The Use of 17 α-methyltestosterone for Promoting Weight Increases in Juvenile Pacific Salmon

1973 ◽  
Vol 30 (8) ◽  
pp. 1099-1104 ◽  
Author(s):  
J. R. McBride ◽  
U. H. M. Fagerlund
Keyword(s):  
Weight Gain ◽  
Chinook Salmon ◽  
Structural Changes ◽  
Coho Salmon ◽  
Condition Factor ◽  
Pacific Salmon ◽  
Juvenile Chinook Salmon ◽  
Test Fish ◽  
Juvenile Pacific Salmon ◽  
Juvenile Chinook

The effect of 17 α-methyltestosterone feeding on the weight of juvenile coho salmon (Oncorhynchus kisutch) and on the weight, length, and condition factor of juvenile chinook salmon (O. tshawytscha) was determined. Significant increases in weight and length but not in condition factor were noted at all levels of steroid tested. Coho fed rations containing 10 mg/kg of the steroid for 42 days showed a 29% net weight gain and chinooks fed 1 mg/kg of the hormone for 84 days exhibited a 17% net weight gain over the respective control groups.A marked thickening of the skin was noted in the coho retained on diets containing 10 and 50 mg/kg of the steroid. This alteration was most evident in those fish fed the highest concentrations of hormone for the longest period.In the coho, diets containing 10 or 50 mg/kg of the hormone evoked marked degenerative changes in the testes. Less drastic alterations were noted in the testes of the chinooks retained on the 1 mg/kg test ration for 84 days. No apparent structural changes were noted in the ovary of any of the test fish.

Temporary Residence by Juvenile Salmon in a Restored Estuarine Wetland

1990 ◽  
Vol 47 (11) ◽  
pp. 2079-2084 ◽  
Author(s):  
David K. Shreffler ◽  
Charles A. Simenstad ◽  
Ronald M. Thom
Keyword(s):  
Chinook Salmon ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
River Estuary ◽  
Oncorhynchus Keta ◽  
Juvenile Chinook Salmon ◽  
Juvenile Pacific Salmon ◽  
Juvenile Chum Salmon ◽  
Juvenile Chinook ◽  
Wetland System

Juvenile Pacific salmon utilizing the recently restored Lincoln Avenue wetland system in the Puyallup River estuary, Tacoma, Washington, were studied during their spring seaward migration in 1987 and 1988. Mark/recapture experiments indicated that 0.06% of the outmigrating juvenile chum salmon (Oncorhynchus keta) and 0.59% of the outmigrating juvenile chinook salmon (O. tshawytscha) entered the wetland. Estimated residence times of individual juvenile chum salmon averaged approximately 2 d (range 1–9 d) and juvenile chinook salmon approximately 5 d (volitional) and 38 d (spray-marked) (total range 1–43 d). The restored wetland system currently provides habitat for the temporary residence of migrating juvenile chum and fall chinook salmon, but rigorous evaluation of the benefit of residency is constrained by the lack of data from comparable natural wetlands.

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Continental Shelf ◽  
Chinook Salmon ◽  
Coho Salmon ◽  
Growing Season ◽  
Juvenile Salmon ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook ◽  
And Storage ◽  
Summer Growth ◽  
Storage Energy

