Environmental Management DOI 10.1007/s00267-014-0302-2, Online Resource 5

ONLINE RESOURCE 5: Predicted rearing conditions, growth, and flow and density index values for the two-year steelhead program at Winthrop National Fish Hatchery

Article Title: Modeling the Potential Impacts of Climate Change on Pacific Salmon Culture Programs: An Example at Winthrop National Fish Hatchery

Authors: Hanson KC, Peterson DP

Journal: Environmental Management

DOI: 10.1007/s00267-014-0302-2

Summary of results for the two-year steelhead program

Under the climate scenario modeled (see Hanson and Peterson, In Press), the projected mean water temperatures are not expected to exceed the physiological tolerances for steelhead (anadromous form of Oncorhynchus mykiss) any time during the holding or rearing cycle (Tables 5-1, Figures 5-1 and 5-2). Average water temperatures are not predicted to rise to within the optimal growth temperature for pathogens of steelhead (Tables 5-1, Figures 5-1 and 5-2), but seasonal increases in water temperatures, especially in May and June, may increase the risk of an epizootic.

Increased summer water temperatures will result in larger smolts. At the end of the rearing cycle two-year steelhead are projected to be 6.1% heavier and 2.0% longer (Table 5-2, Figure 5-3). Large relative increases in flow index values are expected during summer. Due to decreased availability of water for rearing in the summer months (Figure 5-2B), flow indices for two-year steelhead are projected to increase by 29-116% (Table 5-3, Figure 5-4).

Due to the extended rearing period, they will experience two cycles of rapid growth and reduced water availability, compounding the effects of higher rearing temperatures (Table 5-3, Figure 5-4).

Sensitivity analyses of flow index values indicated a strong effect of water availability during June-September, and also a moderate effect of increased water temperature in June (Figures 5-5 and 5-6). The density index is also predicted to increase and peak in summer, but overall the relative increases were relatively minor for two-year steelhead (≤6.0% relative increase; Table 5-3, Figure 5-4). However, the density index observed at WNFH has, at times, approached the threshold value of 0.2 near the end of the production cycle (Table 5-3).

We modeled rearing densities based on the WNFH’s target value of 50,000 smolts for the two-year steelhead programs [such that the sum of the one-year and two-year steelhead programs produced 100,000 smolts total, (USFWS2007)] which was less than the actual rearing densities recorded during recent years (USFWS 2005). Consequently, the modeled flow and density index values were substantially lower than WNFH recorded values. In practice, higher rearing densities will result in higher density index values and greater risk of stress, disease, and mortality to hatchery fish.

References

Hanson KC, Peterson DP (In Press). Modeling the potential impacts of climate change on Pacific salmon culture programs: an example at Winthrop National Fish Hatchery. Environmental Management DOI 10.1007/s00267-014-0302-2

USFWS (2005) Hatchery and Genetic Management Plan. Unpublished Report, Winthrop National Fish Hatchery, US Fish and Wildlife Service, Winthrop, WA

USFWS (2007) Leavenworth, Entiat and Winthrop National Fish Hatcheries assessments and recommendation. Columbia River Basin Hatchery Review Team, U.S. Fish and Wildlife Service, Portland, OR

Rearing Temperature (oC)
Month / Life-History Stage / Water Source / 10 year historical baseline / 2040s predicted
April / egg/fry / 100% GW / 8.2 / 8.6
May (1) / egg/fry / 100% GW / 8.6 / 9.3
June (1) / egg/fry / 100% GW / 9.0 / 9.9
July (1) / egg/fry / 100% GW / 10.3 / 10.4
August (1) / egg/fry / 100% GW / 10.8 / 11.0
September (1) / egg/fry / 100% GW / 10.8 / 10.9
October (1) / egg/fry / 100% GW / 10.3 / 10.2
November (1) / egg/fry / 50% GW, 50% SW / 7.3 / 7.2
December (1) / juvenile / 50% GW, 50% SW / 5.9 / 6.0
January (1) / juvenile / 40% GW, 60% SW / 5.1 / 5.2
February (1) / juvenile / 30% GW, 70% SW / 5.2 / 5.3
March (1) / juvenile / 30% GW, 70% SW / 6.6 / 6.6
April (1) / juvenile / 30% GW, 70% SW / 7.8 / 8.4
May (2) / juvenile / 100% GW / 8.6 / 9.3
June (2) / juvenile / 100% GW / 9.0 / 9.9
July (2) / juvenile / 100% GW / 10.3 / 10.4
August (2) / juvenile / 100% GW / 10.8 / 11.0
September (2) / juvenile / 100% GW / 10.8 / 10.9
October (2) / juvenile / 60% GW, 40% SW / 9.5 / 9.5
November (2) / juvenile / 50% GW, 50% SW / 7.3 / 7.2
December (2) / juvenile / 50% GW, 50% SW / 5.9 / 6.0
January (2) / juvenile / 40% GW, 60% SW / 5.1 / 5.2
February (2) / juvenile / 30% GW, 70% SW / 5.2 / 5.3
March (2) / juvenile / 30% GW, 70% SW / 6.6 / 6.6
April (2) / smolt / 30% GW, 70% SW / 7.8 / 8.4

