This study was funded by the U.S. Department of Energy (DOE) Water Power Technologies Office. The laboratory studies were conducted at Pacific Northwest National Laboratory, which is operated by Battelle for the DOE under Contract DE-AC05-76RL01830.

1. Acid/base encapsulation
<ol>
	<li>Mix a 1:2 ratio by the weight of H2C2O4 (oxalic acid) and NaHCO3 (sodium bicarbonate) in a mixing cup (see Table of Materials). If the acid-base powder mix is crystallized, grind it down using a mortar and pestle (Figure 1A).</li>
	<li>Retrieve the size 3 vegetable-based capsules and the semi-automatic capsule filling machine to begin the process (see Table of Material...

Optimizing Balloon Tag Assembly to Recover Sensor Fish and Live Fish

<ol>
	<li>Uria-Martinez, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=U.S.+Hydropower+Market+Report.">U.S. Hydropower Market Report.</a> Oak Ridge National Laboratory. , (2021).</li><li>Kao, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+stream-reach+development:+a+comprehensive+assessment+of+hydropower+energy+potential+in+the+United+States.">New stream-reach development: a comprehensive assessment of hydropower energy potential in the United States.</a> Oak Ridge National Laboratory. , (2014).</li><li>Martinez, J. J., Deng, Z. 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D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+implementation+of+a+new+autonomous+sensor+fish+to+support+advanced+hydropower+development.">Design and implementation of a new autonomous sensor fish to support advanced hydropower development.</a> Review of Scientific Instruments. 85, 115001 (2014).</li><li>Deng, Y., Jia, Y., Haoran, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+ionicity+and+chain+structure+on+the+physicochemical+properties+of+protic+ionic+liquids.">Effects of ionicity and chain structure on the physicochemical properties of protic ionic liquids.</a> AIChE Journal. 66 (10), e16982 (2020).</li><li>Salalila, A., Deng, Z. D., Martinez, J. J., Lu, J., Baumgartner, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+fish-friendly+self-cleaning+horizontal+irrigation+screen+using+autonomous+sensors.">Evaluation of a fish-friendly self-cleaning horizontal irrigation screen using autonomous sensors.</a> Marine and Freshwater Research. 70, 1274-1283 (2019).</li><li>Martinez, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+characterization+of+turbine+hydraulic+environment+to+support+development+of+fish-friendly+hydropower+guidelines+in+the+lower+Mekong+River+region.">In situ characterization of turbine hydraulic environment to support development of fish-friendly hydropower guidelines in the lower Mekong River region.</a> Ecological engineering. 133, 88-97 (2019).</li><li>Heisey, P. G., Mathur, D., D'Allesandro, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+technique+for+assessing+fish+passage+survival+at+hydro+power+stations.">A new technique for assessing fish passage survival at hydro power stations.</a> International Atomic Energy Agency. , (1993).</li><li>Heisey, P. G., Mathur, D., Rineer, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+reliable+tag-recapture+technique+for+estimating+turbine+passage+survival:+application+to+young-of-the-year+American+shad+(Alosa+sapidissima).">A reliable tag-recapture technique for estimating turbine passage survival: application to young-of-the-year American shad (Alosa sapidissima).</a> Canadian Journal of Fisheries and Aquatic Sciences. 49 (9), 1826-1834 (1992).</li><li>Mathur, D., Heisey, P. G., Euston, E. T., Skalski, J. 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P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+and+ecological+evaluation+of+a+fish-friendly+surface+spillway.">Physical and ecological evaluation of a fish-friendly surface spillway.</a> Ecological Engineering. 110, 107-116 (2018).</li><li>Trumbo, B. r. a. d. l. y. . A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+hydroturbine+pressures+to+enhance+salmon+passage+survival+and+recovery.">Improving hydroturbine pressures to enhance salmon passage survival and recovery.</a> Reviews in fish biology and fisheries. 24, 955-965 (2014).</li><li>Pohanish, R. 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This study concluded that three-capsule balloon tags injected with 5 mL of water at 18.3 &#176;C had a slower start inflation time and consistently larger volume compared to two-capsule and four-capsule balloon tags. When the balloon tags were injected with water at 12.7 &#176;C, the average volume was smaller, and the inflation time was longer. The three-capsule begins deflating first, followed by the four-capsule, and lastly the two-capsule. The inflation and deflation periods associated with each water temperature can...

