ARROW LAKES RESERVOIR NUTRIENT RESTORATION PROGRAM, YEARS 11 and 12 (2009 and 2010) REPORT
by
E. U. Schindler, D. Sebastian,
T. Weir, H. Andrusak, G.F. Andrusak,
M. Bassett and K. I. Ashley
Fisheries Project Report No. RD 137 2013
Resource Management Ministry of Forests, Lands and Natural Resource Operations Province of British Columbia
Funding by
Fish and Wildlife Compensation Program
and
Arrow Lakes Power Corporation A subsidiary of Columbia Power and Columbia Basin Trust
Fisheries Project Reports frequently contain preliminary data, and conclusions based on these may be subject to change. Reports may be cited in publications but their manuscript status (MS) must be noted. Please note that the presentation summaries in the report are as provided by the authors, and have received minimal editing. Please obtain the individual author's permission before citing their work.
ARROW LAKES RESERVOIR NUTRIENT RESTORATION PROGRAM YEARS 11 and 12 (2009 and 2010) REPORT
by
E. U. Schindler1, D. Sebastian2,
T. Weir3, H. Andrusak4, G.F. Andrusak4
M. Bassett1 and K. I. Ashley5
1 Resource Management, Ministry of Forests, Lands and Natural Resource Operations, Province of BC, 401-333 Victoria St., Nelson, BC, V1L 4K3
2 British Columbia Conservation Foundation, Suite 200-1383 McGill Rd, Kamloops, BC V2C 6K7
3 Fish, Wildlife and Habitat Management Branch, Ministry of Forests, Lands and Natural Resource Operations, Province of BC, PO Box 9338 STN PROV GOVT, Victoria, BC, V8W 9M2
4 Redfish Consulting Ltd., 5244 Hwy 3A, Nelson, BC, V1L 6N6
5 Ecological Restoration Program, BC Institute of Technology, 700 Willingdon Ave.,Burnaby, BC, V5G 3H2
ACKNOWLEDGEMENTS
Funding for the eleventh and twelfth year (2009 and 2010) of the Arrow Lakes Reservoir Nutrient Restoration Project was provided by the Fish and Wildlife Compensation Program – Columbia Basin and Columbia Power Corporation.
The Fish and Wildlife Compensation Program – Columbia Basin is a joint initiative between BC Hydro, the province of British Columbia and Fisheries and Oceans Canada. The program was established to conserve and enhance fish and wildlife compensation populations affected by BC Hydro dams in the Canadian portion of the Columbia River Basin.
The contributions from the province of British Columbia are primarily from the Ministry of Forests, Lands and Natural Resource Operations and the Ministry of Environment.
Funding is provided by Arrow Lakes Power Corporation (ALPC) which owns the Arrow Lakes Generating Station. ALPC is jointly owned by Columbia Power Corporation and Columbia Basin Trust. Columbia Power Corporation manages the operations of the ALPC on behalf of the joint venture. The funding is being provided as a compensatory benefit for the operations of the Arrow Lakes Generating Station on the Lower Arrow Lake.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report i EXECUTIVE SUMMARY
This report summarizes results from the eleventh and twelfth year (2009 and 2010) of nitrogen and phosphorus additions to the Upper Arrow Lakes Reservoir (referred to as Upper Arrow in the report). The nutrient restoration program was conducted using an adaptive management approach in an effort to restore reservoir productivity lost as a result of nutrient retention and uptake in upstream reservoirs (Revelstoke and Mica). The primary objective of the nutrient restoration program is to restore kokanee (Onchorhynchus nerka) populations, which are the primary food source for rainbow trout (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus).
Secchi disc measurements were typical of previous years’ results with a seasonal pattern with decreased spring to summer transparency associated with increased phytoplankton biomass and increased turbidity due to spring runoff, followed by increased transparency in the late summer and fall months.
Upper and Lower Arrow Lakes Reservoir (referred to as Upper Arrow and Lower Arrow in the remainder of the report) is a warm monomictic lake with with isothermal temperatures from late fall to early spring and stratification during the summer months. In 2009, the maximum water temperature of the season occurred in July in Upper Arrow and in August in Lower Arrow. In 2010, the maximum water temperature occurred in August in Upper and Lower Arrow.
Total phosphorus concentrations ranged from 2 to 5 µg/L, in Upper Arrow and 2 to 4 µg/L in Lower Arrow, with the exception of a higher value of 7 µg/L observed at AR 8 in April. In 2010, concentrations ranged from 2 to 3 µg/L, in Upper Arrow and 2 to 5 µg/L in Lower Arrow. These results are indicative of ultra-oligotrophic conditions.
Over the spring to fall sampling season nitrate collected from epilimnetic integrated samples decreased, with the decline corresponding with phytoplankton uptake and utilization during summer stratification. Nitrate concentrations in discrete samples collected within the photic zone (2, 5, 10, 15 and 20 m) were similar to previous years with a seasonal decline in July and August and September in Lower Arrow.
From April to late June in 2009, chryso/cryptophytes contributed to approximately half of the overall abundance with a shift to mostly bacillariophytes in July through September. In October and November, phytoplankton composition showed a trend similar to the spring results. The 2010 results were similar to 2009 except bacillariophytes contributed to the majority of the abundance through November. The trend of chrysophytes and cryptophytes being dominant in the spring and decreasing during the summer months could be attributable to increased Daphnia sp. biomass, indicating grazing on phytoplankton is likely occurring.
Overall zooplankton abundance and biomass increased in 2009 and decreased in 2010 in Upper Arrow compared to the 2008 results. Copepods dominated in the spring with Daphnia spp. increasing in the late summer and fall months, a consistent trend observed in some but not all previous years. In Lower Arrow, copepods dominated in the spring but then shifted to Daphnia spp. biomass being dominant during July onward.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report ii
The annual average mysid biomass at deep stations was slightly higher than the long term average in 2009 and 2010.
Kokanee escapement (in the index tributaries) to Upper Arrow and Lower Arrow was 305,000 and 146,000 respectively in 2009. In 2010 the escapement was 345,000 and 156,000 in Upper Arrow and Lower Arrow, respectively. In Upper Arrow the majority of kokanee spawned in the Hill Creek spawning channel in both years.
The mean spawner size at Hill Creek in 2009 and 2010 was 24.1 and 24.2 cm respectively, slightly larger than the long term average of 23.7 cm. Fecundity was 258 and 272 eggs/female in 2009 and 2010 respectively, a slight increase from 2007 and 2008 results.
The hydroacoustic estimates of kokanee of all age classes (after spawning occurred) increased in 2009 and 2010 from the 2008 results. The estimates in 2009 and 2010 were a total of 9.1 and 14.5 million, respectively. In 2009, there was an estimated 6.4 million fry in 2009 and 12 million fry in 2010. The mean kokanee biomass in 2009 and 2010 was 10.2 kg.ha-1 and 8.2 kg.ha-1 respectively (the long term average in the nutrient addition period was 9.7 kg.ha-1.
The results from 2009 and 2010 indicate all trophic level responses have been positive to addition of nutrients to Upper Arrow. Phytoplankton composition was suitable to move carbon efficiently through the food web to kokanee. This is indicative of a positive response to the adaptive management of closely monitored seasonal applications of limiting macronutrients.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report iii TABLE OF CONTENTS
Page Acknowledgements ……………………………………………………………………………....i
Executive Summary ……………………………………………………………………………..ii
Table of Contents ……………………………………………………………………………….iv
List of Figures …………………………………………………………………………………..vi
List of Tables …………………………………………………………………………………..xiv
Introduction ……………………………………………………………………………………...1
Methods …………………………………………………………………………………………..2 Fertilizer additions ………………………………………………………………………..3
Physical data, chemical, phytoplankton, zooplankton and mysid sampling ……………...6
Phytoplankton …………………………………………………………………………….7
Zooplankton ………………………………………………………………………………8
Mysis diluviana …………………………………………………………………………...9
Kokanee …………………………………………………………………………………..9 Spawner numbers, size and fecundity …………………………………………...10 Fry to adult survival……………………………………………………………..10 Age determination ……………………………………………………………….11 Trawl sampling ………………………………………………………………….11 Hydroacoustic survey ……………………………………………………………12 Kokanee Biomass ………………………………………………………………..13 Analysis of Annual Biomass ……………………………………………………..14 Stock Recruitment-Ricker model ………………………………………………...14
Results …………………………………………………………………………………………..15 Temperature ……………………………………………………………………………..15 Dissolved Oxygen ……………………………………………………………………...... 16 Secchi ……………………………………………………………………………………18
Integrated samples – 0-20 m …………………………………………………………….19 Discrete Samples ………………………………………………………………………...37 Hypolimnion Samples …………………………………………………………………...41
Phytoplankton …………………………………………………………………………...50
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report iv Zooplankton……………………………………………………………………………...70
Mysis diluviana ………………………………………………………………………….81
Kokanee ………………………………………………………………………………….87 Spawner escapement estimates ………………………………………………….87 Spawner size and fecundity ……………………………………………………...89 Age at maturity …………………………………………………………………..94 Trawl catch ……………………………………………………………………...97 Fish density …………………………………………………………………….104 Abundance ……………………………………………………………………...106 Biomass ………………………………………………………………………...109 Fry to adult survival rates ……………………………………………………...111 Spawner-return spawner relationship …………………………………………112
Discussion ……………………………………………………………………………………..115
Recommendations ……………………………………………………………………………128
References ……………………………………………………………………………………..129
Appendices ...... 137
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report v LIST OF FIGURES
Figure 1. Nitrogen and phosphorus loading to Upper Arrow (mg/m2/week) from fertilizer, April to September, 2009 and 2010. ……………………………………………...4 Figure 2. Temperature profiles at station AR 2 and AR 7, April to November, 2009. ……16 Figure 3. Temperature profiles at station AR 2 and AR 7, April to November, 2010. ……16 Figure 4. Oxygen profiles at station AR 2 and AR 7, April to November, 2009. …………17 Figure 5. Oxygen profiles at station AR 2 and AR 7, April to November, 2010. …………17 Figure 6. Upper Arrow Secchi disk depths, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..18 Figure 7. Lower Arrow Secchi disk depths, stations AR 6-8 April to November, 2009 and 2010. ……………………………………………………………………………..19 Figure 8. Annual average Secchi disk depths and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ……………………………………………...19 Figure 9. Upper Arrow turbidity, stations AR 1-3 April to November, 2009 and 2010. …20 Figure 10. Lower Arrow turbidity, stations AR 1-3 April to November, 2009 and 2010. ….20 Figure 11. Annual average turbidity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. …………………………………………………………...20 Figure 12. Upper Arrow conductivity, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………………21 Figure 13. Lower Arrow conductivity, stations AR 6-8 April to November, 2009 and 2010. ……………………………………………………………………………………21 Figure 14. Annual average conductivity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ………………………………………………………22 Figure 15. Upper Arrow total phosphorus, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..23 Figure 16. Lower Arrow total phosphorus, stations AR 6-8 April to November, 2009 and 2010. ……………………………………………………………………………..23 Figure 17. Annual average total phosphorus and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. …………………………………………………23 Figure 18. Upper Arrow total dissolved phosphorus, stations AR 1-3 April to November, 2009 and 2010. …………………………………………………………………..24 Figure 19. Lower Arrow total dissolved phosphorus, stations AR 6-8 April to November, 2009 and 2010. …………………………………………………………………..24 Figure 20. Annual average total dissolved phosphorus and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ……………………………………..25 Figure 21. Upper Arrow orthophosphate, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..25 Figure 22. Lower Arrow orthophosphate, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..26
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report vi Figure 23. Annual average orthophosphate, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..26 Figure 24. Upper Arrow total nitrogen, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………………27 Figure 25. Lower Arrow total nitrogen, stations AR 6-8 April to November, 2009 and 2010. ……………………………………………………………………………………27 Figure 26. Annual average total nitrogen and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2010. ………………………………………………………28 Figure 27. Upper Arrow dissolved inorganic nitrogen, stations AR 1-3 April to November, 2009 and 2010. …………………………………………………………………..29 Figure 28. Lower Arrow dissolved inorganic nitrogen, stations AR 6-8 April to November, 2009 and 2010. …………………………………………………………………..29 Figure 29. Annual average dissolved inorganic nitrogen and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ……………………………………..29 Figure 30. Upper Arrow silica, stations AR 1-3 April to November, 2009 and 2010. ……..30 Figure 31. Lower Arrow silica, stations AR 6-8 April to November, 2009 and 2010. ……..31 Figure 32. Annual average silica and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ……………………………………………………………….31 Figure 33. Upper Arrow pH, stations AR 1-3 April to November, 2009 and 2010. ……….32 Figure 34. Lower Arrow pH, stations AR 6-8 April to November, 2009 and 2010. ………32 Figure 35. Annual average pH and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. ……………………………………………………………….32 Figure 36. Upper Arrow alkalinity, stations AR 1-3 April to November, 2009 and 2010….33 Figure 37. Lower Arrow alkalinity, stations AR 6-8 April to November, 2009 and 2010. ...33 Figure 38. Annual average alkalinity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1998 to 2010. …………………………………………………………...34 Figure 39. Upper Arrow total organic carbon, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..35 Figure 40. Upper Arrow total organic carbon, stations AR 1-3 April to November, 2009 and 2010. ……………………………………………………………………………..35 Figure 41. Annual average total organic carbon and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2010. ……………………………………………...35 Figure 42. Upper Arrow and narrows chlorophyll a, stations AR 1-5 April to November, 2009. ……………………………………………………………………………..36 Figure 43. Lower Arrow chlorophyll a, stations AR 6-8 April to November, 2009. ………36 Figure 44. Annual average chlorophyll a and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2009. ……………………………………………………...37 Figure 45. Discrete total dissolved phosphorus concentrations, stations AR 2 and AR 7. June – September 2009. ………………………………………………………………37
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report vii Figure 46. Discrete total dissolved phosphorus concentrations, stations AR 2 and AR 7. June – September 2010. ……………………………………………………………....38 Figure 47. Discrete dissolved inorganic nitrogen concentrations, stations AR 2 and AR 7. June – September 2009. …………………………………………………………38 Figure 48. Discrete dissolved inorganic nitrogen concentrations, stations AR 2 and AR 7. June – September 2010. …………………………………………………………39 Figure 49. Discrete nitrogen:phosphorus (dissolved fractions, weight:weight) ratios, stations AR 2 and AR 7. June – September 2009. ……………………………………….39 Figure 50. Discrete nitrogen:phosphorus (dissolved fractions, weight:weight) ratios, stations AR 2 and AR 7. June – September 2010. ……………………………………….40 Figure 51. Discrete chlorophyll a concentrations, station AR 2. June – September 2009. …40 Figure 52. Discrete chlorophyll a concentrations, station AR 7, June – September 2009. …41 Figure 53. Upper Arrow turbidity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………………….41 Figure 54. Lower Arrow turbidity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. ……………………………………………………………………..42 Figure 55. Upper Arrow conductivity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………...42 Figure 56. Lower Arrow conductivity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. …………………………………………………………...43 Figure 57. Upper Arrow total phosphorus in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………...43 Figure 58. Lower Arrow total phosphorus in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. …………………………………………………………...44 Figure 59. Upper Arrow total dissolved phosphorus in discrete hypolimnetic samples, AR 1- 3, May – October, 2009 – 2010. ………………………………………………...44 Figure 60. Lower Arrow total dissolved phosphorus in discrete hypolimnetic samples, AR 6- 8, May – October, 2009 – 2010. ………………………………………………...45 Figure 61. Upper Arrow orthophosphate in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………...45 Figure 62. Lower Arrow orthophosphate in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. …………………………………………………………...46 Figure 63. Upper Arrow total nitrogen in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………...46 Figure 64. Lower Arrow total nitrogen in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. …………………………………………………………..47 Figure 65. Upper Arrow dissolved inorganic nitrogen in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. ………………………………………………47 Figure 66. Lower Arrow dissolved inorganic nitrogen in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. ………………………………………………48
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report viii Figure 67. Upper Arrow silica in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. ……………………………………………………………………..48 Figure 68. Lower Arrow silica in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. ……………………………………………………………………..49 Figure 69. Upper Arrow alkalinity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010. …………………………………………………………...49 Figure 70. Lower Arrow alkalinity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010. …………………………………………………………...50 Figure 71. Phytoplankton abundance by group in integrated 0-20 m samples, AR 1- 4, April to November, 2009 and 2010. …………………………………………………...52 Figure 72. Phytoplankton abundance by group in integrated 0-20 m samples, AR 5- 8, April to November, 2009 and 2010. …………………………………………………...53 Figure 73. Phytoplankton biovolume (mm3/L) by group in integrated 0-20 m samples, AR 1- 4, April to November, 2009 and 2010. ………………………………………….54 Figure 74. Phytoplankton biovolume (mm3/L) by group in integrated 0-20 m samples, AR 5 - 8, April to November, 2009 and 2010. ………………………………………...55 Figure 75. Output of one-way analysis (JMP program) of inedible diatom (bacillariophyte) abundance, stations AR 1 – 8 April to November, 2009. ……………………….56 Figure 76. Output of one-way analysis (JMP program) of inedible diatom (bacillariophyte) abundance, stations AR 1 – 8 April to November, 2009. ……………………….56 Figure 77. Average phytoplankton abundance and biovolume in Upper Arrow, stations AR 1 -3, May to October, 1997 to 2010. ………………………………………………57 Figure 78. Average phytoplankton abundance by group in Upper Arrow, April to October/November, 1998 to 2010. ………………………………………………58 Figure 79. Average phytoplankton biovolume by group in Upper Arrow, April to October/November, 1998 to 2010. ………………………………………………58 Figure 80. Average phytoplankton abundance and biovolume in the Narrows, stations AR 4 - 5, May to October, 1997 to 2010. ……………………………………………….59 Figure 81. Average phytoplankton abundance by group in the Narrows, April to October/November, 1998 to 2010. ………………………………………………60 Figure 82. Average phytoplankton biovolume by group in the Narrows, April to October/November, 1998 to 2010. ………………………………………………60 Figure 83. Average phytoplankton abundance and biovolume in the Narrows, stations AR 6 - 8, May to October, 1997 to 2010. ……………………………………………….61 Figure 84. Average phytoplankton abundance by group in Lower Arrow, April to October/November, 1998 to 2010. ………………………………………………62 Figure 85. Average phytoplankton biovolume by group in Lower Arrow, April to October/November, 1998 to 2010. ………………………………………………62 Figure 86. The trend of Asterionella formosa, Fragilaria crotonensis and Synedra acus, nana and ulna, stations AR 1, AR 5 and AR 8, June to November, 1998 to 2010. …...63
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report ix Figure 87. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 – 8, early June, 1998 to 2010. …………………...64 Figure 88. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, late June, 1998 to 2010. ……………………...65 Figure 89. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, July, 1998 to 2010. …………………………..66 Figure 90. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, August, 1998 to 2010. ………………………..67 Figure 91. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, September, 1998 to 2010. ……………………68 Figure 92. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, October, 1998 to 2010. ………………………69 Figure 93. Seasonal composition of zooplankton as a percentage of average density in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010. ………………………...... 71 Figure 94. Seasonal average zooplankton in Upper and Lower Arrow, 1997 to 2010. ……72 Figure 95. Seasonal composition of zooplankton as a percentage of average biomass in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010. ………………………….74 Figure 96. Seasonal average zooplankton biomass in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010. …………………………………………………………75 Figure 97. Seasonal biomass of zooplankton in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010. …………………………………………………………76 Figure 98. One way ANOVA and paired students t-test for total zooplankton biomass, April to November, 2009. ……………………………………………………………..77 Figure 99. One way ANOVA and paired students t-test for total zooplankton biomass, April to November, 2010. ……………………………………………………………...77 Figure 100. One way ANOVA and paired students t-test for total zooplankton biomass, stations AR 1 -8, 2009. ………………………………………………………….78 Figure 101. One way ANOVA and paired students t-test for total zooplankton biomass, stations AR 1 -8, 2010. ………………………………………………………….78 Figure 102. Average (April to October) total zooplankton density (top) and Daphnia density (bottom) in Kootenay Lake and Upper and Lower Arrow; 1997 to 2010. ……...79 Figure 103. Average (April to October) total zooplankton biomass (top) and Daphnia biomass (bottom) in Kootenay Lake and Upper and Lower Arrow; 1997 to 2010. ……...80 Figure 104. Seasonal average density of M. diluviana in deep sites, 1997 to 2010. ………..81 Figure 105 Monthly average density of M. diluviana by life stage in deep sites in Upper Arrow (AR 1-3), 2009 and 2010. ………………………………………………..81 Figure 106 Monthly average density of M. diluviana by life stage in deep sites in Lower Arrow (AR 6-8), 2009 and 2010. ………………………………………………..82 Figure 107. Seasonal average density of M. diluviana in shallow sites, 1997 to 2010. ……...82
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report x Figure 108. Monthly average density of M. diluviana by life stage in shallow sites in Upper Arrow (AR 1-3), 2009 and 2010. ………………………………………………..83 Figure 109. Monthly average density of M. diluviana by life stage in shallow sites in Lower Arrow (AR 6-8), 2009 and 2010. ………………………………………………..83 Figure 110. Seasonal average biomass of M. diluviana in deep sites, 1997 to 2010. ……….84 Figure 111. Monthly average biomass of M. diluviana by life stage in deep sites in Upper Arrow (AR 1-3), 2009 and 2010. ……………………………………………….84 Figure 112. Monthly average biomass of M. diluviana by life stage in deep sites in Lower Arrow (AR 6-8), 2009 and 2010. ………………………………………………..84 Figure 113. Seasonal average biomass of M. diluviana in shallow sites, 1997 to 2010. …….85 Figure 114. Monthly average biomass of M. diluviana by life stage in shallow sites in Upper Arrow (AR 1-3), 2009 and 2010. ………………………………………………..85 Figure 115. Monthly average biomass of M. diluviana by life stage in shallow sites in Lower Arrow (AR 6-8), 2009 and 2010. ………………………………………………..86 Figure 116. Mysis diluviana biomass by station at deep sites, April to November 2009…….86 Figure 117. Mysis diluviana biomass by station at deep sites, April to November 2010.…....87 Figure 118. Trends in kokanee spawner returns to Hill Creek and three key index streams (Drimmie, Halfway and Kuskanax) in the Upper Arrow Reservoir, 1966-2010. Note: estimates for 1993, 1994 and 2003 for index streams were based on average escapements in previous four years. Index stream estimates have been expanded by 1.5 (including Hill Creek below channel). …………………………………...88 Figure 119. Trends in kokanee spawner returns to four index streams (Burton/Snow, Caribou, Deer and Mosquito) in the Lower Arrow Reservoir 1966-2010. Note: estimates for 1993, 1994, and 2003 for index streams based on average escapements in previous four years. All index stream estimates were expanded by 1.5 to approximate total run size. ………………………………………………………88 Figure 120a. Length frequency histograms and assumed age by mode of Hill Creek kokanee spawners for 1994-1999. Sample size (n) ranged from 101-298 per year. ……...90 Figure 120b. Length frequency histograms and assumed ages by mode of Hill Creek kokanee spawners for 2000-2005. Sample size (n) ranged from 199-287 per year. ……...91 Figure 120c. Length frequency histograms and assumed age by mode of Hill Creek kokanee spawners for 2006-2010. Sample size (n) ranged from 203-260 per year. ……...92 Figure 121. Trends in spawner mean length and fecundity at Hill Creek Spawning Channel from 1977-2010. ………………………………………………………………………..93 Figure 122. Comparison of average fecundity of Hill Creek (1977-2010) and Bridge Creek spawners (1990-2003). Note: sample sizes were usually >100 fish. ………………93 Figure 123. Kokanee spawner length frequency by age based on otolith analyses for Hill Creek in a) 2008 b) 2009 and c) 2010. …………………………………………………...96 Figure 124a. Kokanee length frequency for Upper Arrow and Lower Arrow basins by age from 2009 trawl sampling with ages verified by scale interpretations. ……………...... 98
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report xi Figure 124b. Kokanee length frequency for Upper Arrow and Lower Arrow basins by age from 2010 trawl sampling with ages verified by scale interpretations. ………………….99 Figure 125a. Kokanee length frequency (proportions) by age for Upper Arrow with Hill Creek spawners overlaid and for Lower Arrow Reservoir from 2009 trawl data. ………100 Figure 125b. Kokanee length frequency (proportions) by age for Upper Arrow with Hill Creek spawners overlaid and for Lower Arrow Reservoir from 2010 trawl data. ………101 Figure 126. Trends in kokanee length at age adjusted to October 1 for a) Upper Arrow and b) Lower Arrow basins based on trawl survey data (1989-2010). Note: due to lack of trawl data in 2007, values are the mean size of spawners for age 2 & 3+, and the fry value is the mean post fertilization. ……………………………………………103 Figure 127. Plot of relative mean size at age for kokanee all years of record on Upper Arrow Reservoir. Note: the data have been normalized against the mean value for each age group. ……………………………………………………………………………104 Figure 128. Longitudinal distribution of age 0+ and age 1-3+ kokanee in ALR during October 2009 and 2010 based on acoustic surveys. Note transects 19 and 20 in the narrows can contain up to 65% non-kokanee (often pygmy whitefish). …………………..106 Figure 129. Kokanee abundance estimates of all ages for a) ALR (combined Upper and Lower Arrow), b) Upper Arrow and c) Lower Arrow based on fall acoustic surveys, 1988 – 2010………………………………………………………………………108 Figure 130. Trends in age 0+ and age 1-3+ kokanee abundance for Arrow Lakes Reservoir based on fall hydroacoustic surveys during 1993-2010. ………………………………..109 Figure 131. Trends in age 1-3+ kokanee abundance and estimated spawner returns to Arrow Lakes Reservoir tributaries including Hill Creek during 1993-2010. ……………109 Figure 132. Trends for in-lake biomass density and spawner biomass density for Arrow Lakes Reservoir kokanee. Note: In-lake biomass estimates were made after spawners had left the reservoir to spawn in tributaries. ATS refers to acoustic and trawl surveys. …………………………………………………………………………………...110 Figure 133. Annual estimates of kokanee biomass (combined in-lake and spawner in metric tons) in ALR based on hydroacoustic and trawl surveys. Dotted vertical line separates pre-treatment from treatment eras. ……………………………………111 Figure 134. Fry to adult survival estimates from Hill and Bridge Creek spawning channels by fry year adjusted for age at return. Note this plot based on adult return data up to and including fall 2010. ……………………………………………………………...112 Figure 135. Spawner to return spawner (S/RS) relationships for Hill and Bridge creeks assuming spawners return at age 3+. ………………………………………………………114 Figure 136. Observed difference in age 0 (R) fall abundance to spawner (S) ratio for two distinct eras in the ALR; pre-nutrient addition (1993-98) and nutrient addition (1999-2010) periods. …………………………………………………………………………..114 Figure 137. Expected mean stock recruitment (Ricker) relationship in juvenile recruits (t+) and adult recruits (t+4) for two distinct productivity eras. ……………………………115
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report xii Figure 138. Relationship between a) Hill Creek spawning channel fry production and late summer fry abundance (hydroacoustic) estimates and b) Combined Hill Creek and Arrow tributary fry production and late summer (acoustic) fry estimates from 1992-2010. Note: the 2004 data point is not shown on figure 78b as tributary spawner counts used to estimate fry production were not conducted in 2003. 121 Figure 139. Relationship between fry output from Hill Creek Spawning Channel and the % fry-to-adult survival rate for the nutrient addition period 1999-2010. Note that red points indicate the most recent two fry years of 2006 and 2007 corresponding to adult returns in 2009 and 2010, respectively. ………………………………….123 Figure 140. Relationship between number of eggs deposited at the Hill Creek spawning channel and the number of fry produced 1984-2010. Note 2004 and 2005 fry years (in pink) were extreme outliers and were not included in the regression. 125
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report xiii LIST OF TABLES
Table 1. Total tonnes of nitrogen and phosphorus dispensed form fertilizer to Upper Arrow between April and September, 1999 to 2010. …………………………………….5 Table 2. Limnological sampling stations for the Arrow Lakes Reservoir Nutrient Restoration Program. ……………………………………………………………..8 Table 3. Upper and Lower ALR tributaries used as index sites for kokanee spawner estimates. …………………………………………………………………………10 Table 4. Age composition (%) of kokanee spawners for Hill Creek during 1985-2010 based on otolith and length frequency analyses. ………………………………..95 Table 5. Kokanee catch statistics from the October trawl surveys in 2009 and 2010. …...97 Table 6. Kokanee size statistics from the October 2009 and 2010 trawl surveys. ………102 Table 7. Comparison of maximum likelihood abundance estimates (and 95% C. L.) for kokanee by basin and year for Arrow Lakes Reservoir during the nutrient addition period, 1999-2010. ……………………………………………………………..107 Table 8. Kokanee fry production from Hill Creek spawning channel 1987-2010. ……...119 Table 9. Theoretical return rates and resulting fry production from increased fry production at Hill Creek spawning channel based on preliminary survival relation in Figure 139. Note production levels with asterisks indicate extrapolation beyond current data. ………………………………………………………………………….....126
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report xiv Introduction
Nutrient additions have been widely used in lakes and reservoirs throughout British Columbia and Alaska as a technique for improving sockeye and kokanee stocks (Stockner and MacIsaac 1996; Perrin et al. 2006; Ashley et al. 1999, Mazumder and Edmundson 2002). Nutrient additions have also been used in Scandinavia as a technique for improving Arctic char and brown trout (Rydin et al. 2008 and Milbrink et al. 2008). Prior to nutrient additions, systems such as Arrow Lakes Reservoir, Kootenay Lake, Packers Lake, and Wahleach Reservoir were ultra-oligotrophic (Pieters et al. 1999; Ashley et al. 1999; Mazumder and Edmundson 2002 and Perrin et al. 2006). An ultra- oligotrophic reservoir or lake has extremely low levels of nutrients, which results in low productivity and biomass at all subsequent trophic levels in the aquatic food web. To address the ultra-oligotrophic status of these systems, a bottom-up approach was taken with the addition of nutrients (nitrogen and phosphorus in the form of liquid fertilizer) to increase the production of Daphnia, a main food source for kokanee. Lake fertilization has been a successful technique used for both the enhancement and conservation of sockeye salmon populations (Hyatt et al. 2004). Fertilization has also been successful in restoring kokanee populations in lakes and reservoirs altered by hydroelectric construction (Ashley et al. 1999; Perrin et al. 2006).
Significant restoration of Upper Columbia basin aquatic systems impacted by hydro developments began several decades ago with construction of two major kokanee spawning channels on Kootenay Lake and Arrow Lakes Reservoir (Redfish Consulting Ltd, 1999). A second major restoration initiative was launched in 1992 on Kootenay Lake designed to restore the declining kokanee (Onchorynchus nerka) population that top predators Gerrard rainbow trout (Onchorynchus mykiss) and bull trout (Salvelinus confluentus) depend on (Ashley et al. 1999). Nutrient addition to the Arrow Lakes Reservoir (ALR) began in 1999 and was modeled after the successful Kootenay Lake experiment aimed at increasing the kokanee population and their salmonid predators.
The ALR was formed in 1967 when the Hugh Keenleyside Dam was constructed on the outlet of the former Lower Arrow Lake. Since then two upstream reservoirs, Mica and Revelstoke have lowered productivity in ALR through retention of nutrients that formerly contributed to ALR production (Schindler et al. 2009a, b; Utzig and Schmidt 2011). In addition to nutrient loss, wide seasonal variation in reservoir levels has also contributed to oligotrophication of ALR. Matzinger et al. (2007) modelled hydraulic alterations caused by annual hydro plant water regulation and predicted that further hydraulic modifications such as deep water withdrawal or increased reservoir levels within the growing season could also reduce lake productivity by up to 40%. A further confounding factor to ALR fish production has been the introduction of Mysis relicta now Mysis diluviana (Audzijonyte and Vainola, 2005) in 1968 (Sebastian et al. 2000) which is known to be a competitor with kokanee for macrozooplanktors. In response to these numerous perturbations the ALR kokanee (Oncorhynchus nerka) population verged on collapse in the late 1990s and a decision was made by the provincial government to proceed with experimental fertilization of the Upper Arrow basin (Pieters et al. 2000). Pieters et al. (1999) described the background physical, chemical and biological data of
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 1 Arrow Lakes Reservoir and the events leading to initial fertilization of the upper basin in 1999, while Schindler et al. (2009a) provides a summary of initial trophic level responses to the nutrient additions.
Ecological impacts and fish losses due to upstream dams on the ALR system have been described by Sebastian et al. (2000) Pieters et al. (1999) Stockner and Ashley (2003) Moody et al. (2007) Arndt (2009) Utzig and Schmidt (2011) and others. The declining kokanee population observed in the ALR in the late 1990s initially responded to lake nutrient additions in a similar manner to Kootenay Lake kokanee where abundance and biomass increased about three fold (Schindler et al. 2009a, b). Because kokanee are most often the keystone species in many southern British Columbia large lakes, their abundance usually determines the health of predator species that are reliant on them as a primary food source. These include piscivorous rainbow trout, bull trout, burbot (Lota lota) and probably lake char (Salvelinus namaycush) and sturgeon (Acipencer transmontanaus) (Andrusak and Parkinson 1984; Arndt 2004a, Arndt and Schwarz 2011draft; Sebastian et al. 2003). Kokanee also provide valued fishing opportunities during the summer months (Sebastian et al 2000; Arndt and Schwarz 2011 draft).