Table 5-1. Historical and predicted future mean monthly water temperatures experienced by steelhead trout (anadromous form of Oncorhynchus mykiss) under the so-called ‘two-year’ steelhead program at Winthrop National Fish Hatchery (NFH). Historical conditions are based on the 10 year historical baseline values (2000 – 2009), and future projected values are for the 2040s. Water sources are separated into either groundwater (GW) or surface water (SW).

Figure 5-1. Historical and predicted future mean monthly water temperatures experienced by adult steelhead trout (broodstock) held under the two-year steelhead program at Winthrop NFH. Historical conditions are based on the 10 year historical baseline values (2000 – 2009), and future projected values are for the 2040s.

Figure 5-2. Comparison of A mean water temperatures (°C) and B water availability (gpm) during rearing of juvenile steelhead reared for two years at Winthrop National Fish Hatchery based on the 10 year historical baseline (2000 – 2009) and projected values for the 2040s. Water availability is presented for months after fish are moved from early rearing (egg and fry) containers, and it was assumed that the facility cannot utilize additional water (above the mean historical value) for months where an increase in mean Methow River flow is projected. The approximate dates of important hatchery events are denoted by labeled vertical lines.

Table 5-2. Predicted monthly size differences of juvenile steelhead trout under the two-year steelhead program at Winthrop NFH. Values are the simulated average differences for fish exposed to predicted water temperatures for the 2040s relative to fish reared at the 10 year historical baseline temperature (2000 – 2009).

Month / Life-History Stage / Weight (g) difference / Length (mm) difference
June (1) / egg/fry / 9.1% / 2.9%
July (1) / egg/fry / 7.6% / 2.5%
August (1) / egg/fry / 6.6% / 2.1%
September (1) / egg/fry / 5.8% / 1.9%
October (1) / egg/fry / 4.5% / 1.5%
November (1) / egg/fry / 3.8% / 1.2%
December (1) / juvenile / 3.8% / 1.2%
January (1) / juvenile / 3.6% / 1.2%
February (1) / juvenile / 3.7% / 1.2%
March (1) / juvenile / 3.4% / 1.1%
April (1) / juvenile / 5.1% / 1.7%
May (2) / juvenile / 6.4% / 2.1%
June (2) / juvenile / 8.1% / 2.6%
July (2) / juvenile / 7.7% / 2.5%
August (2) / juvenile / 7.3% / 2.3%
September (2) / juvenile / 6.8% / 2.2%
October (2) / juvenile / 6.3% / 2.0%
November (2) / juvenile / 5.8% / 1.9%
December (2) / juvenile / 5.7% / 1.9%
January (2) / juvenile / 5.5% / 1.8%
February (2) / juvenile / 5.5% / 1.8%
March (2) / juvenile / 5.2% / 1.7%
April (2) / smolt / 6.1% / 2.0%

Figure 5-3. Predicted monthly size differences of juvenile steelhead trout reared under the two-year steelhead program at Winthrop NFH. Values are the simulated average differences for fish exposed to predicted water temperatures for the 2040s relative to fish reared at the 10 year historical baseline temperature (2000 – 2009).

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Environmental Management DOI 10.1007/s00267-014-0302-2, Online Resource 5

Table 5-3. Mean input conditions used to simulate flow and density indices in monthly time-steps (i), and bias correction factor used to adjust those index values for the two-year steelhead program at Winthrop National Fish Hatchery.

