apparent survival and capture effects in colorado pikeminnow · apparent survival and capture...
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Apparent Survival and Capture effects in Colorado Pikeminnow
Scott Clark1, Mary Conner2, Scott Durst3 and Nate Franssen3
1University of New Mexico, 2Utah State University, 3U.S. Fish and Wildlife Service
In-hand ages of Colorado Pikeminnow Age Captures %
1 6618 39.6% 2 6903 41.3% 3 2442 14.6% 4 223 1.3% 5 311 1.9% ≥6 213 1.3%
>95% of all fish handled between ages 1-3
Year Stocked Age 1 Age 2 Age 3+ 2003 175,928 74 (4) 1 (0) 3 (1) 2004 280,000 190 (4) 128 (2) 1 (1) 2005 302,270 154 (6) 231 (8) 12 (1) 2006 313,854 393 (13) 177 (14) 42 (1) 2007 475,790 270 (26) 125 (11) 14 (3) 2008 270,234 395 (34) 207 (40) 31 (7) 2009 468,000 899 (115) 449 (52) 36 (5) 2010 214,470 1042 (88) 1053 (140) 36 (11) 2011 426,588 552 (26) 874 (21) 177 (7) 2012 395,640 675 (37) 442 (32) 38 (5) 2013 439,264 428 (29) 355 (17) 60 (5) 2014 393,442 196 (21) 191 (30) 39 (11) 2015 402,087 308 (20) 203 (21) 64 (6) Total 5576 (423) 4435 (388) 553 (64)
Dataset
Cohort 2009 2010 2011 2012 2013 2014 2015 2016 A 1 9 16 17 18 19 20 21 B 2 10 17 18 19 20 21 C 3 11 18 19 20 21 D 4 12 19 20 21 E 5 13 20 21 F 6 14 21 G 7 15 H 8
Numbers represent unique survival estimates First and Second time intervals allowed assessment of age-specific estimates and potential capture effects Different matrices for each age group (Age 1, 2, and 3+)
Sampling Intervals (years)
“Time”
2nd time interval 1st time interval
Mean (95% CI) Age 1 = 0.19 (0.09-0.36) Age 2 = 0.16 (0.09-0.28) Age 3+ = 0.08 (0.03-0.21)
Mean (95% CI) Age 1 = 0.37 (0.23-0.54) Age 2 = 0.22 (0.12-0.36) Age 3+ = 0.50 (0.25-0.74)
Age 1 Age 2 Age 3+
Mean (95% CI) Age 1 = 0.33 (0.17-0.58) Age 2 = 0.39 (0.22-0.62) Age 3+ = 0.28 (0.12-0.56)
Mean (95% CI) Age 1 = 0.43 (0.25-0.63) Age 2 = 0.48 (0.28-0.69) Age 3+ = 0.35 (0.17-0.61)
Detection probability
• Comparatively high to UCRB studies (mean = ~0.10 for adults)
First time interval
Second time interval
Age-specific Estimates Age Apparent Survival
Detection Probability
1 0.19 (0.09-0.36) 0.31 (0.16-0.54) 2 0.25 (0.15-0.39) 0.37 (0.21-0.59) 3 0.22 (0.12-0.36) 0.42 (0.24-0.63) 4 0.54 (0.34-0.72) 0.42 (0.20-0.68)
Strong effect of TL over first encounter interval
Potential Capture Effects
Cohort 2009 2010 2011 2012 2013 2014 2015 2016 A 1 9 16 17 18 19 20 21 B 2 10 17 18 19 20 21 C 3 11 18 19 20 21 D 4 12 19 20 21 E 5 13 20 21 F 6 14 21 G 7 15 H 8
Second time interval; fish do not have to be handled
First time interval – survival interval following the first encounter; fish must be handled Numbers represent unique survival estimates
First and Second time intervals allowed assessment of age-specific estimates and potential capture effects
Sampling Intervals (years)
Individual Year 1 Year 2 Year 3 Year 4 Year 5
IND_01 1 1 1 1 1
Individual Year 1 Year 2 Year 3 Year 4 Year 5
IND_01 1 0 0 0 1 Observed
MARK
Age 2 Age 3+
Mean (95% CI) Age 1 = 0.19 (0.09-0.36) Age 2 = 0.16 (0.09-0.28) Age 3+ = 0.08 (0.03-0.21)
Mean (95% CI) Age 1 = 0.37 (0.23-0.54) Age 2 = 0.22 (0.12-0.36) Age 3+ = 0.50 (0.25-0.74)
Age 3+ rebound strongly in the second year
Capture effects linger for age 2 fish
Age 1
Cohort 2009 2010 2011 2012 2013 2014 2015 2016 A 1 9 16 17 18 19 20 21 B 2 10 17 18 17 18 21 C 3 11 18 19 20 21 D 4 12 19 20 21 E 5 13 20 21 F 6 14 21 G 7 15 H 8
Cohort 2009 2010 2011 2012 2013 2014 2015 2016 A 22 30 37 38 39 40 41 42 B 23 31 38 39 40 41 42 C 24 32 39 40 41 42 D 25 33 40 41 42 E 26 34 41 42 F 27 35 42 G 28 36 H 29
Age 2
Age 1
Age 2 – First encountered at age 1 Age 2 – First encountered at age 2
Parameter Beta SE Lower CI Upper CI Intercept 5.020 3.557 -1.952 11.993 Age 1 -4.847 3.448 -11.605 1.912 Age 2 -3.463 3.455 -10.236 3.310 C1t Age 1 -1.089 0.352 -1.780 -0.399 C2t Age 1 -0.231 0.440 -1.092 0.631 C1t Age 2 -2.651 0.321 -3.280 -2.022 C2t Age 2 -2.293 0.390 -3.058 -1.528 C1t Age 3+ -6.968 3.471 -13.771 -0.164 C2t Age 3+ -4.346 3.599 -11.400 2.707
Mean survival (95% CIs): Age 2 – first encountered at age 1 = 0.37 (0.23-0.54) Age 2 – first encountered at age 2 = 0.19 (0.11-0.30)
Resultant Management Actions New capture/handling protocols (TL relationship) • Age-1 (tag implantation) and adult fish • Reduction in detection probability • Quantifying effects?
• Adult-monitoring passes
Summary • No appreciable survival increase until age 4 • Potential capture effects
• Low survival of age 3+ following first encounter • Direct evidence from age 2
• New capture protocols based on TL relationship • Age-1 and adult fish • Reduction in detection probability • Quantifying effects
• Identify recruitment bottlenecks • Hatchery or environmental-related factors?