Salmon Run Timing

Salmon begin their return to the Copper River in late April, although the “run” really begins late in the second week of May, when Chinook and sockeye salmon arrive in large numbers. Early July, the Chinook are gone, and by late July, the various runs of sockeye are almost over, and the coho start to arrive. By October, except for the few late run coho, the season of the salmon is over. Between 1985 and 2004, on average about 2.5 million salmon returned each year to the Copper River/Bering River system.

There have been three multi-year studies of salmon run timing within the Copper River:

1. Spawning distribution and run timing of Copper River sockeye salmon

The purpose of this three-year (2005-07) project was to use radiotelemetry techniques to assess the spawning distribution and run timing for adult sockeye salmon Oncorhynchus nerka stocks in the Copper River, Alaska. This report summarizes the results from the 2007 field season and synthesizes results from the 2005-2007 studies. Specific objectives were to: (1) estimate the proportions of sockeye salmon returning to major spawning areas of the Copper River (Lower Copper, Chitina, Tonsina, Klutina, Tazlina, Gulkana and Upper Copper rivers) such that the proportions were within 10% of the true proportions 95% of the time; and (2) describe the stock-specific, migratory timing profiles of sockeye salmon in the Copper River at the point of capture in Baird Canyon. In 2007 the largest proportion of spawners returned to the Klutina River drainage (0.54), followed by the Tazlina (0.10), Gulkana (0.09), Lower Copper (0.09), Upper Copper ( 0.07), Chitina (0.05), and Tonsina (0.05) rivers. Run-timing patterns at the capture site varied among stocks in 2007. The mean date of passage at Baird Canyon varied from 5 June for the Tazlina stock to 22 July for the Tonsina stock.

Spawning distributions varied significantly over the three-year study period (χ2 = 85.6, df = 12, P < 0.001). The largest proportion of spawners returned to the Klutina River in all three years (0.35 in 2005, 0.45 in 2006, and 0.54 in 2007). Contributions by the remaining six spawning tributaries included: Lower Copper (0.06–0.07), Chitina (0.05–0.08), Tonsina (0.05–0.06), Tazlina (0.10-0.12), Gulkana (0.07–0.16), and Upper Copper (0.07–0.28) rivers. Run timing patterns followed similar trends across years; fish returning to rivers in the upper reaches of the Copper River tended to have earlier run timing than those returning to the lower reaches of the Copper River. Mean date of passage at Baird Canyon ranged from 31 May for the Tazlina River (2005) to 22 July for the Tonsina River (2007).

Citation: Wade, G. D., K. M. van den Broek, J. W. Savereide, and J. J. Smith. 2008. Spawning distribution and run timing of Copper River sockeye salmon. U.S. Fish and Wildlife Service, Office of Subsistence Management, Fisheries Resource Monitoring Program, Final Report (Study No. 05-501). The Native Village of Eyak, Cordova, Alaska.

2. Inriver Abundance, Spawning Distribution and Run Timing of Copper River Chinook Salmon, 2002–2004
From 2002–2004, radiotelemetry methods were used to estimate spawning distribution, run timing, and inriver abundance of Chinook salmon Oncorhynchus tshawytscha in the Copper River, Alaska. Chinook salmon were captured in fish wheels in the lower Copper River near Baird Canyon, and approximately 500 fish each year were fitted with radio transmitters. Radio-tagged fish were tracked to upriver destinations using a combination of ground-based receiving stations and aerial tracking techniques. Chinook salmon in the Copper River spawned in six major tributaries, and their spawning distribution varied considerably during the study for the Gulkana, Tonsina, and Chitina stocks, while the Klutina, Tazlina, and East Fork Chistochina stocks remained relatively constant. The estimated spawning proportions by major tributary were 0.10 (2002), 0.11 (2003) and 0.12 (2004) for the Klutina River; 0.08, 0.10 and 0.19 for the Tonsina River; 0.27, 0.17 and 0.20 for the Gulkana River; 0.29, 0.34 and 0.22 for the Chitina River; 0.04, 0.05 and 0.02 for the Tazlina River; and, 0.05, 0.05 and 0.06 for the East Fork Chistochina River. The estimated proportions of Chinook salmon located in the nine aerial index streams accounted for 0.46 (2002), 0.34 (2003), and 0.35 (2004) of Chinook salmon total escapement.

