New PIT tags - Collision analysis - Approval Process

Joseph Zydlewski, Todd Gilmore USFSW – CRFPO, Vancouver, WA

Sean CaseyDigital Angel/ Destron Fearing

Gayle ZydlewskiUSFWS-AFTC

Increasing read range

Antenna

Read Distance PIT

Transceiver

• Improvements to the transceiver and antenna

• Use of larger tag (e.g. the 23 mm tags currently available)

• Improvement to the tag (ongoing improvements to the 12 mm tag)

Benefits of increased read range

• Higher efficiency in antennas

• Ability to use larger antenna

Is there a problem ?

RISK OF COLLISION

How big is the risk?

With some 2,000,000 fish released above dams,there is concern as read ranges increase.

Solution- Assess risk to a possible problem spot

• Calculate risks of data loss due to collisions

Case Study - McNary Juvenile By-pass

• Data from the McNary bypass was queried for 9 days that spanned a range from high “tag returns” to “low tag returns”

Records Tags Begin End DurationRecords/

h Fish/h

4-May 41925 10468 5/4/02 0:00 5/5/02 23:59 47:59:04 873.72 218.15

9-May 41263 10569 5/8/02 0:00 5/9/02 23:59 47:59:54 859.67 220.19

19-May 65536 16813 5/18/02 0:00 5/21/02 23:59 95:59:48 682.69 175.14

25-May 48261 12556 5/25/02 0:00 5/27/02 0:00 47:59:36 1005.58 261.62

4-Jun 8875 2263 6/3/02 0:00 6/5/02 5:10 53:10:36 166.90 42.56

25-Jun 7250 1873 6/25/02 0:00 6/26/02 23:59 47:58:53 151.10 39.04

10-Jul 43201 10990 7/9/02 0:00 7/12/02 23:57 95:57:36 450.20 114.53

25-Jul 1790 446 7/24/02 0:37 7/25/02 23:45 47:07:33 37.98 9.46

16-Aug 710 180 8/15/02 0:26 8/16/02 23:26 47:00:05 15.11 3.83

Juvenile by-pass

d1= 10.21m d2= 6.32m d3= 10.21m

Coil 1 Coil 2 Coil 3 Coil 4

For a given fish passing the coils, information can be

extracted

Coil 1 Coil 2 Coil 3 Coil 4

• Average speed

• Reads per coil

21 0 1

Calculations

• For multiple reads – an average time was calculated (a single time point was used)

• For a missed read…– If reads “stradle” the miss, average speed was

used to calculate time of passing (e.g. speed from coil 1 to coil 3 to calculate time at coil 2)

– If reads were “on the ends” (coils 1 or 4) but multiple coils picked up the fish, times were extrapolated using speeds between coils

– If a single coil picked up the fish, group average speeds were used to calculate time passing other antennas

Proximity Calculations• So for each fish that was read on at least one

antenna, three pieces of information were now available for each antenna– Was the fish read ?– Time passing the antenna– Speed

• NOW calculate, for each fish, what the closest fish (temporally) was to a given fish !

• 17 percent of the tags are read at <1 second interval• No significant decrease in the proportion of tags read

in this bin– range from 81-93%, average 88%, 1 sec bin is 82%

Proportion of reads and failures at different time intervals

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

1 2 3 4 5 6 7 8 9 10 11

One second time bins

Fre

qu

en

cy

ReadsFails

This resolution is not fine enough to demonstrate collisions

>10

• At this resolution (1 second), fish can range from being 0-290 cm apart (based on average speeds)

• Approximately 17 percent of read fish fall into this category

• Assume – Even temporal distribution of fish between 0

and 1 second – B- tag interferes with another B tag at 15 cm

(approx 6 inches)

Increased incidence of collisions influenced by:

• Tag strength (presented as multiples of B-tag read range)– Suppose a new tag has read range 5

times that of a B-tag

• Proportion of “high strength” tags in the system

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

0

25

50

75

100

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

Percent loss per coil

Tag strength ratio

Percent of "strong" tags used

Percent "loss" per coil

For example, if 50% of all tags were 5x as strong, the collision rate would be blamed for 2.7% loss (per coil) vs 0.8% (using just B-tags)

With four coils – what percent of total misses are there?

• Assume a low coil efficiency (without collisions) of 80%

• With B-tags, one would expect an average of 79.2% efficiency

• With 50% B-tags and 50 % “new” tags, one would expect a 77.3% efficiency

No collisions = 0.16%B-tag collisions=0.18%

50/50 B-tag/new tag= 0.27%

How about the worst of the worst scenerio?

• A tag that has a read range 20X that of the B tag

• Used as the standard in the basin (100%)

The loss at McNary? 1.4%(Recall that 0.2 is from antenna efficiency)

Conclusions

• Use of tags with increased read range are likely to have an imperceptible effect on read efficiency – but should be considered!

• Collisions do occur, regardless of the tag being used and efforts to reduce these should be taken where convenient– e.g. “clamping” the field

PIT Tag Steering Committee Role

• Encourage and take measures to reduce collisions

• Support the use of increased read range tags in Columbia basin

• Delineate and implement tests to estimate impact of increased read range tags on “tag of choice”

Tag coating

• Reasons for new coating– Reduce size of coat – Increase “room” for tag coil

• Several potential synthetic polymers

Thicker wall Thinner wall

Major Questions

• Tag retention• Survival • Growth

• Smolt Physiology

• Adult return rates• Use in wild fish

Short term

Long term

Evaluation of growth in Chinook juveniles

TeflonEpoxy

PolyethyleneGlass

Control

• 9 replicate tanks– 27 fish per group

(5 groups/tank)

• Monitor– Daily survival– Daily tag loss– Bi-weekly

inventory for growth, retention

GLASS PET EPOXY TEFLON

GROWTH OF JUVENILE CHINOOK AFTER TAGGING

0

1

2

3

4

CONTROL GLASS PET EPOXY TEFLON

ENCAPSULATION MATERIAL

PE

RC

EN

T G

RO

WT

H

0-14 days

15-28 days

*

Ultrasound image of PIT tag in juvenile Chinook

Ultrasound image of PIT tag in juvenile Chinook

Preliminary Summary

• No apparent effect of polyethylene, epoxy, and glass on growth (by 28 days)

• Teflon effect on growth may be due to encapsulation shape

FDA approved materials for implantation

Assess effects on growth, survival and retention

Wide scale implementation on hatchery fish

with monitoring

Routine use in hatchery and wild fish

Approach to new materials