LIMNOLOGICAL AND SOCKEYE SALMON PRODUCTIVITY INVESTIGATIONS IN SALMON AND GLACIAL LAKES: 1994-1995 PROJECT REPORT G. L. Todd G. B. Kyle REGIONAL INFORMATION REPORT' NO. 5J96-02 Alaska Department of Fish and Game Division of Commercial Fisheries Management and Development P.O. Box 25526 Juneau, AK 99802-5526 February 1996 I The Report Information Report Series was established in 1987 to provide an information access system for all unpublished divisional reports. These reports frequently serve diverse ad hoc informational purposes or archives basic uninterpreted data. To accommodate timely reporting of recently collected information, reports in this series undergo only limited internal review and may contain preliminary data; this information may be subsequently finalized and published in the formal literature. Consequently, these reports should no be cited without approval of the author or the Division of Commercial Fisheries. LEVNOLOGICAL AND SOCKEYE SALMON PRODUCTIVITY INVESTIGATIONS IN SALMON AND GLACIAL LAKES: 1994-1995 PROJECT REPORT G. L. Todd G. B. Kyle REGIONAL INFORMATION REPORT NO. 5596-02 Alaska Department of Fish and Game Division of Commercial Fisheries Management and Development P.O. Box 25526 Juneau, Alaska 99802-5526 February 1996 AUTHORS Gary L. Todd is the project biologist for the Nome area lake investigations for the Alaska Department of Fish and Game, Limnology Unit, Division of Commercial Fisheries Management and Development, 34828 Kalifomsky Beach Road, Suite B, Soldotna Ak 99669. Gary B. Kyle is the southcentral Regional Lirnnologist for the Alaska Department of Fish and Game, Limnology Unit, Division of Commercial Fisheries Management and Development, 34828 Kalifornsky Beach Road Suite B, Soldotna Ak 99669. ACKNOWLEDGMENTS We thank the following people involved with this joint project: Pete Velsko (ADF&G) for logistical support, Joe Webb (BLM) for logistical support and project planning, Richard Dederick (ADF&G) and Leah Weyapuk (KAWERAK) for Salmon Lake smolt and lirnnology data collection, Larry Wilhnott and Jason McClellan (BLM) for Glacial Lake smolt and Salmon Lake adult data collection, and Stan Carlson (ADF&G) for statistical support in data analysis. TABLE OF CONTENTS Section INTRODUCTION ........................................................................................................................ 7- Study Site Description ........................................................................................................ 3 MATERIALS AND METHODS .................................................................................................... 3 Smolt Enumeration and Sampling ........................................................................................ 3 Adult Enumeration and Sampling......................................................................................... 4 Limnology Surveys ............................................................................................................4 Hydroacoustic/Townet survey .............................................................................................5 RESULTS ............................................................................................................................ 5 Smolt Abundance. Size. and Age. ......................................................................................... 5 Adult Abundance. Size. and Age .......................................................................................... 5 Li~nnologicalPanmeter; .................................................................................................... 6 Light Penetration, Temperature, and Dissolved Oxygen ...................1 ................................. 6 General Water Chemistry ............................................................................................... 6 Nutrients ................................................................................................................. 7 Phytoplankton .............................................................................................................. 7- Zooplankton ................................................................................................................... 1 Salmon Lake Hydroacoustic Estimate of Rearing Fish ............................................................ 8 DISCUSSION ............................................................................................................................ 8 RECOMMENDATIONS............................................................................................................... 9 LITERATURE CITED ................................................................................................................ 