Arndt (2004b) summarized ALR sport fish statistics and demonstrated improved growth and condition of 2003 rainbow trout and bull trout attributable to increased kokanee abundance (Arndt 2004a). Schindler et al. (2009a) compared a number of years pre- nutrient addition trophic level data with the first eight years of nutrient addition trophic level data and concluded that nutrient addition was highly beneficial to production at all trophic levels up to and including kokanee. More recently Arndt and Schwarz (2011) analysed the sport fishery statistics and rainbow and bull trout biological parameters and confirmed a strong response to nutrient additions although there has been a decline in the more recent years. Unfortunately the ALR system is hydrologically and operationally complex which has considerable influence on annual productivity; thus close monitoring of trophic level responses to nutrient additions is essential.
In terms of evaluating the higher trophic level responses to ALR nutrient additions there is a good data set on kokanee that dates back to the early 1970s. The early time series data provides the current ALR nutrient addition and monitoring program with context that shows trends over four decades, primarily based on kokanee spawner abundance from several index streams and the Hill Creek spawning channel. Escapements approaching one million were suggested for the 1960s and early 1970s based on run reconstruction assuming that Upper Columbia stocks approached 0.5 million (Sebastian et al 2000). In the early 1980s Hill Creek spawning channel was constructed in an effort to replace ~ 0.5 million kokanee estimated lost due to the Revelstoke Dam blocking access to key spawning areas in the Upper Columbia River. Hill Creek initially experienced large escapements during the late 1980s possibly due to displaced Upper Columbia kokanee but the restoration target of 0.5 million has yet to be achieved. Hill Creek spawning channel data includes annual estimates of kokanee fry production and numbers of returning spawners as well as biological characteristics (e.g. length, weight, fecundity, sex ratio and egg retention).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 2 There are several partnerships involved in the ALR nutrient restoration program led by the Ministry of Forests, Lands and Natural Resource Operations (MoFLNRO). Most of the ALR work is funded by a compensation program jointly established by the provincial government and BC Hydro. The Fish and Wildlife Compensation Program (FWCP) - Columbia Basin has administered the nutrient restoration project and most monitoring of the trophic levels with much of the technical support provided by the province. Since 1999, the Columbia Power Corporation which operates the Arrow Lakes Reservoir Generating Station at Hugh Keenleyside Dam has also provided funding for the nutrient restoration program.
This report describes the results from the eleventh and twelfth year (2009 and 2010) of a multi-year (1999-2010) nutrient addition program on Arrow Lakes Reservoir, with the results and analysis of monitoring of physical limnology, water chemistry, phytoplankton, zooplankton, mysid shrimp and kokanee. Concern over the declining kokanee, a landlocked sockeye salmon (Oncorhynchus nerka) and keystone of the local ecosystem, resulted in a two year comprehensive study of the Upper and Lower Arrow Lakes Reservoir commencing in 1997 (Pieters et al. 1998 and 1999). A fertilization program was then initiated in 1999 to try and restore kokanee populations by replacing nutrients lost from upstream impoundments. The project was modelled on the existing, successful Kootenay Lake fertilization project (Ashley et al. 1999; Schindler et al. 2011a).
The two years of pre-fertilization monitoring, 1997 and 1998, are described in Pieters et al. (1998, 1999) and the first three years of fertilization, 1999, 2000 and 2001 are described in Pieters et al. (2000, 2003a, 2003b). The fourth and fifth years of the fertilization program results from 2002 and 2003 are described in Schindler et al. 2006b and a summary report of results from 1999 to 2004 are described in Schindler et al. 2006c. The sixth and seventh years (2004 and 2005) of the fertilization program are described in Schindler et al. 2007b. The eighth and ninth year results are described in Schindler et al. 2009 and 2010. The tenth year is described in Schindler et al. 2011b.
This report summarizes the 2009 and 2010 results of the Arrow nutrient restoration program with the results compared with previous trend data summarized by Sebastian et al. (2000) and Schindler et al. (2011b). A list of personnel contributing towards the project is summarized in Appendix 1. A list of the program work is summarized in Appendix 2.
Methods
Fertilizer additions During 1999 to 2003, the seasonally adjusted blend of fertilizer was modeled on the Kootenay Lake loading (Ashley et al. 1999, Schindler et al. 2011a). The results in 2003 indicated a closer examination of monthly phytoplankton biomass, species composition and water chemistry parameters was required to adaptively manage the weekly loading schedule in future years of the program. In 2009 and 2010, adaptive management was continued to be implemented to ensure an adequate nitrogen to phosphorus (N:P) ratio was present for optimal phytoplankton growth.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 3
An agricultural grade liquid fertilizer blend of ammonium polyphosphate (10-34-0 N- P2O5 – K2O), % by weight) and urea ammonium nitrate (28-0-0,N-P2O5-K2O, % be weight) was used for additions to Upper Arrow. The total weight of fertilizer applied in 2009 was 47 tonnes of phosphorus and 239 tonnes of nitrogen. Applications started on April 26th and continued weekly until September 13th (except the week of August 02nd where no fertilizer was added). The nitrogen to phosphorus (N:P) ratio (weight:weight) of the fertilizer varied throughout the season, with a range of 0.67:1 in the spring to 8.2:1 in the late summer. Phosphorus loading ranged from 6.3 to 19.5 mg/m2 and nitrogen loading ranged from 5 to 87 mg/m2 in 2009 (Fig. 1). The total weight of fertilizer applied in 2010 was 43.6 tonnes of phosphorus and 235 tonnes of nitrogen. Applications started on April 18th and continued weekly until September 5th. The nitrogen to phosphorus ratios were 0.67:1 in the spring to 8.2:1 in the late summer of 2010. The total tonnes of phosphorus and nitrogen added to Upper Arrow from 1999 to 2010 are listed in Table 1.
N loading to Upper Arrow - mg/m2/week N loading to Upper Arrow - mg/m2/week 120 120 100 100
80 80
60 60
40 40 N - mg/m2/week N - mg/m2/week 20 20
0 0 Apr 26 May 24 Jun 21 Jul 19 Aug 16 Sep 13 Apr 18 May 16 Jun 13 Jul 11 Aug 08 Sep 05 Date - 2009 Date - 2010
P loading to Upper Arrow - mg/m2/week P loading to Upper Arrow - mg/m2/week 25 25
20 20
15 15
10 10 P - mg/m2/week 5 5 P - mg/m2/week
0 0 Apr 26 May 24 Jun 21 Jul 19 Aug 16 Sep 13 Apr 18 May 16 Jun 13 Jul 11 Aug 08 Sep 05 Date - 2009 Date - 2010
Figure 1. Nitrogen and phosphorus loading to Upper Arrow (mg/m2/week) from fertilizer, April to September, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 4 Table 1. Total tonnes of nitrogen and phosphorus dispensed form fertilizer to Upper Arrow between April and September, 1999 to 2010.
Year Phosphorus - tonnes Nitrogen - tonnes 1999 52.8 232.3 2000 52.8 232.3 2001 52.8 232.3 2002 52.8 232.3 2003 52.8 267.8 2004 39.1 276.9 2005 45.0 278.8 2006 41.6 244.9 2007 46.8 267.5 2008 49.5 255.4 2009 47.0 239.0 2010 43.6 235.1
The seasonal loading of fertilizer was intended to approximate pre impoundment spring freshet conditions for phosphorus (P) loading, and to compensate for biological uptake of dissolved inorganic nitrogen (DIN) as the season progressed. Phosphorus peaked in late spring and declined through the summer (Fig. 1). Weekly nitrogen began with low rates in the spring and increased through the summer in an attempt to inhibit the growth of cyanobacteria (blue-green algae) which can be associated with low N:P ratios (Smith, 1983; Pick and Lean, 1987).
Fertilizer application In 2009 and 2010 fertilizer was dispensed from the Galena Bay ferry for the first seven weeks of the season. During the remainder of the season fertilizer was dispensed from the Shelter Bay ferry where the fertilizer was dispensed over a 15 km distance beginning mid-way between hydroacoustic transects 3 and 4, travelling to the mid-way point between hydroacoustic transects 5 and 6 at which point the ferry travelled north - northwest 15 km to the ferry slip (Appendix 3). One half of the fertilizer was dispensed as the ferry travelled south and the other half was dispensed on the return trip. All fertilizer was thoroughly mixed into the prop wash of the ferry.
Galena Bay ferry A 7,700 litre capacity tank and truck capable of hauling this amount was used to dispense the fertilizer. The number of trips varied depending on the weekly loading schedule (Appendix 4). The fertilizer was stored at a tank farm located at the Hill Creek Spawning Channel where the contractor would fill their truck with the appropriate amount and blend of fertilizer and drive on to the ferry and dispense during the passenger run. Two diffuser pipes were installed in opposing corners on the rails of the ferry so the dispensed fertilizer could directly be mixed into the propeller wash of the ferry. The diffuser units were 3.6 m in length, 7.5 cm in diameter and had 0.6 cm orifices spaced at
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 5 30 cm intervals along the length of the pipe (Pieters et al. 2003). The ferry crossing time was approximately 25 minutes; the distance traveled approximately 6 km. The pump was generally activated 5 minutes after leaving the ferry terminal to prevent application of fertilizer in the shallower regions.
Shelter Bay ferry The Shelter Bay ferry was used for a portion of the season and the fertilizer was dispensed over a course of 15 km and a total of 2.5 hours of dispensing time. Two dispenser pipes were placed on the stern of the ferry (size of pipes was similar to those used on the Galena Bay ferry), and hoses were connected from the delivery trucks to the pipes where the fertilizer blend could mix into the propeller wash of the ferry. The fertilizer delivery trucks drove on to the ferry and the product would be directly dispensed from the delivery trucks to the reservoir. Weekly loads were distributed equally with one half released on the departure trip and one half on the return trip.
Physical data, chemical, phytoplankton, zooplankton and mysid sampling Physical data and phytoplankton samples were collected at eight established sampling stations (AR 1-8) (Table 2). Chemical, zooplankton and mysid samples were collected at six established sampling stations (AR 1-3 and AR 6-8). Stations AR 1 through AR 4 are located in Upper Arrow, station AR 5 is located in the former river channel that connected the original Upper and Lower Arrow lakes pre dam impoundment. Stations AR 6 to AR 8 are located in Lower Arrow (Appendix 3).
Temperature and oxygen profiles were obtained using a SeaBird profiler,. At all stations the profiler logged information every 10 centimetres from the surface to 5 m off the bottom.
Temperature and oxygen profiles were obtained using a SeaBird, (SBE 19 plus profiler, Bellevue, Washington). At all stations, the profiler logged information every 10 centimetres from the surface to 5 m off the bottom. The SeaBird also recorded specific conductance and turbidity. These data are not shown in graphs or tables but are mentioned in the text. Water transparency was measured at each station using a standard 20-cm Secchi disk without a viewing chamber.
During both years, water samples were collected from stations AR 1 – 3 and AR 6 – 8 from April through November using a 2.54-cm (inside diameter) tube sampler to collect an integrated water sample from 0-20 m. A Van Dorn sampler was used to collect hypolimnetic water samples (5 m off the bottom) from May to October (Table 3.1). Water samples were placed in coolers on icepacks and shipped within 24 h of collection to Maxxam Analytics, Inc. in Burnaby, BC. Samples were analyzed for turbidity, pH, total phosphorus (TP), total dissolved phosphorus (TDP), orthophosphate (OP), total nitrogen (TN), nitrate plus nitrite, silica, alkalinity and total organic carbon (TOC). As well, selective parameters, such as secchi and conductivity (data from Seabird) were measured at stations AR 4 and AR 5. Chlorophyll a (Chl a) samples were collected from stations AR 1 – 8 from April to November using the integrated tube sampler (described above) at 0-20 m. Chlorophyll a was analyzed by the Ministry of Environment,
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 6 University of British Columbia in Vancouver BC. Prior to shipping to the lab, Chl a samples were prepared by filtering a portion of the integrated water sample through a filter with 0.45 μm pore size. Samples were analyzed using a fluorometric method (Strickland and Parsons, 1972).
Additional water samples were taken at stations AR 2 and AR 7 at discrete depths from June to September, using a Van Dorn sampler, in the epilimnion of Arrow Lakes Reservoir. These samples were obtained from depths of 2, 5, 10, 15, and 20 m for analysis at the lab (described above) of TP, TDP, OP and DIN. Chl a was also analyzed at the UBC Fisheries, MoE, Vancouver lab.
Integrated results were compared using the statistics software R (ver. 2.14.1). Comparisons considered for each year were; differences in means for stations (AR 1 – 3, and AR 6 – 8), basin (Upper and Lower) and seasons. Seasons are separated by; spring (April – June), summer (July – September) and fall (Oct – November). In addition, 2009 and 2010 annual means were compared, as well as to a pooled 1997 – 2008 calculated mean. For consistency across years, AR 4 – 5 were omitted from this dataset.
In this report, monthly variations of 2009 and 2010 data are illustrated in the figures of this report. As well, annual variations (1997 – 2010) are shown for each parameter.
Phytoplankton Phytoplankton samples were collected from stations AR 1-8 from April through November using the integrated sampler described above. Samples were preserved in acid Lugol’s iodine solution immediately after collection and couriered to West Vancouver for processing by Eco-Logic Ltd. Prior to quantitative enumeration, samples were shaken for 60 seconds, carefully poured into 25 mL settling chambers, and allowed to settle for a minimum of 6-8 hours. Counts were done using 25 mL settling chambers on a Carl Zeiss inverted phase-contrast plankton microscope (Utermohl 1958). Counting followed a two- step process: 1. micro-phytoplankton (20-200 μm) within 5 to 10 random fields were enumerated at 250X magnification, and 2. pico-phytoplankton (0.2-2.0 μm) and nano- phytoplankton (2.0-20.0 μm) within or touching a 10 to 15 mm transect line were counted at 1560X magnification. The micro-phytoplankton includes diatoms, dinoflagellates, and filamentous blue-greens. The pico-phytoplankton includes minute (< 2.0 μm) autotrophic cells in Class Cyanophyceae, and the nano-phytoplankton includes auto-, mixo-, and heterotrophic flagellates in Classes Chrysophyceae and Cryptophyceae. In total, about 250 to 300 cells were consistently enumerated in each sample to ensure statistical accuracy (Lund et al. 1958). The compendia of Prescott (1978) and Canter-Lund and Lund (1995) were used as taxonomic references (Stockner 2010). The phytoplankton species list and estimates of each species’ biomass (cell biovolume) used for the computation of population and class biomass estimates for Arrow Lakes Reservoir in 2009 and 2010 are given in Appendix 3.1 in Stockner 2010. This list also identifies genus and species of edible and inedible phytoplankton to zooplankton. Edible and inedible phytoplankton are discussed later in the report.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 7 Table 2. Limnological sampling stations for the Arrow Lakes Reservoir Nutrient Restoration Program.
Site ID EMS Site No. Site name Depth (m) AR 1 E225768 Arrow Lake @ Albert Point 220 AR 2 E225769 Arrow Lake @ Ann Point 285 AR 3 E225770 Arrow Lake @ Turner Creek 155 AR 4 E225771 Arrow Lake @ Slewiskin Creek 75 AR 5 E225779 Arrow Lake, downstream Mosquito Creek 50 AR 6 E225781 Arrow Lake @ Johnson Creek 145 AR 7 E225782 Arrow Lake @ Bowman Creek 155 AR 8 E225783 Arrow Lake @ Cayuse Creek 85
Zooplankton Samples have been collected monthly at six stations (AR 1-3, AR 6-8) from May to October in 1997, April to October in 1998 through 2001. In 2002 the sampling season was lengthened from April to November. In 2009, samples were collected from April 12th to November 03rd using a Clarke-Bumpus sampler. In 2010, samples were collected from April 20th to November 08th. The April samples were collected at a later date in 201 compared to 2009 due to mechanical issues with the sampling boat. At each of the stations, three replicate oblique tows were made. The net had 153-um mesh and was raised from a depth of 40 m to 0 m at a boat speed of 1 m/s. Tow duration was 3 min, with approximately 2,500 L of water filtered per tow. The exact volume sampled was estimated from the revolutions counted by the Clarke-Bumpus flow meter. The net and flow meter were calibrated before or after each sampling season. All calibrations were done in a flume at the Civil Engineering Department at the University of British Columbia.
Zooplankton samples were rinsed from the dolphin bucket through a 100-µm filter to remove excess lake water and were then preserved in 70% ethanol. Zooplankton samples were analyzed for species density, biomass (estimated from empirical length-weight regressions, McCauley 1984), and fecundity. Samples were re-suspended in tap water that had been filtered through a 74-µm mesh and were sub-sampled using a four- chambered Folsom-type plankton splitter. Splits were placed in gridded plastic petri dishes and stained with Rose Bengal to facilitate viewing with a Wild M3B dissecting microscope (at up to 400X magnification). For each replicate, organisms were identified to species level and counted until up to 200 organisms of the predominant species were recorded. If 150 organisms were counted by the end of a split, a new split was not started. Using a mouse cursor on a live television image, the lengths of up to 30 organisms of each species were measured for use in biomass calculations. Lengths were converted to biomass (ug dry weight) using an empirical length-weight regression from McCauley (1984). The number of eggs carried by gravid females and the lengths of these individuals were recorded for use in fecundity estimates.
Rare species, e.g., Leptodiaptomus sicilis, were counted and measured as “Other Copepods” or “Other Cladocerans” as appropriate. Zooplankton species were identified
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 8 with reference to taxonomic keys (Pennak 1989, Brooks 1959, Wilson 1959, Sandercock and Scudder 1996).
Mysis diluviana Samples of mysids from Arrow Lakes Reservoir were collected at six stations (AR 1-3, AR 6-8) monthly from May to December in 1997, January to December in 1998 through 2004, February to December in 2005, February to November in 2006 and April to November in 2007-2010. Sampling was done at night, around the time of the new moon, to decrease the chance of mysids seeing and avoiding the net. With the boat stationary, three vertical hauls were done at each station using a 1-m2 square-mouthed net with 1,000 µm primary mesh, 210µm terminal mesh, and 100-µm bucket mesh. Two hauls were made in deep water (0.5 nautical miles from both west and east of lake centre), and one haul was made in shallow water near either the west or east shore. The net was raised from the lake bottom with a hydraulic winch at 0.3 m/s. The contents of the bucket were rinsed through a filter to remove excess lake water and were then preserved in 100% denaturated alcohol (85% ethanol, 15% methanol).
Samples have been analyzed for density, biomass (estimated from an empirical length- weight regression, Lasenby 1977), life history stage, and maturity (Reynolds and DeGraeve 1972). The life history stages identified were juvenile, immature male, mature male, breeding male, immature female, mature female, brooding female (brood pouch full of eggs or embryos), disturbed brood female (brood pouch not fully stocked with eggs, but at least one egg or embryo left to show that female had a brood), and spent female (brood pouch empty, no eggs or embryos remaining).
Samples were re-suspended in tap water that had been filtered through a 74-µm mesh filter, placed in a plastic petri dish, and viewed with a Wild M3B dissecting microscope at up to 160X magnification. All mysids in each sample were counted and had their life history stage and maturity identified. Using a mouse cursor on a live television image, the body length (tip of rostrum to base of telson) of up to 30 individuals of each stage and maturity was measured for use in biomass calculations. Lengths were converted to biomass (mg dry weight) using an empirical length-weight regression (Smokorowski 1998).
Kokanee Each fall standardized trawl and acoustic surveys are conducted, index stream kokanee escapement estimates are made, and biological sampling is conducted at the Hill Creek spawning channel. The sport fishery is also monitored by the FWCP with the most recent results reported by Arndt and Schwarz (2011). In 2005 a comprehensive review of all kokanee escapement data and Hill Creek biological data was conducted by the Ministry of Environment (presently Ministry of Forests, Lands and Natural Resource Operations, MoFLNRO) to ensure quality control of data entry. Since 2005 minor discrepancies exist between previously reported data and the revised database but these do not make any appreciable change to long-term trends in escapements or fish sizes. Kokanee spawner data in this report was obtained from the MoFLNRO Nelson office using the 2010 data base.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 9 Spawner numbers, size and fecundity ALR kokanee numbers returning to spawning streams have been estimated for most systems since 1966 with more rigorous enumerations made from 1988 onward (Sebastian et al. 2000; Schindler et al. 2009a). Spawner numbers are estimated each fall through a combination of aerial surveys each fall and visual ground counts. Since 2004 three aerial surveys per spawning season have been conducted around the time of known peak spawning based on Hill Creek daily counts ensuring a good estimation of peak spawning numbers. These estimates serve as indices of abundance since budget limitations do not provide the opportunity to estimate total numbers through the area-under-the-curve (AUC) methodology (see Hill and Irvine 2001; Parken et al. 2003). However, total counts are conducted at a fish fence located at the entrance to the Hill Creek spawning channel. A more complete description of methods employed for all kokanee enumerations can be found in Sebastian et al. (2000). Run timing generally occurs between late August and late September with the peak of spawning usually recorded during the third week of September. Streams surveyed and used as index sites for estimates of abundance are shown in Table 3. Estimates from a number of smaller systems periodically enumerated can be found in Appendix 5.
Table 3. Upper and Lower ALR tributaries used as index sites for kokanee spawner estimates.
Upper Arrow Lower Arrow Hill Creek spawning channel Burton/Snow Creeks Drimmie Creek Caribou Creek Halfway River Deer Creek Kuskanax Creek Mosquito Creek
The primary source of kokanee biological data is acquired each year from randomly sampled spawners returning to the Hill Creek spawning channel. At Hill Creek the total number of fish in the system is estimated through a combination of manual counts into the channel through a fence at the lower end and ground survey estimates of fish spawning downstream of the channel. Kokanee are sub-sampled at the lower channel fence site for length, weight, sex, fecundity and egg retention. Annual egg deposition is estimated from the total number of females (from sex ratio of sampled fish) and mean fecundity less egg retention, determined from samples taken within the channel over the spawning period. Fry out-migration is determined each spring as described by Redfish Consulting Ltd (1999). In addition to the Hill Creek data the trawl caught kokanee of various sizes are used for age determination, size-at-age, and biomass estimations.
Fry to adult survival Hill Creek spawning channel data has been used to monitor trends in kokanee fry-to-adult survival rates. For pre-fertilization years where age data was lacking, it was assumed that all the fish returned at age 3+ (Schindler et al 2011b). However, both length frequency distributions and otolith analyses have suggested that some years (particularly post- fertilization) have included a mix of ages returning. Previous attempts in earlier reports to adjust for multiple spawner return years has led to some confusion and difficulty
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 10 interpreting the results and assumptions when reported by adult return year. For simplicity, the fry to adult survival estimates in this report have been recalculated based on fry production years and these cohorts have been followed through to the estimated number of adults of each age produced. No attempt has been made to estimate or compare fry to adult survival for age 2+ versus age 3+ spawners within the same cohort, but rather the combined percent return of all ages from that fry year has been reported. The data used for fry survival estimates are shown in Appendix 6 with highlights showing the data used to calculate a specific year. In the absence of otolith data, age proportions have been estimated from the length frequency distributions as described in the next section. Where otolith ages are in doubt as a result of combined length frequency and trawl age data or where there is disagreement between different aging specialists, the age proportions have defaulted to the length frequency method.
Previous attempts to adjust the spawner-recruitment (S/R) ratio to account for multiple spawner ages presented in some years did not appear to change the long-term trend appreciably. Therefore, for simplicity the S/R ratios presented in this report were derived from a simple trend assuming age 3+ returns accepting that some individual years may be misrepresented while long term trends are sufficiently reliable.
Age determination As with other large lakes, there remains some uncertainty around age determination of ALR kokanee spawners. In many large lake projects age analysis of mature kokanee has been problematic owing to scale resorption and/or poor quality scales due to spawning condition. This led to use of otoliths in recent years in effort to gain more clarity and accuracy in ageing but as with scale reading there have been mixed results. For example, in 2006 there was only 40% agreement between two investigators, so the ages defaulted to a single age at return (i.e. age 3+) represented by a single mode on the length frequency distribution. The most credible age determinations over the period of record has been derived from trawl captured fish that provide samples of all age groups evident from length frequency analysis and mostly consistent with scale interpretation. In the absence of otolith ageing, adult ages have been estimated to be either a single age (3+) when unimodal or a combination of two ages (2+ and 3+) when bimodal. These determinations were made based on the spawner length frequency distribution compared with the size distribution of age 2+ trawl caught kokanee. Note: ages of kokanee referred to in this report are described by the following example: age 1+ are fish that have grown through one winter and two summers, etc.
Trawl sampling Standardized mid-water trawl samples have been collected in the fall of each year since 1999 (except 2007) to monitor annual variation in kokanee density, and obtain length and weight-at-age data. Scale samples have been collected from all size groups to confirm age. Trawling is always conducted concurrent with acoustic surveys during the new moon, when the fish are typically found in a layer at the thermocline and are least able to avoid the sampling gear. Three trawl stations are located within each of the two main basins (Appendix 2) and three trawls are usually conducted at each station. Stepped- oblique trawls ensure a representative sample of fish is obtained from each depth strata
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 11 where fish are observed on an echosounder. The net is typically fished for 16 minutes over consecutive 5 m depth layers from beneath the observed fish layer to a few meters above the layer. The trawl net is a 15 meter long beam trawl with a 5 m by 5 m square opening towed at 0.8 m s-1. The net consists of graduated mesh panels from 10 cm (stretched mesh) at the head bar to 0.6 cm at the cod end. Net depths are estimated from the cable angle and the length of cable deployed. A geographic positioning system (GPS) is used to determine distances travelled, boat speed and trawl sample volumes.
All kokanee captured in the trawls are kept on ice until processed the following morning. The species, fork length, weight, scale code and stage of maturity are recorded. The trawl surveys provide species verification for the acoustic survey, an index of kokanee abundance, age structure and size-at-age. Using length correction factors suggested by Sebastian et al. (1995), kokanee lengths are adjusted to an October 1 standard enabling growth comparisons with previous fall surveys (also see Sebastian et al. in Pieters et al. 2003).
Hydroacoustic survey ALR hydroacoustic surveys in 2009 were conducted at night during October 14-17 in the limnetic area of the ALR. Limnetic habitat for kokanee surveys was defined as habitat where water depth was greater than 20 meters depth at survey time (Pennak 1964). In 2010, the survey was conducted during October 4-7. Acoustic surveys each consisted of 18 transects, 10 in the upper basin and 8 in the lower basin (Appendix 3); however in 2009 one transect (transect 11) was omitted due to excessively noisy data.
The transducer was towed on a planer alongside the boat at a depth of 1.0 m and data was collected continuously along survey lines at 5-8 pings.s-1 while cruising at 2 m.s-1 (7.2 km.hr-1). Navigation was by GPS, radar and a 1:50,000 Canadian Hydrographic Services chart. The sounder was field calibrated prior to each survey at depths of 15-20 m using a standard -40.4 dB copper calibration sphere, and following methods outlined in the manual (Kongsberg Maritime AS, 2008). Echosounder specifications,field settings, post processing parameter and data processing specifications are presented in Appendix 7.
The Simrad survey data were stored on a Panasonic “Toughbook” PC laptop and then analyzed using SONAR 5-Pro Echo Processing Software Version 5.9.9 (Balk and Lindem, 2009). Transect data were visually inspected and false echoes excluded from the analysis. Lower exclusion lines were set at 2 meters from bottom of the reservoir and inspected for quality, while surface exclusion lines were set at 3m depth. Echo integration was the method used to generate target densities per unit area by depth stratum. Integration analysis followed the Software Guided Analysis (SGA) process in SONAR 5, recommended by Balk and Lindem (2009) for vertical mobile surveys. The SGA process is a biomass estimation guide based on the Standard Operating Procedures for Acoustics in the Great Lakes (Parker-Stetter et al. 2009). Data were converted and inspected down to a threshold of -70 dB, considered well below the minimum target strength of kokanee fry. Integration data were scaled using the size distribution source derived from in-situ single echo detections. The working threshold was set to -60dB, determined through TS distribution analysis to capture the vast majority of kokanee fry detections yet exclude
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 12 interference from smaller Mysis diluviana noise. Habitat was stratified by 5 m depth layers and then longitudinally stratified into zones of relatively homogeneous transects if required. Within each habitat zone the mean density and standard error was estimated for each depth stratum. A Monte Carlo Simulation procedure was used to combine all strata and develop maximum likelihood estimates and statistical bounds for each zone and again for the combined zones using 30,000 iterations per run. Fish density statistics by depth and maximum likelihood population estimates with bounds are presented in Appendix 8. Habitat areas adjusted by pool level are shown in Appendix 9.
Acoustic size distributions were used to proportion the fish population into two size classes representing age 0+ fish and combined ages 1-3+ fish. Fork lengths of trawl caught fish were converted to the acoustic scale using Love’s (1977) empirical relation and compared to acoustic target size distributions in order to verify the age cut-off for the two size groups (Appendix 10). Since it was not possible to distinguish between age 1, 2 and 3+ fish using acoustic data, the proportions of these age groups were estimated from trawl catches. This methodology is known to be somewhat problematic for two reasons: (1) the reliability of proportioning the trawl catch can be compromised by small sample sizes when densities are low and, (2) a negative bias in capture of age 1 fish tends to skew the age proportions in favor of age 2 fish (Sebastian and Scholten in Andrusak et al. 2001). The issue of potentially low samples sizes led to increasing trawl efficiency by doubling of the trawl time from 8 to 16 minutes per 5m layer in Arrow Lakes Reservoir starting in 2000. Despite concerns with trawl bias, trends in abundance within specific age groups should still be valid for generating an index measure of total kokanee biomass.
Kokanee Biomass Biomass estimates for pelagic habitat were determined from acoustic abundance proportioned into age groups based on both trawl and acoustic surveys (Appendix 13). Mean weights at age from the trawl data were applied to the total estimated numbers of fish at each age to determine total biomass in the reservoir. In most years actual weights of spawners have been used to calculate Hill Creek spawner biomass (data on file MoFLNRO, Nelson BC) and this was again the case in 2009 and 2010. The sum of all weights for all age groups was then divided by the surface area of “pelagic habitat” to determine an average biomass density (kg.ha-1). It is acknowledged that a negative bias in capture of age 1 kokanee can result in over estimating kokanee biomass by this method. On the other hand, Parkinson (1988) and others have recognized that trawl capture efficiency is very low for larger fish, which could lead to an under estimate of biomass. Although trawl bias will affect the accuracy of the biomass estimates, it is not expected to affect overall long term trends in biomass assuming that trawl sampling bias for kokanee remains constant over time when using the same methods and equipment. Quantifying trawl bias by size (eg. age group) for kokanee could be very difficult and costly. The practicality of fine-tuning the existing trawl methods in order to improve the accuracy of kokanee biomass estimates would have to be weighed against other stock assessment priorities.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 13 Analysis of Annual Biomass Estimates of biomass (metric tons) and biomass density (kg.ha-1) provide good indicators of how nutrient addition influences trophic productivity in ALR. The effect of nutrient additions on kokanee biomass and biomass density on ALR was tested using a generalized linear mixed effects model (Pinheiro and Bates 2000; Venables and Dichmont 2004). The model analyzed the effect of nutrient addition from distinct limnological eras (pre and post fertilization) on kokanee biomass (metric tons) and biomass density (kg.ha-1) as the response variable collected from hydroacoustic surveys from 1993-2010. The predictor variable was Era (pre-fertilization and post-fertilization), which was modeled as a fixed effect. In order to account for inter-annual variation in biomass and biomass density due to causes other than fertilization, year was included in the model as a random effect. Pre fertilization era included biomass estimates from 1993- 1998 and post fertilization era included data from 1999 to 2010. Candidate models were also compared with the Akaike Information Criteria (AIC) with correction for small sample sizes (AICc) to determine which model was the best fit to the data (Burnham and Anderson 2002). Analyses were performed using R 2.10 (R Development Core Team 2007).
Stock Recruitment-Ricker model The ALR kokanee data used for the stock-recruitment analysis was obtained through hydroacoustic surveys on the reservoir from 1993-2010. Stock-recruitment analysis requires an accurate and precise measure of the reproductivity of the mature fish. Stock recruitment also requires an estimate of recruitment where this can refer to either the life stage at which the fish first become vulnerable to fishing gear or the population still alive any set time after the egg stage (Haddon 2001). Similar to the estimate of mature fish, there will be error in estimation of the recruits.
The stock-recruit model used the classic Ricker (1975) model, Rt+0 =St exp(a-bSt+wt), which when transformed translates into a linear regression in the form of ln(Rt+4/St)=a- bSt+wt where, Rt+0 is considered the total recruits resulting from spawning in year t, a is the maximum productivity at low stock size, b is the density dependent parameter representing increase in total mortality per unit increase in spawning numbers St, and wt is the error term. It was assumed that the vast majority of spawners were age-3 and recruits were modeled as age 0 fall fry from acoustic estimates. Two linear models analyzed the effect of nutrient addition from distinct limnological eras. Tests for determining if slopes and intercepts were different between the two models from the two eras were conducted using an ANCOVA analysis. Candidate models were also compared with the Akaike Information Criteria (AIC) with correction for small sample sizes (AICc) to determine which model was the best fit to the data (Burnham and Anderson 2002).
