Adult Chum Salmon Oncorhynchus Keta Research Articles

Characteristics of adult chum salmon Oncorhynchus keta from the commercial stock at Iturup Island in 2023

Characteristics of adult chum salmon Oncorhynchus keta from the commercial stock at Iturup Island in 2023

Relationships between growth traits and scale stable isotopes (δ 13 C, δ 15 N) of adult chum salmon Oncorhynchus keta in Hokkaido, Japan

Stable isotope analysis (SIA) in combination with growth analysis using scales collected from adult chum salmon Oncorhynchus keta migrating back to Hokkaido, Japan, was performed to describe the variation of isotopic composition of carbon (δ13C) and nitrogen (δ15N) in scales and to examine relationships with growth traits [age, fork length (FL), and relative growth ratio in the last growth period [(RGRlast)]. Scale stable isotope (SI) values in 3- to 6-year-old fish were highly variable, ranging from −17.6‰ to −14.3‰ for δ13C and 9.5‰ to 13.4‰ for δ15N. The δ15N was positively correlated with FL, and this tendency may indicate changes in trophic level with growth. Significant effect was not detected between δ15N and RGRlast, it can be inferred that factors potentially yielding high δ15N may not necessarily result in higher growth rates. No trend found between FL and δ13C may imply that there is no clear segregation in feeding locations between the 3- to 6-year groups. This study provided basic information for scale SI values of chum salmon adults and indicated that SIA using scales could be a new approach to elucidating the trophic ecology of chum salmon.

The behavioural homing response of adult chum salmon Oncorhynchus keta to amino-acid profiles.

Adult chum salmon Oncorhynchus keta homing behaviour in a two-choice test tank (Y-maze) was monitored using a passive integrated transponder (PIT)-tag system in response to river-specific dissolved free amino-acid (DFAA) profiles and revealed that the majority of O. keta showed a preference for artificial natal-stream water and tended to stay in this maze arm for a longer period; natal-stream water was chosen over a nearby tributary's water, but not when the O. keta were presented with a non-tributary water. The results demonstrate the ability of O. keta to discriminate artificial stream waters containing natural levels of DFAA.

Species and Life History Affect the Utility of Otolith Chemical Composition for Determining Natal Stream of Origin for Pacific Salmon

AbstractTo test the utility of otolith chemical composition as a tool for determining the natal stream of origin for salmon, we examined water chemistry and otoliths of juvenile and adult Chum Salmon Oncorhynchus keta and Coho Salmon O. kisutch from three watersheds (five rivers) in the Norton Sound region of Alaska. The two species are characterized by different life histories: Coho Salmon rear in freshwater for up to 3 years, whereas Chum Salmon emigrate from freshwater shortly after emergence. We used laser ablation (LA) inductively coupled plasma (ICP) mass spectrometry (MS) to quantify element: Ca ratios for Mg, Mn, Zn, Sr, and Ba, and we used multicollector LA‐ICP‐MS to determine 87Sr:86Sr ratios in otolith regions corresponding to the period of freshwater residence. Significant differences existed in both water and otolith elemental composition, suggesting that otolith composition could be used to discriminate the natal origin of Coho Salmon and Chum Salmon but only when 87Sr:86Sr ratios were included in the discriminant function analyses. The best discriminant model included 87Sr:86Sr ratios, and without 87Sr:86Sr ratios it was difficult to discriminate among watersheds and rivers. Classification accuracy was 80% for Coho Salmon and 68% for Chum Salmon, indicating that this method does not provide sufficient sensitivity to estimate straying rates of Pacific salmon at the scale we studied.

Appropriateness of the Darroch Estimator for Monitoring Adult Chum Salmon on the Middle Yukon River, Alaska

