglers. Determine if barotrauma affects survival of tournament-released fish. Determine and compare effectiveness of the three most popular barotrauma treatment techniques which are side-fizzing, mouth-fizzing, and deep-release. Determine if timing of treatment influences survival of affected fish, and Determine if level of training influences survival of treated fish.
  • The first three columns in this table are the same as presented in the table on the previous slide. The column labeled BT-neg represents percent survival of tournament fish that did not have barotrauma. The BT-pos column shows percent survival of tournament fish that did exhibit barotrauma. These Barotrauma positive fish were left untreated for the condition. For the first 3 events when water temp was 60 or less, percent survival was very high, at least 91%, for both groups of fish, those without barotrauma and those having barotrauma. At higher temps, 80 degrees and above, survival decreased considerably ranging from 43-83% for both groups of fish. For two of the 5 tournaments, BassChamps 2 and Permian SIT, barotrauma positive fish experienced statistically significant lower survival than fish not having barotrauma. These results demonstrate that barotrauma can indeed lower survival of tournament-released fish.
  • This table shows survival percent by type of treatment and timing of treatment, 1 hour and 5 hours after the onset of the condition. There are slight differences in percent survival between the timings for side fizz, 6%, and mouth fizz, 5%. However, statistically, these survival rates did not differ significantly between the timings. Thus, timing of treatment did not influence survival.
  • Next is our results concerning level of fizzer training. The percent survival values differ by no more than 6% between minimal and hands-on. For both fizzing methods, fish survival was statistically similar for minimally-trained and hands-on trained fizzers Thus, l evel of training received by fizzers was unrelated to survival of treated fish
  • We also evaluated if presence of blood and fish size was related to survival of barotrauma-treated fish. We found no statistically significant difference in survival of side-fizzed fish between those that bleed and those that did not. Alternatively for mouth fizzing, we found we found statistically significant lower survival of mouth fizzed fish that bled compared to those that didn’t bleed, 43 versus 89% For fish size, lengths of surviving and dead fish varied by less than 1 inch for all three treatment types. There was no statistically significant relationship between fish and survival.
  • Why did mouth fizzing cause lower survival? We believe it is due to trauma to the rete mirabile and close proximity of other vital organs to the mouth fizzing needle insertion location. The rete mirabile is the anterior (forward) area of the swim bladder within the green circle. It is different than the posterior portion of the swim bladder in that it contains a much higher density of blood vessels and is the location at which gas is exchanged in and out of the swim bladder. In mouth fizzing, the needle impacts this most important part of the swim bladder as shown. Also, close by the mouth fizzing insertion location are the verterbral column and the anterior kidney which is sandwiched between the vertebral column and the rete mirabile. Both of these organs are vital to a fish’s health. If mouth fizzing and your syringe fills rapidly with blood, you have hit the anterior kidney, and in our experience this is usually fatal. In looking at the overall layout of the swim bladder, side fizzing is safer because the swim bladder presents a larger target and vital organs are more distant from the needle insertion location.
  • I would like to acknowledge our partners and cooperators for this project. The National Park Service provided use of their dock for our study and purchased the large holding pens, and Sul Ross University provided the fish tags we used. Cooperators in our study were Bass Champs, BASS-elite Series, FLW, Texas Bass Federation, Permian Bass Club, and Angler’s Lodge. We would also like to extend our thanks to the many Inland fisheries staff that helped and participated in our study.

Transcript

  • 1. Barotrauma in Tournament-Caught Largemouth Bass At Amistad Reservoir and Comparison of Treatment Methods
  • 2. Barotrauma
    • Primary Cause
    • Removing fish from the high-depth, high-pressure zone to the surface results in a substantial increase in the volume of air within a fish, which in turn, affects fish buoyancy
    • External symptoms
    • swollen belly due to over-inflated air bladder
    • floating upside down
    • can not re-submerge
    • bulging eyes
    • everted stomach
  • 3. Air Bladder Function
    • Compensate for pressure-depth relationship in water
      • pressure doubles for every 33 feet of depth
      • neutral buoyancy (conserve energy)
      • more air at deep depths and less at shallow depths
    • Air exchange
      • circulatory system
      • rete mirabile
      • very slow
      • 1 hour per 6 inches in depth
    air bladder rete mirabile
  • 4.
      • Fish released immediately after capture
      • - usually no barotrauma
      • Fish retained in live wells for later release
      • - high probability of barotrauma
      • Barotrauma is highly specific to
      • tournament-held fish
    Barotrauma in Black Bass
  • 5.
    • What depth of capture results in barotrauma?
    • Strong correlation between depth of capture and barotrauma
    • However, capture depth is not a 100% accurate indicator of barotrauma
    • Although a fish air bladder is acclimated to a certain depth, fish regularly move up and down the water column to feed and in response to changing environmental conditions
    Capture Depth and Barotrauma
  • 6. Depth Barotrauma Treatments
  • 7.
    • Few agencies provide recommendations
      • 5 of 49 agencies
      • 3 against and 2 promote venting
    • Limited scientific study
      • Barotrauma impact on survival
      • Comparison of treatment methods
    • Tournament mortality puts considerable number of fish at risk
      • 30,000 fish/year at Amistad
    • Lowering tournament mortality helps maintain high quality fisheries
    Barotrauma
  • 8. How prevalent is Barotrauma at Amistad? What percent of Amistad tournament anglers apply barotrauma treament to their fish? How much does barotrauma affect survival of tournament-released bass? Which of the treatment methods is best for increasing survival of affected fish? Does timing of treatment influence survival of affected fish? Does amount of experience in applying fizzing affect fish survival?