Estimates of key management parameters: under the ecologically distinct productive era's for maximum escapement (Smax) were derived by using relationships outlined in Martell et al. (2008) to set them as leading parameters. Smax represented the spawner abundance expected to generate maximum recruitment. Parameter estimates were obtained using ordinary least squares estimation from the log normal transformed linear regression
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 14 (Walters and Martell 2004). Analyses were performed using R 2.10 (R Development Core Team).
Results
Temperature Arrow Lakes Reservoir is a warm monomictic water body, with isothermal temperatures from late fall to early spring and stratification during the summer months. The reservoir began to stratify in June, then displayed warming surface temperatures in July and August (Fig. 2 and Fig. 3). A less variable epilimnion was established in the late summer and fall (Fig. 2 and Fig. 3). In 2009, warmest temperatures were observed in July; in Upper Arrow at AR 1 (20.5°C), and in the Narrows at AR5 (21.8°C). In the Lower Arrow, warmest temperatures were observed in August at AR 7 (20.26°C). In 2010, Upper Arrow was the warmest at AR 3 (20.06°C), Narrows at AR 4 (20.58°C) and Lower Arrow at AR 8 (21.43°C). For all stations, maximum temperatures were observed in August. In 2009 and 2010, hypolimnetic temperatures ranged from 4 – 6ºC throughout the year.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 15 2009 ‐ AR 2 Temperature (°C) 2009 ‐ AR 7 Temperature (°C)
0 5 10 15 20 25 0 5 10 15 20 25 0 0
50 50
Apr 12 Apr 14
(m) May 12 (m) May 11 100 100 Jun 14 Jun 16 Depth Jul 12 Depth Jul 14 150 Aug 09 150 Aug 11 Sep 08 Sep 07 Oct 06 Oct 05 200 200 Nov 04 Nov 03 Figure 2. Temperature profiles at station AR 2 and AR 7, April to November, 2009.
2010 ‐ AR 2 Temperature (°C) 2010 ‐ AR 7 Temperature (°C)
0 5 10 15 20 25 0 5 10 15 20 25 0 0
50 50
Apr 20 Apr 19
(m) May 17 (m) May 17 100 100 Jun 14 Jun 16 Depth Jul 12 Depth Jul 14 150 Aug 10 150 Aug 09 Sep 07 Sep 08 Oct 12 Oct 04 200 200 Nov 09 Nov 08 Figure 3. Temperature profiles at station AR 2 and AR 7, April to November, 2010.
Dissolved Oxygen Results of oxygen profiles were similar to previous years. Arrow Reservoir is well oxygenated from the surface to the bottom depths at each station (data on file at the Ministry of Forests, Lands and Natural Resource Operations). In 2009, there was an increase in oxygen in the spring at 20 m depth for the Upper and Lower basins, typical of
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 16 an orthograde profile (Fig. 4). In 2010, oxygen was consistent through the water column, with increases in oxygen in April (Fig. 5). Nutrient enrichment has had no detectable effect on hypolimnetic oxygen concentrations.
2009 ‐ AR 2 Oxygen (mg/L) 2009 ‐ AR 7 Oxygen (mg/L)
0 5 10 15 20 25 0 5 10 15 20 25 0 0
50 50
Apr 12 Apr 14
(m) May 12 (m) May 11 100 100 Jun 14 Jun 16 Depth Jul 12 Depth Jul 14 150 Aug 09 150 Aug 11 Sep 08 Sep 07 Oct 06 Oct 05 200 200 Nov 04 Nov 03 Figure 4. Oxygen profiles at station AR 2 and AR 7, April to November, 2009.
2010 ‐ AR 2 Oxygen (mg/L) 2010 ‐ AR 7 Oxygen (mg/L)
0 5 10 15 20 25 0 5 10 15 20 25 0 0
50 50
Apr 20 Apr 19
(m) May 17 (m) May 17 100 100 Jun 14 Jun 16 Depth Jul 12 Depth Jul 14 150 Aug 10 150 Aug 09 Sep 07 Sep 08 Oct 12 Oct 04 200 200 Nov 09 Nov 08 Figure 5. Oxygen profiles at station AR 2 and AR 7, April to November, 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 17 Secchi Secchi measurements evaluate the transparency of water to light and can serve as a general indicator of productivity (Wetzel, 2001). The depth at which the disc can be visualized represents the transparency of the water, where increasing secchi depths indicate increasing transparency. Secchi disc measurements on Arrow Reservoir in 2009 and 2010 suggest a typical seasonal pattern of decreasing transparency associated with the spring phytoplankton bloom, followed by an increase in transparency as the bloom gradually abates by the late summer and fall (Fig. 6 and Fig. 7). Summer means for both 2009 and 2010 were significantly lower than spring and summer values.
In 2009 and 2010, secchi disc measurements were taken at the Narrows, located between the Upper and Lower basins. The Lower basin was slightly more transparent; however not significantly higher than the other areas (Upper = 6.52, Narrows=6.38, Lower=8.13 m). Likewise, in 2010, there was not a significant trend to secchi depths across basin (Upper=5.09, Narrows=5.64, Lower=5.99 m).
The annual secchi depth mean for 2010 was significantly lower than in 2009 (Fig.8). As well, the decreased transparency in 2010 was significantly lower than the pooled 1997 – 2008 secchi depth measurements. There was not a significant difference between pooled 97-08 data and the 2009 mean. The decreased transparency in 2010 coincides with a slight increase in average phytoplankton biovolume (discussed further in the report).
Upper Arrow Secchi 0
5
10 AR 1
AR 2
Secchi Disc Depth (m) Disc Secchi 15 AR 3
20 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 6. Upper Arrow Secchi disk depths, stations AR 1-3 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 18 Lower Arrow Secchi 0
5
10
AR 6
AR 7 Secchi Disc Depth (m) Disc DepthSecchi 15
AR 8
20 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 2009 2010 Figure 7. Lower Arrow Secchi disk depths, stations AR 6-8 April to November, 2009 and 2010.
Secchi
0
2 (m)
4 Depth
Disc
6
Secchi 8
10 8 0 2 4 6 8 0 99 00 0 0 00 00 01 1 2 20 20 2 2 2
Figure 8. Annual average Secchi disk depths and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Integrated samples – 0-20 m
Turbidity Turbidity is caused by suspended particles (e.g., fine particulate matter), plankton and other small organisms (Wetzel and Likens, 2000). In 2009, turbidity in the spring was lower than in the summer for both the Upper and Lower basin, although, there was a decrease in October for both basins (Fig.9 and Fig.10). In 2010 in the Upper basin, there was an increase in turbidity from spring to summer, then a decrease in the fall (Fig.9). The Lower basin showed less variability across seasons (Fig.10). For both Arms, there was no significant difference across stations.
In 2010, there was a decrease in turbidity from 2009, however not a significant difference between annual averages (Fig.11). The pooled average of turbidity from 1997 – 2008 (0.51 NTU) was significantly lower than the 2009 mean (0.67 NTU), although not the 2010 mean (0.55 NTU).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 19 Upper Arrow Turbidity 2.0 AR 1
AR 2 1.5 AR 3
1.0 Turbidity (NTU) Turbidity
0.5
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 9. Upper Arrow turbidity, stations AR 1-3 April to November, 2009 and 2010. Lower Arrow Turbidity 2.0 AR 6
AR 7 1.5 AR 8
1.0 Turbidity (NTU) (NTU) Turbidity
0.5
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 10. Lower Arrow turbidity, stations AR 1-3 April to November, 2009 and 2010.
Turbidity
1.00
0.80
0.60 (NTU)
0.40
Turbidity 0.20
0.00
98 00 02 04 06 08 10 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 11. Annual average turbidity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 20 Conductivity – integrated 0-20 m Conductivity or specific conductance is a measure of resistance of a solution to electrical flow (Wetzel, 2001). In an aqueous solution, the resistance to an electrical current declines with increasing ion content (Wetzel, 1983). For both 2009 and 2010, conductivity was also measured at the Narrows; there was no significant difference between basins. In 2009, conductivity decreased in the summer and was significantly higher in the spring (131 µS/cm) than in the summer (114 µS/cm) and fall (115 µS/cm) (Fig.12 and Fig.13). The same trend of decreasing conductivity was also observed in 2010; however, all seasons were significantly different (spring=132, summer=115 and fall=109 µS/cm) (Fig.12 and Fig.13).
In 2010, there was not a significant difference from the annual mean (119.6 µS/cm) compared to the 2009 mean (119.9 µS/cm) (Fig.14). As well, neither year was significantly different from the pooled 1997 – 2008 mean (118 µS/cm).
Upper Arrow Conductivity 180 AR 1
AR 2 160 AR 3
140
120 Conductivity (uS/cm) 100
80 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 12. Upper Arrow conductivity, stations AR 1-3 April to November, 2009 and 2010. Lower Arrow Conductivity 180
160 AR 6
AR 7 140 AR 8
120 Conductivity (uS/cm) 100
80 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 13. Lower Arrow conductivity, stations AR 6-8 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 21
Figure 14. Annual average conductivity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Phosphorus Phosphorus is commonly used as an indicator of productivity due to the valuable role it plays in biological metabolism. Phosphorus is monitored throughout the season to both evaluate limitations, and to monitor the non-uptake of phosphorus associated with nutrient additions. Results for phosphorus may be slightly inflated as values reported under the reportable detection limit (RDL) were set to the RDL. For phosphorus variables, this is 2 µg/L. In 2009 and 2010, 9% total phosphorus (TP) values were reported less than the RDL. For total dissolved phosphorus, a greater proportion of values were reported at less than the RDL (2009; 46% and 2010; 48%).
In 2009, TP ranged between 2 – 5 µg/L in the Upper basin (Fig.15), and in the Lower basin, TP ranged from 2 – 4 µg/L, with the exception of a higher value of 7 µg/L observed at AR 8 in April (Fig.16). There was not a significant seasonal pattern in 2009, although the summer mean was slightly lower than the spring mean for the whole lake. There was not a significant difference between basins, or stations. In 2010, Upper Arrow ranged from 2 – 3 µg/L throughout the sampling season (Fig.15). In Lower Arrow, more seasonal variability was observed, where TP ranged from 2 – 5 µg/L, with a decrease in the early summer and increase in late summer (Fig.16). There was not a significant seasonal trend observed for the whole reservoir. The 2009 TP mean was 2.94 µg/L, and in 2010 was slightly lower at 2.79 µg/L (Fig.17). Both years are lower than the pooled mean for Arrow between 1997 and 2008 (3.52 µg/L), although, only 2010 is statistically lower.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 22 Upper Arrow Total Phosphorus 10.0 AR 1
8.0 AR 2
AR 3 6.0
TP (µg/L) TP 4.0
2.0 RDL
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 15. Upper Arrow total phosphorus, stations AR 1-3 April to November, 2009 and 2010. Lower Arrow Total Phosphorus 10.0 AR 6
8.0 AR 7
AR 8 6.0
TP (µg/L) (µg/L) TP 4.0
2.0 RDL
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 16. Lower Arrow total phosphorus, stations AR 6-8 April to November, 2009 and 2010.
Total Phosphorus
10.0
8.0
6.0 (µg/L)
TP 4.0
2.0 RDL
0.0 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 17. Annual average total phosphorus and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 23 Total dissolved phosphorous in 2009 ranged from 2 – 3 µg/L in the Upper basin (Fig.18), and from 2 – 5 µg/L in Lower Arrow (Fig.19). There was a slight decrease in both basins of TDP during the summer (Fig.18 and Fig.19). In 2010, TDP ranged from 2 – 4 µg/L, a slight increase was observed in the late summer in Upper Arrow (Fig.18) and in the late summer and fall in Lower Arrow (Fig.19). In 2009, a seasonal trend was observed, where the spring mean was significantly higher than the summer and fall values. In 2010, the trend was not observed, and there was not a significant difference across seasons. The annual averages for 2009 and 2010 do not differ significantly from each other (2.44 µg/L and 2.38 µg/L; respectively), or with the pooled 1997 – 2008 average (2.65 µg/L) (Fig.20).
Upper Arrow Total Dissolved Phosphorus 10.0 AR 1
8.0 AR 2 AR 3
6.0
4.0 TDP (µg/L) TDP
2.0 RDL
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 18. Upper Arrow total dissolved phosphorus, stations AR 1-3 April to November, 2009 and 2010.
Lower Arrow Total Dissolved Phosphorus 10.0 AR 6
8.0 AR 7
AR 8 6.0
4.0 TDP (µg/L) TDP
2.0 RDL
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 19. Lower Arrow total dissolved phosphorus, stations AR 6-8 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 24 Total Dissolved Phosphorus
6.0
5.0
4.0 (µg/L)
3.0
TDP 2.0 RDL
1.0
0.0 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 20. Annual average total dissolved phosphorus and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
In 2009 and 2010, 27% and 40% (respectively) of orthophosphate (OP) values were reported less than the RDL of 1 µg/L. Orthophosphate ranged from 1 – 2 µg/L in 2009 and from 1 – 3 µg/L in 2010 (Fig.21 and Fig.22). In 2010, the increase in OP in the fall was significantly higher than the spring and summer means (Fig.21 and Fig.22). For both years, there was not a significant difference between the Upper and Lower basin. The annual averages for 2009 and 2010 do not differ significantly from each other (1.21 µg/L and 1.33 µg/L; respectively); however, 2009 differed significantly with the pooled 1997 – 2008 average (1.66 µg/L) (Fig.23).
Upper Arrow Orthophosphate 5.0 AR 1
4.0 AR 2 AR 3
3.0
OP (µg/L) (µg/L) OP 2.0
1.0 RDL
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 21. Upper Arrow orthophosphate, stations AR 1-3 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 25 Lower Arrow Orthophosphate 5.0 AR 6
4.0 AR 7
AR 8 3.0
OP (µg/L) OP 2.0
1.0 RDL
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 22. Lower Arrow orthophosphate, stations AR 1-3 April to November, 2009 and 2010.
Orthophosphate
5.0
4.0
3.0 (µg/L)
OP 2.0
1.0 RDL
0.0 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 23. Annual average orthophosphate, stations AR 1-3 April to November, 2009 and 2010.
Nitrogen In fresh water, complex biochemical processes utilize nitrogen in many forms consisting of dissolved molecular N2, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and organic nitrogen. A major source of nitrogen in lakes is the nitrate in precipitation in their watersheds (Horne and Goldman, 1994). Nitrate is the most abundant form of inorganic nitrogen in lakes (Horne and Goldman, 1994). Total nitrogen is comprised of dissolved inorganic forms (i.e., nitrate, nitrite and ammonia) and particulate nitrogen (mainly organic).
In 2009, total nitrogen (TN) decreased from the spring through the sampling season, with the exception of an increase in August at AR 1 in Upper Arrow (Fig. 24), and in July at AR 6 in Lower Arrow (Fig. 25). The average for Upper Arrow (179 µg/L) was slightly higher than the average observed in Lower Arrow (143 µg/L). In 2010, in Upper Arrow, an increase in TN was observed in the late summer and fall (Fig. 24), in Lower Arrow,
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 26 less seasonal differentiation was observed (Fig. 25). As in the previous year, TN in 2010 in Upper Arrow (174 µg/L) was slightly higher than in Lower Arrow (135 µg/L). Total nitrogen was measured from 2004 onward, and no significant difference is apparent in the 2009 and 2010 TN, or with the pooled 2004 – 2008 mean (Fig. 26).
Upper Arrow Total Nitrogen AR 1
500 AR 2
AR 3 400
300
TN (µg/L) 200
100
0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 24. Upper Arrow total nitrogen, stations AR 1-3 April to November, 2009 and 2010.
Lower Arrow Total Nitrogen 500 AR 6
AR 7 400 AR 8
300
TN (µg/L) 200
100
0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 25. Lower Arrow total nitrogen, stations AR 6-8 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 27 Total Nitrogen
225
200
(µg/L) 175
TN
150
125 4 5 6 7 8 9 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 2 2 2 2 2 2
Figure 26. Annual average total nitrogen and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2010.
Dissolved inorganic nitrogen (DIN), consists of nitrite, nitrate and ammonia. Nitrate and ammonia are the forms of nitrogen most readily available to phytoplankton (Wetzel, 2001). Previous analysis primarily resulted in ammonia at or below the minimum detection limit of 5 µg/L in Arrow Reservoir. Ammonia was not analyzed in 2009 and 2010; therefore the dissolved inorganic nitrogen is represented by the nitrate and nitrite data including an inferred ammonia value of 5 µg/L.
A seasonal trend in 2009 was observed by a significant decrease in DIN in the summer months, then a slight increase in the fall (Fig. 27 and Fig. 28). As well, in 2009, the DIN mean for Lower Arrow (73 µg/L) was significantly lower than the Upper Arrow mean (102 µg/L). Similarly, 2010 followed the same seasonal trend, where the spring DIN mean was significantly higher than the remainder of the sampling season (Fig. 28), amplified by high DIN values observed in May and June at AR1 (Fig. 28). As in 2009; 2010 Lower Arrow exhibited a lower DIN (57 µg/L) than observed in Upper Arrow (98 µg/L). The lowest values in 2009 were reported at 9 µg/L at AR 6 and AR 7 in September, in 2010, the minimum DIN value was recorded at AR 7 in August of 9 µg/L (Fig. 28). Dissolved inorganic nitrogen decreased from 2009 (88 µg/L) to 2010 (73 µg/L), however not significantly (Fig. 29). Although both 2009 and 2010 are significantly lower than the pooled 1997 – 2008 average (122 µg/L). This may be attributed to changes in sampling methodology. From 1997 to 2003, integrated samples were collected from 0- 30 m and from 2004 to 2010 samples were collected from 0-20 m. The 0-30 m samples collected nitrate enriched water as the sample was collected below the thermocline.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 28 Upper Arrow Dissolved Inorganic Nitrogen 300 AR 1
250 AR 2
AR 3 200
150 DIN (µg/L) (µg/L) DIN 100
50
0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 27. Upper Arrow dissolved inorganic nitrogen, stations AR 1-3 April to November, 2009 and 2010.
Lower Arrow Dissolved Inorganic Nitrogen 300
250 AR 6
AR 7 200 AR 8
150 DIN (µg/L) 100
50
0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 28. Lower Arrow dissolved inorganic nitrogen, stations AR 6-8 April to November, 2009 and 2010.
Dissolved Inorganic Nitrogen
150
125
(µg/L)
100 DIN
75
50 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 29. Annual average dissolved inorganic nitrogen and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 29 Silica Silica is an integral structural component in diatomaceous algae and is considered a major factor influencing algal production in many lakes (Wetzel, 2001). Dissolved reactive silica was measured as an indicator of available silica to diatoms.
Silica in both Upper and Lower Arrow, in 2009, was consistently high for the spring months, followed by a decrease in late summer, and a gradual increase in the fall (Fig. 30 and Fig. 31). Silica in 2010 followed the same trend, however more emphasized in Lower Arrow (Fig. 31). A low silica value in 2010 was observed in May in Upper Arrow, which was not consistent with seasonal trends in Arrow (Fig. 30). For both years, there was not a significant difference between means of Upper and Lower basins. In 2009, seasonally, the spring mean (3.9 mg/L) was significantly higher than the summer (2.1 mg/L) and fall (2.3 mg/L) means. Likewise, in 2010, spring mean (3.7 mg/L) was significantly higher than the summer (1.9 mg/L) and fall (2.1 mg/L) means.
Annual observations of silica in Arrow Lakes Reservoir show a decreasing trend from 2005 (Fig. 32). There was not a significant difference in the 2009 and 2010 means (2.8 mg/L and 2.6 mg/L; respectively). However, both years are significantly lower than a pooled average from 1997 – 2008 (3.8 mg/L).
North Arm Dissolved Silica
10.0 AR 1
AR 2 8.0 AR 3
6.0
4.0 Silica (mg/L)Silica
2.0
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 30. Upper Arrow silica, stations AR 1-3 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 30 Lower Arrow Dissolved Silica 10.0 AR 6
AR 7 8.0 AR 8
6.0
4.0 Silica (mg/L)Silica
2.0
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 31. Lower Arrow silica, stations AR 6-8 April to November, 2009 and 2010.
Silica
6.0 5.5 5.0
4.5 (mg/L) 4.0 3.5 Silica 3.0 2.5 2.0 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 32. Annual average silica and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010. pH In 2009 and 2010, pH in Arrow Lakes Reservoir indicated slightly alkaline conditions. In 2009, pH fluctuated around 7.88 pH units from April to November (Fig. 33 and Fig. 34), slightly higher values were observed in the spring months in Upper Arrow (Fig. 33). In 2010, pH was approx. 7.84 pH units, both Upper and Lower Arrow showed consistent values across the sampling period (Fig. 33 and Fig. 34). There was no significant difference between 2009 and 2010 pH values, and were consistent with values observed since 1997, with the exception of 2005 (Fig. 35).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 31 Upper Arrow Total pH 9.0 AR 1
AR 2 8.5 AR 3
8.0 pH (pH units) pH (pH 7.5
7.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 33. Upper Arrow pH, stations AR 1-3 April to November, 2009 and 2010.
Lower Arrow Total pH 9.0
AR 6
AR 7 8.5 AR 8
8.0 pH (pH units) pH (pH 7.5
7.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 34. Lower Arrow pH, stations AR 6-8 April to November, 2009 and 2010.
pH
8.0
7.8
7.6 units)
(pH 7.4 pH
7.2
7.0 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 35. Annual average pH and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 32 Alkalinity Alkalinity is the buffering capacity of lake water (i.e., the sum of the titratable bases) to resist pH changes and involves the inorganic carbon components in most fresh waters (Wetzel, 2001). In 2009, peak alkalinity was observed in the spring (56.3 mg/L), and then decreased in the summer (49.9 mg/L) and fall (50.0 mg/L) (Fig. 36 and Fig. 37). This trend was more prominent in Upper Arrow (Fig. 36), although there was not a statistically significant difference between Upper and Lower means (52.5 and 52.2 mg/L; respectively). Alkalinity in 2010 followed a similar seasonal trend as in 2009 (Fig. 36 and Fig. 37). However the seasonal decreased throughout the sampling period. Spring, summer and fall means were significantly different from one another (56.3, 49.9, 46.3 mg/L; respectively). As in 2009, there was not a significant difference between Upper and Lower Arrow (51.2 and 51.6 mg/L; respectively), although the seasonal trend was more pronounced in Upper Arrow (Fig. 36 and Fig .37).
Alkalinity in 2009 (52.3 mg/L) did not differ significantly from the 2010 mean (51.4 mg/L), a slight increase from 2008, however not a significant difference from the pooled 1997 – 2008 mean (Fig. 38)
Upper Arrow Alkalinity 80
AR 1
70 AR 2
AR 3
60 Alkalinity (mg/L)
50
40 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 36. Upper Arrow alkalinity, stations AR 1-3 April to November, 2009 and 2010. Lower Arrow Alkalinity 80
AR 6
70 AR 7
AR 8
60 Alkalinity (mg/L)Alkalinity
50
40 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 2009 2010 Figure 37. Lower Arrow alkalinity, stations AR 6-8 April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 33 Alkalinity
70
65
60 (mg/L) 55
50 Alkalinity 45
40 8 0 2 4 6 8 0 9 0 0 0 0 0 1 9 0 0 0 0 0 0 1 2 2 2 2 2 2
Figure 38. Annual average alkalinity and 95% confidence intervals from stations AR 1-3 and AR 6-8, 1998 to 2010.
Total Organic Carbon Total organic carbon (TOC) includes both dissolved and particulate organic carbon (Wetzel, 2001). Dissolved carbon dioxide and bicarbonate (both forms of inorganic carbon) are the major sources of inorganic carbon for photosynthesis in freshwater systems. Utilization of inorganic carbon provides the foundation for much of the organic productivity in an ecosystem. In 2009, TOC ranged from the RDL of 0.5 mg/L to 2.9 mg/L, although a high TOC value (5.3 mg/L) was observed at AR 2 in September (Fig. 39 and Fig.40). There was not a seasonal trend, and Upper and Lower Arrow means did not differ significantly (1.3 and 1.4 mg/L; respectively). In 2010, TOC ranged from the RDL to 2.2 mg/L, although in June, a higher TOC value (3.4 mg/L) was observed at station AR 8 (Fig. 39 and Fig .40). Similar to 2009, no seasonal trend was observed, and basin means did not differ significantly (Upper=1.1; Lower=1.3 mg/L).
Total organic carbon in Arrow was measured from 2004 onward, there was a marginal increase in 2009 from 2008, and then a decline to 2010 (Fig. 41). However, the difference between means in 2009 (1.3 mg/L) and 2010 (1.2 mg/L) was not significant, as well both years did not differ significantly from the pooled 2004 – 2008 mean (1.2 mg/L).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 34 Upper Arrow Total Organic Carbon
6.0 AR 1
AR 2 5.0 AR 3 4.0
3.0
TOC (mg/L) TOC 2.0
1.0
0.0 Apr-12 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 Nov-04 Apr-20 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 Nov-09 2009 2010 Figure 39. Upper Arrow total organic carbon, stations AR 1-3 April to November, 2009 and 2010.
Lower Arrow Total Organic Carbon
5.0 AR 6
4.0 AR 7
AR 8
3.0
2.0 TOC (mg/L)TOC
1.0
0.0 Apr-14 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 Nov-03 Apr-19 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 Nov-08 2009 2010 Figure 40. Upper Arrow total organic carbon, stations AR 1-3 April to November, 2009 and 2010.
Total Organic Carbon
2.0
1.5
1.0 (mg/L)
TOC 0.5
0.0 4 5 6 7 8 9 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 2 2 2 2 2 2
Figure 41. Annual average total organic carbon and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 35 Chlorophyll a Chlorophyll a (Chl a) is the primary photosynthetic pigment in algae (Wetzel, 2001). It also indicates a lake’s phytoplankton standing crop. Chl a ranged from 0.1 to 5.6 μg/L in Upper Arrow and from 0.2 to 5.9 μg/L in Lower Arrow in 2009 (Figs. 42 and 43). Results at stations AR 4 and AR 5 ranged from 0.3 to 2.4 μg/L (Fig. 42). The peak results in Upper Arrow occurred in late June at station AR 1 and October at station AR 3. In Lower Arrow, the peak occurred in in August and September and November at station AR 6.
Upper Arrow and Narrows Chlorophyll a
6
5
4 AR1 AR2 3 AR3 2 AR4
Chlorophyll a (µg/L) a Chlorophyll 1 AR5
0 Apr/12 May/12 Jun/14 Jun/28 Jul/12 Aug/09 Sep/08 Oct/06 Nov/04 2009
Figure 42. Upper Arrow and narrows chlorophyll a, stations AR 1-5 April to November, 2009. Lower Arrow Chlorophyll a
6
5
4 AR6 3 AR7
2 AR8
Chlorophyll a (µg/L) a Chlorophyll 1
0 Apr/14 May/11 Jun/16 Jun/28 Jul/14 Aug/11 Sep/07 Oct/05 Nov/03 2009
Figure 43. Lower Arrow chlorophyll a, stations AR 6-8 April to November, 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 36 Total Organic Carbon
2.0
1.5
1.0 (mg/L)
TOC 0.5
0.0 4 5 6 7 8 9 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 2 2 2 2 2 2
Figure 44. Annual average chlorophyll a and 95% confidence intervals from stations AR 1-3 and AR 6-8, 2004 to 2009.
Discrete Samples
TDP In 2009, for both the Upper (AR 2) and Lower basin (AR 7), total dissolved phosphorus (TDP) ranged from the RDL (2 µg/L) to 3 µg/L in June and July (Fig. 45). TDP for the lower depths (15-20 m) was reported at or below the RDL (2 µg/L) (Fig. 45). In 2010, TDP values at AR 2 ranged from 2 – 3 µg/L, however only August and September results were reported at 3 µg/L (Fig. 46). June values of TDP at Lower Arrow were reported at or below the RDL, however, for August and September, TDP ranged from 2 – 3 µg/L (Fig. 46). In July at AR 7, TDP was higher than samples from the rest of the season and ranged from 5 – 6 µg/L (Fig. 46).
AR 2 TDP (µg/L) AR 7 TDP (µg/L) 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 0
5 5
10 10 (m) (m)
Depth 15 Depth 15 14‐Jun 16‐Jun
12‐Jul 14‐Jul 20 20 09‐Aug 11‐Aug
08‐Sep 07‐Sep 25 RDL 25 RDL Figure 45. Discrete total dissolved phosphorus concentrations, stations AR 2 and AR 7. June – September 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 37 AR 2 TDP (µg/L) AR 7 TDP (µg/L) 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 0
5 5
10 10 (m)
Depth 15 15 14‐Jun (m) Depth 16‐Jun 12‐Jul 14‐Jul 20 20 10‐Aug 09‐Aug
25 07‐Sep 25 08‐Sep RDL RDL Figure 46. Discrete total dissolved phosphorus concentrations, stations AR 2 and AR 7. June – September 2010. DIN In 2009, dissolved inorganic nitrogen (DIN) ranged from 9 – 162 µg/L. As well, DIN increased down through the epilimnion. Higher results were observed in June for Upper and Lower Arrow (Fig.47). In 2010, DIN ranged from 9 – 155 µg/L in Upper Arrow at station AR 2, however DIN in Lower Arrow (AR7) did not exceed 90 µg/L (Fig.48). For both Upper and Lower Arrow, DIN peaked in the June samples (Fig.48). The results indicate N:P ratios need to be closely monitored especially in Lower Arrow.
AR 2 DIN (µg/L) AR 7 DIN (µg/L) 0 50 100 150 200 0 50 100 150 200 0 0
5 5
10 10 (m) (m)
Depth 15 Depth 15 14‐Jun 16‐Jun
12‐Jul 14‐Jul 20 20 09‐Aug 11‐Aug
08‐Sep 07‐Sep 25 DL 25 Figure 47. Discrete dissolved inorganic nitrogen concentrations, stations AR 2 and AR 7. June – September 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 38 AR 2 DIN (µg/L) AR 7 DIN (µg/L) 0 50 100 150 200 0 50 100 150 200 0 0
5 5
10 10 (m) (m)
Depth 15 Depth 15 14‐Jun 16‐Jun 12‐Jul 14‐Jul 20 20 10‐Aug 09‐Aug 07‐Sep 08‐Sep 25 25 Figure 48. Discrete dissolved inorganic nitrogen concentrations, stations AR 2 and AR 7. June – September 2010.
N:P The ratio of DIN to TDP is the N:P ratio, and is a measurement of limitations of productivity in a lake. A N:P ratio < 14 (weight:weight) is indicative of nitrogen limitation, and a ratio >14 is indicative of a phosphorus limitation (Koerselman and Meuleman, 1996).
In 2009, N:P generally increased with depth in the epilimnion. Upper Arrow showed more variation and a greater range of 3 – 80.5 (Fig. 49). In Lower Arrow, the N:P ratio was less than in Upper Arrow and did not exceed 51 (Fig. 49). For both stations, the ratio was highest in June, corresponding to high DIN values (Fig. 47). Similar to 2009, 2010, N:P increased down through the epilimnion, Upper Arrow was more variable and ranged from 3 – 77.5; peaking in June (Figs. 49 and 50). Lower Arrow did not exceed 45, and was nitrogen limited with the exception of the 20m sample in August and all June samples (Figs. 49 and 50).
AR 2 N:P AR 7 N:P 0 20 40 60 80 100 0 20 40 60 80 100 0 0
5 5
10 10 (m) (m)
Depth 15 Depth 15 14‐Jun 16‐Jun
12‐Jul 14‐Jul 20 20 09‐Aug 11‐Aug
08‐Sep 07‐Sep 25 25 Figure 49. Discrete nitrogen:phosphorus (dissolved fractions, weight:weight) ratios, stations AR 2 and AR 7. June – September 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 39 AR 2 N:P AR 7 N:P 0 20 40 60 80 100 0 20 40 60 80 100 0 0
5 5
10 10 (m) (m)
Depth 15 Depth 15 14‐Jun 16‐Jun 12‐Jul 14‐Jul 20 20 10‐Aug 09‐Aug 07‐Sep 08‐Sep 25 25 Figure 50. Discrete nitrogen:phosphorus (dissolved fractions, weight:weight) ratios, stations AR 2 and AR 7. June – September 2010.
Chlorophyll a Chlorophyll a results ranged between 0.3 and 3.5 µg/L in Upper Arrow and 0.4 and 2.6 µg/L in Lower Arrow (Figs. 51 and 52). Peak biomass occurred in August in both basins. The average over the depths and months was 1.0 µg/L in Upper Arrow and 0.8 µg/L in Lower Arrow. Discrete phytoplankton taxonomy samples were not collected in 2009, therefore comparisons cannot be made between chlorophyll a and phytoplankton.
AR 2 Chlorophyll a (µg/L) 012345 0
5 14-Jun-09
12-Jul-09 10 09-Aug-09
Depth (m) 15 08-Sep-09
20
25
Figure 51. Discrete chlorophyll a concentrations, station AR 2. June – September 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 40 AR 7 Chlorophyll a (µg/L) 012345 0
5
16-Jun-09 10 14-Jul-09 11-Aug-09 15 07-Sep-09 Depth (m)
20
25
Figure 52. Discrete chlorophyll a concentrations, station AR 7, June – September 2009.
