A PIT Tag Approach to Estimate Multiple Steelhead Populations at Bonneville Dam

1. A PIT Tag Approach to Estimate Multiple Steelhead Populations at Bonneville Dam Jeffrey K. FryerColumbia River Inter-Tribal Fish Commission

2. Background • CRITFC has been sampling salmon at the Bonneville Dam adult fish trap since 1985, starting with sockeye and expanding to Chinook salmon. • Early studies were to collect length and scales to estimate age composition and use scale patterns to estimate stock composition. • Studies have been expanded to collect genetics material and, since 2006, PIT tag sampled fish. • We added steelhead in 2007, taking over a program long run by ODFW and WDFW. In 2009, this became a Columbia Basin Accords project funded by BPA and PIT tagging added.

3. Methods • Salmon and steelhead are sampled for scales, measured for length, and PIT tagged at the Adult Fish Facility on the Bonneville Dam Washington shore ladder. Genetics samples are also collected. • Tagging was conducted throughout the steelhead run, approximately 1/3 with 23 mm tags and 2/3 with standard 12.5 mm tags. • Data on the movement of these fish through sites with PIT tag detection was downloaded from www.ptagis.org. Fish ladder sites detect virtually 100% of passing fish, in stream sites lesser amounts.

8. Uses of steelhead data • Reconstruct runs and run forecasts • US v. Oregon Technical Advisory Committee slices and dices data into numerous categories-wild, hatchery, A run, B run. • The B (>=78 cm) run size is very important for management and last year, based on our data compared with Lower Granite Dam data, 15,000 B-run fish were unaccounted for.

9. Steelhead PIT tagged at Bonneville Dam in 2009

10. How well did the 23 mm tags (32.6%) work versus 12.5 mm tags (67.4%)?

11. Percentage of Steelhead missed by tag type * * * We combined 20 mm and 12.5mm tags in subsequent analyses

12. 6.3% 7.2% 8.7% 45.3% 9.6% 49.5% 66.6% 2009 Steelhead detections at upstream dams

13. Last detection site by Statistical Week sampled at Bonneville

15. Last detection site by Statistical Week for steelhead >= 78 cm (B-run)

16. Destination of tagged PIT tagged steelhead by length

17. Where did those 15,000 missing B-run fish go? • 24 steelhead that we measured and tagged were subsequently recaptured upstream and measured with lengths ranged from 56.5 cm to 73.0 cm. • Steelhead on average were 1.1 cm longer when measured upstream, suggesting that a steelhead we measure that at 77.0 cm is actually 78.0 cm. If this change were made, the B-run estimate would increase by around 6,000 fish.

18. How well does our sample represent the run?Percent of run sampled versus run size

19. How well does our sample represent the run?Sample and run broken down by week During weeks 32-34, 376 fish (15.5% of our sample) represented 271,406 steelhead passing (44.9% of run)

20. What worked • We sampled about as many steelhead as we could have under the conditions we are sampling under. • 23.5 mm tags worked about as well as 12.5 mm tags. Since there was no advantage, we’ll use 12.5 mm tags in the future. • Video with imprinted PIT tags was useful for checking questionable PIT tag numbers and lengths, though we did not get this working until late in the season.

23. What didn’t work • Sampling restrictions at Bonneville Dam imposed by the Fish Passage Operations and Maintenance group. These include: • No sampling when the instantaneous temperature water hits 72.0 F until the average daily water temperature hits 71.5 F. • Reduced sampling when the instantaneous water temperature hits 70.0 F until the average daily water temperature hits 69.5 F • No sampling of fish 100.0 cm or over (though sampling a 99.5 cm fish is permissible). • Shad restrictions (though few steelhead come through when shad pass)

24. Our biggest problem…

26. Bonneville Dam-WA shore

27. This has the effect of reducing the number of fish we can sample. In theory, the reduction should be 50% and we should still get a representative sample. In actuality…

28. I looked at previously PIT tagged Chinook salmon to test these assumptions. In actuality: 1.) Only 26.2% of these fish used the trap side of the ladder when the trap was in operation, compared to 43.8% when not in operation. 2.) Percentage jacks:

29. One argument from FPOM is that this is a one year fluke that may not recur. Also, since there are biases in sampling (and in other areas of fisheries management, such as fisheries monitoring), we shouldn’t worry about this bias.

30. Percentage of previously PIT tagged Chinook that are jacks

31. What does this have to do with steelhead? • I don’t know-there are insufficient previously PIT tagged steelhead to do similar analyses. However, there is a possibility that the steelhead sample is badly biased as well. • Regardless, the trap configuration is decreasing our sample size. • US v. Oregon TAC, Pacific Salmon Commission, and CRITFC are pushing to for changes in trap operation.

32. Conclusions • Our PIT tagging should ultimately produce a wealth of information on steelhead migration and distribution, age composition at upstream sites, A/B run issues, and others. • Every effort should be made to reduce sources of bias in our sampling operation. • Trap and sampling biases should be taken into account in data analysis.

34. Acknowledgements

35. Estimated escapement at upstream dams as estimated from visual dam counts and PIT tags

36. How well does our sample represent the run?Cumulative sample and run proportion

37. Median Steelhead passage time at mainstem dams in minutes