Mean values used to initiate simulations / Bias correction factors
i / Month / Ni a / Ci (ft3) b / Wi (g) c / di d / rFIi e / rDIi e
1 / May (1) / 55,000 / 220 / 0.22 / 30 / - / -
2 / June (1) / 54,780 / 220 / 0.67 / 31 / 0.398 / 0.751
3 / July (1) / 54,561 / 356 / 1.71 / 30 / 0.431 / 0.436
4 / August (1) / 54,343 / 653 / 3.58 / 31 / 0.578 / 0.571
5 / September (1) / 54,125 / 1,510 / 6.30 / 31 / 0.470 / 0.583
6 / October (1) / 53,909 / 2,683 / 10.02 / 30 / 0.526 / 0.509
7 / November (1) / 53,693 / 2,650 / 13.09 / 31 / 0.463 / 0.492
8 / December (1) / 53,478 / 2,650 / 16.01 / 30 / 0.415 / 0.432
9 / January (1) / 53,264 / 2,650 / 18.75 / 31 / 0.397 / 0.390
10 / February (1) / 53,051 / 2,650 / 21.41 / 31 / 0.405 / 0.409
11 / March (1) / 52,839 / 2,650 / 25.73 / 28 / 0.389 / 0.409
12 / April (1) / 52,628 / 2,650 / 31.34 / 31 / 0.426 / 0.439
13 / May (2) / 52,417 / 3,533 / 38.77 / 30 / 0.448 / 0.464
14 / June (2) / 52,208 / 4,417 / 47.17 / 31 / 0.493 / 0.510
15 / July (2) / 51,999 / 4,417 / 58.66 / 30 / 0.515 / 0.531
16 / August (2) / 51,791 / 4,417 / 72.47 / 31 / 0.571 / 0.579
17 / September (2) / 51,584 / 4,417 / 87.16 / 31 / 0.593 / 0.582
18 / October (2) / 51,377 / 5,300 / 101.33 / 30 / 0.522 / 0.522
19 / November (2) / 51,172 / 5,300 / 111.18 / 31 / 0.484 / 0.492
20 / December (2) / 50,967 / 5,300 / 118.91 / 30 / 0.469 / 0.473
21 / January (2) / 50,763 / 5,300 / 124.94 / 31 / 0.442 / 0.426
22 / February (2) / 50,560 / 5,300 / 129.95 / 31 / 0.470 / 0.481
23 / March (2) / 50,358 / 5,300 / 139.58 / 28 / 0.506 / 0.522
24 / April (2) / 50,157 / 5,300 / 151.85 / 31 / 0.538 / 0.524

a Abundance (Ni) based on production target of at least 50,000 smolts, and assuming a monthly mortality rate of 0.4% estimated from hatchery data from 2003-2009.

b Mean hatchery capacity (Ci) during 2003-2009.

c Initial or “seed” average fish mass (for Wi) calculated by dividing total fish mass by number of fish in the facility annually from 2000-2009; subsequent monthly values are based on growth model and rearing conditions.

d Number of days (di) in the monthly time-step i.

e Bias correction factors are the ratio between mean empirical index values and simulated historical values, as: , and . For additional details see Online Resource 2. Historical and bias-corrected future index values are presented in Figure 5-4.

Figure 5-4. Mean historical and bias-corrected future flow index (a) and density index (b) values for two-year steelhead at Winthrop National Fish Hatchery. Values for the 2040s have been bias corrected by multiplying the uncorrected future values by rFIi or rDIi (see Table 5-3 for bias correction values). The horizontal lines in each plot denote the target “do not exceed” value for each index.

Figure 5-5. Predicted flow index values for juvenile steelhead during year one of the two-year steelhead program during at Winthrop NFH based on incremental changes in water availability and temperature during June-September. Water availability is measured in cubic feet per second (cfs). Contour lines are 0.1 isopleths. Points represent historical average conditions (circles) and conditions projected for the 2040s (triangles).

Figure 5-6. Predicted flow index values for juvenile steelhead during year two of the two-year steelhead program during at Winthrop NFH based on incremental changes in water availability and temperature during June-September. Water availability is measured in cubic feet per second (cfs). Contour lines are 0.1 isopleths. Points represent historical average conditions (circles) and conditions projected for the 2040s (triangles).

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