Hypolimnion samples
Turbidity Hypolimnetic turbidity results in 2009, ranged in from 0.2 – 0.9 NTU in the Upper and Lower basins of Arrow Lakes Reservoir (Figs.53 and 54). In Upper Arrow, turbidity peaked in July at station AR 1 (0.9 NTU) (Fig. 53) and in Lower Arrow, peak turbidity was observed in May at station AR 8 (0.8 NTU) (Fig. 54). In 2010, turbidity ranged from 0.1 – 0.4 NTU in Upper Arrow (Fig. 53) and 0.1 – 0.5 NTU in Lower Arrow (Fig. 54). For both years, there was not a seasonal expression in the hypolimnion layer.
Upper Arrow Hypolimnetic Turbidity 2.0
AR 1 1.5 AR 2
AR 3 1.0 Turbidity (NTU) Turbidity 0.5
0.0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 53. Upper Arrow turbidity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 41 Lower Arrow Hypolimnetic Turbidity 2.0
AR 6
1.5 AR 7
AR 8
1.0 Turbidity (NTU) Turbidity 0.5
0.0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 54. Lower Arrow turbidity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Conductivity In 2009, hypolimnetic conductivity in Upper Arrow ranged from 143 – 153 (µS/cm) (Fig. 55), however decreased in Lower Arrow and ranged from 129 – 132 (µS/cm) (Fig. 56). The decrease was observed in 2010 as well, where Upper Arrow ranged from 143 – 148 (µS/cm) (Fig. 55) and Lower Arrow 131 – 133 (µS/cm) (Fig. 56).
Upper Arrow Hypolimnetic Conductivity 160
150
140 AR 1
AR 2
Conductivity (uS/cm) (uS/cm) Conductivity 130 AR 3
120 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 55. Upper Arrow conductivity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 42 Lower Arrow Hypolimnetic Conductivity 160 AR 6
AR 7 150 AR 8
140
Conductivity (uS/cm) (uS/cm) Conductivity 130
120 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 56. Lower Arrow conductivity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Phosphorus Total Phosphorus (TP) in 2009 ranged from 2 µg/L (RDL) to 6 µg/L in Upper Arrow, although a high TP value (9 µg/L) was reported in October at station AR 1 (Fig. 57). In the Lower basin TP ranged from 2 – 6 µg/L (Fig. 58). In Upper Arrow, a decrease in TP was observed in August (Fig. 57), however this trend was not observed in Lower Arrow (Fig. 58). In 2010, TP ranged from the RDL (2 µg/L) to 5 µg/L, minimum values were reported in July (Figs.57 and 58).
Upper Arrow Hypolimnetic Total Phosphorus 10.0 AR 1
8.0 AR 2
AR 3 6.0
TP (µg/L) TP 4.0
2.0 RDL
0.0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 57. Upper Arrow total phosphorus in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 43 Lower Arrow Hypolimnetic Total Phosphorus 10.0 AR 6
8.0 AR 7
AR 8 6.0
TP (µg/L) TP 4.0
2.0 RDL
0.0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 58. Lower Arrow total phosphorus in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
In 2009, total dissolved phosphorus (TDP) ranged from the RDL of 2 µg/L to 4 µg/L (Figs. 59 and 60), although a high value of 8 µg/L was observed in October at AR 1 (Fig. 59). There was not a seasonal trend observed for either basin in 2009. In 2010, TDP ranged from 2 – 4 µg/L, and the higher values were observed in August – October for both Upper and Lower Arrow (Figs. 59 and 60).
Upper Arrow Hypolimnetic Total Dissolved Phosphorus 10.0 AR 1
8.0 AR 2
AR 3 6.0
4.0 TDP (µg/L) TDP
2.0 RDL
0.0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 59. Upper Arrow total dissolved phosphorus in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 44 Lower Arrow Hypolimnetic Total Dissolved Phosphorus 10.0 AR 6
8.0 AR 7
AR 8 6.0
4.0 TDP (µg/L) TDP
2.0 RDL
0.0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 60. Lower Arrow total dissolved phosphorus in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
In 2009, orthophosphate (OP) ranged from the RDL of 1 µg/L to 2 µg/L, aside from values at or below the RDL in Upper Arrow from June – August, there was no obvious seasonal trend (Figs. 61 and 62). In 2010, in Upper Arrow, OP was 1 µg/L until September, where OP increased to 3 µg/L for AR 1 and AR 2 (Fig. 61). In Lower Arrow, aside from AR 6 at 2 µg/L in May, all values were at or below the RDL for the remainder of the sampling season (Fig. 62).
Upper Arrow Hypolimnetic Orthophosphate 5.0 AR 1
4.0 AR 2
AR 3 3.0
OP (µg/L) OP 2.0
1.0 RDL
0.0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 61. Upper Arrow orthophosphate in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 45 Lower Arrow Hypolimnetic Orthophosphate 5.0 AR 6
4.0 AR 7
AR 8 3.0
OP (µg/L) OP 2.0
1.0 RDL
0.0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 62. Lower Arrow orthophosphate in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Nitrogen Hypolimnetic total nitrogen (TN) in 2009 ranged from 170 – 300 µg/L; in Upper Arrow, results showed more variability (Fig. 63), where as in Lower Arrow, TN was consistent around 204 µg/L for AR 6 – 8 (Fig. 64). Neither Upper nor Lower Arrow showed any seasonal trends (Figs. 63 and 64). In 2010, a greater range was observed in both Upper and Lower Arrow. Total nitrogen in Upper Arrow ranged from 110 – 470 µg/L, peaking in September in AR1 and AR 3 (Fig. 63). In Lower Arrow, TN was slightly less variable, and ranged from 130 – 360 µg/L; peaking in June at AR 6 (Fig. 64). As in 2009, hypolimnetic nitrogen showed no obvious seasonal trends (Figs. 63 and 64).
Upper Arrow Hypolimnetic Total Nitrogen 600 AR 1
500 AR 2
AR 3 400
300 TN (µg/L) 200
100
0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 63. Upper Arrow total nitrogen in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 46 Lower Arrow Hypolimnetic Total Nitrogen 600 AR 6
500 AR 7
AR 8 400
300 TN (µg/L) 200
100
0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 64. Lower Arrow total nitrogen in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
In 2009, dissolved inorganic nitrogen (DIN) ranged from 136 – 198 µg/L in the Upper basin (Fig. 65) and 134 – 185 µg/L in the Lower basin (Fig. 66). In 2010, DIN ranged from 130 – 183 µg/L in the Upper basin (Fig. 65), and 136 – 181 µg/L in the Lower (Fig. 66). For 2009 and 2010, Upper Arrow showed a greater variability through the sampling season than Lower Arrow, as well, there was no significant seasonal trend observed (Figs. 65 and 66).
Upper Arrow Hypolimnetic Dissolved Inorganic Nitrogen 300 AR 1
250 AR 2
AR 3 200
150 DIN (µg/L) 100
50
0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 65. Upper Arrow dissolved inorganic nitrogen in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 47 Lower Arrow Hypolimnetic Dissolved Inorganic Nitrogen 300 AR 6
250 AR 7
AR 8 200
150 DIN (µg/L) 100
50
0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 66. Lower Arrow dissolved inorganic nitrogen in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Silica Silica in 2009 ranged from 3.6 – 4.4 mg/L in Upper Arrow (Fig. 67), and similarly, in Lower Arrow ranged from 3.7 – 4.3 mg/L (Fig. 68). These values were consistent throughout the sampling season (Figs. 67 and 68). In 2010, in Upper Arrow, silica ranged from 2.1 – 4.1 mg/L, where lower values were reported for AR 1 in May and July (Fig. 67). In the Lower basin, silica ranged from 3.6 – 4.4 mg/L, a trend of increasing values was observed in June for all stations (Fig. 68). Otherwise in 2010, there was not a seasonal trend of hypolimnetic silica in Arrow.
Upper Arrow Hypolimnetic Silica 6.0
5.0
4.0
3.0 AR 1 2.0 Silica (mg/L) AR 2
1.0 AR 3
0.0 May-12 Jun-14 Jul-12 Aug-09 Sep-08 Oct-06 May-18 Jun-14 Jul-12 Aug-10 Sep-07 Oct-12 2009 2010 Figure 67. Upper Arrow silica in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 48 Lower Arrow Hypolimnetic Silica 6.0
5.0
4.0
3.0 AR 6
2.0
Silica (mg/L) AR 7
AR 8 1.0
0.0 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 68. Lower Arrow silica in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Alkalinity Alkalinity in 2009 in Upper Arrow ranged from 59 – 63 mg/L (Fig.69). In Lower Arrow, alkalinity was slightly lower and ranged from 54 – 58 mg/L (Fig.70). In 2010, alkalinity in Upper Arrow ranged from 59 – 65 mg/L, with the exception of a low value (55 mg/L) in June at station AR 2 (Fig.69). As well in 2010, Lower Arrow alkalinity was consistent during the sampling season, and aside from AR 8 in September (51 mg/L), results fluctuated minimally (54 - 58 mg/L) (Fig.70).
Upper Arrow Hypolimnetic Alkalinity
80
75 AR 1
AR 2 70 AR 3
65 Alkalinity (mg/L) Alkalinity
60
55
50 May/12 Jun/14 Jul/12 Aug/09 Sep/08 Oct/06 May/18 Jun/14 Jul/12 Aug/10 Sep/07 Oct/12 2009 2010 Figure 69. Upper Arrow alkalinity in discrete hypolimnetic samples, AR 1-3, May – October, 2009 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 49 Lower Arrow Hypolimnetic Alkalinity
80
75
AR 6 70 AR 7 65 AR 8 Alkalinity (mg/L)
60
55
50 May-11 Jun-16 Jul-14 Aug-11 Sep-07 Oct-05 May-17 Jun-16 Jul-14 Aug-09 Sep-08 Oct-04 2009 2010 Figure 70. Lower Arrow alkalinity in discrete hypolimnetic samples, AR 6-8, May – October, 2009 – 2010.
Phytoplankton
Abundance In Upper Arrow, peak abundance occurred in late June at station AR 1 in 2009 and 2010. At station AR2, peak abundance occurred in July in 2009 and August in 2010. At stations AR3, abundance was low in April and May and then remained fairly consistent (between 4,000 and 6,000 cells/ml) from June to October with a decrease in November. In 2010, peak abundance occurred in August at station AR 3 (Fig. 71). Chryso/cryptophytes (edible size of phytoplankton for zooplankton) were the main contributor to overall abundance to early June. Bacillariophytes were the main contributor to overall abundance from late June to October. In November, both groups had similar contributions to overall abundance. In 2009, at station AR 1, Asterionella formosa contributed 78% to the overall bacillariophyte abundance and 48% to overall abundance. Asterionella formosa is a large celled diatom not considered edible for zooplankton. In 2010, Synedra nana and Synedra acus were the main contributors (inedible phytoplankton for zooplankton) towards the overall abundance at station AR 3.
In 2009 at station AR 5 (narrows), abundance was low in April and May, increased in early June, remained fairly constant to September, with a decrease and a slight increase again in October and a decrease in November. In 2010, abundance remained fairly consistent from April to the end of June with an increase in July, slight decrease in August through October and then another decrease in November (Fig. 72).
In 2009 in Lower Arrow (stations AR 6-8), abundance was low in April and May, with a gradual increase to August, with a decreasing trend September through November. In 2010, abundance was fairly uniform from April through late June, with the peak occurring in July and a decrease in August, an increase in September and October and then a decrease in November (Fig. 72).
From April to late June in 2009, chryso/cryptophytes contributed to approximately half of the overall abundance with a shift to mostly bacillariophytes in July through September. In October and November, phytoplankton composition showed a trend similar to the
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 50 spring results. The 2010 results were similar to 2009 except bacillariophytes contributed to the majority of the abundance through November.
The main contributor to bacillariophytes in 2009 and 2010 during the peak abundance months was Synedra nana and Synedra acus (both inedible phytoplankton for zooplankton).
Biovolume Biovolume trends in 2009 and 2010 were similar to the abundance trend (Figs. 73 and 74). The plots in the abundance figures illustrate a higher contribution of cyanophytes to the overall abundance than they contribute to overall biovolume. This is due to the phytoplankton being Syneococchus sp., a small celled cyanophyte. Dinophytes contributed more to overall biovolume than to abundance due to the species being a slightly larger size. Dinophytes are considered edible for zooplankton.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 51 AR 1 Phytoplankton Composition AR 1 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 14000 14000
12000 12000
10000 10000
8000 8000
6000 6000
4000 4000 Abundance (cells/ml) Abundance 2000 (cells/ml) Abundance 2000
0 0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 2 Phytoplankton Composition AR 2 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 2000 Abundance (cells/ml) Abundance Abundance (cells/ml) Abundance 0 0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 3 Phytoplankton Composition AR 3 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 14000 14000
12000 12000
10000 10000
8000 8000
6000 6000
4000 4000 Abundance (cells/ml) Abundance 2000 (cells/ml) Abundance 2000
0 0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 4 Phytoplankton Composition AR 4 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 2000 Abundance (cells/ml) Abundance Abundance (cells/ml) Abundance
0 0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010 Figure 71. Phytoplankton abundance by group in integrated 0-20 m samples, AR 1- 4, April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 52
AR 5 Phytoplankton Composition AR 5 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 2000 Abundance (cells/ml) Abundance Abundance (cells/ml) Abundance
0 0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 6 Phytoplankton Composition AR 6 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 2000 Abundance (cells/ml) Abundance Abundance (cells/ml) Abundance
0 0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010
AR 7 Phytoplankton Composition AR 7 Phytoplankton Composition chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 Abundance (cells/ml) Abundance 2000 Abundance (cells/ml)Abundance
0 0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010
AR 8 Phytoplankton Composition AR 8 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 10000 10000
8000 8000
6000 6000
4000 4000
2000 2000 Abundance (cells/ml) Abundance Abundance (cells/ml) Abundance
0 0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010 Figure 72. Phytoplankton abundance by group in integrated 0-20 m samples, AR 5- 8, April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 53 AR 1 Phytoplankton Composition AR 1 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.6 1.6 1.4 1.4 1.2 1.2 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 Biovolume (mm3/L) Biovolume (mm3/L) Biovolume 0.2 0.2 0.0 0.0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 2 Phytoplankton Composition AR 2 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) 0.2 (mm3/L) Biovolume 0.2
0.0 0.0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9
Date - 2009 Date - 2010
AR 3 Phytoplankton Composition AR 3 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.6 1.6 1.4 1.4 1.2 1.2 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 Biovolume (mm3/L) Biovolume Biovolume (mm3/L) 0.2 0.2 0.0 0.0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010
AR 4 Phytoplankton Composition AR 4 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) 0.2 Biovolume (mm3/L) 0.2
0.0 0.0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9 Date - 2009 Date - 2010 Figure 73. Phytoplankton biovolume (mm3/L) by group in integrated 0-20 m samples, AR 1- 4, April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 54 AR 5 Phytoplankton Composition AR 5 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) 0.2 Biovolume (mm3/L) 0.2
0.0 0.0 Apr 12 May 12 Jun 14 Jun 28 Jul 12 Aug 9 Sep 8 Oct 6 Nov 4 Apr 20 May 18 Jun 14 Jun 23 Jul 12 Aug 10 Sep 7 Oct 12 Nov 9
Date - 2009 Date - 2010
AR 6 Phytoplankton Composition AR 6 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) Biovolume 0.2 (mm3/L) Biovolume 0.2
0.0 0.0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010
AR 7 Phytoplankton Composition AR 7 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) Biovolume Biovolume (mm3/L) 0.2 0.2
0.0 0.0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010
AR 8 Phytoplankton Composition AR 8 Phytoplankton Composition
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes 1.4 1.4
1.2 1.2
1.0 1.0
0.8 0.8
0.6 0.6
0.4 0.4 Biovolume (mm3/L) 0.2 Biovolume (mm3/L) 0.2
0.0 0.0 Apr 14 May 11 Jun 16 Jun 28 Jul 14 Aug 11 Sep 7 Oct 5 Nov 3 Apr 19 May 17 Jun 16 Jun 24 Jul 14 Aug 9 Sep 8 Oct 4 Nov 8 Date - 2009 Date - 2010 Figure 74. Phytoplankton biovolume (mm3/L) by group in integrated 0-20 m samples, AR 5 - 8, April to November, 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 55 Comparisons amongst stations The strategy of applying nutrients is to ensure favourable growing conditions for phytoplankton and zooplankton. Inedible phytoplankton are unfavourable for zooplankton and inedible diatoms, especially the Asternionella, Fragilaria and some Synedra sp. have tended to be the main genus contributing to the inedible portion. From the phytoplankton dataset, the inedible diatoms were separated for abundance and biovolume by station. Each dot for each station represents one month (April to November). The 2009 results indicate there is a decreasing trend of inedible diatoms from stations AR 1 to AR 8. Results from station AR 8 indicated that the peak abundance was slightly above the mean (horizontal line at 1600 cells/ml) (Fig. 75). The results from 2010 show a similar trend with less variation amongst stations (except for one data point at station AR 3) (Fig. 76). Inedible diatom biovolume demonstrates a similar trend.
Figure 75. Output of one-way analysis (JMP program) of inedible diatom (bacillariophyte) abundance, stations AR 1 – 8 April to November, 2009.
Figure 76. Output of one-way analysis (JMP program) of inedible diatom (bacillariophyte) abundance, stations AR 1 – 8 April to November, 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 56 Comparisons amongst years
Upper Arrow Average phytoplankton abundance in Upper Arrow 2009 was slightly higher than the average from 1997 to 2008 (Fig. 77). In 2010, the average abundance was similar to the 1997 to 2008 average. The average phytoplankton biovolume was slightly higher in 2009 and 2010 compared to the 1997 to 2008 average. The average abundance and biovolume from 1997 to 2008 were 4959 cells/ml and 0.51 mm3/L respectively.
8000 Upper Arrow average May to October 1.00 0.90 7000 0.80 6000 0.70 5000 0.60
4000 0.50
0.40 3000 0.30
2000 (mm3/L) Biovolume Abundance (cells/ml) Abundance 0.20 1000 0.10
0 0.00 1997 1999 2001 2003 2005 2007 2009 Year
Figure 77. Average phytoplankton abundance and biovolume in Upper Arrow, stations AR 1 -3, May to October, 1997 to 2010.
When comparing the abundance average of the phytoplankton groups from 1998 to 2008 compared to the 2009 and 2010 results, bacillariophytes were higher than the pooled average while the chryso/cryptophytes and cyanophytes were lower than the 1998 to 2008 pooled average (Fig. 78). Cyanophytes were higher in the earlier years due to greater contriubtions of Syneococchus, a smaller size of phytoplankton. When comparing the biovolume averages, bacillariophytes in 2009 and 2010 were slightly higher than the 1998 to 2008 average while the chrsyo/cryptophyte averages were similar. The cyanophyte average was similar in 2009, while in 2010 the average was slightly higher compared to the 1998 to 2008 average (Fig. 79).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 57 Upper Arrow
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
6000
5000
4000
3000
2000
Abundance (cells/ml) Abundance 1000
0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
Figure 78. Average phytoplankton abundance by group in Upper Arrow, April to October/November, 1998 to 2010.
Upper Arrow
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
0.90 0.80 0.70 0.60 0.50 0.40 0.30
Biovolume (mm3/L) 0.20 0.10 0.00 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
Figure 79. Average phytoplankton biovolume by group in Upper Arrow, April to October/November, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 58 Narrows Average phytoplankton abundance and biovolume in the Narrows (stations AR 4 and 5) in 2009 and 2010 was less than the pooled average from 1997 to 2008 (Fig. 80). The average abundance and biovolume from 1997 to 2008 were 5276 cells/ml and 0.60 mm3/L respectively.
8000 Narrows average May to October 1.00 0.90 7000 0.80 6000 0.70 5000 0.60
4000 0.50
0.40 3000 0.30
2000 (mm3/L) Biovolume Abundance (cells/ml) Abundance 0.20 1000 0.10
0 0.00 1997 1999 2001 2003 2005 2007 2009 Year
Figure 80. Average phytoplankton abundance and biovolume in the Narrows, stations AR 4 - 5, May to October, 1997 to 2010.
When comparing the abundance averages of phytoplankton groups from 1998 to 2008 compared to the 2009 and 2010 results, bacillariophytes were higher while the chryso/cryptophytes and cyanophytes were lower than the 1998 to 2008 average (Fig. 81). Cyanophytes were higher in the earlier years due to greater contributions of Syneococchus, a smaller size of phytoplankton. When comparing the biovolume averages, bacillariophytes in 2009 and 2010 were slightly lower than the 1998 to 2008 average while the chrsyo/cryptophyte averages were lower. The cyanophyte average was similar in 2009 and 2010 compared to the 1998 to 2008 average (Fig. 82).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 59 Narrows
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
6000
5000
4000
3000
2000 Abundance (cells/ml) Abundance 1000
0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
Figure 81. Average phytoplankton abundance by group in the Narrows, April to October/November, 1998 to 2010.
Narrows
chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
0.90 0.80 0.70 0.60 0.50 0.40 0.30
Biovolume (mm3/L) 0.20 0.10 0.00 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
Figure 82. Average phytoplankton biovolume by group in the Narrows, April to October/November, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 60 Lower Arrow Average phytoplankton abundance and biovolume in Lower Arrow (stations AR 6-8) in 2009 and 2010 was less than the pooled average from 1997 to 2008 (Fig. 83). The average abundance and biovolume from 1997 to 2008 were 4334 cells/ml and 0.48 mm3/L respectively.
8000 Lower Arrow average May to October 1.0000 0.9000 7000 0.8000 6000 0.7000 5000 0.6000
4000 0.5000
0.4000 3000 0.3000
2000 Biovolume (mm3/L) Abundance (cells/ml) Abundance 0.2000 1000 0.1000
0 0.0000 1997 1999 2001 2003 2005 2007 2009 Year
Figure 83. Average phytoplankton abundance and biovolume in the Narrows, stations AR 6 - 8, May to October, 1997 to 2010.
When comparing the abundance averages of phytoplankton groups from 1998 to 2008 compared to the 2009 and 2010 results, bacillariophytes were lower in 2009 and higher in 2010. The average chryso/cryptophytes and cyanophytes inn both years were lower than the 1998 to 2008 average (Fig. 84). Cyanophytes in the earlier years were higher due to greater contributions of Syneococchus, a smaller size of phytoplankton. When comparing the biovolume averages, bacillariophytes in 2009 and 2010 were slightly lower than the 1998 to 2008 average while the chrsyo/cryptophyte averages were lower. The cyanophyte average was similar in 2009 and higher in 2010 compared to the 1998 to 2008 average (Fig. 85).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 61 Lower Arrow chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
6000
5000
4000
3000
2000
Abundance (cells/ml) Abundance 1000
0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 84. Average phytoplankton abundance by group in Lower Arrow, April to October/November, 1998 to 2010.
Lower Arrow chryso-cryptophytes dinophytes chlorophytes bacillariophytes cyanophytes
0.90 0.80 0.70 0.60 0.50 0.40 0.30 Biovolume (mm3/L)Biovolume 0.20 0.10 0.00 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 85. Average phytoplankton biovolume by group in Lower Arrow, April to October/November, 1998 to 2010.
Comparisons of select species of inedible diatoms The trend of biovolume of four species of inedible diatoms, Asterionella formosa, Fragilaria crotonensis and Synedra acus, nana and ulna were plotted by month (June to
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 62 November) within each year by station over the 1998 to 2010 period. The trend of stations AR 1, (Upper Arrow), AR 5 (the narrows) and AR 8 (Lower Arrow) are illustrated in Figure 86. Higher biovolume occurred at station AR 1 in 2003, 2005, 2009 and 2010. At station AR 5, the higher biovolumes occurred in 2001, 2003, 2005 and 2007. At station AR 8, the higher biovolumes occurred in 2001 and 2003. This trend amongst stations indicates the spatial variability that can occur within one year and also within the time series. Since these species are inedible to zooplankton, it allows further understanding of efficiency of phytoplankton to zooplankton.
AR 1
1.60 Asterionella formosa Fragilaria crotonensis Synedra sp. 1.40
1.20
1.00
0.80
0.60
0.40 Biovolume (mm3/L) Biovolume 0.20
0.00 Jul 98 Jul 99 Jul 00 Jul 01 Jul 02 Jul 03 Jul 04 Jul 05 Jul 06 Jul 07 Jul 08 Jul 09 Jul 10 Jul Jan 98 Jan 99 Jan 00 Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06 Jan 07 Jan 08 Jan 09 Jan 10 Jan Date
AR 5
1.60 Asterionella formosa Fragilaria crotonensis Synedra sp. 1.40
1.20
1.00
0.80
0.60
0.40 Biovolume (mm3/L) 0.20
0.00 Jul 98 Jul 99 Jul 00 Jul 01 Jul 02 Jul 03 Jul 04 Jul 05 Jul 06 Jul 07 Jul 08 Jul 09 Jul 10 Jan 98 Jan 99 Jan 00 Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06 Jan 07 Jan 08 Jan 09 Jan 10 Date
AR 8 1.60 Asterionella formosa Fragilaria crotonensis Synedra sp. 1.40
1.20
1.00
0.80
0.60
0.40 Biovolume (mm3/L) 0.20
0.00 Jul 98 Jul 99 Jul 00 Jul 01 Jul 02 Jul 03 Jul 04 Jul 05 Jul 06 Jul 07 Jul 08 Jul 09 Jul 10 Jul Jan 98 Jan 99 Jan 00 Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06 Jan 07 Jan 08 Jan 09 Jan 10 Date
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 63 Figure 86. The trend of Asterionella formosa, Fragilaria crotonensis and Synedra acus, nana and ulna, stations AR 1, AR 5 and AR 8, June to November, 1998 to 2010. Comparisons of edible and inedible phytoplankton amongst select months The total biovolume of phytoplankton populations were also separated out by edible and inedible components by station and select months over the years (June through October). The early June results indicate the long term average of the edible biovolume is higher than the inedible biovolume. The early June results demonstrate that there is variation when comparing one year to the next (Fig.87). A one way ANOVA and students paired t- test was conducted using JMP (SAS software – version 10). Each point within each year represents one station. During some years, there is greater variation amongst stations than others. Nutrient loading from fertilizer to Upper Arrow was similar from one year to the next (1999 to 2010). The plot also shows there is a higher contribution of edible than inedible phytoplankton during this time.
Figure 87. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 – 8, early June, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 64
In late June, there is a higher contribution of edible than inedible phytoplankton over the time series (the horizontal line in each graph illustrates the mean biovolume) (Fig. 88). During 2003 to 2005 and 2007 to 2008, there is a slightly higher proportion of inedible phytoplankton to edible.
Figure 88. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, late June, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 65 In early July, the long term average of inedible phytoplankton is higher than the long term average of edible phytoplankton (Fig. 89). The inedible portion of phytoplankton steadily increased from 1999 to 2003 even though the nutrient loading was similar during from mid- June to early July (weekly rates of phosphorus added was 15 mg/m2. During 2004 through 2010, the weekly phosphorus inputs from fertilizer varied from 0.0 to 15 mg/m2. The years where the inedible phytoplankton biovolume was higher for all stations than the long term average occurred in 2003, 2004 and 2007 with 2007 being the highest. The phosphorus inputs during this year varied from 5.2 to 11.7 mg/m2. This demonstrates the requirement of ensuring an adaptive management strategy needs to occur with this program. Each point on the graph within one year represents one station. The spatial variation amongst stations also varies from one year to the next. The greatest spatial variation occurred in 2001, 2004, 2005 and 2007 amongst the edible portion. The greatest spatial variation for inedible phytoplankton occurred in 2002 and 2007.
Figure 89. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, July, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 66 In August, the long term average of inedible phytoplankton is higher than the long term average of edible phytoplankton (Fig. 90). Highest edible phytoplankton biovolume occurred in 2004 and 2008. The highest inedible phytoplankton biovolume occurred in 2001, 2003 and 2004.
Figure 90. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, August, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 67 In September, the long term average of edible phytoplankton is less than the long term average of inedible phytoplankton (Fig. 91). There is more variation amongst years than the trend in August (Fig. 90). The lowest edible biovolume occurred in 2008 (statistically significant from the long term mean) while the highest biovolumes occurred in 2000, 2001, 2003 and 2007. The highest inedible biovolume occurred in 2001, 2005 and 2010.
Figure 91. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, September, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 68 In October, the long term average of edible and inedible phytoplankton was similar (Fig. 92). The highest edible biovolume occurred in 1999, 2000, 2001 and 2009. The highest inedible biovolume occurred in 2005 and 2010. In 2005, nutrients were added until the third week of September, the latest time of the year compared to others. In 2010, nutrients were added until the first week of September, the same strategy applied during other years.
Figure 92. One way ANOVA and paired students t-test for edible and inedible phytoplankton, stations AR 1 -8, October, 1998 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 69 Zooplankton Species Present Twenty species of macrozooplankton were identified in the samples over the course of the study, with copepods such as Diaptomus ashlandi, Epishura nevadensis, Diacyclops bicuspidatus thomasi,and Leptodiaptomus ashlandi (Marsh), and the cladocerans Daphnia galeata mendotae and Bosmina longirostris being the most numerous. Four calanoid copepod species, Epischura nevadensis (Lillj.), Leptodiaptomus ashlandi (Marsh), Leptodiaptomus pribilofensis (Juday and Muttkowski) and Leptodiaptomus sicilisi (Forbes), were identified in samples from Arrow Lakes Reservoir. Only one cyclopoid copepod species, Diacyclops bicuspidatus thomasi (Forbes), was identified during the same time period.
In Upper Arrow, the average zooplankton density in 2009 was dominated by copepods - 77% copepods, 8% Daphnia spp., and 14% cladocerans other than Daphnia sp (Fig. 93). Numerically, the results were as follows: copepods – 10.0 individuals/L, Daphnia sp. 1.0 individuals/L, cladocerans other than Daphnia spp. 1.9 individuals/L (Fig. 94). In Lower Arrow, the composition was slightly different with 83% copepods (19 individuals/L), 9 % Daphnia sp. (2 individuals/L) and 7% cladocerans other than Daphnia sp. (1.7 individuals/L).
The 2010 results in Upper had percentage contributions of the three groups as follows: 88% copepods, 1.5% Daphnia spp and 10% cladocerans other than Daphnia sp (Fig. 93). Numerically, average abundance was as follows: copepods 12 individuals/L, cladocerans other than Daphnia sp. 1.4 individuals/L, and Daphnia sp 0.2 individuals/L (Fig. 94). The Lower Arrow results were 85% copepods (25 indivudals/L), 7% Daphnia sp. (2 individuals/L), and 8% cladocerans other than Daphnia sp (2.5 individuals/L).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 70 Other Cladocera Daphnia Copepoda 100
90
80
70
60
50
40
% composition % 30
20
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
100
90
80
70
60
50
40
% composition % 30
20
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 93. Seasonal composition of zooplankton as a percentage of average density in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 71 30 6.0 Copepoda Upper Arrow 5.5 Daphnia 25 5.0 Other Cladocera 4.5 20 4.0 3.5 15 3.0 2.5 10 2.0 1.5 density Copepoda (ind/L) Copepoda density 5 1.0 0.5 density Daphnia and other cladocera cladocera (ind/L) other and Daphnia density 0 0.0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Year
30 6.0 Copepoda Lower Arrow 5.5 Daphnia 25 5.0 Other Cladocera 4.5 20 4.0 3.5 15 3.0 2.5 10 2.0 1.5 density Copepoda (ind/L) Copepoda density 5 1.0 0.5 density Daphnia and other cladocera cladocera (ind/L) other and Daphnia density 0 0.0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Year
Figure 94. Seasonal average zooplankton in Upper and Lower Arrow, 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 72 In Upper Arrow, the average zooplankton biomass in 2009 was as follows - 44% copepods, 49% Daphnia spp., and 7% cladocerans other than Daphnia sp (Fig. 95). Numerically, the results were as follows: copepods – 17 ug/L, Daphnia sp. 19 individuals/L, cladocerans other than Daphnia spp. 3 ug/L (Fig. 96). In Lower Arrow, the composition was slightly different with 38% copepods (30 ug/L), 58 % Daphnia sp. (46 ug/L) and 3% cladocerans other than Daphnia sp. (3 ug/L).
The 2010 results in Upper had percentage contributions of the three groups as follows: 80% copepods, 12% Daphnia spp and 8% cladocerans other than Daphnia sp (Fig. 95). Numerically, average biomass was as follows: copepods 19 ug/L, cladocerans other than Daphnia sp. 2 ug/L, and Daphnia sp 3 ug/L (Fig. 96). The Lower Arrow results were 47% copepods (36 ug/L), 48% Daphnia sp. (37 ug/L), and 5% cladocerans other than Daphnia sp (2.5 ug/L).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 73 Upper Arrow Other Cladocera Daphnia Copepoda 100%
90%
80%
70%
60%
50%
40% % biomass % 30%
20%
10%
0% 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Lower Arrow 100
90
80
70
60
50
% biomass 40
30
20
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 95. Seasonal composition of zooplankton as a percentage of average biomass in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 74 80 Upper Arrow Copepoda 70 Daphnia Other Cladocera 60
50
40
30 biomass (ug/L)
20
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
80 Lower Arrow Copepoda 70 Daphnia Other Cladocera 60
50
40
30 biomass (ug/L)
20
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 96. Seasonal average zooplankton biomass in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 75 Seasonal patterns In 2009 in Upper Arrow copepods were the main contributors to the overall zooplankton population in the spring with Daphnia appearing in July, peaking in September and maintaining a population through November. In Lower Arrow a similar trend followed Upper Arrow except Daphnia peaked in August. In 2010, copepods were the main contributors for the entire season, a pattern observed in 2004, 2005 and 2007. The pattern in Lower Arrow in 2010 was similar to that of 2009 and previous years (Fig. 97). Lower Arrow Daphnia biomass was higher than Upper Arrow for the duration of the data set. Temperatures in Lower Arrow tend to be higher than Upper Arrow during July, August and September. The generation time of zooplankton can vary with temperature and Daphnia’s generation time improves with increased temperature. With Lower Arrow having a higher temperature than that observed in Upper, it could be one of the explanations of higher biomass (Gillooly, 2000).