Hydropower is a significant renewable energy resource worldwide. In the United States, hydropower contributes an estimated 38% or 274 TWh of electricity generated from renewable sources1 and has the potential to add approximately 460 TWh per year2. However, as hydropower development increases, concerns about fish injury and mortality during hydraulic passage have become paramount3. Various mechanisms contribute to fish injuries during passage, including rapid decompression (barotrauma), shear stress, turbulence, strikes, cavitation, and grinding4. Although these injury mechanisms may not have an immediate impact on the overall condition of the fish, they can render them more vulnerable to diseases, fungal infections, parasites, and predation5. Additionally, direct physical injuries resulting from collisions with turbines or other hydraulic structures can lead to significant mortality, emphasizing the importance of mitigating these risks in hydropower development.
One of the most common methods for evaluating fish passage conditions is releasing Sensor Fish and live fish through hydraulic structures6,7. The Sensor Fish is an autonomous device designed to study the physical conditions that fish experience during passage through hydraulic structures, including turbines, spillways, and dam bypass alternatives8,9. Equipped with a 3D accelerometer, 3D gyroscope, temperature sensor, and pressure sensor9, the Sensor Fish provides valuable data on fish passage conditions.
Balloon tags, which are self-inflating balloons attached externally to Sensor Fish and live fish, assist in their recovery after passing through hydraulic structures. The balloon tags consist of dissolvable capsules filled with gas-generating chemicals (e.g., oxalic acid and sodium bicarbonate), a silicone stopper, and a fishing line. Prior to deployment, water is injected through the silicone stopper into the balloon. The water dissolves the vegetable-based capsules, triggering a chemical reaction that produces gas&#160;inflating the balloon. In this neutralization reaction, sodium bicarbonate, a weak base, and oxalic acid, a weak acid, react to form carbon dioxide, water, and sodium oxalate10. The chemical reaction is provided below:
2NaHCO3+ H2C2O4 &#8594; 2CO2 + 2H2O + Na2C2O4
The inflated balloon increases the buoyancy of the Sensor Fish and live fish, enabling them to float on&#160;the water surface for easier recovery.
The number of balloon tags required to achieve flotation and facilitate the retrieval of a sample (e.g., Sensor Fish or live fish) may vary based on the volume and mass characteristics of the sample. The duration of balloon tag inflation can be adjusted by injecting water at different temperatures. Colder water will increase the inflation time, while warmer water will decrease it. Balloon tags have been successfully employed in various locations, including the Farmers Screen, a unique horizontal, flat-plate fish and debris screen structure in Hood River, Oregon11, and a Francis turbine at Nam Ngum Dam in the Lao People&#39;s Democratic Republic12. Another commercially available balloon tag example is the Hi-Z Turb&#39;N Tag13,14. The Hi-Z Turb&#39;N Tag allows inflation time to be adjusted between 2 min and 60 min, depending on the injected water temperature13. This technology has been used in fish studies at many field sites, including studies involving Chinook salmon smolts released at Rocky Reach Dam on the Columbia River and juvenile American shad at Hadley Falls Dam on the Connecticut River15,16. Both technologies utilize acid-base&#160;chemical reactions to inflate the balloon tags for recovery.
This method offers cost-effectiveness and simplicity in manufacturing, with an estimated material cost of only $0.50 per balloon. As described here, the manufacturing process is easy to follow, making balloon tag production accessible to anyone.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3D Printed Silicone Stopper Plate</td>
			<td>NA</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>ARC800 Sensor Fish</td>
			<td>ATS</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>FDM 3D printer</td>
			<td>NA</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Manual Capsule Filler Machine CN-400CL (Size #3)</td>
			<td>Capsulcn</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Mold Star 15 SLOW</td>
			<td>Smooth-On</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Oil-Resistant Buna-N O-Ring</td>
			<td>McMaster-Carr</td>
			<td>SN: 9262K141</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxalic Acid, 98%, Anhydrous Powder (C2H2O4)&#160;</td>
			<td>Thermo Scientific&#160;</td>
			<td>CAS: 144-62-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Rubber Band Expansion Tool</td>
			<td>iplusmile</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Separated Vegetable Cellulose Capsules (Size #3)</td>
			<td>Capsule Connection</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Smiley Face YoYo Latex balloon</td>
			<td>YoYo Balloons, Etc.</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate Powder (CHNaO3)&#160;</td>
			<td>Sigma</td>
			<td>CAS: 144-55-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectra Fiber Braided Fishing Line (50 lbs.)</td>
			<td>Power Pro</td>
			<td>NA</td>
			<td></td>
		</tr>
	</tbody>
</table>