10 APPENDIX .......................................................................................................................... 31 LIST OF TABLES -Table 1. Daily migration of sockeye salmon smolts from Glacial Lake, 1995. 2. Population estimate, size, and age of Glacial Lake sockeye salmon smolts by sample period, 1995. 3. Size and age of Salmon Lake sockeye salmon smolts, 1995. 4. Daily migration of sockeye salmon adults for Salmon Lake, 1995. 5. Mean len,@ and age composition of adult sockeye salmon sampled at Salmon Lake, 1995. 6. Aerial survey estimates of sockeye salmon in the Salmon Lake system and in Glacial Lake, and the harvest of sockeye salmon destined for Salmon Lake in the Port Clarence District, 1963- 1995. 7. Summary of lirnnological parameters (seasonal means by year, station, and depth) for Salmon Lake, 1994-1995. 8. Sumnary of limnological parameters (seasonal means by year, station, and depth) for Glacial Lake, 1994- 1995. 9. Summary of seasonal mean macro-zooplankton density and biomass in Salmon Lake, 1994-1995. 10. Summary of seasonal mean macro-zooplankton density and biomass in Glacial Lake, 1994-1995. 1 1. Densities and population estimates of juvenile fish rea~gin Salmon Lake by transect based on the 26 September 1995 hydroacoustic survey. 12. Seasonal mean macro-zooplankton density and biomass for 20 sockeye salmon nursery lakes in Alaska, showing the relative comparison for Salmon and Glacial lakes. LIST OF FIGURES 1. Map of the Nome area (Seward Peninsula) showing the location of Salmon and Glacial lakes, and the Pilgrim River. 2. Map of Salmon Lake showing general morphometric information, and the locations of the lirnnological survey stations and hydroacoustic transects. 3. Map of Glacial Lake showing general morphometric information, and locations of the lirnnological survey stations. 4. Migration timing by age class for sockeye salmon smolts emigrating Glacial Lake, 1995. 5. Mean density of edible and non-edible phytoplankton at 1 m in Salmon and Glacial lakes, 1994. 6. Macro-zooplankton density and biomass by sample date in Salmon Lake, 1995. 7. Macro-zooplankton density and biomass by sample date in Glacial Lake, 1995. 8. Map of Salmon Lake showing the distribution of rearing fish by density for the 26 September 1995 hydroacoustic survey. 9. Relative percent of rearing fish by depth stratum in Salmon Lake based on the 26 September 1995 hydroacoustic survey. LIST OF APPENDICES Appendix A: Results of analysis for elements in water samples collected from Salmon and Glacial lakes in 1994. A. 1. ICP-MS analysis Appendix B: Results of analysis for phytoplankton in water samples collected from Salmon and Glacial lakes in 1994. B. 1. Phytoplankton density, volume, and carbon content for samples collected from station 1 at Salmon Lake, 1994. B.2. Phytoplankton density, volume, and carbon content for samples collected from station 3 at Salmon Lake, 1994. B.3. Phytoplankton density, volume, and carbon content for samples collected from station 1 at Glacial Lake, 1994. B.4. Phytoplankton density, volume, and carbon content for samples collected from station 3 at Glacial Lake, 1994. ABSTRACT In 1994 and 1995 limnological and fisheries investigations were conducted on Salmon and Glacial lakes to assess sockeye salmon Oncorhynchus nerka rearing capacity and the potential to increase the run size of these stocks. Both lake systems were sampled for emigrating smolts; in Salmon Lake the smolt either migrated earlier than the time of gear deployment or avoided the trap, while a total of 13,485 sockeye salmon smolts were enumerated at Glacial Lake. An adult weir was installed in Pilgrim River, the outlet of Salmon Lake and resulted in a partial escapement count of 2,170. It is believed a portion of the sockeye salmon escapement entered the lake before the weir was fish proof as the aerial index count was over 6,000. Both lakes are ultra-oligotrophic as nutrient and chlorophyll a concentrations were low compared to other lakes supporting sockeye salmon. In 1995, when these lakes were sampled over the summer, a modest level of macro- zooplankton biomass was observed in Salmon Lake (250 mg/m2) and a lower level (100 rn@m2) was found in Glacial Lake. On a comparative basis of macro-zooplankton biomass in other Alaskan Ilursery.lakes. these two lakes appear to currently have a deficient number of sockeye salmon. Historical aerial survey estimates of sockeye salmon escapement in Salmon Lake have averaged 1,850 and in Glacial Lake the average has been 700. Based on the first 111 year of sampling in 1995, the zooplankton forage base indicates that both lakes could support additional numbers of rearing fry. However, the critical question is what level of additional sockeye salmon fry can these lakes support and simultaneously maintain