160 Upper Arrow Other Cladocera 140 Daphnia 120 Copepoda 100
80
60
biomass (ug/L) 40
20
0 Nov-97 Aug-98 Nov-99 Aug-00 Nov-01 Aug-02 Nov-03 Aug-04 Nov-05 Aug-06 Nov-07 Aug-08 Nov-09 Aug-10 May-97 May-99 May-01 May-03 May-05 May-07 May-09 Date 160 Lower Arrow Other Cladocera 140 292 Daphnia 120 Copepoda 100
80
60
40 biomass (ug/L) 20
0 Nov-97 Aug-98 Nov-99 Aug-00 Nov-01 Aug-02 Nov-03 Aug-04 Nov-05 Aug-06 Nov-07 Aug-08 Nov-09 Aug-10 May-97 May-99 May-01 May-03 May-05 May-07 May-09 Date Figure 97. Seasonal biomass of zooplankton in Upper Arrow (top) and Lower Arrow (bottom), 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 76 The trend of total zooplankton biomass within the year for 2009 and 2010 is illustrated in Figures 98 and 99. Each point within one month represents results from each station (AR 1 – 8). The average biomass is similar in 2009 and 2010. Biomass amongst months is statistically significant from April through November (2009 results: p<0.0001; F=15.0474; 2010 results:p<0.0001; F=10.2402).The peak months for biomass are August, September and October. There was greater spatial difference amongst stations in August, September and October as well. The spatial differences amongst stations are illustrated in Figures 100 and 101. Each point represents one month (April through November) for each station in 2009 and 2010. During 2009, station AR 6 had the most biomass while in 2010 station AR 8 had the most biomass. In 2009 variation amongst stations was slightly statistically significant (p=.0236; F=2.7443). In 2010, the spatial variation was statistically significant (p<0.0025; F=4.0110).
Figure 98. One way ANOVA and paired students t-test for total zooplankton biomass, April to November, 2009.
Figure 99. One way ANOVA and paired students t-test for total zooplankton biomass, April to November, 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 77
Figure 100. One way ANOVA and paired students t-test for total zooplankton biomass, stations AR 1 -8, 2009.
Figure 101. One way ANOVA and paired students t-test for total zooplankton biomass, stations AR 1 -8, 2010.
Comparison to Kootenay Lake The trend of increased zooplankton density in 2009 and 2010 for Upper and Lower Arrow followed the trend of Kootenay Lake (Fig. 102). Daphnia density increased in Kootenay Lake in 2009 and 2010 compared to 2008 while in Upper Arrow results were similar in 2009 and decreased in 2010. The Lower Arrow results were similar to the Kootenay Lake trend. Lower Arrow zooplankton biomass was similar to Kootenay Lake biomass in 2009 and 2010 (Fig. 103). Results were less for Upper Arrow compared to Lower Arrow and Kootenay Lake. Daphnia biomass in Lower Arrow was higher than Kootenay Lake even though the density was similar. This indicates that the organisms in Lower Arrow are larger in size than the ones in Kootenay Lake. Upper Arrow Daphnia biomass was less than Lower Arrow and Kootenay Lake. The trend in 2010 decreased from 2009 results.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 78 50
Upper Arrow Lower Arrow 40 Kootenay
30
20
zooplankton density (ind/L) density zooplankton 10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
5 Upper Arrow Lower Arrow 4 Kootenay
3
2 Daphnia density (ind/L) density Daphnia 1
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
Figure 102. Average (April to October) total zooplankton density (top) and Daphnia density (bottom) in Kootenay Lake and Upper and Lower Arrow; 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 79 120 Upper Arrow Lower Arrow 100 Kootenay
80
60
40 zooplankton biomass (ug/L) biomass zooplankton 20
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year
80 Upper Arrow 70 Lower Arrow Kootenay 60
50
40
30
20 Daphnia biomass (ug/L) biomass Daphnia
10
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Figure 103. Average (April to October) total zooplankton biomass (top) and Daphnia biomass (bottom) in Kootenay Lake and Upper and Lower Arrow; 1997 to 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 80 Mysis diluviana Mysid density was higher at deep sites in 2009 and 2010 compared to 2008 results. Density was higher in Upper Arrow compared to Lower Arrow (Fig.104). Peak density in Upper Arrow occurred in September in 2009 and July in 2010. In 2009, the main contribution to overall density was immature mysids. In 2010, the main contributor to the peak was juveniles (Fig. 105). In Lower Arrow, there is no distinct peak in either year (Figs. 104 and 106).
1200
Upper Arrow 1000 Lower Arrow )
2 800
600
400 Density (individuals/m Density
200
0 Jul-97 Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10
Date Figure 104. Seasonal average density of M. diluviana in deep sites, 1997 to 2010.
Upper Arrow average Mysis density - 2009 Upper Arrow average Mysis density - 2010 Juvenile Immature Mature Juvenile Immature Mature 1000 1000 900 900 800
) 800 2 ) 700 2 700 600 600 500 500 400 400 300 300 200 200 100 100 Density (individuals/m Density 0 Density (individuals/m 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month
Figure 105 Monthly average density of M. diluviana by life stage in deep sites in Upper Arrow (AR 1-3), 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 81 Lower Arrow average Mysis density - 2009 Lower Arrow average Mysis density - 2010 Juvenile Immature Mature Juvenile Immature Mature
1000 1000 900 900 ) ) 2 2 800 800 700 700 600 600 500 500 400 400 300 300 200 200 Density (individuals/m Density Density (individuals/m 100 100 0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 106 Monthly average density of M. diluviana by life stage in deep sites in Lower Arrow (AR 6-8), 2009 and 2010.
Density of mysids in shallow sites is less than the density observed in deep sites (Fig. 107). During all years, densities were higher in Upper Arrow than in Lower Arrow. The results in 2009 and 2010 were similar to the results from 2003 through 2008.
1200 Upper Arrow
1000 Lower Arrow
800 ) 2
600
400 Density (individuals/m Density 200
0 Jul-97 Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Figure 107. Seasonal average density of M. diluviana in shallow sites, 1997 to 2010.
Immatures were the dominant life stage observed in shallow sites in Upper and Lower Arrow. The peak density occurred in October in 2009 and August in 2010 in Upper Arrow (Fig. 108). In Lower Arrow, the peak in 2009 occurred in July and in 2010, there was no obvious peak (Fig. 109).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 82 Upper Arrow average Mysis density - 2009 Upper Arrow average Mysis density - 2010 Juvenile Immature Mature Juvenile Immature Mature 400 400 350 350 ) ) 2 2 300 300 250 250 200 200 150 150 100 100 50 50 Density (individuals/m Density Density (individuals/m Density 0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 108. Monthly average density of M. diluviana by life stage in shallow sites in Upper Arrow (AR 1-3), 2009 and 2010.
Lower Arrow average Mysis density - 2009 Lower Arrow average Mysis density - 2010 Juvenile Immature Mature Juvenile Immature Mature 200 200 ) ) 2 150 2 150
100 100
50 50 Density (individuals/m Density Density (individuals/m Density 0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 109. Monthly average density of M. diluviana by life stage in shallow sites in Lower Arrow (AR 6-8), 2009 and 2010.
Biomass in deep sites increased in 2009 but decreased in 2010 even though density had increased in 2010 (Fig. 110). This was due to higher biomass of matures in 2009 compared to 2010 (Figs. 111 and 112). Since matures are larger, they will have a higher contribution to the overall biomass. Peak biomass occurred in September in Upper Arrow and November in Lower Arrow in 2009. In 2010, there was no distinct peak. The biomass in Lower Arrow was the highest on record from 1997 to 2010.
The average biomass in Upper and Lower Arrow combined was 2220 mg/m2 in 2009 and 1379 mg/m2 in 2010. The long term average from 1997 to 2010 was 952 mg/m2. Therefore results in 2009 and 2010 were higher than the long term average.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 83 8000 Upper Arrow 7000 Lower Arrow
6000
5000
4000
3000 Biomass (mg/m2) 2000
1000
0 Jul-97 Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Figure 110. Seasonal average biomass of M. diluviana in deep sites, 1997 to 2010.
6000 Upper Arrow average Mysis biomass - 2009 6000 Upper Arrow average Mysis biomass - 2010 Juvenile Immature Mature 5000 Juvenile Immature Mature 5000 ) ) 2 2 4000 4000
3000 3000
2000 2000 Biomass (mg/m Biomass (mg/m
1000 1000
0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 111. Monthly average biomass of M. diluviana by life stage in deep sites in Upper Arrow (AR 1-3), 2009 and 2010.
Lower Arrow average Mysis biomass - 2009 Lower Arrow average Mysis biomass - 2010 6000 Juvenile Immature Mature 6000 Juvenile Immature Mature 5000 5000 )
2 4000
) 4000 2 3000 3000
2000 2000 Biomass (mg/m 1000 Biomass (mg/m 1000
0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 112. Monthly average biomass of M. diluviana by life stage in deep sites in Lower Arrow (AR 6-8), 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 84 Biomass in shallow sites slightly increased in Upper Arrow in 2009 and decreased in 2010 (Fig. 113). Results from Lower Arrow remained similar to those observed in earlier years. Immatures were the life stage that contributed to most of the overall biomass during both years (Figs. 114 and 115). A description of the life stages of mysids is well documented in Vidmanic, 2011.
8000 Upper Arrow 7000 Lower Arrow
6000
5000 ) 2
4000
3000 Biomass (mg/m
2000
1000
0 Jul-97 Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Figure 113. Seasonal average biomass of M. diluviana in shallow sites, 1997 to 2010.
Upper Arrow average Mysis biomass - 2009 Upper Arrow average Mysis biomass - 2010 2500 600 Juvenile Immature Mature Juvenile Immature Mature
2000 500 ) ) 2
2 400 1500 300 1000 200 Biomass (mg/m 500 (mg/m Biomass 100
0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 114. Monthly average biomass of M. diluviana by life stage in shallow sites in Upper Arrow (AR 1-3), 2009 and 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 85 Lower Arrow average Mysis biomass - 2009 Lower Arrow average Mysis biomass - 2010
600 Juvenile Immature Mature 600 Juvenile Immature Mature
500 500 ) )
2 400 2 400
300 300
200 200 Biomass (mg/m Biomass (mg/m 100 100
0 0 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Month Month Figure 115. Monthly average biomass of M. diluviana by life stage in shallow sites in Lower Arrow (AR 6-8), 2009 and 2010.
Spatial patterns In 2009, the peak total mysid biomass (all life stages) occurred at station AR3, followed by station AR6 and AR 8 (Fig. 116). In 2010, the peak biomass occurred at station AR7, followed by AR1, AR6 and AR8. In 2009, results amongst stations were not statistically significant while in 2010, differences between stations AR6 and AR8, AR 7 and AR8 and AR1 and AR8 were statistically significant.
Figure 116. Mysis diluviana biomass by station at deep sites, April to November 2009.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 86
Figure 117. Mysis diluviana biomass by station at deep sites, April to November 2010.
Kokanee
Spawner Escapement Estimates After three years of spawner numbers declining below pre-nutrient addition levels in both Upper and Lower Arrow tributaries, the 2009 and 2010 returns were very strong. In fact the returns to upper basin streams in both years were about three times higher than in 2007-2008 while lower basin streams saw a 45-55% increase over the previous two years. The escapement estimates for Hill Creek were ~242,000 (2009) and slightly higher at ~267,000 in 2010 with numbers below the channel of ~45,000 in 2009 and ~38,000 in 2010 (Fig. 118). The 2009 estimate for Upper ALR index streams including Hill Creek was approximately 305,000 while the Lower Arrow tributary estimate was about 146,000 (Figs. 118, 119). There were further increases in 2010 spawner numbers in the index streams with ~ 345,000 in the Upper basin tributaries and ~156,000 in the Lower basin tributaries. The magnitude of increase was far greater in the Upper basin tributaries but this was largely due to high returns to the Hill Creek spawning channel.
Prior to lake fertilization the Upper Arrow streams including Hill Creek and spawning channel supported ~0.3-0.4 million spawners during the late 1980s through to the early 1990s (Figs. 118; Appendix 5). These escapements decreased through the 1990s with a similar declining pattern evident for the lower basin streams (Fig. 119). The upper basin tributaries had a record low escapement of 34,000 in 1996 and only 25,000 in the lower basin in 1997. Upon commencement of nutrient additions in 1999 spawner numbers in both basins increased to peak numbers of greater than 0.40 million for a combined return in the index streams of 0.87 by 2004. Since 2004 there has been a four year decline in spawner returns with the 2007 and 2008 estimates of 95,000 actually similar to the mid 1990s before nutrient additions commenced. The spawner numbers however, rebounded in 2009 and 2010 with estimates for the Upper Arrow Basin index streams and Hill Creek the second highest since nutrient additions began. The Lower Arrow estimates in 2009 and 2010 were higher than the previous three years but still far lower than during 1999- 2005 or the first seven years of nutrient addition. The substantial improvement observed
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 87 for the Upper Arrow tributaries was not matched by the 2009 and 2010 returns to the Lower Arrow tributaries.
500,000
450,000 Hill Creek + channel 400,000 Upper Arrow index tribs 350,000 300,000 250,000 200,000 150,000 Number of spawners 100,000 50,000 0 66 69 74 78 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 118. Trends in kokanee spawner returns to Hill Creek and three key index streams (Drimmie, Halfway and Kuskanax) in the Upper Arrow Reservoir, 1966-2010. Note: estimates for 1993, 1994 and 2003 for index streams were based on average escapements in previous four years. Index stream estimates have been expanded by 1.5 (including Hill Creek below channel).
600,000
500,000
400,000
300,000
200,000 Number of spawners
100,000
0 66 69 74 78 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 119. Trends in kokanee spawner returns to four index streams (Burton/Snow, Caribou, Deer and Mosquito) in the Lower Arrow Reservoir 1966-2010. Note: estimates for 1993, 1994, and 2003 for index streams based on average escapements in previous four years. All index stream estimates were expanded by 1.5 to approximate total run size.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 88 Spawner size and fecundity A good time series of biological data has accumulated over the last twenty five years as part of routine monitoring of the Hill Creek spawning channel performance. Spawner size and specifically length frequency distributions provide good indicators of in-lake conditions for kokanee and show some significant changes over the period of record. There have been a series of major shifts in size frequencies that reflect density dependent responses resulting in increases and decreases in growth (Fig. 120). Schindler et al (2009a) show shifts in length distributions which occurred in the early 1980s that were most likely attributed to the consequence of dam impacts which initially reduced spawning habitat and decreased reservoir productivity. They noted that the average size of Hill Creek kokanee in the early 1980s (e.g. 1984) was larger than the 1970s (data on file) most likely because overall numbers in the reservoir were lower after the completion of Revelstoke Dam which blocked spawner access to the Upper Columbia River. Although in decline, ALR was probably still fairly productive at that time resulting in favourable growing conditions for low numbers of fish. Arndt (2009) speculated that a period of trophic upsurge following construction of Revelstoke impoundment may have contributed to a period of elevated productivity in Arrow Lakes Reservoir. As spawner numbers from channel production built up, the spawner sizes decreased by the late 1980s and remained stable and unimodal into the 1990s. Mean size in the mid 1990s continued to decline despite decreasing abundance presumably due to continuing decline in lake productivity (Fig. 120a). Of significance was the large size reflected in the 1999 & 2000 histograms that demonstrated exceptionally good growth when in-lake abundance was relatively low but reservoir productivity had been improved significantly through nutrient additions (Fig. 120 a and b). As in-lake and spawner abundance increased (see next section) during the early 2000’s mean spawner size declined (Fig. 120b). Mean size from 2003 until 2006 was comparatively small ranging ~210-230 mm. The 2006 and 2007 size frequency distributions again shifted to larger size fish as in-lake abundance declined dramatically from 2004-2007 (see below). During the last two years spawner size has actually increased slightly even though spawner numbers have increased dramatically, a signal that in-lake conditions have been very good for kokanee.
For most years on record length frequency distributions for Hill Creek spawners have displayed a single mode ranging between 200-270 mm. (Fig. 120). A shift to a bimodal distribution was first evident in 1986 and 1987 following a single mode of very large individuals in 1985 (Schindler et al 2009a; not shown here). Some four cycles later in 2000, a bimodal pattern appeared again that followed a mode of very large individuals in 1999 (Fig. 120). The 2001 length frequency histogram was even more pronounced and this bimodality carried into 2002 (Fig. 120b). Age data (below) indicated that two age groups (i.e. age 2+ and 3+ fish) contributed to the spawning populations from 2000-2002. After 2002 and for three consecutive years a single dominant mode was evident and mean size declined from 258 mm in 2001 to ~210 mm in 2004 and 2005. Starting in 2006 and again in 2007 there was a shift to larger size fish presumably in response to good growing conditions and lower kokanee abundance in the reservoir. The 2007 histogram suggests a bimodal distribution whereas a single mode is evident from 2008-2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 89 1994 (n=298) 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
1995 (n=158) 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
1996 (n=101) 2+ 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
1997 (n=128) 3+
30
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% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
1998 (n=104) 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
1999 (n=115) 2+ 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 Fork Length (mm)
Figure 120a. Length frequency histograms and assumed age by mode of Hill Creek kokanee spawners for 1994-1999. Sample size (n) ranged from 101-298 per year.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 90 2000 (n=225)
30 2+ 3+ 20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2001 (n=242)
30 3+ 2+ 20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2002 (n=287) 2+
30
20 3+ frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2003 (n=237) 3+
30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2004 (n=230) 3+ 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2005 (n=199) 3+ 30
20
frequency 10 %
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 Fork Length (mm)
Figure 120b. Length frequency histograms and assumed ages by mode of Hill Creek kokanee spawners for 2000-2005. Sample size (n) ranged from 199-287 per year.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 91 2006 (n=206) 3+
30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2007 (n=205)
30 3+
20 2+ frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2008 (n=203) 2+? 30
20 frequency
% 10
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2009 (n=260) 3+ 30
20 frequency
% 10 4+
0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
2010 (n=227) 3+ 30
20
frequency 10 % 0 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400
Fork Length (mm)
Figure 120c. Length frequency histograms and assumed age by mode of Hill Creek kokanee spawners for 2006-2010. Sample size (n) ranged from 203-260 per year.
The size frequency shifts described above have resulted in rather dramatic changes in average size and fecundity of Bridge and Hill creek spawners during the last three decades. (Note: biological data collection at Bridge Creek ceased after 2002). Except for the peak in the mid 1980’s, mean size and fecundity between 1977 and 1995 remained fairly constant (Fig. 121). The high growth and fecundity in 1985 may be related to lower kokanee abundance in the reservoir at that time as described earlier. In 1996 and 1997 there was a sharp decline in mean size and fecundity despite low abundance. After 1997 with low in-lake abundance and the commencement of nutrient additions in 1999,
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 92 fecundity rose substantially to peak levels of >400 eggs /female by 2000 (Figs. 121,122). The pattern of changes in fecundity of Hill Creek spawners was nearly identical to Bridge Creek spawners (Fig. 122). In-lake abundance estimates at this time were moderately high and building. After 2000 there was a sharp decline in mean size and fecundity. During the mid 2000s when in-lake abundance was highest, Hill Creek mean fecundities fell to only 189 (2004) and 214 (2005) but have been gradually increasing since then to 258 (2009) and 272 in 2010.
35 600 Females 30 Males Fecundity 500
25 400 20 300 15 Length (cm) 200 10 Fecundity(no of eggs) 5 100
0 0 77 78 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 121. Trends in spawner mean length and fecundity at Hill Creek Spawning Channel from 1977-2010.
500 450 400 350 300 250 200
150 Hill Creek 100
Mean fecundity (no. of eggs) (no. fecundity Mean Bridge Creek 50 0 77 78 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 122. Comparison of average fecundity of Hill Creek (1977-2010) and Bridge Creek spawners (1990-2003). Note: sample sizes were usually >100 fish.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 93 Age at maturity Differences in age proportions determined using length frequency analyses from trawl and spawners are compared with age proportions derived from otolith interpretation in Table 4. Prior to fertilization bimodal length frequency distributions occurred in only 3 years out of 14 (eg 1986, 1987 and 1996) indicating the likelihood of a mix of age 2+ and 3+ spawners. All other years fish were assumed to spawn at age 3+ based on their size. Some of the initial years of otolith analysis experienced disagreement between different contractors and with frequency analysis. However since employing the Casselman (1990) method starting in 2007, the otolith ageing has been more reliable. The results generally appear to be more comparable to length frequency / trawl aging than previous otolith analyses. An exception was 2008, when otolith data indicated two ages while a single mode suggested a single age (Fig. 123). A review of otolith and size at age from trawl data separated by basins (Upper and Lower Arrow) resulted in Sebastian and Andrusak (in Schindler et al. 2011) reporting the age at maturity in 2008 as primarily 2+ while acknowledging uncertainty. Spawner ageing in 2009 was straight forward with a single peak of 3+ fish supported by otolith analyses. In 2010, however, a new problem was encountered. By excluding fish using the suggested Casselman rating of 5 or less, the majority of the age 3+ fish were eliminated creating a clear bias in results towards younger fish. Further examination led to a decision to discount the rating that year and use the entire otolith dataset (see discussion for more details). This anomaly requires closer scrutiny in future and it may be decided to include all but the very lowest ratings of otoliths in order to best represent the age composition of the spawners.
The ageing data for Hill Creek spawners since commencement of lake nutrient additions in 1999 has been variable including temporary shifts in the age of maturity. Based on length frequency distributions alone, a shift in size and age-at-maturity most likely occurred from 1999 to 2002, when length frequencies were bimodal (Fig. 120). The data from 2003-2006 suggests a shift back to a dominance of age 3+ fish. The 2007 data indicated yet another shift in age-at-maturity with three age groups present although the majority still appeared to be age 3+. In 2008, the dominance of age 2+ spawners suggests good growing conditions in the reservoir for early-maturing cohorts. As reservoir abundance increased through to 2009-10 there appeared to be a shift back to dominant age at maturity of 3+.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 94 Table 4. Age composition (%) of kokanee spawners for Hill Creek during 1985-2010 based on otolith and length frequency analyses.
Year Sample % by otolith analysis Sample % by length frequency1 (n) 2+ 3+ 4+ (n) 2+ 3+ 4+ 1985 110 0 100 0 1986 98 60 40 5 1987 123 30 70 0 1988 141 0 100 0 1989 113 0 100 0 1990 147 0 100 0 1991 148 0 100 0 1992 175 0 100 0 1993 301 0 100 0 1994 298 0 100 0 1995 158 0 100 0 1996 101 48 52 0 1997 128 0 100 0 1998 104 0 100 0 1999 182 20 73 7 115 51 49 0 2000 194 52 46 2 225 67 33 0 2001 253 49 51 <1 242 53 44 2 2002 200 50 50 287 76 24 0 20032 159 (94) (6) 237 0 100 0 2004 99 5 94 1 199 0 100 0 2005 99 2 92 5 205 0 100 0 20063 100 0 (48) (51) 206 0 100 0 20074, 74 38 43 19 205 24 76 0 5 20084 55 78 22 203 100 0 0 20094 104 11 85 4 260 0 100 0 20106 115 14 82 4 227 0 100 0
1 Ageing based on length frequency analysis plus scale ages from trawling 2. Otolith analyses deemed to be out by one year based on trawl age 2+ size in Upper Arrow which did not overlap spawners 3. Only 40% agreement in otolith interpretation between two analysts so will default to length frequency proportions for survival calculations 4. Otolith determinations considered reliable based on Casselman ratings >5 even though different from length frequency analyses. 5. 2007 Otolith proportions have been changed from previous reports to reflect Casselman rating of >5 only. 6. 2010 used all otolith samples since Casselman’s rating of >5 eliminated only age 4 and 3 fish leaving overstated proportions of age 2+ spawners (see discussion)
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 95
Figure 123. Kokanee spawner length frequency by age based on otolith analyses for Hill Creek in a) 2008 b) 2009 and c) 2010.
Reservoir pool elevation and habitat areas The 2009 reservoir level at time of the hydroacoustic survey was of 433.19 m or 7.05m below full pool. In 2010 the level was 434.50 or 5.74m below full pool (Appendix 9). The areas of limnetic habitat (>20m depth) were estimated at 19,550 ha in Upper Arrow in 2009 and 19,676 ha in 2010. The limnetic area of the Lower Arrow is much smaller at 9,480 ha in 2009 and 9,653 in 2010. Pool level at the time of survey is required to adjust habitat areas at depth for extrapolating fish densities to estimate total abundance.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 96 Trawl catch Except for 2007, pelagic trawl surveys have been conducted on ALR annually since 1988. Three cohorts are typically sampled and the 2009 data was no exception as illustrated in Figures 124 and 125. Of the total catch in both basins, 72 % were age 0+, 12% age 1+ and 16% age 2+ (Table 5). The 2010 trawls caught three age groups in Upper Arrow and four ages in Lower Arrow. Over 90% of the 2010 fish were fry as a result of the very strong fry year. When the size frequency of the 2009 Hill Creek spawners are overlaid on the trawl frequency distribution there is strong evidence that most spawners were age 3+ in both 2009 and 2010. This data supports the otolith age analysis indicating a shift back towards dominance of age 3+ at maturity. During the 2009 trawl survey 7 pygmy whitefish were captured in the pelagic zone, 5 in the Upper Arrow and 2 in the Lower Arrow. In most years only kokanee have been captured but future trawl work needs to be mindful of any increase in pygmy whitefish numbers.
Table 5. Kokanee catch statistics from the October trawl surveys in 2009 and 2010.
Basin Station Hauls age 0 age 1 age 2 age 3 Total Upper Arrow T1 Albert Pt. 3 25 2 0 0 27 Oct 2009 T2 Halfway R. 3 13 6 11 0 30 T3 Nakusp 3 5 2 4 0 11 Total of Upper 9 43 10 15 0 68 Percent (%) by age 63 15 22 0 100 Lower Arrow T6 Johnston Cr. 3 30 2 5 0 37 Oct 2009 T7 Bowman Cr. 3 28 6 4 0 38 T8 Cayuse Cr. 3 27 4 5 0 36 Total of Lower 9 85 12 14 0 111 Percent (%) by age 76 11 13 0 100 Total Arrow Both basins 18 128 22 29 0 179 2009 Percent (%) by age 72 12 16 0 100
Basin Station Hauls age 0 age 1 age 2 age 3 Total Upper Arrow T1 Albert Pt. 3 43 1 0 0 44 Oct 2010 T2 Halfway R. 3 69 2 2 0 73 T3 Nakusp 3 225 9 20 1 255 Total of Upper 9 337 12 22 1 372 Percent (%) by age 91 3 6 <1 100 Lower Arrow T6 Johnston Cr. 3 194 6 3 1 204 Oct 2010 T7 Bowman Cr. 3 35 4 6 3 48 T8 Cayuse Cr. 3 41 1 1 0 43 Total of Lower 9 270 11 10 4 295 Percent (%) by age 92 4 3 1 100
Total Arrow Both basins 18 607 23 32 5 667 2010 Percent (%) by age 91 3 5 1 100
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 97 Upper Arrow 2009
40
35 Age 0 (n=43)
30 Age 1 (n=10)
25 Age 2 (n=15)
20
15 Number offish 10
5
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 Fork length (mm)
Lower Arrow 2009 40 Age 0 (n=85) 35 Age 1 (n=12) 30 Age 2 (n=14) 25
20
15 Number offish 10
5
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 Fork length (mm)
Figure 124a. Kokanee length frequency for Upper Arrow and Lower Arrow basins by age from 2009 trawl sampling with ages verified by scale interpretations.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 98 Upper Arrow 2010 100
90 Age 0 (n=337) 80 Age 1 (n=12) 70
60 Age 2 (n=23) 50 40 30 Number offish 20 10 0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 Fork length (mm)
Lower Arrow 2010 100 90 Age 0 (n=270) 80 Age 1 (n=11)
70 Age 2 (n=9) 60 Age 3 (n=5) 50 40
Number offish 30 20 10 0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 Fork length (mm)
Figure 124b. Kokanee length frequency for Upper Arrow and Lower Arrow basins by age from 2010 trawl sampling with ages verified by scale interpretations.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 99 Upper Arrow 2009 trawl and Hill Creek spawners 70 Age 0 (n=43) 60 Age 1 (n=10) 50 Age 2 (n=15) Spawners (n=203) 40
30
Proportion (%) Proportion 20
10
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 Fork length (mm)
Lower Arrow 2009 trawl 60 Age 0 (n=85) 50 Age 1 (n=13) Age 2 (n=13) 40
30
20 Proportion (%) Proportion
10
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 Fork length (mm)
Figure 125a. Kokanee length frequency (proportions) by age for Upper Arrow with Hill Creek spawners overlaid and for Lower Arrow Reservoir from 2009 trawl data.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 100 Upper Arrow 2010 trawl and Hill Creek spawners 70 Age 0 (n=337) 60 Age 1 (n=12) 50 Age 2 (n=23) Spawners (n=227) 40
30
Proportion (%) Proportion 20
10
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 Fork length (mm)
Lower Arrow 2010 trawl 70 Age 0 (n=270) 60 Age 1 (n=11)
50 Age 2 (n=9)
Age 3 (n=5) 40
30
Proportion (%) Proportion 20
10
0 10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 Fork length (mm)
Figure 125b. Kokanee length frequency (proportions) by age for Upper Arrow with Hill Creek spawners overlaid and for Lower Arrow Reservoir from 2010 trawl data.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 101 Kokanee growth Kokanee size statistics by age from 2009 and 2010 trawling are presented in Table 6. Except for age 1+ fish in 2010, the data suggests that mean length at age adjusted to October 1 was slightly larger in Lower Arrow compared with Upper Arrow, although not statistically significant. Comparing the mean lengths at age within basins between years indicates that growth was slightly better in 2009 than 2010 in both basins.
Table 6. Kokanee size statistics from the October 2009 and 2010 trawl surveys.
Survey time Basin Station Age 0 Age 1 Age 2 Age 3 October 2009 Upper Ave. length (mm) 58 135 202 Length range (mm) 46-75 97-180 172-224 Standard deviation 7.1 28.1 15.0 Sample size (n) 43 10 15 October 2009 Lower Ave. length (mm) 63 147 214 Length range (mm) 39-76 101-178 154-235 Standard deviation 6.7 28.7 23.2 Sample size (n) 85 12 14 October 2010 Upper Ave. length (mm) 56 126 187 197 Length range (mm) 36-82 87-156 160-203 Standard deviation 8.1 25.3 10.9 Sample size (n) 337 12 22 1 October 2010 Lower Ave. length (mm) 63 117 191 214 Length range (mm) 41-80 93-152 164-223 191-229 Standard deviation 6.8 20.9 21.4 13.9 Sample size (n) 270 11 9 5
Twenty two years of ALR trawl data indicates that size and growth of kokanee prior to fertilization were relatively stable except for two low growth years in 1996-97 (Fig. 126). Since nutrient additions, the variations in size at age have increased for all ages and appear to have experienced two peaks (2000 and 2006) and a valley in 2004. The peaks and valleys have been more extreme than prior to nutrient additions. The previous notion that fry size did not appear to respond to nutrients has been disproven by plotting relative length of all age groups on one graph (Fig. 127). Although the fry response is slightly more subdued than older age groups, it appears that all ages have responded in a similar fashion to fertilization in terms of general trends.
The response at the onset of fertilization was particularly dramatic since kokanee juvenile and spawner lengths had already begun to respond in 1998 to extremely low densities in the reservoir (Fig 126). A somewhat surprising result from the initial year of nutrient addition in 1999 was that age 3+ fish benefitted in their final summer with an average growth increment of 50mm prior to spawning. After peaking in 1999 and 2000 at lengths 20-30% above average size, the growth declined very significantly to reach a minimum by 2004 of about 10-15% below average or similar to 1996 (Fig. 127). A second smaller peak occurred with age 2+ and spawners reaching 10-12% above average in 2006. With much lower densities in 2007, there did not appear to be a further increase in size as would be expected suggesting other factors were determining fish density and growth response (see discussion). A decrease in spawner size in 2007 and 2008 was at least
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 102 partly due to a shift toward age 2+ spawners, rather than decreasing growth. Declining fish sizes in 2009 and 2010 however were consistent with higher abundance in the lake.
(a) Upper Arrow 300
Spawners 250
200 age 2
150
age 1 Mean f ork length (mm) 100
age 0 50
0 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Survey year
(b) Lower Arrow 300
250 age 2
200
age 1 150
Mean fork length (mm) fork length Mean 100
age 0
50
0 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Survey year
Figure 126. Trends in kokanee length at age adjusted to October 1 for a) Upper Arrow and b) Lower Arrow basins based on trawl survey data (1989-2010). Note: due to lack of trawl data in 2007, values are the mean size of spawners for age 2 & 3+, and the fry value is the mean post fertilization.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 103 140%
130%
120% age
at 110%
100% length
age 0 90% age 1 Relative 80% age 2 70% Spawners
60% 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Figure 127. Plot of relative mean size at age for kokanee all years of record on Upper Arrow Reservoir. Note: the data have been normalized against the mean value for each age group.
