The Kitwanga River is a tributary of the Skeena River, located 250 km from the coast and supports significant runs of Pacific salmon. Kitwanga sockeye are genetically unique and a distinct conservation unit as described under Canada’s Wild Salmon Policy. Historically, sockeye returns to the Kitwanga were in the tens of thousands and they supported a number of sustenance and economic fisheries. In more recent times the stock has been depressed and in many years returns are not enough to meet the minimum biological requirements for the stock. In response to this conservation concern the Gitanyow, with help from organizations like the Pacific Salmon Commission and Fisheries and Oceans Canada, have initiated a rebuilding plan to preserve the genetic uniqueness of the stock and to try and rebuild it to more historical levels. Rebuilding efforts have included the creation of spawning platforms in 2006 and 2007 in Gitanyow Lake, the enhancement of the stock through hatchery production in 2006 & 2007 and a reduction in the overall exploitation rate on the stock through the implementation of strict fisheries management guidelines. The results of the rebuilding efforts have been mixed as the stock has responded positively in some year classes but not in others. To date, millions of dollars have been spent to rebuild the stock and many more millions of dollars have been foregone in lost revenues in the Canadian commercial catch, in efforts to get more spawners back to the Kitwanga River and Gitanyow Lake.

Since 1999, the GFA in partnership with DFO and other organizations have been studying Kitwanga sockeye and Gitanyow Lake in an attempt to better understand the stock and the environment where they reside. Annual smolt and adult enumeration operations have been ongoing for over 10 years, while Gitanyow Lake studies were performed between 1999 and 2003. Lake studies were abandoned due to funding constraints and because it was found that freshwater smolt production from the system at that time was very high and the lake limnology was not likely impacting smolt production. However, since that time we have noticed a significant decrease in freshwater smolt production which has renewed the need to look at the lake biology in more detail.

Babine sockeye are the single largest sockeye stock in the northern boundary area. The stock currently provides approximately 90% of the Skeena sockeye. Recent returns have generally been below average, and the 2013 return in the range of 400,000 was one of the lowest since the early 1950’s. Although the specific causes for reduced productivity in recent years are unknown; one potential contributing factor may be losses due to infectious or parasitic disease. For instance, disease outbreaks of Ich and Loma in the Fulton River spawning channels in 1994 and 1995 resulted in exceedingly high prespawn mortalities (PSM) that ultimately lead to an estimated 154 million fewer sockeye salmon fry than the historical average. More recently in 2009 and 2013, Ich and Loma were found in association with upwards of 40% PSM in the largest channel at Fulton, resulting in sharp decreases in production from those two brood years. Another pathogen known to cause significant mortality in British Columbian and Alaskan Sockeye salmon populations is IHNV. Despite the potential impact that these pathogens may have on the productivity of Skeena sockeye stocks, our knowledge concerning the basic epidemiology (i.e. prevalence and distribution) of these agents is limited to that obtained through opportunistic sampling by DFO stock assessment and science staff.

Consequently the objective of this project is to conduct routine monitoring of Babine Sockeye stocks to better understand the disease epidemiology of deadly pathogens (Ich, Loma, and IHNV) with the goal of acquiring information to aid management in developing strategies to reduce disease impacts.