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.

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.

Swimming speeds and buoyancy compensation of migrating adult chum salmon Oncorhynchus keta revealed by speed/depth/acceleration data logger

2001 ◽  
Vol 204 (22) ◽  
pp. 3895-3904 ◽  
Author(s):  
Hideji Tanaka ◽  
Yasuaki Takagi ◽  
Yasuhiko Naito
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Release Site ◽  
Oncorhynchus Keta ◽  
Horizontal Distance ◽  
Data Logger ◽  
Body Angle ◽  
Chum Salmon Oncorhynchus Keta ◽  
Acceleration Data ◽  
Free Ranging

SUMMARY Although the homing migration of Pacific salmon is well documented, the swimming behaviour of the returning salmon has been poorly described, principally as a result of the difficulties encountered in monitoring salmon behaviour in the sea. The present study describes the use of a recently developed electronic data logger to obtain simultaneous recordings of the swimming speed, depth, fin-beating activity and body angle of free-ranging chum salmon Oncorhynchus keta during their homing migration in coastal waters. Chum salmon migrated horizontally at speeds of 1.5–3.0 km h–1. The gross horizontal distance salmon moved during total recording periods were 1.24- to 19.0-fold greater than the net distance from the release site to the retrieval points. It is suggested that homing salmon did not drift passively but swam actively to the spawning grounds. Salmon preferred the surface water, but also made frequent vertical migrations. The travelled depth of each salmon ranged from 0.36 to 0.64 km per hour. Salmon descended at faster rates and steeper angles than they ascended. Both tailbeat frequency and tail thrust were higher during the ascent than the descent phase. These results suggest that chum salmon spent more energy during the ascent than the descent phase. Profiles of descent rate assumed an arched shape with respect to a change in hydrostatic pressure, while ascent rate increased with decreasing depth. High tailbeat frequencies were found during the course of ascent, which suggests that the salmon did not regulate the volume of air in the swim bladder during short-term vertical migrations.

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.

Treatments Before Frozen Storage Affecting Thaw Drip Formation in Pacific Salmon

1977 ◽  
Vol 34 (9) ◽  
pp. 1431-1435 ◽  
Author(s):  
E. Bilinski ◽  
R. E. E. Jonas ◽  
Y. C. Lau ◽  
G. Gibbard
Keyword(s):  
Key Words ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Frozen Storage ◽  
Freezing Rate ◽  
Slow Freezing ◽  
Oncorhynchus Keta ◽  
Temperature Range ◽  
Chum Salmon Oncorhynchus Keta

Freshly caught chum salmon, Oncorhynchus keta, were stored in ice or refrigerated seawater for 0.3 and 10 days and were then gutted and frozen at two different rates (1 or 14.5 h through the temperature range of 0 to −5 °C). The amount of thaw drip (TD) was determined in steaks following 1.5, 4, 8, and 12 mo of storage at −28 °C. A significant increase in TD occurred with the slow freezing rate or with a delay before freezing. These effects were not suppressed by a prolonged frozen storage, which also produced an increase in TD. There was no marked difference between fish held in ice and refrigerated seawater before freezing. Similar results were obtained with coho salmon, O. kisutch, frozen without prior chill stowage. Key words: Pacific salmon, thaw drip, chill stowage, freezing rates Oncorhynchus keta, O. kisutch

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.

Sign in / Sign up

Export Citation Format

Share Document