Fish density Acoustic survey data for 2009 and 2010 are illustrated by density contour plots (Appendix 12) to express kokanee distribution at depth across the reservoir at night. Typically, a north- south depth gradient is apparent with elevated densities higher up in the water column at the North end of Upper Arrow, which then gradually disperses over a wider range of depths along the entire length of the ALR. This gradient was far less apparent in 2009 than other years, however was again clearly apparent in 2010 (Appendix 12). At the most northern survey stations (transects 1-3 - Beaton Arm) fish were found closer to the surface, especially in 2010. In 2009 highest densities were found from 20-30 meters in Beaton compared to ~5-15 meters in 2010. The fish layer remained at the same general depth throughout the Upper Basin in 2009, with a high density area near the outlet at the same depth. Lower Arrow densities were deeper yet in 2009, with the majority of kokanee found from ~25-35 meters throughout. In 2010 the layer became progressively deeper across the entire length of both basins with the exception of a group found somewhat higher (~10m) near the south end of Upper Arrow at transects 8-9. In both years the fish layer spreads out at the south end near Castlegar, with the layer expanding to cover depths from 10 to 40+ meters.
Age partitioning of acoustic data provides insight into how the various age groups respond in the reservoir to variable conditions such as internal flows, depth variation and food availability. There are two obvious patterns that appear from year-to-year. First, in the main basins where 99% of the trawl catches have been kokanee, the highest fry densities were found at the northern and southern ends of both basins; this distribution was again evident in 2009 and 2010 (Fig. 128), particularly at transect 2 in 2010. Secondly, high fry densities are usually found in the survey transects located in the “narrows” (# 19-20) between the two basins. These transect data almost certainly represent other fish species (previous trawling indicated only 35% were kokanee at transect 20).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 104 Similar to previous years the lowest densities of fry and age 1-3+ kokanee both years were found in the central sections of both basins (Fig. 128). This may indicate these areas are less productive for kokanee since it has been observed in Kootenay Lake that the highest densities of fry are often found in the vicinity of where the nutrients are added (Schindler et al. 2009b). The age 1-3+ fish in 2009 were recorded in low densities throughout the upper basin with far higher densities at the outlet area (Transects # 8-10). This did not hold true in 2010 when the age 1-3+ component were present in lower densities at transects 8-10 and more evenly distributed compared to 2009. The lower basin densities in 2009 and 2010 were fairly comparable and similar to most other years with slightly higher densities recorded at the outlet area (i.e. transects 16, 17), particularly in 2010. There was higher abundance and biomass of zooplankton in Lower Arrow compared to Upper Arrow (Figs. 97 and 100). During 2010 the highest abundance and biomass occurred at station AR8, coinciding with higher densities of kokanee as described earlier (Fig. 101). The pattern of increased kokanee densities near the outlet of Lower Arrow has been noted many years, where given their wide depth dispersal (Appendix 13), these fish may well be vulnerable to entrainment at the Keenleyside Dam, as has been speculated previously.
Excluding the narrows area the total transect fish densities in 2009 ranged from 125-855 fish·ha-1 with a mean of 286 fish·ha-1 in the upper basin and 408 fish·ha-1 in the lower basin (Appendices 14, 15). In 2010 there was a considerable increase with the entire reservoir fish densities ranging from 271-2188 fish·ha-1. The upper basin mean density estimate was 446 fish·ha-1, the highest since 2002. The lower basin mean density was 668 fish·ha-1, also the highest since 2002.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 105 a) 2009
800
700
600 Age 0 Age 1-3+
500
400
300
Density (fish/ha) 200
100
0 1234567891020191811121314151617
b) 2010 800 Age 0 Age 1-3+ 700
600
500
400
300
200 Density (fish/ha) 100
0 1 2 3 4 5 6 7 8 9 1020191811121314151617
Transect number`
Figure 128. Longitudinal distribution of age 0+ and age 1-3+ kokanee in ALR during October 2009 and 2010 based on acoustic surveys. Note transects 19 and 20 in the narrows can contain up to 65% non-kokanee (often pygmy whitefish).
Abundance A comprehensive time series of kokanee abundance estimates for ALR is available based on hydroacoustic surveys conducted since 1991, with additional manual echo counts made in 1988 and 1989. Prior to nutrient additions, kokanee abundance in the reservoir remained < 5 million declining as low as ~ 2.5 million in 1997. However, in response to lake fertilization that commenced in 1999, kokanee numbers increased fourfold to ~20 million in 2001-02. Since then total abundance declined to a low of ~5 million in 2005 and 2007 with encouraging increases in 2008 and 2009 followed by the third highest estimate of ~ 15 million in 2010 (Figs. 129, Table 7). Despite the decline from the peak years of 2001 and 2002 the abundance levels remain well above the pre-fertilization years
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 106 and a positive upward trend is currently evident. The upper basin has consistently supported more kokanee than the lower basin since the onset on nutrient additions. For example, during the last two years ~60% of the total estimated abundance was in the upper basin (Table 7). Prior to fertilization, Upper Arrow produced ~50% of the total numbers of kokanee although it has about two thirds of the total reservoir pelagic habitat area. Since fertilization it appears that kokanee production per unit area in Upper Arrow has become almost equal to Lower Arrow, which has also increased since nutrient addition began. The 2010 estimate in the lower basin was the third highest for the period of record. Evidently both basins have benefited from fertilization but undoubtedly high fry production from Hill Creek contributes significantly to the higher numbers in the upper basin.
The fall fry estimate of 6.4 million in 2009 was higher than expected from the low spawner return in 2008, suggesting some improvements in egg-to-late summer fry survival have occurred (Figs. 130, 131). The further increase to 12 million fry in 2010 was anticipated from the strong spawner return and larger size (higher fecundities) in 2009. Additional channel production in 2009 (see discussion) also contributed to the strong fry year in 2010.
Table 7. Comparison of maximum likelihood abundance estimates (and 95% C. L.) for kokanee by basin and year for Arrow Lakes Reservoir during the nutrient addition period, 1999-2010.
Nutrient Month Upper Arrow Lower Arrow Arrow Reservoir addition (millions) (millions) (millions) Year 1 1999 October 4.0 (3.2-4.9) 2.1 (1.8-2.4) 6.1 (5.3-7.1) 2 2000 October 7.6 (7.1-8.1) 4.1 (3.6-4.6) 11.6 (10.9-12.4) 3 2001 October 13.4 (12.2-14.6) 6.5 (5.5-7.5) 20.0 (18.3-21.4) 4 2002 October 12.5 (11.3-13.6) 7.7 (5.9-9.6) 20.1 (18.1-22.3) 5 2003 September 7.6 ( 7.0-8.7) 3.8 (3.5-4.3) 11.7 (10.8-12.7) 6 2004 October 4.6 ( 4.0-5.0) 2.8 (2.5-3.2) 7.3 (6.7-8.0) 7 2005 October 3.3 (2.8-3.7) 1.8 (1.5-2.1) 5.0 (4.5-5.6) 8 2006 October 6.3 (5.9-6.8) 2.4 (2.2-2.7) 8.8 (8.4-9.8) 9 2007 October 3.6 (3.0-4.2) 1.9 (1.6-2.3) 5.5 (5.0-6.0) 10 2008 October 5.9 (4.5-7.3) 2.6 (2.0-3.1) 8.3 (6.8-9.8) 11 2009 October 5.4 (4.0-6.6) 3.6 (3.0-4.1) 9.1 (8.1-10.3) 12 2010 October 8.6 (7.3-10.0) 6.0 (3.8-8.0) 14.5 (12.0-17.1)
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 107 a) Arrow Reservoir - hydroacoustic estimates (all ages combined) 25
20
15
10
5 Numbers of kokanee (millions) Numbers of kokanee
0 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Survey year
b) Upper Arrow 15
12
9
(millions) 6
Numbers of kokanee Numbers of kokanee 3
0 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Survey year
c) Lower Arrow 10
8
6
(millions) 4 Numbers of kokanee Numbers of kokanee 2
0 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Survey year
Figure 129. Kokanee abundance estimates of all ages for a) ALR (combined Upper and Lower Arrow), b) Upper Arrow and c) Lower Arrow based on fall acoustic surveys, 1988 – 2010.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 108
18 pre-treatment Nutrient additions 16
14 age 0 12 age 1-3 10
8
6
Number of fish (in millions) 4
2
0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 130. Trends in age 0+ and age 1-3+ kokanee abundance for Arrow Lakes Reservoir based on fall hydroacoustic surveys during 1993-2010.
10.0 2.0 pre-treatment nutrient addition 9.0 1.8
8.0 1.6 age 1-3 7.0 1.4 Spawners 6.0 1.2
5.0 1.0
4.0 0.8
3.0 0.6 (millions) spawners
in-lake abundance (millions) abundance in-lake 2.0 0.4
1.0 0.2
- 0.0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
Year
Figure 131. Trends in age 1-3+ kokanee abundance and estimated spawner returns to Arrow Lakes Reservoir tributaries including Hill Creek during 1993-2010.
Biomass After fertilization began in-lake biomass of all ages groups increased during 1999-2001 (Appendix 11; Fig. 132). Biomass density prior to fertilization (n=6 years) averaged 2.8 kg.ha-1 whereas the fertilization era (n=12 years) has produced 9.7 kg.ha-1. This increase during the fertilization years represents a threefold difference. The 2009 estimate of 10.2 kg.ha-1 was slightly above average while the 2010 estimate of 8.2 kg.ha-1 was slightly
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 109 lower than the treatment era average. Since acoustic surveys occur after the spawners have moved into the streams the spawner biomass can be added to the in-lake biomass estimates to represent total biomass. The average additional spawner biomass was estimated at 1.4 kg.ha-1 and 2.9 kg.ha-1 for pre and post-fertilization periods respectively. The 2009 and 2010 spawner biomass density estimates of 2.5 and 2.7 kg.ha-1 respectively were just under the fertilization era average. Although the biomass increase since fertilization has been impressive, there was a decline in the mid-2000s with a recovery in 2008-2010.
Analysis of biomass density (kg.ha-1; Fig. 132) using a linear mixed-effects (LME) model, with era (pre vs. post) designed as a fixed effect and year as a random effect indicated a significant (p=<0.05) increase post-fertilization compared to pre-fertilization. The analysis of biomass (combined in-lake and spawners in metric tons; Fig. 133) using a linear mixed-effects (LME) model, with era (pre vs. post) designed as a fixed effect and year as a random effect also indicated a significant (p=<0.001) increase in biomass post fertilization compared to pre-fertilization. Data covered the period from 1993 to 2010 (Appendix 15).
18 pre‐treatment nutrient addition 16
14
12 (kg/ha)
In‐lake biomass 10 Spawner biomass density
8
6
Biomass 4
2
0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Year
Figure 132. Trends for in-lake biomass density and spawner biomass density for Arrow Lakes Reservoir kokanee. Note: In-lake biomass estimates were made after spawners had left the reservoir to spawn in tributaries. ATS refers to acoustic and trawl surveys.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 110 700
600 tons)
500 (metric
400
300 biomass 200
100 Kokanee 0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Year
Figure 133. Annual estimates of kokanee biomass (combined in-lake and spawner in metric tons) in ALR based on hydroacoustic and trawl surveys. Dotted vertical line separates pre-treatment from treatment eras.
Fry-to-Adult Survival Rates Coarse scale estimations of kokanee fry-to-adult survival rates can provide some insight into how ARL kokanee have reacted to reservoir fertilization. It is recognized that fry survival estimates are more useful as trends rather than individual values since they integrate survival conditions over a 2-4 year period and it is not known at what stage mortality occurs. Prior to nutrient additions, fry to adult survival rates in both Hill and Bridge Creeks had fallen to <2% by the early to mid 90’s and had reached minimum values of <1% (Fig. 134). Prior to this there was a peak of high survival rates from 1985- 1987. It is speculated at that time the upper basin would be experiencing loss of fry production due to blockage of upstream kokanee spawning migrations by the Revelstoke Dam. Hence lower fry abundance in the basin provided good growing conditions and high survival. This scenario is supported by the hydroacoustics data during the late 1980s; at that time abundance in the reservoir was very low (Fig. 129). The declining trend in survival rates from 1986 through to 1995 changed beginning with the 1996 fry cohort that grew in their final year in the fertilized reservoir. Following the initial year of fertilization survival rates climbed to nearly 9% in Bridge Creek and 11% in Hill Creek over the next 3-4 years. A somewhat surprising result from the initial year of nutrient addition in 1999 was the immediate increase in the fry to adult survival rate of 3.5 times the previous year based on the 1996 fry year (Fig. 134). The 1997-2000 cohorts also survived at rates > 5% at the same time that reservoir abundance estimates had ramped up to record high levels (i.e. 2001 & 2002). Survival rates for the 2001-2003 cohorts declined to < 5% while at the same time reservoir abundance was declining.
A survival of >20% for the 2004 cohort was considered to be very high compared with other cohorts, or alternately that fry production from Hill Creek was under-estimated that year. Assuming that tributary fry from 2004 would have experienced similar survival rates to Hill Creek fry (i.e. >20%) once they entered the reservoir, their returns too should
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 111 have been elevated. Instead, returns to Arrow Lake tributaries in 2007 and 2008, particularly Upper Arrow, were the lowest since nutrient additions began. All the evidence suggests that even though Hill Creek had two poor production years, it appears to have produced the majority of fry to the lake in both 2004 and 2005 and that tributary fry production must have been very low following those extreme high water events in fall of 2003 and 2004. The decline in survival rates for the 2006 and 2007 cohorts likely reflects increased in-lake abundance in 2009 and 2010 (Fig. 129).
25%
Hill 20%
(%) Bridge
15% survival
10% adult
to
Fry 5%
0% 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Fry Year
Figure 134. Fry to adult survival estimates from Hill and Bridge Creek spawning channels by fry year adjusted for age at return. Note this plot based on adult return data up to and including fall 2010.
Spawner–Return Spawner (S/RS) Relationship When adult returns equal their parental numbers the spawner to return spawner ratio (S/RS) is one (1.0). The ALR kokanee S/RS trend over time can be characterized as having two peaks and two troughs (Fig. 135). There were several cycles in the 1980s that had S/RS ratios > 1 but starting with the 1990-1993 cycle and the subsequent 5 cycles through to 1998 the S/RS was < 1.0 indicating that the return numbers did not equal their parental numbers (Fig. 135). During this period Hill and Bridge creek escapements fell to very low levels with some S/RS ratios calculated between 0.1-0.4. Concurrent with these low ratios was low in-lake abundance (Fig. 129) and this set of circumstances led to the decision to fertilize the Upper Arrow basin. The downward trend of the S/RS ratios initially changed in 1999 when both Hill and Bridge creek spawning runs reached replacement levels and did so until 2005. This peak was followed by a trough of four years with recruit numbers again less than their parent numbers. A further change occurred in 2009 when the S/RS number for Hill Creek was slightly > 1.0 and the following year (2010) the S/RS ratio was 2.5. These estimates were made on the
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 112 assumption that the vast majority of spawners return at age 3+. It should be noted that occasional years where there is a mix of spawner ages may not be well represented by this approach, however, the long-term trends will indicate in a general way whether stocks are in a building or declining state.
Analysis of the Ricker model using spawners (age 3+) and recruits (age 0 fall fry), suggests an increase in the productive capacity and survival of kokanee in the ALR following nutrient addition in 1999 (Fig. 136, Appendix 15). The transformed Ricker model demonstrates a higher intercept (a=3.97; 95% C.I. = 3.19-4.74) relating to productivity in the post fertilization era compared to the pre fertilization era (a=3.07; 95% C.I. = 1.0-5.11). It is notable however that as demonstrated by the parameter confidence intervals, there is considerable uncertainty in the estimates. Both models suggest that increasing spawner numbers results in a linear decline in the instantaneous survival rate (ln[recruits per spawner]) displaying a density dependent mortality response (Fig. 79, Appendix 15). The slope declines steeper in the pre fertilization era (b= -2.77) compared with the post fertilization era (b= -2.3), suggesting higher post fertilization survival. However, the ANCOVA analysis (not shown, data on file) indicated that while the intercept differences between the eras were significant (p<0.05) suggesting system productivity had increased, the slopes were not (p>0.05), suggesting there has been no significant difference in survival between eras.
The Ricker generated curves indicates that spawner abundance (Smax) expected to generate maximum recruitment to fall age 0 fish was estimated to be ~360,000 spawners in the pre-fertilization era (Fig. 137). Conversely, under increased lake productivity, the spawner abundance (Smax) expected to generate maximum recruitment was estimated to be ~408,000 spawners (i.e. suggests that Smax would be ~13% higher with nutrient enrichment).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 113 8.0
7.0 Hill Creek Bridge Creek 6.0
5.0
4.0
3.0
2.0
1.0
Spawner/retutn spawnerratio 0.0 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 Spawner return year Figure 135. Spawner to return spawner (S/RS) relationships for Hill and Bridge creeks assuming spawners return at age 3+.
Figure 136. Observed difference in age 0 (R) fall abundance to spawner (S) ratio for two distinct eras in the ALR; pre-nutrient addition (1993-98) and nutrient addition (1999-2010) periods.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 114
Figure 137. Expected mean stock recruitment (Ricker) relationship in juvenile recruits (t+) and adult recruits (t+4) for two distinct productivity eras.
Discussion
Kokanee are the keystone species in the ALR and Kootenay Lake and their rapid decline in abundance during the late 1980s and throughout the 1990s was similar to the decline observed on Kootenay Lake during the 1980s (Schindler et al. 2009b). In both cases the declines have been attributed to upstream reservoir uptake of nutrients that resulted in ultra-oligotrophic conditions which significantly impacted kokanee as well as other fish species (Daley et al. 1980, Pieters et al. 1999, Ashley et al. 1999 and numerous other authors). The ALR fertilization program was initiated in 1999 in an effort to restore the nutrient balance in the upper basin that in turn would restore the kokanee population.
Arrow Lakes Reservoir is an oligotrophic system based on chemistry results from samples collected (Wetzel, 2001). Results from discrete profile data indicated low nitrogen to phosphorus ratios (weight:weight) in Lower Arrow during July, August and September at 2, 5, and 10 metres in 2009 and 2010. These results coincide with higher bacillariophyte biovolume compared to April, May and June results where nitrogen:phosphorus ratios are higher. Adaptively managing the weekly nutrient loading rates resulted in overall nitrogen to phosphorus ratios favourable for phytoplankton growing conditions. Phytoplankton species compostion is key for zooplankton growth, especially Daphnia, the preferred food source for kokanee. The overall average phytoplankton abundance and biovolume in Arrow was slightly higher than the long term average.
In 2009, the contribution of zooplankton biomass was similar to the 2008 results in Upper and Lower Arrow with copepods being dominant in the spring with Daphnia being the main contributor for the remainder of the season. In 2010, copepods dominated for the
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 115 entire season in Upper Arrow and followed the 2008 and 2009 pattern in Lower Arrow. Timing of Daphnia in Arrow Lakes Reservoir could provide a better understanding of the overall trend in the kokanee populations. In Lake Washington, USA, juvenile sockeye salmon also prefer Daphnia as their preferred food source (Beauchamp et al. 2004, Scheuerell et al. 2005). Hampton et al. (2006) observed that sockeye will shift to feeding on Daphnia when the abundance of Daphnia reaches 0.4 individuals/L. In Arrow Lakes Reservoir, this abundance level typically occurs in July or August. In 2009 Daphnia reached this abundance in Upper Arrow and Lower Arrow in July while in 2010, results in Upper Arrow achieved this in August while in Lower Arrow the abundance of 0.4 individuals/L was achieved in July. Mysid biomass in 2009 and 2010 was higher than the long term average in Arrow Lakes Reservoir, however, not at levels that outcompeted zooplankton.
Prior to experimental fertilization there had been annual monitoring of kokanee spawner numbers back to 1988 and standardized in-lake kokanee abundance since 1993 (Sebastian et al. 2000). With the onset of nutrient additions a more extensive monitoring program of all trophic levels was undertaken and has been continuous since experimental fertilization of the ALR commenced eleven years ago. Schindler et al. (2011b) have described the response of each trophic level to fertilization noting that in reference to kokanee their numbers have increased as well as growth, higher fecundity, higher fry-to-adult survival rates, biomass and spawner-recruit ratios > 1. All of these metrics support the notion that improved growing conditions now exist within the reservoir. As discussed below there has been considerable variability in kokanee abundance and size observed during the last twelve years even though nutrient loadings have been fairly constant. Clearly there are a number of factors at play, some of which have been identified (e.g. recruitment limitations) and others which are still speculative (e.g. entrainment of zooplankton and kokanee during increased water withdrawal during the summer growing season).
The index streams showed a similar pattern of increasing escapements to a peak in 2004 followed by a decline to 2007 and 2008. However they have not recovered in 2009-10 as the Hill Creek returns have. The most recent counts, especially in the lower basin tributaries, have been lower than the pre-fertilization era. The extremely low returns to Upper Arrow tributaries in 2007 and 2008 can be traced to a combination of low adult returns, small size of spawners (low fecundity and egg deposition) and poor incubation conditions in the fall of 2003. There is cause to believe that incubation conditions and egg-to-fry survival may have been well below average as a result of an extreme fall freshet in 2003 (and to a lesser extent in 2004) which exceeded previous historical maximums for the month of November (Water Survey of Canada stream flow Records). The same conditions are also believed to have impacted Hill Creek fry production but clearly not to the same extent as in tributaries. As a consequence the returns in 2007 and 2008 were the lowest since fertilization began but the strong Hill Creek returns in 2009 and 2010 give reason for cautious optimism going forward signaling that in-lake conditions have improved since 2007.
The variation in the size of Hill Creek spawners over the period of record can provide some insight into what dynamics are at play in the reservoir that may be regulating the
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 116 kokanee population. When nutrient additions commenced, the immediate increase in spawner size was clearly a strong positive density dependent growth response to increased food supply. Size declined in 2001-02 as in-lake abundance increased and age 1-3+ kokanee reached peak levels. Similar responses have been observed on Kootenay Lake (Schindler et al. 2011ab), Alouette Reservoir (Harris et al. 2007) and in Bucks Lake, California (Grover 2006). After 2001 Hill Creek spawner size decreased to pre- fertilization size for four years however in-lake abundance during this period was about four fold higher than pre-fertilization estimates. Mean size of spawners increased slightly in 2006 and 2007 before levelling off from 2008-2010. Meanwhile abundance has been increasing since 2007 with the 2010 level moving back towards the 2002 peak. The fact that in-lake abundance decreased from 2003 to a low in 2007 while mean size only increased slightly has been of some concern. However, the recent rebuild in abundance and size since 2007 is reassuring in terms of nutrients transferring to fish. If there was one unusual year, it was 2007 where fall density reached a minimum level and the growth response should have been strongly positive but actually declined slightly from 2006. Schindler et al. (2010) speculated that increased flows during summer of 2007 may have entrained large quantities of zooplankton and fish from Lower Arrow Reservoir and this could help to explain low kokanee density coupled with a lack of positive growth response due to lower productivity. A more thorough investigation of the effects of changing summer flows on various trophic levels in Arrow should be a focus for some future synthesis work on Arrow Lakes Reservoir. All of the above described changes emphasize the importance of continuous monitoring of the key biological parameters. Forecasting shifts in size, fecundity and spawner numbers is especially important for spawning channel management where fry production is a primary objective.
Age determination is a fundamental metric required for kokanee population management and is particularly important for evaluating their response to fertilization. Many attempts at conventional ageing of ALR kokanee using scales or otoliths of mature fish have been unsatisfactory and problematic not only on ALR but also for Okanagan Lake kokanee (Andrusak et al. 2006). The most reliable ageing method is to use trawl length frequencies aided by scale analyses to determine juvenile ages with reasonable certainty. Spawner ages are then estimated by overlaying their length distribution with the younger fish of known length-at-age using otoliths to verify ages. The more recent ageing results using otoliths are in general agreement with the trawl ageing method for most years in terms of identifying whether the spawner returns are primarily one age (unimodal) or consist of two ages groups (bimodal). Only occasionally (e.g. 2008) did length frequency indicate one age (unimodal) while otoliths indicate two main age groups. In most years the dominant age of ALR kokanee spawners has been age 3+. There have been two periods during the fertilization project when age at maturity shifted from age 3+ to a mix of ages 2+ and 3+; the first was when rapid growth occurred during initial nutrient enrichment in 1999-2000 followed by 2 years of declining growth in 2002-03 as in-lake kokanee age 1-3+ numbers reached maximum abundance. The second period was in 2007 and 2008 also as growth rates declined from a peak in growth in 2006. The 2007-08 ages at return may also be a function of being from two very low fry recruitment cohorts (2004-05). Interestingly, the small average size of spawners in 2008 may be attributed to the shift in age at maturity to primarily 2+ in response to low recruitment levels. This
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 117 should be a concern to fisheries managers that limiting fry recruitment to low levels may not always lead to larger spawners, but could result in a shift to a younger age at maturity resulting in medium to smaller spawners. In the last two years the age at maturity has reverted back to predominately age 3+. It is noteworthy that in 2010 the otolith analyses using the Casselman (1990) recommendation of accepting a rating of 5 or greater on otolith features resulted in an extreme bias toward smaller younger fish. The rating essentially eliminated the large majority of larger older fish as their 3rd annulus was most often rated at 5 or lower. Consequently, a decision was made to base the age proportions in 2010 on the entire otolith dataset in order to include the 3+ samples which were in the majority. The future recommendation is therefore to examine the age proportions with and without ratings >5 to check for bias before defaulting to use of good quality otoliths only.
Established nearly three decades ago the Hill Creek spawning channel has been a key component of kokanee restoration on the ALR by the MoFLNRO and the FWCP (Sebastian et al. 2000). Prior to channel construction Hill Creek supported ~ 10,000- 13,000 kokanee spawners (Lindsay 1977). The channel was completed in 1981 and spawning kokanee initially used the channel in 1984 (Lindsay 1982; Sebastian et al. 2000). The channel is approximately 3.2 km long and 6.1 m wide, designed to support a theoretical number of 150,000 kokanee spawners. Kokanee numbers returning to spawn in Hill Creek and the spawning channel rose dramatically during the late 1980s and declined during the 1990s. A deliberate 50% reduction in spawning channel adult loading from 150,000 to 75,000 during 1991-94 likely contributed to the low returns to Hill Creek in 1995 through 1999 when the 50% target loading could not be met (Table 8). The intent was to increase kokanee size at maturity by reducing their numbers in the reservoir (Sebastian et al 2000). However declining reservoir productivity and possibly high predation rates drove the kokanee population to very low levels and the expected growth response did not occur until extremely low levels were reached in 1998. With commencement of nutrient additions spawner numbers again increased from 1999 through 2004 and then decreased to pre-treatment levels by 2008. In 2009 and 2010 returns again increased dramatically.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 118 Table 8. Kokanee fry production from Hill Creek spawning channel 1987-2010.
Spawning Spawner Mean Egg Females2 Egg Fry Egg-to-fry year counts1 Fecundity Retention Deposition3 emigration4 survival (no.) (egg no.) (egg no.) (%) (millions) (millions) (%) 1987 73,437 9.92 4.36 44 1988 150,000 13.8 7.92 57 1989 150,000 15.7 5.76 37 1990 180,000 12.4 5.49 44 1991 75,000 219 13 49 7.57 2.87 38 1992 75,000 263 33 50 8.63 3.00 35 1993 75,000 248 31 52 8.54 3.43 40 1994 75,000 302 51 51 9.41 2.22 24 1995 16,328 274 1 51 2.26 0.68 30 1996 25,030 172 8 52 2.15 0.69 32 1997 22,566 182 6 50 1.99 0.93 47 1998 19,087 226 12 44 1.81 0.86 47 1999 78,024 424 36 41 12.37 3.72 30 2000 102,400 469 2 47 22.36 8.46 38 2001 122,400 379 7 41 18.82 8.32 44 2002 151,826 212 5 39 12.26 3.93 32 2003 133,951 233 9 48 14.43 0.23 1.6 2004 199,820 189 4 35 9.53 0.67 7.0 2005 142,755 214 5 48 12.99 4.66 36 2006 91,649 240 8 48 10.21 5.46 52 2007 97,731 236 4 46 10.07 6.96 69 2008 72,068 236 4 38 6.41 3.76 59 2009 241,508 258 7 50 30.07 20.05 67 2010 345,171 272 5 43 30.35
1. Refers only to fish in the spawning channel; other Hill Creek production is primarily surplus since natural fry capacity is estimated at 100,000 based on pre-channel maximum spawner returns. 2. Derived by sampling at spawning channel; note: 1992-94 used 50% as sampling bias suspected 3. Potential egg deposition based on number of adults in channel x (fecundity – retention) x % females. 4. Fry emigration from spring time sampling does not include non-channel production which is estimated at up to 100,000 fry/yr.
The spawning channel goal has been to produce 0.5 million spawners but the highest returns to date have only been 0.32 million. None the less, Hill Creek is a substantial producer of all kokanee in the reservoir. For the upper basin Hill Creek escapement numbers have represented ~74% of the total enumerated in the major (index) spawning streams. The 2010 escapement was the highest since 2004 with Hill Creek representing 91% of total index stream escapement for the upper basin and ~64% for the entire reservoir. It is currently not known if depressed spawner returns to tributaries are a result of changing environmental (climatic) conditions or primarily a symptom of competition with fry from the spawning channel which have a productive advantage due to much better egg-to-fry survival in the channel. The extent to which Hill Creek fish use Lower Arrow to rear remains unknown and is key to assessing the affects Hill Creek spawning channel is having on Lower Arrow kokanee. Some consideration should be given to determine if otolith micro-chemistry could be used to differentiate between Hill Creek and Lower Arrow tributary spawners in order to assess the extent to which Hill Creek fish use Lower Arrow basin for rearing. Future management targets for kokanee production
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 119 from Hill Creek will depend on overall priorities of whether kokanee are being produced primarily for predators or for anglers.
Figure 138 shows the relationship between springtime fry output from the spawning channel and tributary streams to late summer fry abundance from acoustic surveys. The purpose was to see how well independent estimates of recruitment and standing stock would correlate in order to verify their reliability. It is recognized that the annual tributary production estimates were theoretical and represent conditions of average egg-to-fry survival (assuming 5%). Even so, the correlations suggest an improved fit when tributary fry are combined with spawning channel fry production (Fig. 138b). The correlation between spawning channel and late summer fry shows considerable scatter with an R2 of 0.52 for nineteen years of data (Fig. 138a). Much of the scatter could be due to changing contributions of the spawning channel to total fry production over time as the channel produces increasingly higher proportions of the total fry. The improved fit when other tributaries are added suggests that theoretical fry production estimates based on stream counts must be reasonably representative most years. Extreme flow years for example would not be well represented by this model without adjusting egg-to-fry survival rates. This model can provide another diagnostic tool to help detect extreme events that have affected fry production prior to reaching their first fall in the reservoir.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 120 a) Hill Creek spawning channel fry 18 16 14 (millions) 12 10 8 y = 0.6359x + 3.0223 estimates R² = 0.5293
fry 6
4 2 Acoustic 0 0 5 10 15 20 25 Spawning channel fry production (millions)
b) Hill Creek and tributary fry 18 16 14 (millions) 12 10 8 estimates
fry 6
4 y = 0.63x + 0.5273 R² = 0.7914 2 Acoustic 0 0 5 10 15 20 25 Spring fry production (millions)
Figure 138. Relationship between a) Hill Creek spawning channel fry production and late summer fry abundance (hydroacoustic) estimates and b) Combined Hill Creek and Arrow tributary fry production and late summer (acoustic) fry estimates from 1992-2010. Note: the 2004 data point is not shown on figure 78b as tributary spawner counts used to estimate fry production were not conducted in 2003.
Fry recruitment from all sources increased dramatically starting in 2000 in response to nutrient additions which increased spawner survival, size, fecundity and egg deposition. After 2001, fry abundance declined for four consecutive years due to density dependent growth leading to smaller sized spawners throughout the ALR system that are believed to have contributed to the system wide low fry production in 2004 and 2005. Since then fry abundance estimates have increased but only to about one half the 2001-2002 levels with 2010 being a phenomenal exception. The 2010 fry increase was largely due to a decision to test the channel capacity by deliberately loading it with 241,500 adults in 2009; well
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 121 beyond its design specifications of 150,000. A record egg deposition of ~30 million eggs experienced surprisingly good survival of 67% and produced 20 million fry (Table 8). The 2010 spawner returns and fecundity were both higher than 2009 and the channel was once again loaded to determine its capacity. However, with a lower ratio of females to males, the final egg deposition in 2010 was comparable to 2009 at 30.2 million. The survival of this second high production year will help to test the channel capacity and ultimately the fry-to-adult survival and adult production as discussed later in this section.
The Hill Creek spawning channel performance as measured by egg/fry survival rates has greatly improved since 2005 when the survival rate was < 10% and fry production was < 1.0 million. Since that time the survival rates have increased ranging between 36-69% during the last four years. This can likely be attributed to more rigorous gravel cleaning at the channel.
