An ongoing sockeye enhancement program has been conducted at Tatsamenie Lake over the period 1990 through 2015. As part of continuing attempts to increase fry to smolt survivals of enhanced Tatsamenie sockeye, fry rearing experiments were conducted at Tatsamenie Lake from 2008 through 2015. The 2009 through 2015 projects involved onshore fry rearing using an IHNV free water source and ‘Capilano’ rearing troughs. The operational plan in 2015 was to continue with the program and evaluate the adult returns from, 2009, 2010 and 2011. For the 2015 project 209,000 eggs of the 1.288 million eggs that were obtained from the BY 2014 Tatsamenie Lake egg take were allocated to the 2015 rearing project. The emergent fry were reared at Snettisham for approximately 30 days to a mean weight of 0.98 gm before delivery by floatplane to Tatsamenie Lake on May 30. A total of 186,000 fry was delivered to Tatsamenie Lake for the extended rearing project. An additional 731,000 unfed fry were released into the lake. All fry from Snettisham hatchery possessed separate unique thermal marks for both the reared group and the directly planted group. The fry were fed EWOS brand fish food applicable to the fry size. Elevated mortalities were observed beginning six days after fry delivery. Fry mortalities continued to rise over the following three weeks in spite of treatment with Chloramine T and Parasite S. A seven day course of Florfenicol was initiated June 25 which resulted in a decrease to minimal mortalities by July 5. A total of 27,699 (14.9%) of the reared fry died as a result of the disease outbreak. The remaining 164,000 fry were released on July 6 at an average weight of 1.7 gms.
The 2015 Tatsamenie smolt mark/recapture and sampling project generated an emigrating smolt population estimate of 558,000 (S.E. = 64,000). The structure of the population by cohort was: 428,000 (76%) wild age 0+, 1+ and 2+; 78,000 (14%) fed age 0+ and 1+; and 57,000 (10%) age 0+ and 1+ directly planted fry. Approximately 58,000 (10%) of the out migrating smolts were age 0+ fish. Of the 0+ smolts, 54,000 (93%) were BY 2014 fed fry. Results from the 2015 smolt sampling and population estimates indicate the combined age 0+ and age 1+ egg to smolt survival of the BY 2013 fed fry was 80%. The BY 2013 unfed and wild combined age 0+ and age 1+ egg to smolt survivals were 4.5% and 1.6% respectively.
Reconstruction of the Tatsamenie Lake 2015 adult return indicates that 56% and 44% of the adult production was of wild and enhanced origin respectively. Total 2015 Tatsamenie sockeye production was estimated at 2,700 fish, 1.6% of total Taku River sockeye production. Canadian and U.S. fisheries in 2015 caught an estimated 1,196
Tatsamenie origin sockeye for an exploitation rate of 44%.