Salmon studies in interior Alaska, 1995
By: by Matthew J. Evenson.
Contributors: Alaska. Division of Sport Fish.; Alaska. Division of Sport Fish. Statewide Research and Technical Services Unit.
Series: Fishery data series -- no. 96-17.
Publisher: Alaska Dept. of Fish and Game, Division of Sport Fish, Research and Technical Services
Published: 1996
Place of publication: Anchorage
Language: eng
Number of pages: 63
Subjects: Salmon -- Alaska, Interior -- Statistics.; Fish-populations -- Alaska, Interior -- Statistics.; Fish-culture -- Alaska, Interior -- Statistics.
Description: Escapements of chinook salmon Oncorhynchus tshawytscha in the Salcha and Chena rivers near Fairbanks, Alaska in 1995 were estimated. A portion of the chum salmon O. keta escapements in the Salcha and Chena rivers was also estimated. A stratified systematic sampling design was used to count chinook and chum salmon during 20 min periods each hour as they passed beneath elevated counting structures on the Salcha and Chena rivers. High water and poor visibility led to an incomplete estimate for the Chena River. As a result, a mark-recapture experiment was conducted to estimate escapement of chinook salmon. Tower count estimates of escapement for chinook and chum salmon in the Salcha River were 13,643 (SE = 471) and 30,784 (SE = 605), respectively. The incomplete estimates of escapement for chinook and chum salmon in the Chena River from tower counts were 5,388 (SE = 275) and 3,519 (SE = 170), respectively. The mark-recapture estimate of escapement for chinook salmon in the Chena River using a maximum likelihood model was 9,680 (SE = 958). Chinook salmon carcasses were collected during early August from both rivers. Females comprised 0.56 (SE = 0.02) of the sample in the Salcha River and 0.66 (SE = 0.02) in the Chena River. Age class 1.4 comprised most of the females sampled in both rivers, while ages 1.2, 1.3, and 1.4 comprised most of the males in the samples. Aerial survey counts of chinook salmon at peak escapement were 3,978 for the Salcha River and 3,567 for the Chena River populations. These aerial counts were 0.44 and 0.46 of the respective abundance estimates. A boat count was conducted in a section of the Chatanika River to index peak escapement of chinook salmon. The count was 444 chinook salmon. This count is the highest on record. Seventy carcasses were collected on a separate survey. Females comprised 0.63 (SE = 0.06) of this sample. Females were most represented by ages 1.3 and 1.4, while males were most represented by ages 1.2 and 1.3. Coho salmon O. kisutch in the mainstem Delta Clearwater River near Delta Junction were counted from a drifting river boat at peak escapement on 23 October. Counts in spring areas adjacent to the mainstem river and in tributaries not accessible by boat were conducted from a helicopter on 2 November. The total count for the entire river was 26,383 coho salmon, which was an above average escapement. The count of coho salmon in the mainstem river was 20,100 (0.76 of total), while the count in tributaries and spring areas was 6,283 (0.24 of total). Three hundred eighty-one carcasses were collected on two separate sampling occasions. Males comprised 0.60 of the sample. Age 2.1 comprised 0.69 of the sample.
Notes: "July 1996."

Includes bibliographical references.

Also issued online.