Nass Chinook Mark-Recapture Project, 2016. Year 8

The Pacific Salmon Commission (PSC) has established a 15% coefficient of variation (CV) as an acceptable level of uncertainty for estimating Sentinel Stock Program (SSP) Chinook Salmon populations that are used in managing US and Canadian Since 2009, the Pacific Salmon Commission (PSC) Chinook Technical Committee (CTC) has established a 15% coefficient of variation (CV) as an acceptable level of uncertainty for estimating
Chinook Salmon populations that are used in managing US and Canadian Chinook Salmon fisheries. We are requesting funding support from the PSC Northern Fund to continue the Upper
Nass Chinook Salmon mark?recapture (MR) program initiated in 2009 in order to achieve the PSC CTC data standard. Past funding from the PSC to the Nisga?a Fisheries and Wildlife Department (NFWD) supported increased marking and recovery efforts for generating accurate estimates of abundance for the Upper Nass Chinook Salmon aggregate population, meeting the CV data standard in six of the seven years that funding was provided (Table 1; Alexander et al. 2010?2015; Beveridge et al. 2016 (draft)). Overall, the Nass Chinook Salmon program has achieved the CV data standard in 15 of 24 (63%) years since the start of the Nisga?a Fisheries Program in 1992. The main factor determining CV has been the number of marked Chinook Salmon
recovered at terminal spawning areas in the Upper Nass River (Figure 2). Achieving an adequate number of marked recoveries has required two conditions to be met: (1) a sufficient number of
Chinook Salmon are marked (>1250) at the fishwheels and (2) sufficient effort is made on the spawning grounds for recovering marks such that >50 marks are recovered. Results from the past
funded studies have indicated that these requirements can be met, even in low return years, by marking adult Chinook Salmon at both fishwheel marking locations (Gitwinksihlkw and Grease
Harbour), examining fish throughout the run at Meziadin Fishway and the Kwinageese videocounting weir, and conducting carcass surveys at Damdochax Creek. These three Upper Nass spawning systems represent on average 39% of the aggregate spawning stock based on stock composition estimates and are geographically separated to be representative of all stocks that spawn above the marking sites.
The primary purposes of the proposed project are to: (1) continue to augment marking and recovery efforts, (2) improve methods for generating accurate and precise MR escapement estimates for the Upper Nass River Chinook Salmon aggregate stock, and (3) achieve unbiased population estimates that meet the PSC CTC data standard (CV ? 15%). This proposal is relevant to the Pacific Salmon Treaty and the goals of the Northern Fund. The Upper Nass Aggregate stock is one of the existing PSC CTC wild Chinook Salmon indicator stocks. The Upper Nass Chinook Salmon population is a large stock group averaging 18,000 spawners per annum (35,000 total run) since 1992. Upper Nass Chinook Salmon are very important relative to the overall coast?wide Chinook Salmon resource and especially to the Nisga?a Nation who harvest between 4000 and 12,000 Chinook Salmon on an annual basis as part of their FSC domestic
fishery. The Nass stock also represents a very stable proportion of the Chinook Salmon captured in other northern BC and Alaskan fisheries. The Upper Nass stocks contribute to Aggregate
Abundance Based Management (AABM) fisheries including Southeast Alaska (SEAK, all gear types), Northern British Columbia (NBC) Troll, and Queen Charlotte Islands (QCI) Sport. In
addition, they contribute to Canadian Individual Stock Based Management (ISBM) fisheries including tidal gillnet, tidal sport, tidal First Nations, freshwater sport, and freshwater First Nations. Upper Nass Chinook Salmon are a completely natural population with no history of enhancement and likely very little, if any straying from enhanced systems.