Ninilchik River Chinook Salmon Stock Assessment and Supplementation, 2016-2018 PDF Download

Author: Holly I. Dickson
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 0

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Book Description
During 2016–2018, an instream video weir enumerated the entire run of Ninilchik River Chinook salmon with average wild and hatchery escapements of 1,121 and 895, respectively. Enumerating the entire run allowed ADF&G to establish a sustainable escapement goal (SEG) based on total escapement versus an SEG based on an index period from 3 to 31 July. The current SEG of 750–1,300 Chinook salmon was met during all 3 years of the study (2016–2018). The current average wild escapement was below the average from when the run was last fully enumerated (1999–2015), but above the average from when the run was expanded based on weir counts (2006–2015). In contrast, the current average hatchery escapement was above the average from 1999–2015. Age-sex-length compositions were assessed during broodstock collection in 2016–2018. Wild Chinook salmon were predominantly ocean age 2 or 3, whereas hatchery-reared were predominantly ocean age 1 or 2. On average, wild Chinook salmon were larger than their hatchery-reared components of the same sex and age class. The sex composition of the wild Chinook salmon run ranged from 18% to 61% female, whereas the hatchery-reared sex composition ranged from 27% to 42% female. Approximately 150,000 age-0 smolt were stocked annually upstream of the weir (RKM 25.8) during 2016–2018, continuing the supplementation of the Ninilchik River with hatchery-reared Chinook salmon. The stocking occurred during the third week in May in 2016 and 2018. In 2017, smolt were stocked in early May at RKM 7.7. The broodstock collection goal to restock the Ninilchik River was met in all years. In 2017, instead of using Ninilchik River broodstock to stock Kachemak Bay terminal fisheries, broodstocks from other Cook Inlet locations were used. In 2018, extra Ninilchik River broodstock was collected to make up for regional broodstock shortfalls. Stocking in Halibut Cove Lagoon was discontinued after 2017 in favor of increased stocking at Nick Dudiak Fishing Lagoon where adaptive stocking methods were used in all years to avoid mortality associated with Chaetoceros spp. diatoms.