1. E FFECT OF S IZE - AT T AGGING ON THE A PPARENT S URVIVAL OF C HINOOK S ALMON IN E NTIAT R IVER, W ASHINGTON PIT Tag Workshop Skamania Lodge, Washington – January 27 th - 29 th, 2015 Presenter: Michael B. Ward Collaborators: Shubha Pandit, Tom Desgroseillier, Keith van den Broek, Michael B. Ward, Chris Jordan, Pamela Nelle, Carl Saunders, Kevin See

2. Objectives To determine if there is an effect of fish size at tagging on the apparent overwinter survival rate for Chinook salmon in the Entiat River subbasin. To determine if changing the minimum size at tagging would be problematic for survival time-series

3. Background Permits since 2011: may tag fish 50-59mm fork length using 9mm PIT tags, ≥ 60mm using 12mm PIT tags Proposed restrictions: may not tag fish 50-59mm; fish from 60-69 may only be tagged with 9mm PIT tags, ≥7 0mm using 12mm tags Proposed restrictions could confound results from on-going studies if detectability or survival rates vary by size class Proposed restrictions may not be justified through improvements in survival Change is occurring towards the end of a critical evaluation period (the 2008-2018 Biological Opinion)

4. Literature: Size at Tagging on Survival Coho: (Many papers, esp. Brakensiek and Hankin 2007; Ebersole et al. 2006; Pess et al. 2011; Quinn and Petersen 1996; etc.). Steelhead: (Tatara 2009; Connolly and Petersen 2003; Zabel et al. 2005). Chinook: (Zabel and Achord 2004; Zabel et al. 2005; Knudsen et al 2009) Zabel and Achord 2004: relative fish length vs. absolute fish length most studies report relative fish length within populations, is significantly related to survival absolute fish length is not significantly related to survival but proposed permit restrictions are in absolute fish length Zabel et al. 2005: relationship between survival and relative fish length varies across populations and years In juvenile brown trout and Atlantic salmon impact of PIT tags (11 to 12 mm) on growth and mortality was negligible (Ombredane et al, 1998; Gries and Letcher, 2002), A few studies (e.g., Brown et al. 2013) showed only tag burden (ratio of transmitter weight to fish weight) was a concern for mortality.

5. Methodology Entiat Intensively Monitored Watershed 7,732 Chinook salmon tagged Summer 2010 – Winter 2013 Mad River VS1 VS2 VS3

6. Methodology Repeated these analyses with equal sample sizes The entire data set with fork length as a covariate Survival estimates calculated using the Barker model for: Varying size classes 50-120mm, 60-120mm, 70-120mm, 80-120mm Four discrete size classes i.e., 50-59, 60-69, 70-79, 80-120mm

7. Methodology Repeated these analyses with equal sample sizes The entire data set with fork length as a covariate Survival estimates calculated using the Barker model for: Varying size classes 50-120mm, 60-120mm, 70-120mm, 80-120mm Four discrete size classes i.e., 50-59, 60-69, 70-79, 80-120mm Absolute Fish Length Relative Fish Length

8. Methodology- Model Selection and Goodness of Fit Barker model Ten candidate models: fully time varying or time constant Selection using evidence (weight) ratio derived from the Quasi- likelihood Akaike Information Criterion (QAIC) adjusted for over- dispersion Used bootstrap simulations to quantify goodness of fit

9. Results: Varying Size Classes Valley segments of Entiat River and Mad River No. tagged = 7,732 50 - 120mm Survival probability VS1VS2VS3Mad

10. Results: Varying Size Classes 60 - 120mm No. tagged = 6,780 70 - 120mm No. tagged = 5,471 80 - 120mm No. tagged = 3,348 Valley segments of Entiat River and Mad River No. tagged = 7,732 50 - 120mm Survival probability VS1VS2VS3Mad VS1VS2VS3Mad VS1VS2VS3Mad VS1VS2VS3Mad

11. Results: Varying Size Classes 60 - 120mm No. tagged = 6,780 70 - 120mm No. tagged = 5,471 80 - 120mm No. tagged = 3,348 Valley segments of Entiat River and Mad River No. tagged = 7,732 50 - 120mm Survival probability VS1VS2VS3MadVS1VS2VS3Mad No. tagged = 3,348 VS1VS2VS3Mad No. tagged = 3,348 No. Marked/Released = VS1VS2VS3Mad No. tagged = 3,348

12. Results: Length as a Covariate Fork Length (mm) Survival probability 0.0 0.2 0.4 0.6 0.8 1.0 608010012060801001206080100120 Aug 2010-March 2011 Aug 2011-March 2012 Aug 2012-March 2013

13. Results: Varying Size Classes Unequal Sample Size 0.0 0.1 0.2 0.3 0.4 0.5 0.6 60 - 120 70 - 120 80 - 120 50 - 120 F 3,34 = 0.023, p = 0.97 F 3,34 = 0.18, p = 0.83 Size class (mm) Survival probability Equal Sample Size=3,348 60 - 120 70 - 120 80 - 120 50 - 120