Fry-to-adult survival rates and spawner to returning spawner relationships are two measures that provide further evidence of how the kokanee population has responded to reservoir fertilization. In the initial years of fertilization fry-to-adult survival rates increased substantially at a time when in-lake kokanee abundance was low. In-lake abundance rose from pre-fertilization estimates of ~ 5 million (all age groups) to highs of ~ 20 million in 2001 and 2002. The 1998 fry cohort peaked at a survival rate of nearly 11% (Fig. 134) while decreasing survival rates of the following four cohorts (1999-2002 fry) provide clear evidence of a density dependent response to high abundance of ages 1+-3+ kokanee during 2001-2003. The high survival rates associated with the 2004 and 2005 fry cohorts could also be interpreted as a density dependent response to lower abundance after 2003 although these estimates are subject to uncertainty around the Hill Creek fry estimates for those two cohorts. Over the twelve year period of fertilization a strong inverse relationship (R2=.79) does exist between fry-to-adult survival rates and fry production from Hill Creek; i.e. the higher the fry production the lower the survival rate (Fig. 139).
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 122 25%
20% (%)
rate
15% y = 0.0951x‐0.465 survival
R² = 0.79 10% adult
to
5% Fry
0% ‐ 1 2 3 4 5 6 7 8 9 10 Fry Output (in millions) Figure 139. Relationship between fry output from Hill Creek Spawning Channel and the % fry-to-adult survival rate for the nutrient addition period 1999-2010. Note that red points indicate the most recent two fry years of 2006 and 2007 corresponding to adult returns in 2009 and 2010, respectively.
The number of recruits produced by parental spawners can be highly variable and are usually dependent on several density dependent factors from the egg stage through to adults. Walters and Martell (2004) describe a lake where recruit growth and survival occurs in foraging arenas where feeding and predation shape the number and size of fish returning to spawn. Since kokanee grow primarily based on the production of the secondary trophic level (zooplankton) the spawner-recruit relationship can be one indicator of the lakes’ trophic status provided that exploitation is not a major factor. A generalized spawner-recruit relationship using spawner to return spawner ratios for both ALR spawning channels using escapement data from a number of consecutive cycles (Note: Bridge Creek data considered unreliable after 2008). Except for 2003 and 2004 egg-to-fry survival rates have been reasonably constant and harvest has been low thus minimizing potentially major sources of error. Predation is still an unknown factor but may cycle following the kokanee with a couple of years lag time.
Very high spawner–return spawner ratios (S/RS >1) for the late 1980s are believed to be due to lower in-lake numbers in the reservoir in the mid 80s resulting from significant habitat loss and subsequent reduced kokanee production from construction of the Revelstoke Dam. Fewer kokanee in the upper basin due to loss of production from above Revelstoke Dam would have resulted in improved growing conditions in the upper basin for those kokanee produced below the dam. This notion is consistent with spawner size and survival data reported at Hill Creek during the mid 80s. However, by the early 1990s declining ALR productivity began to be reflected in the kokanee population and the S/RS ratios fell to < 1 until fertilization began in 1999. Despite declining numbers of kokanee in the mid 1990s anticipated growth responses did not occur until very low levels were reached in 1998. The positive S/RS ratios for both spawning channel populations from 1999-2005 signalled a reversal of the 1990s decreasing trend (Fig. 135) and total abundance in the reservoir greatly increased. The declining S/RS rates since 2005 were
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 123 not entirely surprising since parental numbers had increased considerably in the early 2000s and 2004 and 2005 fry channel fry production was low. The low S/RS ratios from 2005-2008 ( < 1.0) can therefore be attributed to a combination of incubation and in-lake survival problems. The 2009 and 2010 S/RS values have once again become > 1.0 and suggesting the 2005-2008 in-lake survival problems may be temporary.
A Ricker Stock Recruitment (S/R) model comparing pre-fertilization and post fertilization eras suggests an increase in productive capacity and survival of kokanee since fertilization began. It also shows that increased spawner numbers results in a decline in the instantaneous survival rate due to density dependent mortality (also shown by Fig. 139). Spawner abundance predicted to maximize recruitment in the pre-fertilized era was estimated at ~360,000 whereas the post fertilized era maximum recruitment estimate suggests ~408,000 spawners, an approximate 13% increase due to increased reservoir carrying capacity from the nutrient additions. This estimate is low most likely due to the poor years in the mid-2000s discussed earlier.
The influence of fertilization on kokanee is most convincing when their biomass is calculated before and after nutrient additions. Analysis of the data indicates nearly a threefold increase in biomass since 1999. However, the decline during the 2004-2007 suggests growing conditions during this period were not optimal. The 2009 and 2010 estimates do signal improvement but certainly not back to the peak period 2001-2003. An initial attempt has been made at modeling estimates of biomass and biomass density in an effort to demonstrate differences between pre and post fertilization. These analyses confirm earlier conclusions in this report that there has been a significant difference in kokanee biomass and biomass density during the fertilization era compared to the pre- fertilization era. All the biological data presented in this report provides clear evidence that lake fertilization has overall been quite successful in restoring kokanee, albeit not to the initial target of ~0.5 million kokanee returning to Hill Creek.
During the last two years Hill Creek spawner numbers have been very high second only to the record number reported in 2004. A key question has been: “was the original adult target of 500,000 spawners achievable at Hill Creek?” This question can be addressed in two parts: 1) what is the capacity of the spawning channel to produce fry, and 2) do the survival rates in the reservoir enable returns to reach the target of a half million adults? To answer the first question a plot of egg deposition vs. fry produced from the channel (only) continues to show a linear relationship (Fig. 140) that strongly suggests maximum fry production has yet to be achieved, even though the channel production reached 20 million fry in 2010. A similar egg deposition of 30.2 million from 267,000 spawners in 2010 will provide a second high output year useful in assessing channel production capacity. The previous maximum fry production from the channel was 8.5 million occurring in 2000 or year 2 of the nutrient addition.
The second question examines the non-linear relation between fry production levels from the channel and their resulting survival in the reservoir. With 12 years of data for the fertilized regime the relation between fry production and survival can be described with a power model (R2=0.79; Fig. 140). Without survival estimates from high fry output years,
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 124 the theoretical survival can only be extrapolated beyond the bounds of existing data so remains highly speculative. Predictions for increased production and survival presented by Schindler et al (2011) suggested that survival may become too low to enable a return of 500,000 adults to Hill Creek. However, including an additional two years (2009 and 2010) to the power model changes the slope slightly and predicts higher survival rates for high fry outputs. The latest numbers suggest it might be possible to achieve a target of 500,000 fry with a fry output of ~23 million. The 2010 production of 20 million fry should help to determine if this survival model is reasonable once adults return in 2012 and 2013. The revised model does suggest that an output of 30 million would not be likely to occur as survival rates would drop below replacement levels. The above analyses is simply to see what might be possible for channel production and does not address the question of what the fry targets should be at Hill Creek spawning channel in relation to fishery targets and conservation of other stream populations.
25
20 y = 0.5376x ‐ 0.8011 R² = 0.8212 15 (millions)
fry
10 #
5
0 0 5 10 15 20 25 30 35 Eggs deposited (millions)
Figure 140. Relationship between number of eggs deposited at the Hill Creek spawning channel and the number of fry produced 1984-2010. Note 2004 and 2005 fry years (in pink) were extreme outliers and were not included in the regression.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 125 Table 9. Theoretical return rates and resulting fry production from increased fry production at Hill Creek spawning channel based on preliminary survival relation in Figure 139. Note production levels with asterisks indicate extrapolation beyond current data.
Fry Production Predicted survival Potential adult Future Fry (millions) Rate in reservoir1 returns to channel2 production3 (%) (millions) 5 4.50 225,000 11 9 3.42 308,000 15 15* 2.70 405,000 20 20* 2.36 472,000 24 23* 2.21 509,000 25 30* 1.96 587,000 29 1. Based on power model in Figure 83 2. Fry x Predicted survival rate 3. Theoretical fry production in channel based on 1:1 sex ratio, fecundity of 200 eggs/female and 50% egg-to-fry survival
There are many challenges when introducing nutrients to large lake systems such as ALR and Kootenay Lake. Some of the logistics associated with fertilizing the upper ALR basin are described earlier in this report. Of interest is that the results of these two large on- going fertilization projects have some similarities, at least during the initial years. Kootenay lake fertilization began in 1992 followed by ALR fertilization seven years later and in each experiment some dramatic changes have occurred to the kokanee population(s). Both ALR and Kootenay Lake kokanee responded almost immediately after nutrient addition began with rapid growth, increased fecundity (e.g. 200 to 400 eggs/female) and a shift in the average age at maturity from age 3+ to a mix of age 2+ and 3+ (Schindler et al. 2011a, b). Escapements increased within two years of fertilization on both systems. When the nutrient additions were deliberately reduced in Kootenay Lake in 1997 the in-lake abundance declined which led to three consecutive low escapement years during 2000-02. When nutrient additions were restored to original levels in 2000, in-lake abundance increased leading to near record escapement levels by 2004 and 2005 while age-at-maturity returned to age 3+ and the average spawner size declined (Schindler et al. 2011a).
After the initial positive response of ALR kokanee to fertilization an unexpected decline in abundance and spawner numbers occurred despite no reduction in nutrient loadings. Most notably the in-lake abundance, S/R ratios and biomass all declined to near pre- nutrient addition levels. It appears that reduction in fry recruitment levels over three consecutive cohorts (2003-2005 fry years) accounts for much of the decline evident during the mid-2000s. Hill Creek spawning channel management and fry production problems partially attributed to natural causes (e.g., extreme fall flows and egg mortality) help to explain part of the kokanee decline. The 2009 and especially the 2010 data indicates recovery from the mid-2000s period has begun but the decline in abundance and escapements since the peak in 2000-2002 also strongly suggests there has been a short
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 126 term decline in reservoir productivity. A longer time series is required to determine what levels of kokanee can be sustained in the ALR with continued nutrient additions and increased fry output from Hill Creek spawning channel.
The survival rates provide some evidence of differences between ALR and Kootenay Lake productivity prior to fertilization. Immediately before nutrient additions to both systems and when abundance and spawner numbers were low the average fry-to-adult survival was ~6% in Kootenay Lake compared with only ~2% on ALR. The first four years after initial nutrient additions to Kootenay showed an average increase of fry-to- adult survival to ~10% followed by a decline to ~4% but with much higher in-lake abundance and spawner numbers than prior to treatment. This decline most likely indicates that Kootenay Lake in the late 1990s was approaching a new, higher carrying capacity. The low survival rates and spawner numbers in the ALR prior to fertilization supports the notion that reservoir carrying capacity at that time was limiting but also suggests that natural stream production did not compensate for the deliberately lower production from the spawning channel. Upon nutrient addition, the average survival in ALR increased to ~8% during the first four years and then returned to 3% but with much higher numbers of spawners returning. The rise in the ALR 2007 survival rate shown by the 2004 fry year (~20%) appears to be unusual but does suggest a high degree of resilience for kokanee to recovery from low population levels. It is not recommended that we manage populations based on this survival curve since there are factors other than productivity (eg. entrainment and predation) which impact kokanee survival.
The primary objective of the nutrient restoration programs has been to increase kokanee numbers to assure sufficient prey items for the top predators-piscivorous rainbow trout and bull trout. With success in increasing the kokanee populations in both ALR and Kootenay Lake the role of predation in maintaining and possibly exacerbating cycles in kokanee response to nutrient addition is becoming the focus of greater attention. Developing reliable methods for tracking predator populations will be important in assessing the overall impact of nutrient addition on fish populations in these systems. Currently monitoring of predators on ALR is done through annual creel census (Arndt and Schwarz 2011) and more recently bull trout spawner assessment through redd counts (Decker and Hagen 2008). On Kootenay Lake a fifty year time series of Gerrard rainbow spawner counts is continuing (data on file MoFLNRO, Nelson) and assessment of Kootenay Lake bull trout was conducted in 2011. The top down effect of predators on kokanee may be different between ALR and Kootenay Lake owing to what appears to be more predators in Kootenay Lake and differences in harvest levels in the fisheries; e.g. a more intensive fishery on Kootenay Lake may serve to limit or “control” predator numbers as they increase. On Kootenay Lake an on-going exploitation study (Poisson Consulting Ltd. and Redfish Consulting Ltd. 2010) and a large scale creel census conducted in 2011 (Andrusak and Andrusak 2012) should provide more insight into the status of the top predators.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 127 Recommendations
1. More attention needs to be directed to the question of reservoir flows to determine if this will be a long term limiting factor for ALR productivity that in turn would limit the kokanee population.
2. Trophic interactions analysis amongst lower trophic levels (eg the variation in temporal timing of Daphnia) over the various years of study.
3. The Hill Creek spawning channel should continue to be evaluated annually for fry production, spawner numbers and associated biological data including sex ratio, length, weight, fecundity and egg retention.
4. The original target of 150,000 spawners for loading of Hill Creek Spawning Channel did not consider the small size and low fecundities of kokanee that occur at higher densities. When available, spawner numbers permitted into the spawning channel should continue to be increased well beyond the original target of 150,000 in order to build on the last two years of high fry production and further test the channel capacity. Fecundity estimates must be done weekly during the spawning period to ensure egg deposition estimates are reliable.
5. The density-dependent relationship between kokanee abundance and fry to adult survival in the reservoir should continue to be tested with higher fry output levels from Hill Creek spawning channel to help determine reservoir carrying capacity with continued nutrient enrichment.
6. The extent to which Hill Creek kokanee utilize Lower Arrow for rearing is unknown and will assist in determining the impact, if any, on Lower Arrow kokanee from high fry output at the spawning channel. Consideration should be given to developing a project to assess this. Otolith micro-chemistry may be a way to differentiate fish from the spawning channel vs Lower Arrow streams from samples of Lower Arrow pre-spawners (i.e. trawl samples).
7. There is some evidence that growth in Lower Arrow kokanee may be different some years from Upper Arrow. Lower Arrow spawners need to be sampled annually from three streams to determine size and age-at-maturity. A minimum of 30 samples per stream should be collected for lengths and otolith samples and analysed following the Casselman rating system; preferably by the same contractor used since 2007. Samples should be collected randomly throughout the spawning period to reduce potential size and age bias known to occur over the spawning period.
8. The acoustic and trawl surveys provide some key information for monitoring the response of kokanee to nutrient addition. This time series needs to be continued into the future.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 128 9. The role of predation on kokanee cycles is not well understood. Long term monitoring of the top predators is recommended. An annual short report on predator status is suggested for ALR and Kootenay Lake to combine and interpret the results of from all the individual monitoring projects.
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Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 136
Appendix 1. Listing of 2009 Arrow Lakes Reservoir project focus, personnel and affiliation.
Project Focus Personnel Affiliation Fertilization Limnologist Eva Schindler Fish and Wildlife, MoE1, Nelson Fertilizer schedule Eva Schindler Fish and Wildlife, MoE1, Nelson Fertilizer application Crescent Bay Crescent Bay Construction, Nakusp Construction Galena Bay ferry Western Pacific Marine, Revelstoke Shelter Bay ferry Western Pacific Marine, Revelstoke Reservoir limnology Don Miller Kootenay Wildlife Services Ltd. sampling Marley Bassett Fish and Wildlife, MoE1, Nelson Eva Schindler Fish and Wildlife, MoE1, Nelson Phytoplankton analysis Dr. John Stockner Eco-Logic Ltd. Zooplankton and mysid Dr. Lidija Vidmanic Limno-Lab Ltd., Vancouver analysis Chemistry reporting Eva Schindler Fish and Wildlife, MoE1, Nelson Marley Bassett Fish and Wildlife, MoE1, Nelson Phytoplankton, zooplankton Eva Schindler Fish and Wildlife, MoE1, Nelson and mysid reporting Kokanee acoustic surveys Dale Sebastian Biodiversity Branch, MoE1, Victoria Tyler Weir Biodiversity Branch, MoE1, Victoria David Johner British Columbia Conservation Foundation Kokanee trawling Don Miller and staff Kootenay Wildlife Services Ltd. Kokanee aerial spawner Grant Thorp Columbia and Aquatic Technical Services surveys Ltd. Eva Schindler Fish and Wildlife, MoE1, Nelson Albert Chirico Fish and Wildlife, MoE, Nelson Marley Bassett Fish and Wildlife, MoE1, Nelson Mark Homis Highland Helicopters, Nakusp Kokanee ground spawner Steve Arndt Fish and Wildlife Compensation Program surveys (FWCP), Nelson James Baxter FWCP, Nelson Teal Moffat BC Hydro, Castlegar Trevor Oussoren BC Hydro, Castlegar Adrienne Shaw BC Hydro, Revelstoke Giles Shearing BC Hydro, Revelstoke Brenda Thomas BC Hydro, Revelstoke Krista Watts BC Hydro, Castlegar Kokanee analysis and Dale Sebastian Biodiversity Branch, MoE1, Victoria reporting Tyler Weir Biodiversity Branch, MoE1, Victoria David Johner British Columbia Conservation Foundation1 Harvey Andrusak Redfish Consulting Ltd. Greg Andrusak Redfish Consulting Ltd. Kokanee report review Steve Arndt FWCP, Nelson Creel survey report Steve Arndt FWCP, Nelson (separate report) Creel survey Glen Olson Nakusp Allsion Alder Hailstorm Ridge Environmental Services, Galena Bay Deb Imeson Scottie’s Marina, Robson Regional support and Jeff Burrows Fish and Wildlife, MoE1, Nelson logistics FWCP Technical Jeff Burrows Fish and Wildlife, MoE1, Nelson Committee Dale Sebastian Biodiversity Branch, MoE1, UBC
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 137
Dave Wilson BC Hydro, Vancouver Trevor Oussoren BC Hydro, Castlegar Steering Committee Wayne Stetski MoE, Cranbrook Ted Down Biodiversity Branch, MoE1, Victoria Kevin Conlin BC Hydro, Vancouver Doug Johnson BC Hydro, Castlegar Bruce MacDonald Fisheries and Oceans Canada, Nelson Greg Mustard Public Representative Gerry Thompson Public Representative Grant Trower Public Representative Joe Nicholas First Nations Representative Keith Louis First Nations Representative Chief Fabian Alexis First Nations Representative Policy Committee Al Martin MoE1, Victoria Rebecca Reid Fisheries and Oceans, Vancouver David Facey BC Hydro, Burnaby Project co-ordination and Eva Schindler Fish and Wildlife, MoE1, Nelson scientific liaison Annual report preparation Eva Schindler Fish and Wildlife, MoE1, Nelson Marley Bassett Fish and Wildlife, MoE1, Nelson Editorial comments Eva Schindler Fish and Wildlife, MoE1, Nelson Dr. Ken Ashley British Columbia Institute of Technology, Burnaby, BC Contract administration John Krebs FWCP, Nelson Eva Schindler Fish and Wildlife, MoE1, Nelson James Baxter FWCP, Nelson Beth Woodbridge FWCP, Nelson Administrative support Jan McCarthy Corporate Services Division,MoE, Nelson Theresa Hall Corporate Services Division, MoE,Nelson Elaine Perepolkin Corporate Services Division, MoE,Nelson Linda Reid Corporate Services Division, MoE,Nelson Anne Reichert Environmental Stewardship, MoE, Nelson 1 Presently Ministry of Forests, Lands and Natural Resource Operations
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 138
Appendix 1 cont’d. Listing of 2010 Arrow Lakes Reservoir project focus, personnel and affiliation.
Project Focus Personnel Affiliation Fertilization Limnologist Eva Schindler Fish and Wildlife, MoE1, Nelson Fertilizer schedule Eva Schindler Fish and Wildlife, MoE1, Nelson Fertilizer application Crescent Bay Crescent Bay Construction, Nakusp Construction Galena Bay ferry Western Pacific Marine, Revelstoke Shelter Bay ferry Western Pacific Marine, Revelstoke Reservoir limnology Don Miller Kootenay Wildlife Services Ltd. sampling Marley Bassett Fish and Wildlife, MoE1, Nelson Eva Schindler Fish and Wildlife, MoE1, Nelson Phytoplankton analysis Dr. John Stockner Eco-Logic Ltd. Zooplankton and mysid Dr. Lidija Vidmanic Limno-Lab Ltd., Vancouver analysis Chemistry reporting Eva Schindler Fish and Wildlife, MoE1, Nelson Marley Bassett Fish and Wildlife, MoE1, Nelson Phytoplankton, zooplankton Eva Schindler Fish and Wildlife, MoE1, Nelson and mysid reporting Kokanee acoustic surveys Dale Sebastian Biodiversity Branch, MoE1, Victoria Tyler Weir Biodiversity Branch, MoE1, Victoria David Johner British Columbia Conservation Foundation Kokanee trawling Don Miller and staff Kootenay Wildlife Services Ltd. Kokanee aerial spawner Eva Schindler Fish and Wildlife, MoE1, Nelson surveys Albert Chirico Fish and Wildlife, MoE, Nelson Mark Homis Highland Helicopters, Nakusp Kokanee ground spawner Steve Arndt FWCP, Nelson surveys Trevor Oussoren BC Hydro, Castlegar Adam Croxall BC Hydro, Revelstoke Giles Shearing BC Hydro, Revelstoke Koreen Morrone BC Hydro, Revelstoke Krista Watts BC Hydro, Castlegar Karen Bray BC Hydro, Revelstoke Kokanee analysis and Dale Sebastian Biodiversity Branch, MoE1, Victoria Reporting Tyler Weir Biodiversity Branch, MoE1, Victoria David Johner British Columbia Conservation Foundation Harvey Andrusak Redfish Consulting Ltd. Greg Andrusak Redfish Consulting Ltd.
Regional support and Jeff Burrows Fish and Wildlife, MoE1, Nelson logistics FWCP Technical Jeff Burrows Fish and Wildlife, MoE1, Nelson Committee Dale Sebastian Biodiversity Branch, MoE1, UBC Brent Mossop BC Hydro, Vancouver Trevor Oussoren BC Hydro, Castlegar Steering Committee Tom Bell Environmental Stewardship, MoE, Nelson Dave Dunbar Environmental Stewardship, MoE1, Cranbrook Ted Down Biodiversity Branch, MoE, Victoria Kevin Conlin BC Hydro, Vancouver Doug Johnson BC Hydro, Castlegar Greg Mustard Public Representative Gerry Thompson Public Representative
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 139
Grant Trower Public Representative Joe Nicholas First Nations Representative Keith Louis First Nations Representative Chief Fabian Alexis First Nations Representative Policy Committee Ralph Archibald MoE, Victoria Rebecca Reid Fisheries and Oceans, Vancouver Edi Thom BC Hydro, Burnaby Project co-ordination and Eva Schindler Fish and Wildlife, MoE1, Nelson scientific liaison Annual report preparation Eva Schindler Fish and Wildlife, MoE1, Nelson Marley Bassett Fish and Wildlife, MoE1, Nelson Editorial comments Eva Schindler Fish and Wildlife, MoE1, Nelson Dr. Ken Ashley British Columbia Institute of Technology, Burnaby, BC Contract administration John Krebs FWCP, Nelson Eva Schindler Fish and Wildlife, MoE1, Nelson Steve Arndt FWCP, Nelson Beth Woodbridge FWCP, Nelson Administrative support Jan McCarthy Corporate Services Division, MoE, Nelson Theresa Hall Corporate Services Division, MoE, Nelson Elaine Perepolkin Corporate Services Division, MoE, Nelson Linda Reid Corporate Services Division, MoE, Nelson Anne Reichert Environmental Stewardship, MoE, Nelson 1 Presently Ministry of Forests, Lands and Natural Resource Operations
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 140
Appendix 2. Arrow Lakes Reservoir physical, chemical, plankton and kokanee sampling program for 2009.
Parameter sampled Sampling frequency Sampling technique Temperature, dissolved oxygen, Apr - Nov (a) SeaBird profiles at 8 AR sampling specific conductance stations from surface to 5 m off the bottom Transparency Apr - Nov Secchi disk (without viewing chamber) at 8 AR sampling stations Water chemistry: Apr - Nov (a) Integrated sampling tube at 0 - 20 m Specific cond., pH, silica, alkalinity and at stations AR 1-3 and AR 6-8. nutrients (TP, TDP, LL SRP, NO3+NO2, NH3); Discrete sample 5 m off the bottom at May - Oct stations AR 1-3, 6-8
Nutrients (TP, TDP, LL SRP, Discrete depth profiles, 2, 5, 10, 15 and NO3+NO2, NH3); Jun - Sep 20 m at stations AR 2 and AR 7.
(b) Integrated 0-20 m and a discrete sample 5 m off the bottom at stations Total and dissolved metals Jun and Sept AR 1-3 and AR 6-8. Chlorophyll a (not corrected for Apr - Nov Integrated sampling tube at 0 - 20 m at phaeophytin) stations AR 1-8
Jun – Sep Discrete samples - 2, 5, 10, 15 and 20 m, stations AR 2 and AR 7 Phytoplankton Apr – Nov (twice in Integrated sampling tube at 0 - 20 m at June) stations AR 1-8 Macrozooplankton Apr - Nov 3 oblique Clarke-Bumpus net hauls (3- minutes each) from 40 to 0 m at stations AR 1-3 and AR 6-8 (150 µm net) Mysid net sampling Apr - Nov 3 replicate hauls with mysid net, two deep and one shallow at stations AR 1- 3 and 6-8 Kokanee acoustic sampling Fall survey Standard MoE Simrad and Biosonics hydroacoustic procedure at 20 transects in Upper and Lower Arrow Kokanee trawling Fall trawl series Standard trawl series using oblique hauls at AR 1-3 and 6-8 in Upper and Lower Arrow Piscivore monitoring Creel survey Data collected from 3 locations – Jan - Dec Castlegar, Nakusp and Shelter Bay (catch, effort and biological information)
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Appendix 2 (cont’d) Arrow Lakes Reservoir physical, chemical, plankton and kokanee sampling program for 2010.
Parameter sampled Sampling frequency Sampling technique Temperature, dissolved oxygen, Apr - Nov (a) SeaBird profiles at 8 AR sampling specific conductance stations from surface to 5 m off the bottom Transparency Apr - Nov Secchi disk (without viewing chamber) at 8 AR sampling stations Water chemistry: Apr - Nov (a) Integrated sampling tube at 0 - 20 m Specific cond., pH, silica, alkalinity and at stations AR 1-3 and AR 6-8. nutrients (TP, TDP, LL SRP, NO3+NO2, NH3); Discrete sample 5 m off the bottom at May - Oct stations AR 1-3, 6-8
Nutrients (TP, TDP, LL SRP, Discrete depth profiles, 2, 5, 10, 15 and NO3+NO2, NH3); Jun - Sep 20 m at stations AR 2 and AR 7.
(b) Integrated 0-20 m and a discrete sample 5 m off the bottom at stations Total and dissolved metals Jun and Sept AR 1-3 and AR 6-8. Chlorophyll a (not corrected for Apr - Nov Integrated sampling tube at 0 - 20 m at phaeophytin) stations AR 1-8
Jun – Sep Discrete samples - 2, 5, 10, 15 and 20 m, stations AR 2 and AR 7 Phytoplankton Apr – Nov (twice in Integrated sampling tube at 0 - 20 m at June) stations AR 1-8 Macrozooplankton Apr - Nov 3 oblique Clarke-Bumpus net hauls (3- minutes each) from 40 to 0 m at stations AR 1-3 and AR 6-8 (150 µm net) Mysid net sampling Apr - Nov 3 replicate hauls with mysid net, two deep and one shallow at stations AR 1- 3 and 6-8 Kokanee acoustic sampling Fall survey Standard MoE Simrad and Biosonics hydroacoustic procedure at 20 transects in Upper and Lower Arrow Kokanee trawling Fall trawl series Standard trawl series using oblique hauls at AR 1-3 and 6-8 in Upper and Lower Arrow
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 142
Appendix 3. Sampling locations of Arrow Lakes Reservoir.
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 143
Appendix 4. Arrow Lakes Reservoir nutrient loading from fertilizer during 2009 – liquid ammonium polyphosphate (phosphorus: 10-34-0; N-P2O5-K2O and liquid urea-ammonium nitrate (nitrogen: 28-0-0; N-P2O5-K2O).
Week Date Load P 10-34-0 Load N 28-0-0 N:P Ferry mg/m2 kgs Tonnes mg/m2 Kgs Tonnes wt:wt 1 Apr 26 7.6 1,440 9.7 5.1 970 0.0 0.67 Galena 2 May 03 7.6 1,440 9.7 5.1 970 0.0 0.67 Galena 3 May 10 11.4 2,168 14.6 7.7 1,460 0.0 0.67 Galena 4 May 17 15.2 2,895 19.5 10.3 1,950 0.0 0.67 Galena 5 May 24 19.5 3,712 25.0 13.2 11,180 31.0 3.0 Galena 6 May 31 19.5 3,712 25.0 58.8 11,180 31.0 3.0 Galena 7 Jun 07 12.5 2,376 16.0 48.2 9,160 27.0 3.9 Galena 8 Jun 14 18.4 3,504 23.6 77.9 14,792 44.4 4.2 Shelter 9 Jun 21 12.5 2,376 16.0 85.1 16,166 52.0 6.8 Shelter 10 Jun 28 6.3 1,188 8.0 48.4 9,189 30.0 7.7 Shelter 11 Jul 05 10.6 2,019 13.6 87.3 16,592 54.4 8.2 Shelter 12 Jul 12 9.7 1,841 12.4 79.6 15,128 49.6 8.2 Shelter 13 Jul 19 11.4 2,168 14.6 86.4 16,406 53.4 7.6 Shelter 14 Jul 26 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 15 Aug 02 0 0 0 0 0 0 0 16 Aug 09 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 17 Aug 16 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 18 Aug 23 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 19 Aug 30 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 20 Sep 06 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter 21 Sep 13 12.2 2,316 15.6 85.5 16,238 52.4 7.0 Shelter Annual Total 248 47,046 317 1,211 238,789 740
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Appendix 4 (cont’d). Arrow Lakes Reservoir nutrient loading from fertilizer during 2010 – liquid ammonium polyphosphate (phosphorus: 10-34-0; N-P2O5- K2O) and liquid urea-ammonium nitrate (nitrogen: 28-0-0; N-P2O5- K2O) (N).
