Efficacy of a New Acoustic Tag
Designed to Indicate Occurrence of
a Predation Event
Andrew Schultz PhD, Reclamation
Virgin...
Acoustic Telemetry Technology
• Advancements have generally followed those
of the electronics field
• Reduction in tag siz...
What’s the problem?
• Predation on acoustic-tagged fishes may be
high
• Are data from the tagged-fish or inside a
predator...
Led Vogel (2011) to conclude:
“Until this critically important issue is
resolved, it is recommended that
acoustic telemetr...
Solutions…Predation Tag?
• Need a tag that can identify an acoustic-
tagged fish has been eaten by a predator
• In 2013 HT...
Objectives
• Evaluate the efficacy of HTI’s Predation Tag
• Quantify time required for Predation Tag to
indicate a predati...
Methods
• Experiments conducted at the Tracy Fish Collection
Facility’s Tracy Aquaculture Facility
• 6 adult striped bass ...
Methods
• Hydrophones placed in each tank
• Predation Tags continually monitored for a
change in signal using an HTI Acous...
Results
• 54 of 60 tags ‘triggered’ as intended
• Overall mean trigger time was 59.3 hr
(SD = 28.1; range = 22.3 to 140)
•...
Results
Trigger Time by Subject (ordered by size)
Discussion / Management Implications
• Efficacy of Predation Tag
• Impact of Predation Tag
• Improvement of Predation Tag
...
Recommendations
• Shorten length of time and improve precision
at which tag ‘triggers’
• Tag life, size and range should c...
Acknowledgements
• Curtis Yip and Nikki Johnson (CA-DWR)
• Kevin Clark (CA-DWR) and Brent Bridges (Reclamation)
• Tracy Te...
Acknowledgements
• Curtis Yip and Nikki Johnson (CA-DWR)
• Kevin Clark (CA-DWR) and Brent Bridges (Reclamation)
• Tracy Te...
Efficacy of a New Acoustic Tag Designed to Indicate Occurrence of  a Predation Event
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Efficacy of a New Acoustic Tag Designed to Indicate Occurrence of a Predation Event

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Andrew Schultz, Virginia Afentoulis
California Department of Water Resources

Prototype HTI acoustic predation tags designed to indicate an acoustic tagged fish had been eaten by a predator were tested by DWR and Reclamation staff at the Tracy Fish Collection Facility’s Tracy Aquaculture Facility. Six adult striped bass (> 400 mm FL) were each sequentially fed ten Chinook salmon with implanted
predation tags. Initial feeding time to predation tag activation time, was recorded for 54 of the 60 predation tags (6 tags failed to activate). Average time for a tag to activate was 57:30:59 (range: 22:18:00 to 140:01:00). Control predation tags (tags turned on but
not in predation indication mode) were surgically implanted in to two groups of ten control Chinook salmon. The control Chinook salmon were held for at least 30 days post‐surgery to check for effects of the predation tag on fish health and recovery from
surgery. There were 3 mortalities within 2 weeks after the surgical implantation. There were no false positives in the control fish, meaning that the tags did not activate in the target species. Predation tags are a promising new technology for determining the fate of acoustically‐tagged salmonids. Once field tested, these
tags could be used in many applications to understand the magnitude of predator impacts on salmonids near
manmade structures.

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Efficacy of a New Acoustic Tag Designed to Indicate Occurrence of a Predation Event