14. Results: Discrete Size Classes Size class (mm) F 3,30 =2.48, p=0.07 Survival probability 0.0 0.2 0.4 0.6 0.8 1.0 50 - 5960 - 6970 - 7980 -120 F 3,24 =0.42, p=0.73 Unequal Sample Size Equal Sample Size=3,348 50 - 5960 - 6970 - 7980 -120

15. Results: Year Effect August 2010 - March 2011 August 2011 - March 2012 August 2012 - March 2013 Equal Sample Size Unequal Sample Size Size class (mm) Survival probability Size class × Year: F 6, 22 =1.43, p=0.25 Size class × Year: F 6, 16 =1.91, p=0.14 -0.5 0.0 0.5 1.0 1.5 2.0 50 - 5960 - 6970 - 7980 -12050 - 5960 - 6970 - 7980 -120 Discrete Size Classes -0.1 0.0 0.1 0.2 0.3 0.4 0.5 Size class × Year: F 6, 36 =0.19, p=0.97 Size class × Year: F 6, 36 = 0.09, p=0.99 60 - 12070 - 12080 - 12050 - 12060 - 12070 - 12080 - 12050 - 120 Varying Size Classes

16. Results: Secesh R. Preliminary results from ISEMP work in the Secesh, courtesy QCI.

17. Summary: Secesh River (preliminary results) Time of tagging and or timing of emigration plays a larger role in juvenile mortality than size at tagging Failure to tag fish <60mm would result in a failure to tag about half of the population prior to emigration The Secesh is fairly typical of Idaho streams – high gradient and cold – greater than 50% of juveniles leave these systems before they’d be taggable under the proposed size restrictions Failing to tag fish <60mm would result in non-representative estimates of growth and survival

18. Summary There is a positive relationship between overwinter survival and size- at-tagging in models using size as a covariate. The effect varies by year. There is no significant difference in apparent survival estimated for four discrete size groups (50-59, 60-69, 70-79, 80-120 mm), and no significant year effect. There is no significant difference in survival for four size groups with varying minimum size limits (50-120, 60-120, 70-120,80-120 mm), and no significant year effect. Model estimates of survival did not converge for sample groups with approx. <200 individuals; however, that effect was only seen when looking at finer spatial and temporal groupings, and not at the population level.

19. Summary There is a positive relationship between overwinter survival and size- at-tagging in models using size as a covariate. The effect varies by year. There is no significant difference in apparent survival estimated for four discrete size groups (50-59, 60-69, 70-79, 80-120 mm), and no significant year effect. There is no significant difference in survival for four size groups with varying minimum size limits (50-120, 60-120, 70-120,80-120 mm), and no significant year effect. Model estimates of survival did not converge for sample groups with approx. <200 individuals; however, that effect was only seen when looking at finer spatial and temporal groupings, and not at the population level. Absolute Fish Length Relative Fish Length

20. Management Conclusions We see no size-at-tagging effect on survival in Chinook that would justify a change in NOAA tagging protocols. Simulated restrictions in sample size as proposed by NOAA did not affect subbasin- or valley segment-scale survival estimates. Simulated restriction in sample size as proposed by NOAA did affect survival estimates at finer spatial/temporal scales. We infer that: Proposed NOAA tagging protocols could impact estimates of other key parameters such as movement or growth Trend information could be confounded by such proposed changes Proposed NOAA tagging protocols may have impacts on steelhead parameter estimation (prelim. results, Entiat and John Day).

22. Size Distribution of Marked Fish

23. Methodology – Barker Model The Barker model has been found to be robust in our systems (Conner et al., 2015) The model incorporates resight data which provides a less biased estimate of survival compared with other models Encounter history matrix was built using four years data (summer and winter from 2010 to 2013) Individuals were marked and released (1), resighted or observed (2), not captured (0), or removed (-1)

24. Research Questions 1.Does the survival probability increases as fish length at tagging increases? Survival Probability Fork Length at tagging 2.Does the estimated survival probability differ if certain fish length group is excluded? >=60, >70, >80 etc 6080100120 Number of Fish Fork Length (mm) 3.What is the survival probability for the discrete classes of fork length at tagging?

25. Research Questions 4.Since the number of samples sizes are varied among the classes, we further asked the questions of whether the survival probability would differ:  With equal samples sizes among the classes.  With unequal sample size.

26. Background 9mm PIT tags probabilities at In- stream Detection Systems The read ranges are typically <50% relative to a 12mm tag Therefore we will need to tag more fish to obtain reliable estimates ISEMP often tags fish 50-59mm; with rare exceptions, use 12mm tags for fish in the 60-70 range

27. Size Distribution of Tagged Fish Fork Length (mm) No. of Fish

28. Results: Discrete Size Classes Valley segments of Entiat River and Mad River No. tagged =7,732 No. tagged =942 50 - 120mm VS1VS2VS3Mad Survival probability

29. Results: Discrete Size Classes No. tagged =3,348 No. tagged =942 80 – 120mm VS1VS2VS3Mad No. tagged =2,073 No. tagged =942 70 - 79mm VS1VS2VS3Mad No. tagged =1,359 No. tagged =942 60 - 69mm VS1VS2VS3Mad No. tagged =942 50 - 59mm VS1VS2VS3Mad Valley segments of Entiat River and Mad River No. tagged =7,732 No. tagged =942 50 - 120mm VS1VS2VS3Mad Survival probability