Aggression and Variation in Growth of Chum Salmon (Oncorhynchus keta) Juveniles in Seawater: Effects of Limited Ration

1987 ◽  
Vol 44 (1) ◽  
pp. 192-197 ◽  
Author(s):  
Michael W. Davis ◽  
Bori L. Olla
Keyword(s):  
Growth Rate ◽  
Chum Salmon ◽  
Condition Factor ◽  
Fork Length ◽  
Oncorhynchus Keta ◽  
Average Growth ◽  
Ration Level ◽  
Chum Salmon Oncorhynchus Keta ◽  
Schooling Fish ◽  
Coefficients Of Variation

Chum salmon (Oncorhynchus keta) were grown in groups of 10 for 40 d on three limiting ration levels, and weight and fork length were measured at day 0 and day 40. Variation in growth of fish within a cohort was estimated from calculation of coefficients of variation for weight, fork length, condition factor, and growth rate. Average growth was significantly less at the lowest ration level than at the two higher levels, where average growth did not differ significantly. However, variation in growth (growth depensation) was significantly higher at the lowest and intermediate ration levels than at the highest ration level; we surmise that this higher variation is associated with increased competition and the disproportionate acquisition of food by larger fish. Aggressive behavior was most intense at the highest ration level. Chum salmon apparently show characteristics of a schooling fish while showing aggression, behaviors that are generally viewed as mutually exclusive.

Estimating target strength of young chum salmon (Oncorhynchus keta)

2022 ◽  
pp. 1-5
Author(s):  
Kenji Minami ◽  
Hokuto Shirakawa ◽  
Yohei Kawauchi ◽  
Huamei Shao ◽  
Makoto Tomiyasu ◽  
...  
Keyword(s):  
Bering Sea ◽  
Chum Salmon ◽  
Fork Length ◽  
Target Strength ◽  
Oncorhynchus Keta ◽  
Biomass Estimation ◽  
Fishery Resource ◽  
Chum Salmon Oncorhynchus Keta ◽  
Acoustic Methods ◽  
The Bering Sea

Although chum salmon (Oncorhynchus keta) is an important fishery resource in Japan, acoustic methods cannot be applied to biomass estimation because the target strength (TS) is unknown. This study clarified the TS for each fork length (FL: 5.5–33.5 cm) of young chum salmon inhabiting the Japanese coastal area to the Bering Sea by measuring free-swimming fish. The size dependences of the TS values were TSmean = 20 log10 FL – 68.0, for both 38 and 120 kHz. This facilitated the estimation of biomass of young salmon using acoustic methods.

Relationship between Otolith Microstructure and the Growth of Juvenile Chum Salmon (Oncorhynchus keta) under Different Prey Rations

1984 ◽  
Vol 41 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Eric C. Volk ◽  
Robert C. Wissmar ◽  
Charles A. Simenstad ◽  
Douglas M. Eggers
Keyword(s):  
Growth Rate ◽  
Chum Salmon ◽  
Harpacticoid Copepod ◽  
Fish Growth ◽  
Oncorhynchus Keta ◽  
Otolith Microstructure ◽  
Increment Width ◽  
Chum Salmon Oncorhynchus Keta ◽  
Otolith Increment ◽  
Juvenile Chum Salmon

Effects of different prey taxa and daily ration levels on fish growth and the relationship between fish growth rate and mean otolith increment width were investigated for juvenile chum salmon (Oncorhynchus keta) in saltwater aquaria. Growth was positively correlated with ration, and food conversion efficiency was much higher for fish fed the harpacticoid copepod, Tigriopus californicus, than either the calanoid copepod, Pseudocalanus minutas, or the gammarid amphipod, Paramoera mohri. Otolith increments were produced daily for at least the first 160 d after hatching and there was a direct relationship between mean daily otolith increment width and fish growth rate. These results illustrate the possibility that otolith microstructure recapitulates juvenile chum growth histories during estuarine residence.

Dynamics of body size, age, and annual growth rate of Anadyr chum salmon Oncorhynchus keta in 1962–2010

2012 ◽  
Vol 52 (3) ◽  
pp. 207-225 ◽  
Author(s):  
A. V. Zavolokin ◽  
V. V. Kulik ◽  
I. I. Glebov ◽  
E. N. Dubovets ◽  
Yu. N. Khokhlov
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Chum Salmon ◽  
Annual Growth ◽  
Oncorhynchus Keta ◽  
Annual Growth Rate ◽  
Chum Salmon Oncorhynchus Keta

Growth of Juvenile Chum Salmon (Oncorhynchus keta) Under Different Feeding Regimes

1969 ◽  
Vol 26 (6) ◽  
pp. 1631-1645 ◽  
Author(s):  
R. J. LeBrasseur
Keyword(s):  
Growth Rate ◽  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Rate Of Growth ◽  
Total Length ◽  
Chum Salmon Oncorhynchus Keta ◽  
Feeding Regimes ◽  
Size Groups ◽  
Juvenile Chum Salmon ◽  
The Mean