Run-timing patterns varied among the major spawning stocks but the same general pattern existed over time, where upriver stocks migrated past the capture site earlier than downriver stocks. The mean date of passage ranged from as early as 26 May for Chinook salmon bound for the upper Copper River in 2003 to as late as 24 June for the 2002 Klutina River mainstem spawners. In addition, over all 3 years of the study, the run timing of Chinook salmon bound for the tributaries of the Tonsina and Klutina rivers was earlier than their mainstem counterparts.

Two-event mark-recapture techniques were used to estimate inriver abundance at the lower boundary of the Chitina subdistrict dip net (CSDN) fishery. In the first event, Chinook salmon were radio-tagged downriver of the CSDN fishery. The total estimated harvest in the CSDN fishery comprised all fish examined for marks in the second event, and those fish harvested with radio tags comprised recaptured fish from the first event. Total abundance was estimated to be 32,873 (SE=8,863) in 2002, 33,488 (SE=8,389) in 2003, and 33,793 (SE=11,038) in 2004 for Chinook salmon ≥ 620 mm mideye-to-fork (MEF). However, based on information regarding catchability of Chinook salmon during the early portion of the run from a concurrent spaghetti tagging mark-recapture study that utilized fish wheels and not the CSDN fishery as the recapture event, the estimates of abundance from this study which expand the mark-recapture estimate to account for the early portion of the run not sampled are likely biased low.

Citation: Savereide, J. W. 2005. Inriver abundance, spawning distribution, and run timing of Copper River Chinook salmon, 2002–2004. Alaska Department of Fish and Game, Fishery Data Series No. 05-50, Anchorage.

3.  Relative abundance, migratory timing, and overwintering and spawning distribution of steelhead in the Copper River Drainage

Radiotelemetry methods were used to determine steelhead Oncorhynchus mykiss spawning locations, stock-specific run timing profiles, overwintering areas, and the magnitude of the total return to the Upper Copper River (tributaries north of the Chugach Mountains). Steelhead were captured with fish wheels and dip nets in the mainstem Copper River below Wood Canyon. A total of 53 steelhead were fitted with radio tags in the fall of 2005 and 42 were fitted in the fall of 2006. Radio-tagged fish were tracked using a combination of ground-based receiving stations and aerial tracking techniques. Overwintering areas included their natal rivers such as the Gulkana and Hanagita Rivers, the Tazlina Lake outlet, and the turbid mainstems of the Copper, Chitina, and Tazlina rivers. Steelhead in the Upper Copper River spawned in the Gulkana, Tazlina, and Chitina river drainages. The estimated proportion of steelhead spawning in the Dickey and Hanagita lake spawning areas was 0.08 (SE=0.06) in 2006 and 0.22 (0.09) in 2007. Based on stock assessment work in these two areas conducted in previous years, the total run of steelhead in the Upper Copper River drainage is likely within the range of 1,000–45,000. The large range reflects a large annual variation in the proportion spawning in these areas, and poor precision of the annual estimates. The estimated spawning proportions by drainage in 2006 were 0.54 (SE=0.11) for the Tazlina, 0.14 (SE=0.07) for the Chitina, and 0.31 (SE=0.10) for the Gulkana. In 2007, the estimated spawning proportions by drainage were 0.39 (SE=0.10) for the Tazlina, 0.38 (SE=0.11) for the Chitina, and 0.22 (SE=0.09) for the Gulkana. In 2005, the mean date of passage past the capture site was 22 September for steelhead bound for the Tazlina drainage and 24 September for steelhead bound for the Chitina and Gulkana drainages. In 2006, the mean date of passage past the capture site was 25 August, 23 August, and 18 August for steelhead bound for the Tazlina, Chitina, and Gulkana drainages, respectively. Outmigration dates from the Tazlina, Gulkana, and Chitina rivers ranged from 20 May to 24 June in 2006 and 4 May to 20 June in 2007.

Citation: Savereide, J. W. 2008. Relative abundance, migratory timing, and overwintering and spawning distribution of steelhead in the Copper River Drainage. Alaska Department of Fish and Game, Fishery Data Series No. 08-56, Anchorage.

© 2011 Copper River Knowledge System