Your SlideShare is downloading. ×
0
Predation Tag – An Effective Means of Determining if a Striper Ate a Salmon?Virginia Afentoulis, (vafentou@water.ca.gov), ...
Upcoming SlideShare
Loading in...5
×

Predation Tag – An Effective Means of Determining if a Striper Ate a Salmon?

378

Published on

The optimal management of salmonids in the Delta requires that the true fate of each tagged fish be known. Loss of tagged salmonids due to predation has been estimated to be as high as 65% (Vogel 2011). This data is ambiguous at best and survival estimates and behavioral results are biased. Hydroacoustic
Technology Incorporated (HTI) has developed a prototype acoustic tag that has the ability to signal when a tagged fish has been eaten by a predatory fish. DWR and USBR staff were given 100 prototype predation tags for efficacy testing in live Chinook salmon.

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
378
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
7
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Predation Tag – An Effective Means of Determining if a Striper Ate a Salmon?"

  1. 1. Predation Tag – An Effective Means of Determining if a Striper Ate a Salmon?Virginia Afentoulis, (vafentou@water.ca.gov), Environmental Scientist, CA Dept. of Water Resources (CDWR), Bay Delta Office, Delta Conveyance – Fish Science. Andrew Schultz (aschultz@usbr.gov) Fisheries Biologist - U.S. Bureau of Reclamation. Curtis Yip (cyip@water.ca.gov), Environmental Scientist, CDWR. Michele (Nikki) Johnson (johnsonm@water.ca.gov) Environmental Scientist, CDWR. C We would like to acknowledge the following people for their help on this work: Kevin Clark, Senior Environmental Scientist, CDWR, Bryce Kozak, Fish and Wildlife Technician, CDWR; Oliver Patton, Fish and Wildlife Scientific Aid, CDWR; Laura Rudolph, Fish and Wildlife Scientific Aid, CDWR, Jamie Suria, Fish and Wildlife Scientific Aid, CDWR; Kevin Kumagai of HTI; Brent Bridges, Scott Porter, Michael Trask and Rene Reyes of the USBR. Introduction Methods Results Conclusions The optimal management of salmonids in the Delta requires that the true fate of each tagged fish be known. Loss of tagged salmonids due to predation has been estimated to be as high as 65% (Vogel 2011). This data is ambiguous at best and survival estimates and behavioral results are biased. Hydroacoustic Technology Incorporated (HTI) has developed a prototype acoustic tag that has the ability to signal when a tagged fish has been eaten by a predatory fish. DWR and USBR staff were given 100 prototype predation tags for efficacy testing in live Chinook salmon (Figure 1). Experiments were carried out in a laboratory setting (US Bureau of Reclamation's Tracy Aquaculture Facility, TAF), with a controlled water supply, maintained at 16oC. Six striped bass (Morone saxatilis) were held in tanks at the TAF and were each sequentially fed 10 live Chinook salmon (Oncorhynchus tshawytscha) with implanted prototype predation tags. In order to monitor the predation tag signal, we placed hydrophones in each of the six striped bass tanks, which were connected to a HTI ATR 290 (Acoustic Tag Receiver) (Figure 2). After a visually confirmed feeding event, predation tags were continuously monitored for a change in signal (referred to as “triggering”) using a laptop running the HTI Acoustic Tag software. The predation tag acoustic signal is activated in the gut by a digestible fuse. The predation tags were designed so that the tag signal would permanently change and would display a different signal visualization. Data from the 60 tags tested were processed in Mark Tags software (Figure 3). Of the 60 predation tags fed to striped bass, 54 triggered indicating that the Chinook salmon had been eaten. The time to trigger was calculated by subtracting the time (and date) a striped bass ate the tagged Chinook salmon from the trigger time (and date). The average time to trigger was 59:15:11 with the minimum and maximum times to trigger = 22:18:00 and 140:01:00 , respectively (Figure 4). The standard deviation was 28:06:37. We proved that the predation tags would work, however we do not believe the tags are ready for widespread use in the field due to the 10% false negatives and relative imprecision at which the tags triggered. In addition, we would suggest that the predation tag be redeveloped to trigger in less than a couple of hours so that fine scale fish behavior studies could get more information from these tags such as these (Figure 5). We think that a failure rate of less than 1% and a time to trigger of 1 hour or less would be preferred. Defecated Tag in Tank Striped Bass Six of the predation tags tested did not trigger inside the striped bass and were considered to be false negatives. Of these six false negatives, 4 were defecated by the striped bass before triggering, 1 never triggered, and 1 triggered at a time so close to when the tag was defecated that we categorized it as “unknown fate”. There were no false positives in the control Chinook Salmon. Our controls were as follows: 20 live Chinook Salmon, implanted with the predation tags in the pre-triggered state, were held for over 30 days. Results Continued Figure 3. A visualization of an actual predation tag triggering, inside a striped bass, detected on a hydrophone. The image for this figure was captured from HTI software that was designed to interpret tag data. Figure1. The prototype predation tag. Figure 4. A box and whisker plot of the time to trigger data showing that the majority of tags triggered after 40 hours and before 70 hours, despite the outliers. The average trigger time is displayed as a red dashed line. Triggering event indicated by appearance of extra line. Wires of digestible fuse Chinook salmon and HTI tag Figure 5. The above visualization of a predator avoidance shows the path of a tagged striped bass in red, and the path of a tagged salmonid, in this case a steelhead (Oncorhynchus mykiss), in green. The elapsed time is roughly 30 minutes in duration. References Vogel, D.A. 2011. Evaluation of fish entrainment in seven unscreened Sacramento River diversions, 2010. Report prepared for the Anadromous Fish Screen Program, CALFED Ecosystem Restoration Program, U.S. Bureau of Reclamation, U.S. Fish and Wildlife Service, NOAA Fisheries, and the California Department of Fish and Game. Natural Resource Scientists, Inc. February 2011. 77 p. plus appendices. Figure 2. Model 290 Acoustic Tag Receiver
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×