AbstractFrom 1996 to 1999, a Darroch two‐sample stratified capture–recapture experiment was conducted on adult chum salmon Oncorhynchus keta in the Yukon River, Alaska. Annual release of marked chum salmon ranged from 8,527 to 18,631 fish. At the recovery site, 15,581–45,232 fish were examined for marks annually. The percentage of tagged fish among those examined for marks ranged from 2.8% to 6.4%. Abundance estimates ranged from 189,742 (SE = 6,967) to 654,296 (SE = 21,921) fish during the four study years. Weekly estimates ranged from 6,796 to 126,268 fish. The assumption of a closed population was evaluated in light of life history and other data. One closure violation due to sample starting and ending dates was mitigated using migration times. We used statistical analysis and modeling to evaluate assumptions of (1) equal probability of capture, (2) equal probability of movement, and (3) random mixing of fish. Logistic regression suggested that the probability of recapture was not independent of length and gender in 8 of 32 weeks among years. Modeling changes in the probabilities of movement and capture indicated that differences in movement would cause little bias in population estimates relative to differences in capture. However, length‐ and gender‐stratified and unstratified population estimates showed little difference (e.g., in 1997: length‐stratified estimate = 351,138 fish, gender‐stratified estimate = 333,842 fish, unstratified estimate = 333,057 fish). Three explanations were offered for these results: violations were due to changes in the probability of movement, statistical tests were overly sensitive, or the estimator was robust to the assumption violations. Probability of recapture was related to bank orientation (i.e., nonrandom mixing) only in 1999. Annual estimates during the study documented a decline in the spawning population. Weekly estimates indicated that run timing was inconsistent among years. The estimates compared favorably with other assessments of the run. We concluded that the Darroch estimator was reasonably applied to data collected via fish wheels for this population.

Evidence of Handling Mortality of Adult Chum Salmon Caused by Fish Wheel Capture in the Yukon River, Alaska

Abstract From 1996 to 1998, marked fish from a mark–recapture experiment were used to examine potential effects of fish wheel capture, handling, and tagging on adult chum salmon Oncorhynchus keta in the Yukon River, Alaska. Four fish wheels equipped with live holding boxes were used to capture fish, two at the marking site and two at the recapture site. During the 3 years of the study we annually marked 8,513–18,632 fish with individually numbered spaghetti tags; annual tag returns external to the mark–recapture experiment (not by project fish wheels) ranged from 594 to 1,007. Individual salmon were captured from one to four times in the four project fish wheels used in the mark–recapture experiment. Tag returns, interviews, carcass surveys, and data from other management projects indicated that the proportion of fish with marks decreased as distance from the marking site increased. Nine possible explanations for these observations were considered, but fish mortality associated with capture and handling a...

Effects of Varying Voltage and Pulse Pattern during Electrical Immobilization of Adult Chum Salmon on Egg Survival to the Eyed Egg Stage

Abstract Electrical shock is becoming widely used to immobilize adult salmon before gamete removal. Working with immobilized fish reduces repetitive motion injuries among workers and decreases staff requirements, but survival rates of eggs obtained from adults immobilized by electrical currents have varied. Eleven DC wave forms and voltage combinations were used to immobilize adult chum salmon Oncorhynchus keta, and survival rates of eggs taken from shocked fish were compared with survival rates from fish immobilized with carbon dioxide. Egg survival rates increased as voltage and pulse pattern intensity decreased. Similar egg survival rates were recorded for those obtained from the carbon dioxide controls (98%) and those obtained at the lower voltage and pulse patterns (96-98%), thus validating the use of electrical immobilization on adult chum salmon before gamete removal.

Trace amounts of saxitoxins in the viscera of chum salmon Oncorhynchus keta

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 175:295-298 (1998) - doi:10.3354/meps175295 Trace amounts of saxitoxins in the viscera of chum salmon Oncorhynchus keta Shigeru Sato, Takehiko Ogata, Masaaki Kodama* School of Fisheries Sciences, Kitasato University, Sanriku, Iwate 022-0101, Japan *Addressee for correspondence. E-mail: m-kodama@nnet.ne.jp ABSTRACT: Low levels of saxitoxins and tetrodotoxin were found in the viscera of adult chum salmon Oncorhynchus keta returning to spawn. The nucleic magnetic resonance and mass spectrum analyses as well as several kinds of chromatographies clearly showed that the purified toxins were saxitoxin and neosaxitoxin. Tetrodotoxin, which was detected by high performance liquid chromatography analysis, could not be isolated. These findings show that saxitoxins and tetrodotoxin are more widely distributed in aquatic organisms than previously thought. KEY WORDS: Saxitoxin · Tetrodotoxin · Chum salmon · Oncorhynchus keta Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 175. Publication date: December 17, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.