Fisheries, Subsistence, and Habitat
Publications Searchable Database
Search Again| Division: | Commercial Fish |
| Title: | Characteristics of fall chum salmon Oncorhynchus keta in the Kuskokwim River drainage. |
| Author: | Gilk, S. E., W. D. Templin, D. B. Molyneaux, T. Hamazaki, and J. A. Pawluk |
| Year: | 2005 |
| Report ID: | Alaska Department of Fish and Game, Fishery Data Series No. 05-56, Anchorage. |
| Abstract: | Fishery managers became aware in the mid 1990s that the Kuskokwim River hosts a run of fall chum salmon Oncorhynchus keta distinct from the more common summer chum salmon population. Between 1993 and 2002, Kuskokwim River commercial and subsistence harvests averaged 205,600 chum salmon per year caught in directed fisheries and as incidental catch in coho salmon O. kisutch directed fisheries; however, harvest statistics do not distinguish fall run from the summer run of chum salmon. Furthermore, the escapement of fall chum salmon is not monitored, although escapement is monitored for several summer chum populations. Distinctive characteristics in the morphology, age and sex composition, and spawning distribution of fall chum salmon are unknown or undescribed. In this project we describe some of these characteristics by comparing 336 fall chum salmon sampled from the South Fork Kuskokwim River with 1,964 summer chum salmon sampled from the Kwethluk, George, and Takotna rivers. In 2004, fish were sampled and examined for length from mideye-to-tail-fork (METF), maximum dorsal-ventral height, and maximum width. Age and sex was determined for each fish, and fecundity parameters were measured for 15 to 20 females from each of the 4 sample groups. Spawning distribution of fall chum salmon was determined through review of historical aerial surveys and augmented with additional surveys in 2004. Multivariate analysis demonstrated a significant difference in the morphology between fall and summer chum salmon, with fall chum salmon generally having greater length from METF, smaller maximum height, and smaller maximum width. The fall chum salmon population had a greater percentage of age-0.2 fish than summer chum salmon populations, but sex ratios were similar and there was no significant difference in fecundities; however, these results may have been influenced by sampling biases. Spawning distribution of fall chum salmon appeared to be limited to a subset of tributary streams in the upper Kuskokwim basin characterized by braided channels and glaciated headwaters. Analysis of 31 single nucleotide polymorphisms in 9 populations in the Kuskokwim River demonstrated sufficient genetic differences between fall and summer chum salmon populations to distinguish the two runs in mixed stock analyses with a high degree of accuracy (>92%). Analysis of mixed stock chum salmon catches from fish wheels operated near Kalskag indicated a low occurrence of fall chum salmon in 2004, but no definitive conclusion could be made about run timing of fall chum salmon from the limited subsample analysis. Greater resolution about run timing may be possible thorough analysis of the remaining mixed stock samples that have been archived. |
| Keywords: | Age, sex, length (ASL), distribution, fall chum salmon, fecundity, fish wheel, George River, Kuskokwim River, Kwethluk River, morphology, Oncorhynchus keta, run timing, South Fork Kuskokwim River, summer chum salmon, Takotna River, weir. |