Juvenile chum salmon were fed on six different concentrations of size-selected zooplankton for 8 weeks. Zooplankton were caught daily and sorted through sieves into size-groups roughly as follows: 6–20 mm total length, mainly euphausiids; 2.5–4.5 mm, mainly copepods; and ≤ 1.5 mm, mainly small copepods. The rate of growth in weight of the fish was found to be dependent upon the concentration of the ration. Fish which were offered no food lost weight, and fish which were offered excess food increased in weight by 5.4% per day. The mean growth rate of the fish held on fixed rations ranged from 2.2 to 5.7% per day and was found to be independent of the type of prey. Electivity experiments showed that all the fish selected copepods 1.6–4.5 mm long in proportion to their abundance and rejected copepods ≤ 1.5 mm. The euphausiids were selected only by fish which had previously fed on euphausiids. The effect of variations in the availability of prey is discussed.

Rule of age and size at maturity of chum salmon (Oncorhynchus keta): implications of recent trends among Oncorhynchus spp.

2005 ◽  
Vol 62 (12) ◽  
pp. 2752-2759 ◽  
Author(s):  
Kentaro Morita ◽  
Shoko H Morita ◽  
Masa-aki Fukuwaka ◽  
Hiroyuki Matsuda
Keyword(s):  
Growth Rate ◽  
Chum Salmon ◽  
Environmental Changes ◽  
Pacific Salmon ◽  
Oncorhynchus Keta ◽  
Size At Maturity ◽  
Chum Salmon Oncorhynchus Keta ◽  
Realistic Modeling ◽  
Recent Trends ◽  
Slow Growing

In the last quarter of the 20th century, the size at maturity of many North Pacific salmon (Oncorhynchus spp.) populations decreased. During this same period, the age at maturity increased, implying that the growth rate of Pacific salmon decreased, probably owing to environmental changes. To elucidate these trends, we identified the rule of age and size at maturity of Japanese chum salmon (Oncorhynchus keta), which was that slow-growing salmon initiated maturation at an older age and smaller size than did fast-growing salmon. We then simulated the potential modification of age and size at maturity in response to changing growth rate using a size-structured model with age- and size-specific maturation rates. This showed that reducing the growth rate without assuming a genetic change was sufficient for realistic modeling of recent changes. In addition, the observed rule of age and size at maturity was consistent with the optimal age and size at maturity in terms of maximizing the fitness. Our results attributed the recent trends in chum salmon's increasing age and decreasing size at maturity to an adaptive phenotypic response to a reduced growth rate.

A genetic analysis of meristic and morphometric variation in chum salmon (Oncorhynchus keta) at three different temperatures

1990 ◽  
Vol 68 (2) ◽  
pp. 225-229 ◽  
Author(s):  
Terry D. Beacham
Keyword(s):  
Chum Salmon ◽  
Fork Length ◽  
Oncorhynchus Keta ◽  
Meristic Characters ◽  
Morphometric Variation ◽  
Morphometric Characters ◽  
Chum Salmon Oncorhynchus Keta ◽  
Different Temperatures ◽  
Character Variation ◽  
Temperature Interactions

A nested mating design was used in which 10 males were mated with 20 female chum salmon (Oncorhynchus keta), and individuals from each of the 20 families were maintained at 6, 10, and 14 °C from egg fertilization until juveniles reached a fork length of about 61 mm. Variation in 11 morphometric and 3 meristic characters was evaluated. Rearing temperature had a marked effect on juvenile morphometric variation, enough to assign correctly 91% of the juveniles reared at 14 °C, 90% of the juveniles reared at 10 °C, and 95% of the juveniles reared at 6 °C. The addition of meristic character variation increased the classification accuracy to 97, 92, and 96%, respectively. As rearing temperatures increased, the observed levels of fluctuating asymmetry for the three meristic characters increased. Morphometric characters tended to have lower heritabilities than did meristic characters. Genotype–temperature interactions generally accounted for between 10 and 30% of observed phenotypic variation for most characters.

Timing and Relative Intensity of Size-Selective Mortality of Juvenile Chum Salmon (Oncorhynchus keta) During Early Sea Life

1982 ◽  
Vol 39 (7) ◽  
pp. 952-957 ◽  
Author(s):  
M. C. Healey
Keyword(s):  
Relative Intensity ◽  
Chum Salmon ◽  
Size Range ◽  
Fork Length ◽  
Open Water ◽  
Oncorhynchus Keta ◽  
Selective Mortality ◽  
Chum Salmon Oncorhynchus Keta ◽  
Time Period ◽  
Juvenile Chum Salmon

Available evidence indicates that mortality of juvenile salmon during early sea life is high and probably size dependent. I used scale analysis to determine the timing and relative intensity of size-selective mortality in chum salmon (Oncorhynchus keta) during early sea life. Significant size-selective mortality could be demonstrated only over the time period that the fish were laying down circuli 2–4 on their scales. The relative intensity of mortality for different sizes of fish suggested that mortality was strongly size selective over the size range 45–55 mm fork length. No particular mortality agent could be identified, but the size range involved corresponds with the size at which chum salmon move from very shallow water and nearshore habitat to open water pelagic habitat.Key words: size-selective mortality, salmon, early sea life

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