Week Date Load P 10-34-0 Load N 28-0-0 N:P Ferry mg/m2 kgs Tonnes mg/m2 Kgs Tonnes wt:wt 1 Apr 18 7.6 1,440 9.7 5.1 970 0.0 0.67 Galena 2 Apr 25 7.6 1,440 9.7 5.1 970 0.0 0.67 Galena 3 May 02 11.4 2,168 14.6 7.7 1,460 0.0 0.67 Galena 4 May 09 15.2 2,895 19.5 10.3 1,950 0.0 0.67 Galena 5 May 16 8.3 1,574 10.6 5.6 4,784 13.3 3.0 Galena 6 May 23 19.5 3,712 25.0 59.6 11,320 31.5 3.0 Galena 7 May 30 23.4 4,454 30.0 81.4 15,460 44.5 3.5 Galena 8 Jun 06 17.3 3,296 22.2 73.2 13,907 41.7 4.2 Shelter 9 Jun 13 11.8 2,233 15.0 80.1 15,213 49.0 6.8 Shelter 10 Jun 20 6.3 1,194 8.0 48.4 9,192 30.0 7.7 Shelter 11 Jun 27 5.9 1,128 7.6 48.8 9,272 30.4 8.2 Shelter 12 Jul 04 10.6 2,019 13.6 87.3 16,592 54.4 8.2 Shelter 13 Jul 11 11.4 2,168 14.6 86.4 16,406 53.4 7.6 Shelter 14 Jul 18 0 0 0 100.2 19,040 68.0 Shelter 15 Jul 25 5.9 1,128 7.6 48.8 9,272 30.4 8.2 Shelter 16 Aug 01 12.2 2,313 15.6 85.5 16,236 52.4 7.0 Shelter 17 Aug 08 12.2 2,313 15.6 85.5 16,236 52.4 7.0 Shelter 18 Aug 15 6.1 1,157 7.8 42.7 8,118 26.2 7.0 Shelter 19 Aug 22 12.2 2,313 15.6 85.5 16,235 52.4 7.0 Shelter 20 Aug 29 12.2 2,313 15.6 85.5 16,235 52.4 7.0 Shelter 21 Sep 05 12.2 2,313 15.6 85.5 16,235 52.4 7.0 Shelter Annual Total 229 43,573 293 1,218 235,103 735
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Appendix 5. Arrow Lakes Reservoir estimated total kokanee spawner numbers (peak counts expanded)
Index systems highlighted in green Expansion factor = 1.5 Upper Arrow 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Hill channel1 150,000 150,000 180,000 75,000 75,000 75,000 75,000 16,328 25,030 22,566 19,087 78,024 102,597 122,400 151,826 133,951 199,820 142,755 92,567 97,731 72,060 241508 Hill Creek other2 148,112 173,437 97,239 160,443 166,871 198,679 99,224 57,126 4,042 36,411 23,453 22,915 39,506 14,696 43,236 21,328 86,370 67,050 29,880 15,840 9,993 45091 Hill Creek egg take Bridge channel1 7,000 14,000 18,000 18,000 28,000 7,981 13,875 12,696 5,758 4,836 3,600 13,000 10,643 14,263 17,262 4,237 54,260 14,500 4,740 3,600 2,340 Alkokolex Bannock 150 0 0 0 128 53 0 1,200 Blanket 150 3,000 1,200 300 750 555 1,395 750 30 2,255 530 4,818 227 240 Cranberry 11,250 6,150 11,700 2,025 2,400 98 630 750 4,524 1,826 6,750 6,300 9,975 4,715 1,046 40,920 2,445 1,677 389 0 358.5 Crawford 3,750 825 270 45 900 90 2,130 1,500 3,246 4,523 Drimmie 12,000 10,500 3,150 7,500 1,650 6,300 1,710 3,450 3,932 1,732 3,300 8,775 7,425 7,646 953 27,015 18,770 6,807 4,359 3,360 16218 Halfway 28,500 30,000 21,150 6,000 2,700 1,680 900 525 1,175 7,050 7,058 12,638 8,850 46,050 4,305 3,150 1,913 620 649.5 Jordan 9,375 12,000 3,150 4,800 3,150 1,080 150 165 75 375 683 5,850 3,488 2,400 2,385 3,945 1,995 30 645 Kuskanax 71,250 65,250 24,150 37,050 15,750 5,003 7,995 750 525 2,715 9,675 8,700 26,775 33,450 63,600 11,595 7,980 2,820 312 1928 McDonald 15,000 6,300 4,590 9,968 7,244 2,277 8,963 17,076 5,997 23,790 10,260 7,151 McKay 1,875 1,650 1,200 2,025 75 75 615 375 1,406 11,130 281 9,120 28,877 1,938 1,031 0 2973 MacKenzie 4,500 2,625 75 Mulvehill 18 0 0 0 39 St. Leon 4,500 9,750 2,700 750 300 1,761 150 75 360 2,067 2,364 5,396 6,300 3,618 1,050 3,306 240 90 6 51 Thompson 3,000 3,150 600 2,147 1,800 1,185 153 1,530 3,518 2,966 2,651 Tonkawatla 6,750 8,250 1,200 6,750 2,550 1,695 525 99 840 975 3,773 10,950 4,203 25,350 8,805 1,875 8,145 1,950 1845
Upper Index stream 111,750 105,750 48,450 50,550 20,100 26,265 36,341 11,385 5,100 4,982 5,622 20,025 24,533 46,838 49,946 35,336 136,665 34,670 17,937 9,092 4,292 18,795 Upper Index tribs+ 409,862 429,187 325,689 285,993 261,971 299,944 210,565 84,839 34,172 63,959 48,162 120,964 166,636 183,934 245,008 190,615 422,855 244,475 140,384 122,663 86,345 305,394 Upper Arrow Total 462,912 490,062 362,739 338,943 306,786 297,124 188,197 113,355 51,224 78,653 66,244 163,232 205,833 270,337 302,271 225,950 561,918 304,793 154,799 137,912 90,671 311,267
Lower Arrow 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Burton 103,500 99,750 114,000 118,500 35,250 78,390 99,600 10,575 56,070 105,450 114,750 181,500 190,950 179,700 113,850 56,100 24,075 18,075 36600 Caribou 47,250 25,500 85,500 72,000 15,750 21,263 55,500 10,125 43,350 50,100 63,600 105,150 61,800 120,750 81,000 23,400 16,650 12,600 29775 Deer 8,250 6,000 9,750 9,000 2,250 1,659 17,250 16,875 11,838 16,977 25,916 19,170 32,273 12,542 10,938 11,477 34,500 17804 Dog 150 75 500 396 Eagle 750 750 300 2,175 915 6,029 5,624 0 345 0 13,875 0 0 0 4088 116 Fauquier 872 62 273 0 Heart 450 375 450 750 300 75 30 555 803 1,038 285 767 92 Mosquito 112,500 50,250 51,000 92,250 33,000 48,300 6,075 2,277 68,250 61,500 58,350 101,400 61,800 117,600 106,050 47,700 43,650 31,875 61668 Little Cayuse 500 333 1,305 2 Octopus 3,750 1,500 2,250 1,500 75 750 1,095 5,955 3,249 1,065 4,814 4,271 1,184 680 740 4,710 3179 Taite 3,750 563 1,500 4,050 1,500 4,335 930 16,715 23,220 11,792 12,012 21,741 510 17,400 11,976 6,834 5,132 10,289 7251 Lower Arrow Index 271,500 181,500 260,250 291,750 86,250 204,938 210,797 147,953 161,175 24,636 184,920 233,925 248,538 405,027 340,466 307,000 450,323 313,442 138,138 95,852 97,050 145,847 Lower Arrow Total 279,450 184,688 264,600 298,800 88,425 209,128 215,238 147,953 165,660 29,521 204,533 271,633 271,113 418,451 368,408 481,598 326,602 145,652 101,723 116,136 156,392 Columbia tribs u/s REV Overall Arrow Index 681,362 610,687 585,939 577,743 348,221 504,882 421,362 232,792 195,347 88,595 233,082 354,889 415,174 588,961 585,474 500,000 873,178 557,917 278,522 218,514 183,395 451,241 Total Arrow 742,362 674,750 627,339 637,743 395,211 506,252 403,435 261,308 216,884 108,174 270,777 434,865 476,946 688,788 670,679 225,950 1,043,516 631,395 300,451 239,634 206,807 467,658
1. Hill Creek and Bridge Creek represent total counts so were not subject to expansion factors. Additional data for Hill for the years 1979-87 available in Hill Creek electronic data records. NOTE: Italicized numbers indicate ground count, all others except Hill and Bridge were counted from the air. All peak counts (except complete counts at Hill and Bridge) have been expanded by 1.5x to represent total spawning escapement. 2. Hill Creek "other" is based on a combination of fence counts, electronic counters and ground counts for the spawning channel AND the creek downstream (see Hill Creek reports). Expansion factor, where applicable, is built into the estimate.
Note: Index counts in bold red italics were based on an average of the four previous years as no data was available ( eg 1993, 1994 and 2003)
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Appendix 6 Hill Creek Spawning Channel production data (fry and adult returns by age and year) and calculated fry to adult survival by cohort
Yellow highlighting shows example of which numbers are used in calculating fry surivival Blue highlights indicates age proportions have been adjusted Fry Total Estimated Fry Production Adult Return Data Age Class Proportions9 Returns by Age Class Brood Fry Fry-Adult Year EE FF Wild7 TOTAL8 Year # 2+ 3+ 4+ 2+ 3+ 4+ Age Data Source Year Year Survival - - - - 1981 ------Hill 1982 1,000,000 - 1,284,026 2,284,026 - - 1981 82 2.80% 1983 900,000 - 1,147,503 2,047,503 1983 15,277 - 1.00 - - 15,277 - assumed all age 3 from length frequency 1982 83 3.52% 1984 - - - 3,000,000 1984 69,936 - 1.00 - - 69,936 - assumed all age 3 from length frequency 1983 84 1.33% 1985 - 175,000 3,229,652 3,404,652 1985 60,176 - 1.00 - - 60,176 - assumed all age 3 from length frequency 1984 85 8.12% 1986 - - 4,511,267 4,511,267 1986 75,889 - 0.95 0.05 - 72,095 3,794 estimated from bimodal frequency distribution 1985 86 9.15% 1987 87,000 - 4,312,695 4,399,695 1987 107,528 0.63 0.37 - 67,743 39,785 - estimated from bimodal frequency distribution 1986 87 6.30% 1988 - - 4,586,296 4,586,296 1988 298,112 0.30 0.70 - 89,434 208,678 - estimated from bimodal frequency distribution 1987 88 5.13% 1989 - - 8,601,185 8,601,185 1989 323,437 - 1.00 - - 323,437 - assumed all age 3 from length frequency 1988 89 2.81% 1990 - - 6,592,040 6,592,040 1990 277,239 - 1.00 - - 277,239 - assumed all age 3 from length frequency 1989 90 4.15% 1991 - - 5,802,397 5,802,397 1991 235,443 - 1.00 - - 235,443 - assumed all age 3 from length frequency 1990 91 3.00% 1992 - - 3,610,373 3,610,373 1992 241,871 - 1.00 - - 241,871 - assumed all age 3 from length frequency 1991 92 2.05% 1993 - - 3,883,792 3,883,792 1993 273,679 - 1.00 - - 273,679 - assumed all age 3 from length frequency 1992 93 0.75% 1994 250,000 123,695 4,550,957 4,924,652 1994 174,224 - 1.00 - - 174,224 - assumed all age 3 from length frequency 1993 94 1.20% 1995 - 59,077 2,805,952 2,865,029 1995 73,840 - 1.00 - - 73,840 - assumed all age 3 from length frequency 1994 95 1.73% 1996 54,000 125,582 1,100,706 1,280,288 1996 29,072 - 1.00 - - 29,072 - assumed all age 3 from length frequency 1995 96 5.98% 1997 155,000 129,514 705,130 989,644 1997 58,977 - 1.00 - - 58,977 - assumed all age 3 from length frequency 1996 97 8.65% 1998 57,750 172,745 1,094,284 1,324,779 1998 42,540 - 1.00 - - 42,540 - assumed all age 3 from length frequency 1997 98 10.86% 1999 - 357,784 968,743 1,326,527 1999 100,939 0.20 0.73 0.07 20,188 73,685 7,066 Andrusak, Arrow fert report 1998 99 8.74% 2000 - 347,462 3,903,039 4,250,501 2000 142,103 0.52 0.46 0.02 73,894 65,367 2,842 Andrusak, Arrow fert report 1999 00 7.16% 2001 - - 8,888,753 8,888,753 2001 137,096 0.49 0.51 - 67,177 69,919 - Andrusak, Arrow fert report 2000 01 3.15% 2002 - - 8,433,296 8,433,296 2002 195,062 0.79 0.21 - 154,099 40,963 - estimated from bimodal frequency distribution 2001 02 2.48% 2003 - - 4,100,045 4,100,045 2003 155,279 - 0.95 0.05 - 147,515 7,764 Carder plus 1 year based on traw l 2+ size 2002 03 3.62% 2004 - - 229,231 229,231 2004 286,190 0.05 0.94 0.01 14,310 269,019 2,862 based on ages by J. DeGisi 2003 04 21.30% 2005 - - 671,233 671,233 2005 209,805 0.02 0.93 0.05 4,238 194,970 10,596 based on ages by J. DeGisi 2004 05 9.55% 2006 - - 5,009,523 5,009,523 2006 122,447 - 1.00 - - 122,447 - default to spaw ner lfreq 2005 06 6.57% 2007 - - 5,634,460 5,634,460 2007 113,571 0.38 0.43 0.19 43,157 48,836 21,578 Lidstone (Casselman rating >5) 2006 07 5.12% 2008 - - 7,042,421 7,042,421 2008 82,061 0.78 0.22 64,008 18,053 - Lidstone (Casselman rating >5) 2007 08 2009 - 3,829,792 3,829,792 2009 286,600 0.11 0.88 0.01 31,526 252,208 2,866 Lidstone (Casselman rating >5) 2008 09 2010 - 2010 317,554 0.15 0.81 0.04 47,633 257,219 12,702 Lidstone (Casselman rating >4) 2009 10 2011 - 2010 11
Example calculation: fry to adult survival for year 2000 fry equals the sum of cohort returns (highlighted in yellow) divided by fry production in 2000. Note that this method requires reliable ages for three consecutive years of adult returns
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Appendix 7. Equipment and Data Processing Specifications.
Echosounder Specifications and Field Settings
Category Parameter Value Echosounder Manufacturer Simrad EK60 Transceiver Frequency 120 kHz Max power 100 W Pulse duration 0.256 ms Band width 8.71 kHz Absorption coefficient 4.43 dB.km-1 Sound speed 1447 m.sec-1 Water column temperature 10.0 ºC Transducer Type split-beam Depth of face 0.75 m Orientation, survey method vertical, mobile, tow foil Sv, TS transducer gain 27.0 dB Angle sensitivity 23.0 dB nominal beam angle 7.0 degrees Data collection threshold -70 dB Ping rate 6 – 8 pps
Data Processing Specifications: SONAR 5 software version 6.0.0
Data conversion Amplitude/ SED thresholds -70 dB (40 Log R TVG) Sv, TS gain (correction) -27.0 dB from field calibration Single target filter analysis threshold -60 to -26 dB (35 1dB bins) Min echo length 0.7 – 1.3 Max phase deviation 0.30 Max gain compensation 3 dB (one way) Fish tracking Minimum no. echoes 3 Max range change 0.30 m Max ping gap 1 Density determination Integration method 20 log r density (total) from Sv/Ts Echo counting method* 40 log r density based on SED Fish size distributions From in situ single echo detections
• Note: echo integration was the main method used for determining fish densities, echo counting was employed only on layers having low fish densities.
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Appendix 8. Maximum likelihood estimates and bounds for all fish and for age 1-3 kokanee in October 2009 (a and b) and October 2010 (c and d) based on Monte Carlo Simulations. a) Statistics for 2009 kokanee of all ages (>–60 dB) two zones (Zone 1=TR 1-7; Zone 2=TR 8- 18)
Std. Stratum Zone Depth N Density Area Statistic1 Abundance Error Pop. 1 5-10 7 1.2 0.8 14171 16,867 1 10-15 7 14.2 5.1 13755 195,200 1 15-20 7 32.4 5.4 13455 436,091 1 20-25 7 39.5 6.1 13250 523,761 1 25-30 7 43.5 5.0 13046 567,795 LB= 7,868,000 1 30-35 7 29.6 4.8 12841 380,041 MLE= 9,083,000 1 35-40 7 12.9 2.9 12636 162,954 UB= 10,080,000 1 40-45 7 7.7 3.0 12432 95,175 1 45-50 7 3.6 1.0 12256 43,959 2 5-10 10 1.4 1.2 17656 25,397 2 10-15 10 12.3 3.0 16938 208,960 2 15-20 10 21.9 5.3 16324 358,257 2 20-25 10 52.2 13.8 15780 824,105 2 25-30 10 95.2 23.0 15236 1,450,423 2 30-35 10 107.9 10.2 14691 1,585,878 2 35-40 10 78.4 13.2 14147 1,109,714 2 40-45 10 45.3 12.9 13603 615,881 2 45-50 10 27.5 10.4 13013 358,041
b) Statistics for 2009 age 1-3+ kokanee (>–44 dB); two zones (Zone 1=TR 1-11, Zone 2=TR 12-18.)
Std. Stratum Zone Depth N Density Area Statistic1 Abundance Error Pop. 1 10-15 7 2.0 0.7 13755 26,875 1 15-20 7 8.1 1.7 13455 108,887 1 20-25 7 10.2 2.5 13250 135,393 1 25-30 7 13.8 1.8 13046 180,256 1 30-35 7 6.5 1.4 12841 82,824 1 35-40 7 2.1 0.6 12636 26,656 1 40-45 7 2.3 1.0 12432 29,003 1 45-50 7 0.9 0.4 12256 11,027 2 10-15 10 0.3 0.2 16938 5,442 LB= 2,263,000 2 15-20 10 4.4 1.3 16324 72,377 MLE= 2,722,000 2 20-25 10 17.7 8.4 15780 278,944 UB= 3,268,000 2 25-30 10 33.9 10.8 15236 517,185 2 30-35 10 40.2 3.8 14691 591,063 2 35-40 10 26.4 5.6 14147 373,696 2 40-45 10 15.2 5.1 13603 207,190 2 45-50 10 9.2 3.7 13013 119,537 1 MLE = maximum likelihood estimate, LB = lower bound, and UB = upper bound
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 149
Appendix 8 – continued
c) Statistics for 2010 kokanee of all ages (>–60 dB); three zones (Zone 1=TR 1-5; Zone 2=TR 6-10, Zone 3=TR 11-18)
Std. Stratum Zone Depth N Density Area Statistic1 Abundance Error Pop. 1 3-5 5 14.1 5.8 10272 145,308 1 5-10 5 52.9 24.0 10142 536,066 1 10-15 5 139.2 38.3 9817 1,366,165 1 15-20 5 87.6 13.3 9513 833,703 1 20-25 5 48.2 8.4 9349 450,474 LB= 11,973,000 1 25-30 5 32.6 5.5 9185 299,532 MLE= 14,513,000 1 30-35 5 18.3 2.7 9021 164,644 UB= 17,100,000 1 35-40 5 11.1 4.0 8857 98,463 1 40-45 5 4.6 1.3 8693 39,849 1 45-50 5 5.5 1.9 8542 46,698 2 5-10 5 24.9 6.0 11056 274,928 2 10-15 5 75.7 25.7 10753 814,075 2 15-20 5 109.6 23.3 10480 1,148,279 2 20-25 5 100.5 26.9 10328 1,037,996 2 25-30 5 94.0 17.5 10176 956,126 2 30-35 5 32.2 5.9 10024 322,772 2 35-40 5 5.7 2.1 9872 56,009 2 40-45 5 4.2 1.1 9720 40,422 2 45-50 5 1.2 0.5 9527 11,539 3 5-10 8 10.7 4.3 11082 118,494 3 10-15 8 22.2 6.2 10577 234,754 3 15-20 8 38.7 3.9 10086 390,332 3 20-25 8 109.9 29.6 9653 1,060,772 3 25-30 8 225.6 98.9 9220 2,079,949 3 30-35 8 122.9 54.4 8787 1,079,691 3 35-40 8 64.6 24.3 8354 540,081 3 40-45 8 32.1 11.3 7921 254,221 3 45-50 8 16.9 5.6 7511 127,116
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Appendix 8 - continued d) Statistics for 2010 age 1-3+ kokanee (>–44 dB); two zones (Zone 1=TR 1-5, Zone 2=TR 6- 18.)
Std. Stratum Zone Depth N Density Area Statistic1 Abundance Error Pop. 1 5-10 5 2.0 1.2 10142 19,824 1 10-15 5 21.8 7.8 9817 214,003 1 15-20 5 13.3 2.8 9513 126,853 1 20-25 5 10.0 2.2 9349 93,418 1 25-30 5 4.4 1.9 9185 40,105 1 30-35 5 2.3 0.8 9021 21,035 1 35-40 5 3.5 1.9 8857 31,063 1 40-45 5 1.9 1.1 8693 16,147 1 45-50 5 2.3 1.2 8542 19,499 LB= 2,185,000 2 10-15 13 1.3 1.0 21,330 28,415 MLE= 2,560,000 2 15-20 13 3.7 1.2 20,566 77,034 UB= 2,948,000 2 20-25 13 18.4 4.4 19,981 366,850 2 25-30 13 40.3 6.1 19,396 782,523 2 30-35 13 21.1 2.5 18,811 396,979 2 35-40 13 10.8 3.1 18,226 196,967 2 40-45 13 4.5 1.8 17,641 79,731 2 45-50 13 3.2 1.5 17,038 53,845
1 MLE = maximum likelihood estimate, LB = lower bound, and UB = upper bound
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Appendix 9. Habitat areas for kokanee surveys.
a) Water level and limnetic habitat areas in Arrow Reservoir during acoustic surveys. Survey Dates Water level Habitat area >20 m depth (km2) Year Month / day (m) Upper Arrow Lower Arrow Total 2004 Oct 3 430.04 194 93 287 2005 Oct 21 430.30 194 93 287 2006 Oct 19 430.50 194 93 287 2007 Oct 17 432.80 196 96 292 2008 Sept 28 437.50 199 100 299 2009 Oct 14-17 433.19 196 96 292 2010 Oct 4-7 434.50 197 97 294
b) Reach map and surface area estimates by Reach at full pool from three different sources: Canadian Hydrographic Series, Pieters et al. (1998) and Fisheries GIS map base. Reach Reservoir description Hydrographic Pieters et al Fisheries No. Charts (1998) Victoria (GIS)2 (digitized)1 (ha) (ha) (ha) 1 and 2 Lower Arrow basin3 15,493 17,724 17,113 3 Narrows 2,200 3,374 4 Upper Arrow basin4 19,298 30,600 21,327 5 Beaton Arm4 3,284 3,150 6 Revelstoke Reach (“flats”)6,437 6,981 Total 46,712 47,724 51,945
1 These estimates were used for expanding the acoustic/ trawl populations. 2. GIS Applications Unit, Fisheries Victoria used Arcview based on 1:50,000 scale polygons, April, 1999. 3. Includes 3,300 ha of shallow habitat (reach 2) which were not used in acoustic population estimates. Total Lower Arrow habitat included in acoustic population estimates is 12,193 ha Note: Narrows and Revelstoke reaches also not included in acoustic estimates (too shallow) 4. Total Upper Arrow acoustic habitat areas include reaches 4 & 5
Areas not included in acoustic population estimates Revelstoke Reach Revelstoke 2 6 Dam Upper Arrow Lower Arrow 3 4 1
Hugh Keenleyside Beaton Arm Dam Narrows 5
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Appendix 9 - continued c) Habitat area estimates by depth stratums used for acoustic population estimates.
Depth Revelstoke Upper Narrows Lower Depth Upper Lower (m) Reach Arrow ' Arrow (m) Arrow Arrow from surface from surface
full pool 6437 22,582 5,500 12,193 41 18,729 8,354 1 22,456 12,092 42 18,665 8,268 2 22,330 11,991 43 18,602 8,181 3 22,205 11,890 44 18,539 8,095 4 22,079 11,789 45 18,476 8,008 5 21,953 11,688 46 18,413 7,921 6 21,827 11,587 47 18,350 7,835 7 21,702 11,486 48 18,286 7,748 8 21,576 11,385 49 18,223 7,662 9 21,450 11,284 50 18,160 7,575 10 21,324 11,183 51 18,068 7,511 11 21,198 11,082 52 17,977 7,447 12 21,073 10,981 53 17,885 7,384 13 20,947 10,880 54 17,794 7,320 14 20,821 10,779 55 17,702 7,256 15 20,695 10,678 56 17,611 7,192 16 20,570 10,577 57 17,519 7,129 17 20,444 10,476 58 17,427 7,065 18 20,318 10,375 59 17,336 7,001 19 20,192 10,274 60 17,244 6,937 20 20,055 10,173 61 17,153 6,874 21 19,992 10,086 62 17,061 6,810 22 19,929 10,000 63 16,969 6,746 23 19,866 9,913 64 16,878 6,682 24 19,803 9,827 65 16,786 6,619 25 19,739 9,740 66 16,695 6,555 26 19,676 9,653 67 16,603 6,491 27 19,613 9,567 68 16,512 6,427 28 19,550 9,480 69 16,420 6,364 29 19,487 9,394 70 16,328 6,300 30 19,424 9,307 71 16,237 6,236 31 19,360 9,220 72 16,145 6,172 32 19,297 9,134 73 16,054 6,109 33 19,234 9,047 74 15,962 6,045 34 19,171 8,961 75 15,870 5,981 35 19,108 8,874 76 15,779 5,917 36 19,045 8,787 77 15,687 5,853 37 18,981 8,701 78 15,596 5,790 38 18,918 8,614 79 15,504 5,726 39 18,855 8,528 80 15,413 5,662 40 18,792 8,441
Data interpolated from Canadian Hydrographic Service charts: # 3056, 3057 and 3058, Areas are in Hectares (Ha.); Full pool elevation reference 440.24 m
Arrow Lakes Reservoir Nutrient Restoration Program, Years 11 and 12 (2009 and 2010) Report 153
Appendix 10. Love’s (1977) empirical relation of fish length to acoustic target strength.
TS = 19.1 log10 (L) – 0.9 log10 (F) - 62 where TS=target strength in decibels (dB), L=length in cm and F=frequency in kHz
HADAS size class Acoustic size range Fish length range2 (db)1 (dB) (mm) -35 -35 -33.1 317 500+ -38 -38 -35.1 221 317 -41 -41 -38.1 154 221 -44 -44 -41.1 107 154 -47 -47 -44.1 75 107 -50 -50 -47.1 52 75 -53 -53 -50.1 36 52 -56 -56 -53.1 25 36 -59 -59 -56.1 18 25 -62 -62 -59.1 12 18 1 HADAS was set up to view 30 dB range in 10 size classes of 3 dB 2 from Love’s (1977) empirical formula (Dorsal aspect).
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Appendix 11. Preliminary estimates of kokanee biomass for Arrow Lakes Reservoir. a) Kokanee number at age based on acoustic abundance and trawl proportions and mean weights by year and age from trawl sampling. Estimated number of fish Mean weight (g) Year Age 0+ Age 1+ Age 2+ Age 3+ Age 0+ Age 1+ Age 2+ Age 3+ 1993 2,960,000 664,151 520,755 15,094 2.2 39.1 111.3 118.2 1994 4,200,000 538,043 357,065 4,891 2.5 40.3 94.5 112.2 1995 2,630,000 450,000 450,000 - 2.7 38.7 91.8 1996 1,910,000 430,986 469,014 - 1.8 23.2 58.6 1997 1,272,000 336,000 564,000 - 1.5 34.6 74.3 1998 2,660,000 768,504 831,496 - 2.8 61.7 131.7 1999 3,860,000 1,330,233 869,767 - 4.9 103.1 238.9 2000 9,600,000 1,405,405 540,541 54,054 4.9 74.8 169.3 171.5 2001 15,400,000 2,592,063 1,861,905 146,032 3.5 54.9 124.9 169.9 2002 13,420,000 4,312,644 2,387,356 - 2.7 30.4 101.1 2003 4,956,000 4,738,122 1,887,845 74,033 3.1 37.3 97.7 136.6 2004 4,640,000 850,617 1,669,136 80,247 3.7 28.5 80.4 95.9 2005 3,290,000 670,635 777,937 241,429 3.5 56.7 97.1 121.5 2006 6,150,000 2,005,714 617,143 77,143 4.0 63.4 167.4 202.0 20071 4,344,000 661,440 496,080 - 3.6 59.7 160.5 - 2008 6,218,000 933,000 1,141,000 3.2 50.8 151.3 2009 6,361,000 1,174,000 1,548,000 3.5 52.0 137.8 2010 11,954,000 981,000 1,365,000 213,000 3.4 33.1 102.1 136.0 b) Calculated biomass (metric tons) in pelagic habitat and biomass density (kg/ha) for pelagic areas surveyed. Biomass (metric tonnes) Biomass Density (kg/ha) Year Age Age Age Age Total Age 0+ Age Age Age Total 0+ 1+ 2+ 3+ 1+ 2+ 3+ 1993 6.6 26.0 57.9 1.8 92 0.22 0.88 1.96 0.06 3.1 1994 10.3 21.7 33.7 0.5 66 0.36 0.75 1.16 0.02 2.3 1995 7.1 17.4 41.3 - 66 0.24 0.59 1.40 - 2.2 1996 3.4 10.0 27.5 - 41 0.12 0.34 0.94 - 1.4 1997 1.9 11.6 41.9 - 55 0.06 0.39 1.41 - 1.9 1998 7.5 47.5 109.5 - 164 0.25 1.59 3.68 - 5.5 1999 18.9 137.2 207.8 - 364 0.64 4.63 7.01 - 12.3 2000 46.6 105.2 91.5 9.3 253 1.59 3.55 3.09 0.31 8.5 2001 53.5 142.3 232.6 24.8 453 1.90 5.06 8.27 0.88 16.1 2002 36.0 131.2 241.4 - 409 1.23 4.50 8.27 - 14.0 2003 15.6 176.9 184.5 10.1 387 0.53 6.03 6.29 0.33 13.2 2004 17.2 24.3 134.2 7.7 183 0.60 0.84 4.65 0.27 6.3 2005 11 38.0 75.6 29.3 154 0.40 1.32 2.63 1.02 5.4 2006 24.4 127.2 103.3 15.6 271 0.85 4.43 3.60 0.55 9.4 2007 16.2 38.2 75.7 - 130 0.55 1.31 2.59 - 4.5 2008 20.0 47.5 172.6 240 0.67 1.60 5.80 - 8.1 2009 22.1 61.1 213.2 296 0.76 2.09 7.31 - 10.2 2010 40.6 32.5 139.4 29.0 241 1.38 1.10 4.73 0.98 8.2 Pre 6 22 52 0.4 81 0.2 0.8 1.8 0.0 2.8 Fert 27 88 156 10 282 0.9 3.0 5.4 0.4 9.7
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Appendix 12. Contour plot showing depth and distribution of the night time kokanee layer over the length of Arrow Reservoir based on hydroacoustic surveys in October 2009 and 2010. Note colour density indicates fish density in no.ha-1 as shown in legend
a) 2009 0 Fish/ha
210‐240 10
180‐210 (m)
150‐180 20 Depth 120‐150
90‐120 30
60‐90
30‐60 40
0‐30 1 2 3 4 5 6 7 8 9 10 18 12 13 14 15 16 17
Transect b) 2010 0 Fish/ha
210‐240 10
180‐210 (m)
150‐180 20 Depth 120‐150
90‐120 30
60‐90
30‐60 40
0‐30 123456789101811121314151617
Transect
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Appendix 13. Summaries of fish density (number/ha) by transect for age 0 and age 1-3 fish during October 2009 and 2010 acoustic surveys.
2009 2010
Transect All ages Age 0 Age 1-3 All ages Age 0 Age 1-3 No. 1 217 160 57 361 303 57 2 286 221 65 718 618 100 3 220 162 57 426 346 80 4 147 122 25 332 276 56 5 166 130 35 282 255 27 6 125 86 39 550 457 93 7 133 89 43 655 489 166 8 634 326 308 512 423 90 9 554 338 216 351 299 52 10 382 218 164 271 182 89 11 795 647 149 12 356 231 126 569 452 117 13 371 245 126 344 224 120 14 248 182 66 314 239 75 15 245 169 75 278 231 47 16 398 318 80 420 270 150 17 379 263 116 438 331 107 18a 855 659 196 2188 2014 173 19b 1433 1289 144 2064 1931 134 20c 1164 922 242 979 786 193
a. Transect No. 18 is new and is used with #11-17 to estimate Lower Arrow abundance b. Transects 19 and 20 are in Reach 2 in the vicinity of the Narrows and are used for qualitative ` information only at this time.
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Appendix 14. Total transect fish density (number/ha) 1999 to 2010.
Transect 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 1 474 420 376 696 300 160 160 301 498 379 217 361 2 459 441 643 1448 480 566 285 359 275 286 718 3 263 733 923 721 330 260 142 274 115 220 426 4 231 389 295 1306 184 253 77 275 206 362 147 332 5 160 298 505 873 214 180 139 224 78 166 282 6 158 442 605 375 561 217 348 218 162 192 125 550 7 130 320 1073 311 574 304 185 255 168 133 655 8 151 434 775 440 629 359 149 337 104 253 634 512 9 167 427 830 372 439 304 210 367 223 554 351 10 134 280 773 1245 284 240 254 318 324 310 382 271
20 1335 807 1109 1606 898 564 497 672 872 618 1164 979 21 1666 19 2191 647 1507 613 664 422 1668 429 1004 1433 2064
18 389 711 1593 3818 540 624 249 638 227 622 855 2188 11 204 502 2621 587 391 490 357 363 323 387 795 12 313 408 705 731 173 238 92 255 75 216 356 569 13 231 637 1181 1662 302 162 197 294 161 371 344 14 178 483 528 473 729 368 234 296 344 138 248 314 15 261 926 1682 1238 500 331 255 528 196 227 245 278 16 203 408 941 734 844 266 285 480 222 193 398 420 17 253 194 781 621 938 693 231 269 241 149 379 438
UpperArrow 233 418 680 779 399 284 195 293 215 299 286 446 Lower Arrow 254 534 1254 1233 552 396 237 390 224 276 408 668
Note: Upper Arrow is represented by transects 1-10 Lower Arrow is represented by transects 11-18 Narrows area is represented by transects 19-21 (not included in annual kokanee population as it includes unknown proportion of other species and represents a very small area
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Appendix 15. a) Estimates of biomass density (kg.ha-1) and biomass (tonnes) used in generalized linear mixed effects model & b) spawner/recruits data for Ricker model analysis.
a) Era Year Biomass Density Biomass Length Pre 1993 5.12963 151.9872 241 Pre 1994 3.97153 115.2941 240 Pre 1995 3.75155 110.5938 235 Pre 1996 2.11498 61.71491 207 Pre 1997 2.29201 67.91064 209 Pre 1998 7.20085 214.4346 250 Post 1999 17.39126 515.2906 297 Post 2000 13.77722 408.2091 302 Post 2001 20.85465 586.6829 259 Post 2002 16.20198 472.7737 213 Post 2003 15.20130 445.8389 214 Post 2004 9.72758 280.9424 206 Post 2005 7.58957 218.0559 212 Post 2006 11.53419 331.3887 259 Post 2007 5.86015 170.9991 247 Post 2008 8.99826 267.5814 228 Post 2009 12.65843 369.3728 241 Post 2010 10.84556 319.7218 243
b) Spawner Era Year Spawners* Recruits* Ln (R/S) Pre 1993 0.350000 4.20 2.484907 Pre 1994 0.300000 2.63 2.170957 Pre 1995 0.261307 1.91 1.989164 Pre 1996 0.216884 1.27 1.767412 Pre 1997 0.108173 2.66 3.202354 Pre 1998 0.270776 3.86 2.657131 Post 1999 0.434864 9.60 3.094485 Post 2000 0.476941 15.40 3.474730 Post 2001 0.688785 13.40 2.969572 Post 2002 0.670675 4.96 2.000877 Post 2003 0.550000 4.68 2.141135 Post 2004 1.043515 3.29 1.148293 Post 2005 0.631393 6.15 2.276279 Post 2006 0.300451 4.34 2.670347 Post 2007 0.239634 6.22 3.256412 Post 2008 0.206815 6.36 3.425961 Post 2009 0.467658 11.95 3.240749 * Fall fry acoustic and spawner estimates in millions
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