balloon tag manufacturing technique for sensor fish and live fish recovery

Fish may experience injuries and mortality when they pass through hydraulic conveyances at hydropower dams, even if these conveyances are designed to be fish-friendly, such as downstream bypass systems, modified spillways&#160;and turbines. The main methods used to study fish passage conditions in hydraulic structures involve direct, in situ testing using Sensor Fish technology and live fish. Sensor Fish data helps identify physical stressors and their locations in the fish passage environment, while live fish are assessed for injuries and mortality. Balloon tags, which are self-inflating balloons attached externally to Sensor Fish and live fish, aid in their recovery after passing through hydraulic structures.
This article focuses on the development of balloon tags with varying numbers of dissolvable, vegetable-based capsules containing a mixture of oxalic acid, sodium bicarbonate powders, and water at two different temperatures. Our research determined that balloon tags with three capsules, injected with 5 mL of water at 18.3 &#176;C, consistently achieved the desired balloon volume. These tags had a mean inflation volume of 114 cm3 with a standard deviation of 1.2 cm3. Among the balloon tags injected with water at 18.3 &#176;C, it was observed that the two-capsule balloon tags took the longest time to reach full inflation. In addition, the four-capsule balloon tags demonstrated a faster inflation start time, while the three-capsule balloon tags demonstrated a faster deflation start time. Overall, this approach proves to be effective for validating the performance of new technologies, improving turbine design, and making operational decisions to enhance fish passage conditions. It serves as a valuable tool for research and field evaluations, aiding in the refinement of both the design and operation of hydraulic structures.

Author Spotlight: Developing Cost-Effective and Customizable Balloon Tags for Fish Passage Studies 

Balloon Tag Manufacturing Technique for Sensor Fish and Live Fish Recovery

This research focuses on developing and evaluating cost-effective balloon tags for fish passage studies and hydraulic structures. Our aim is to assess the effectiveness of different balloon tag configurations for the recovery of sensor fish and live fish after they pass through these hydraulic structures. The balloon tag protocol we developed offer a cost effectiveness, customizability, and adjustable inflation times.It is a low-cost solution for large scale studies with limited budgets. It helps to understand the impact of hydraulic structures on fish and can be tailored to different species and environments. We have developed a cost-effective balloon tag manufacturing process.This will enhance our understanding of balloon tag performances under different conditions, enabling tailored testing and facilitating environmental impact assessments for developing and operating fish-friendly hydropower systems.

A study was conducted to determine the optimal methods for manufacturing balloon tags, focusing on the volume and temperature of water injected into the balloon. The study examined various input parameters, including the inflation start time, full inflation time, deflation start time, and the volume of the balloon at full inflation. The study was conducted at a desk with an ambient temperature of 21 &#176;C.
A total of 360 balloon tags were prepared for the study. The tags were divided into 36...

Watch this Scientific Journal Video about Developing Cost-Effective and Customizable Balloon Tags for Fish Passage Studies at JoVE.com

A protocol is presented for designing and manufacturing balloon tags to recover Sensor Fish and live fish, allowing assessment of their physical condition and biological performance in hydraulic structures. The method optimizes balloon tag performance by considering factors such as balloon volume, inflation/deflation times, component selection, and the characteristics of the injected water.

Fish may experience injuries and mortality when they pass through hydraulic conveyances at hydropower dams, even if these conveyances are designed to be ...

balloon-tag-manufacturing-technique-for-sensor-fish-live-fish