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- Title
Evidence of density- and size-dependent mortality in hatchery-reared juvenile white sturgeon (Acipenser transmontanus) in the Kootenai River.
- Authors
Justice, Casey; Pyper, Brian J.; Beamesderfer, Raymond C.P.; Paragamian, Vaughn L.; Rust, Pete J.; Neufeld, Matthew D.; Ireland, Susan C.
- Abstract
We evaluated effects of stocking level and size-at-release on survival rates of hatchery-reared juvenile white sturgeon (Acipenser transmontanus) in the Kootenai River using Cormack–Jolly–Seber and related models implemented in Program MARK. A total of 119 768 marked and unmarked hatchery juveniles were released from 1992 to 2006, of which 2938 passive integrated transponder (PIT)-tagged fish were subsequently recaptured. Annual survival rates of marked groups ranged from 0.01 to 0.84 (mean = 0.45) during the first year at large, from 0.48 to 1.0 (mean = 0.84) in the second year, and averaged 1.0 during all subsequent years. First year survival rates declined substantially in recent years, particularly for small fish (<25 cm fork length). Approximately 59% of the variation in first year survival was explained by a negative relationship with estimated juvenile abundance (linear regression, P < 0.01). Length-at-release of individuals explained a substantial proportion of the within-year variation in survival during the first year at large. Our results provide strong evidence of density- and size-dependent mortality in hatchery-reared juvenile white sturgeon in the Kootenai River. Management actions that prioritize the release of fewer, larger-sized fish will likely improve first year survival rates and subsequent recruitment to the spawning-age population.
- Subjects
KOOTENAI River; WHITE sturgeon; HATCHERY fishes; FISH mortality; FISH anatomy; FISH growth; AQUATIC resources; FISHERY management; FISHERIES
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2009, Vol 66, Issue 5, p802
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/F09-034