Stock status of Chena River Arctic grayling in 1997, and radiotelemetry studies, 1997-1998
By: by William P. Ridder.
Contributors: Alaska. Division of Sport Fish.
Series: Fishery data series -- no. 98-39.
Publisher: Alaska Dept. of Fish and Game, Division of Sport Fish
Published: 1998
Place of publication: Anchorage, Alaska
Language: eng
Number of pages: 102
Subjects: Arctic grayling -- Alaska -- Chena River.; Arctic grayling -- Radio tracking -- Alaska -- Chena River.; Fisheries -- Alaska -- Statistics.
Other titles: Federal aid in sport fish restoration (Alaska)
Description: Stock status of Arctic grayling Thymallus arcticus in the lower 152 km of the Chena River was described by population abundance, age and length composition, recruitment, and survival rate estimates during July 1997. Parameter estimates were influenced by low capture probabilities brought on by extreme water conditions during the sampling (record low discharge and high temperatures). Abundance estimates for the defined stock (150 mm FL) could not be made due to the exclusion of small fish in parameter estimates for the upper study section. However, estimates of the population of large fish (270 mm FL) was 11,502 Arctic grayling (SE = 1,729). Stock-size Arctic grayling (150 - 269 mm FL) represented 66 % of all captured fish 150 mm FL. Annual recruitment of age-5 fish between 1996 and 1997 was 3,774 Arctic grayling (SE = 560) and annual survival during this period was 51.3% (SE = 6.3%). Estimated abundance of 1992 brood year (age-5) hatchery-reared Arctic grayling, released in 1993, was 388 fish (SE = 87). Survival of age-5 hatchery-reared Arctic grayling from July of 1996 to July of 1997 was 47.6 % (SE = 3.5%). Estimated abundance of 1993 brood year (age-4) hatchery-reared Arctic grayling, released in 1994, was 173 fish (SE = 48). Survival of age-4 hatchery-reared Arctic grayling from July of 1996 to July of 1997 was 30.2% (SE = 3.3%). From 1992 through 1994, a total of 126,371 age-1 and 23,199 age-0 Arctic grayling have been released into the Chena River. Estimated abundance of all releases of Arctic grayling in 1997 was 561 fish (SE = 99). Though low initial post-release survival (~60% during the first month) and low overwinter survival (~8% per year) is indicated for the failure of the releases, rapid post-release emigration may have influenced these parameter estimates. Sampling to detect emigration was not conducted. Radio telemetry of 54 Arctic grayling inhabiting four forks of the Chena River and the mainstem river upstream of river kilometer 144 in August was used to estimate the proportion that later entered the lower 144 km of the mainstem. Eight aerial surveys were conducted between September 1997 and July 1998. Of fish alive eight months after tagging, 34% (SE = 9%) had overwintered and 37% (SE = 9%) spawned below river kilometer 144. Fish overwintered and spawned as low as river kilometer 35 of the mainstem and in all four forks and two tributaries. The percentage of fish present in the lower 144 km during open water ranged from 0% at tagging in mid-August to 13% in September, 35% in late April, 29% in May, 8% in June, and 0% in July. Accurate estimates of the duration of residence in the lower river could not be determined due to failure of remote sensing to detect radio tags. On 28 July, 60% of tagged fish were within 5 km of release sites.
Notes: "December 1998"

Includes bibliographical references (p. 56-61).

Also issued online.

Partially financed by the Federal Aid in Sport Fish Restoration Act ... under Project F-10-13, Job No. 3-2(a), and F-10-12, Job no. 3-2-(a).