  1. 1. Efficacy of a New Acoustic Tag Designed to Indicate Occurrence of a Predation Event Andrew Schultz PhD, Reclamation Virginia Afentoulis, CA DWR
  2. 2. Acoustic Telemetry Technology • Advancements have generally followed those of the electronics field • Reduction in tag size, improving detection range and tag life, continues to be primary objective of innovation • Widespread and proven tool to study salmonid behavior and survival
  3. 3. What’s the problem? • Predation on acoustic-tagged fishes may be high • Are data from the tagged-fish or inside a predator? • Common methods used to determine fates of acoustic-tagged fish are problematic and unproven • High priority, often costly projects, are providing potentially inaccurate data for use toward management, conservation and regulatory actions/decisions
  4. 4. Led Vogel (2011) to conclude: “Until this critically important issue is resolved, it is recommended that acoustic telemetry studies on juvenile salmon to estimate fish survival over long Delta reaches be postponed until the problem can be reliably resolved.”
  5. 5. Solutions…Predation Tag? • Need a tag that can identify an acoustic- tagged fish has been eaten by a predator • In 2013 HTI developed a prototype Predation Tag • Based on digestion • Similar in size, shape and weight (1.3 g) to normal acoustic tags used for juvenile salmonids
  6. 6. Objectives • Evaluate the efficacy of HTI’s Predation Tag • Quantify time required for Predation Tag to indicate a predation event has occurred • Compare results within and between test subjects
  7. 7. Methods • Experiments conducted at the Tracy Fish Collection Facility’s Tracy Aquaculture Facility • 6 adult striped bass (512 – 688 mm FL) used as subjects • Held in 711 L tanks on the same indoor recirculating system at 16C • Trained to eat on demand via a tether system • Each striped bass was sequentially fed 10 live juvenile Chinook salmon surgically implanted with the new Predation Tag • Control group – 20 juvenile salmon surgically implanted with new Predation Tag and held for 30 days
  8. 8. Methods • Hydrophones placed in each tank • Predation Tags continually monitored for a change in signal using an HTI Acoustic Tag Receiver • Data processed using HTI Mark Tags software • Mixed-model univariate method of analysis to test for between and within subject effects
  9. 9. Results • 54 of 60 tags ‘triggered’ as intended • Overall mean trigger time was 59.3 hr (SD = 28.1; range = 22.3 to 140) • No difference in trigger time within (P = 0.89) or between (P = 0.93) subjects • No significant trend in trigger time with respect to subject size was observed within the size range tested • Control group had no false positives
  10. 10. Results Trigger Time by Subject (ordered by size)
  11. 11. Discussion / Management Implications • Efficacy of Predation Tag • Impact of Predation Tag • Improvement of Predation Tag • Further expenditure of resources and effort toward development of this and similar technologies • Acoustic tag technology featuring a method to determine if tag was consumed, will likely become the new standard
  12. 12. Recommendations • Shorten length of time and improve precision at which tag ‘triggers’ • Tag life, size and range should come in line with current non-predation tags • Further efficacy testing warranted as tag modified • Test efficacy in field setting • Test relationship of trigger time and evacuation rate across variables such as temperature, food, predator size and species
  13. 13. Acknowledgements • Curtis Yip and Nikki Johnson (CA-DWR) • Kevin Clark (CA-DWR) and Brent Bridges (Reclamation) • Tracy Technical Advisory Team: Carl Dealy, Donald Portz, Zachary Sutphin and Connie Svoboda • Reclamation Staff: Scott Porter, Mike Trask, Rene Reyes, Brandon Wu, Terry Bartlett, Domingo Sanchez, Thomas Walden and Joel Imai • CA-DWR Staff: Oliver Patton, Laura Rudolph, Elaine Jeu, Benjamin Martin, Kendall Pegan, Jamie Suria, Don Santos and Bryce Kozak • HTI Staff: Kevin Kumagai, Sam Johnston, Patrick Nealson, Barbara Rowdon, Scott Hemmings and Caroline Mercado
  14. 14. Acknowledgements • Curtis Yip and Nikki Johnson (CA-DWR) • Kevin Clark (CA-DWR) and Brent Bridges (Reclamation) • Tracy Technical Advisory Team: Carl Dealy, Donald Portz, Zachary Sutphin and Connie Svoboda • Reclamation Staff: Scott Porter, Mike Trask, Rene Reyes, Brandon Wu, Terry Bartlett, Domingo Sanchez, Thomas Walden and Joel Imai • CA-DWR Staff: Oliver Patton, Laura Rudolph, Elaine Jeu, Benjamin Martin, Kendall Pegan, Jamie Suria, Don Santos and Bryce Kozak • HTI Staff: Kevin Kumagai, Sam Johnston, Patrick Nealson, Barbara Rowdon, Scott Hemmings and Caroline Mercado

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