    • Develop scientifically-based best management practices for
    • treatment of tournament-retained black bass afflicted with barotrauma
    Study Goal and Questions
  • 9. Study Methods
    • Five Amistad tournaments in 2009
      • Assessed 3,625 actual tournament fish for barotrauma
      • Interviewed 900 anglers/teams
      • Determined 3-day post release survival of 433 fish
      • Fish were differentially marked by clipping fins
      • Stocked into large holding pens
      • Fish were held for 3-days
      • Fish were removed, identified according fin clips, and counted to calculate survival
    8’ x 10’ x 37’ deep
  • 10. Methods
    • Barotrauma treatment experiments
      • Spring 2009 and 2010
      • 464 fish >14 inches collected by electrofishing
      • Each fish was individually tagged for later identification
      • Fish were stocked into cages and equally pressurized by lowering cages to 35’
      • After fish attained neutral buoyancy at 35’ cages were raised to induce barotrauma
  • 11. Methods
    • Immediate release, no treatment, treatments
    • Treatment 1 or 5 hours after onset of barotrauma
    • Minimally trained and hands-on fizzers
    • Fizzing event data collected (blood, time, etc)
    • Fish stocked in large holding pens
    • 3-d survival
  • 12. Results: Incidence of barotrauma and treatment
    • On average, 45% of tournament-weighed fish at Amistad experience barotrauma
    • 45% of 30,000 fish/year is roughly 13,500 fish having barotrauma
    Incidence (%) 24 68 55 1 Bass Champs 9 42 83 9 Permian SIT 7 35 80 5 FLW-Stren 6 46 60 3 BASS-Elite 17 34 58 2 Bass Champs Treat Fish Temp Mo Event
  • 13. *Chi-square Results: Barotrauma impact on survival
    • For 2 of the 5 tournaments, barotrauma fish had statistically significant lower survival than non-barotrauma fish
    • On average, survival was 89% for fish not having barotrauma and 81% for fish having barotrauma
    • Barotrauma does indeed negatively affect survival, 8% difference overall
    Survival (%) 3-day 93 98 55 1 Bass Champs 43* 66 83 9 Permian SIT 83 80 80 5 FLW-Stren 93 100 60 3 BASS-Elite 91* 100 58 2 Bass Champs BT-pos BT-neg Temp Mo Event
  • 14. Results: Comparison of treatment methods *Chi-square
    • Side-fizzed and deep-released fish experienced statistically similar survival (94-97%) compared to barotrauma fish not receiving treatment (97%)
    • Mouth-fizzed fish experienced significantly lower survival (83%) than untreated barotrauma-fish (97%), suggesting that mouth fizzing lowered survival
    Survival (%): 3 day 97 97 97 BT-side fizz 100 100 100 Controls 83* 78 89 BT-mouth fizz 94 92 97 BT-deep release 97 97 97 BT-no treatment 100 100 100 BT-Immediate release Combined 2010 trial 2009 trial Treatment
  • 15. *Chi-square Results: Timing of treatment
    • Timing of treatment was unrelated to survival regardless of treatment method. Fish survival was statistically similar for fish treated 1 hour versus 5 hours after barotrauma onset.
    Survival (%): 3 day 94 94 Deep release 86 81 Mouth fizz 94 100 Side fizz 5 h 1 h Treatment
  • 16. *Chi-square Results: Fizzer experience
    • For both fizzing methods, fish survival was statistically similar for minimally-trained and hands-on trained fizzers
    • Level of training received by fizzers was unrelated to survival
    Survival (%): 3 day 86 81 Mouth fizz 94 100 Side fizz Hands-on Minimal Treatment
  • 17. Results : Bleeding *Chi-square
    • Fish that were bleeding from the needle insertion site had lower survival than those that did not bleed, especially for mouth-fizzed fish.
    Survival (%) 89* 43 Mouth 98 90 Side No blood Blood Fizz type
  • 18. Results Summary
    • 45% of Amistad tournament fish had barotrauma, represents 13,500 fish/year
    • 6-24% of anglers/teams treated their fish during the tournament
    • Barotrauma lowers survival of tournament fish, however by only 8%
    • Side-fizzing and deep-release did not increase or decrease survival
    • Mouth-fizzing decreased survival by 14%
    • Timing of treatment did not affect survival
    • Level of fizzer experience did not affect survival
  • 19. Why did mouth-fizzing cause lower survival? swim bladder vertebral column rete mirabile fizzing needle
    • Trauma to the rete mirabile
    • Close proximity of anterior kidney
    • and vertebral column
    • Bleeding
    • -anterior kidney
    Anterior kidney swim bladder
  • 20. Recommendations
    • Although treatment did not increase survival, we recommend that fish be treated.
      • Tournament anglers, organizations, and TPWD receive criticism when fish are floating at release sites. These fish appear dead to the untrained eye.
    • Use side fizzing or deep-release as these did not lower survival. Mouth fizzing lowered survival.
    • Although overall survival did not differ statistically speaking for timing of treatment, we recommend treatment be applied ASAP after onset of barotrauma.
      • Side-fizzed fish treated within 1 hour had 100% survival.
    • Only minimal training is necessary to successfully perform side fizzing
      • Fizzing instructions such as the ones we developed are likely sufficient for most anglers.
    • Differences exacerbated
    • Deep water
  • 21. Partners Cooperators Inland Fisheries staff