Abstract.—Size-selective mortality combined with longer winters at high-latitudes is expected to exert strong directional selection on size, growth, and energy use and storage capacity in northern fish populations. Here, we tested the hypotheses that juvenile Pacific salmon <em>Oncorhynchus </em>spp. grow faster, reach larger size, and accumulate higher energy reserves in the marine environment at northern latitudes using juvenile Chinook salmon <em>O. tshawystcha </em>and coho salmon <em>O. kisutch </em>collected on the continental shelf from the California coast to the Bering Sea. Size reached at the end of the growing season, the quantity of energy stored prior to the onset of winter, and summer growth of juvenile Chinook and coho salmon during their first year at sea varied significantly among regions of the continental shelf. Latitudinal trends were detected for the fall size of subyearling and yearling Chinook salmon and storage energy in yearling Chinook salmon. However, they were opposite to expectations, with values decreasing from southern to northern areas. Latitudinal trends were also apparent for summer growth in juvenile yearling Chinook salmon. However, in contrast to fall size and storage energy, higher growth rates were generally observed in northern rather than in southern regions. Similarly, summer growth generally decreased from northern to southern regions in juvenile coho salmon. Storage energy did not exhibit a consistent trend with latitude in juvenile subyearling Chinook salmon and coho salmon. The different response of juvenile Chinook salmon and coho salmon to a latitudinal cline in temperature and the length of the growing season suggest that both species utilize the marine environment differently. We suggest that regional variations in juvenile salmon growth and energy accumulation may result from differences in prey quality (i.e., lipids), diet, and interspecific competition for prey resources.

Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream

1994 ◽  
Vol 51 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
C. S. Shirvell
Keyword(s):  
Chinook Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Microhabitat Use ◽  
Net Energy ◽  
Optimal Position ◽  
Juvenile Chinook Salmon ◽  
Natural Stream ◽  
Juvenile Chinook ◽  
Seasonal Streamflow

The microhabitats at positions selected by juvenile coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) following a change in streamflow differed from microhabitats occupied at normal streamflows. At drought streamflow (37% mean seasonal streamflow (MSF)), juvenile coho salmon selected slower, darker, and higher sites above the streambed (P < 0.05) than sites selected at normal (75% MSF) or flood (159% MSF) flows. Juvenile chinook salmon microhabitat use changed similarly with changes in streamflow, but the differences were not significant. Up to one fifth of the fish chose positions with faster water velocities than those available either 30 cm above or 30 cm lateral to them. These fish chose positions inconsistent with the hypothesis of optimal position selection based on maximizing net energy gain. On average, fish moved 6.8 m following a change in streamflow. Juvenile coho salmon generally moved upstream in response to decreasing streamflows and downstream in response to increasing streamflows. Juvenile chinook salmon tended to move offshore and downstream in response to all streamflow changes. These results show that juvenile coho and chinook salmon will move to find suitable microhabitat following a change in streamflow and that the microhabitats are not the same at all streamflows.

Downstream migrations of juvenile Pacific salmon (Oncorhynchus spp.) in a glacial transboundary river

1997 ◽  
Vol 54 (12) ◽  
pp. 2837-2846 ◽  
Author(s):  
Michael L Murphy ◽  
K V Koski ◽  
J Mitchel Lorenz ◽  
John F Thedinga
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Transboundary Rivers ◽  
Delayed Entry ◽  
Transboundary River ◽  
Spawning Areas ◽  
Seventh Order ◽  
Juvenile Pacific Salmon

Migrations of juvenile Pacific salmon (Oncorhynchus spp.) in the glacial Taku River (seventh order) were studied to assess movement from upriver spawning areas (in British Columbia) into lower-river rearing areas (in Alaska). Differences between fyke-net catches in the river and seine catches in the river's estuary indicated that many downstream migrants remained in the lower river instead of migrating to sea. In particular, age-0 coho salmon (O. kisutch) and chinook salmon (O. tshawytscha) moved downriver from May to November but were not caught in the estuary. Age-0 sockeye salmon (O. nerka), coho presmolts, and other groups delayed entry into the estuary after moving downriver. We tagged groups of juvenile coho (ages 0-2) from the fyke net with coded-wire to determine when they left the river. One-third of all tags recovered from sport and commercial fisheries occurred 2-3 years later, showing that many coho remained in fresh water for 1-2 years after moving to the lower river. Lower-river areas of large glacial rivers like the Taku River can provide essential rearing habitat for juvenile salmon spawned upriver and are important to consider in integrated whole-river management of transboundary rivers.

Do chemically contaminated river estuaries in Puget Sound (Washington, USA) affect the survival rate of hatchery-reared Chinook salmon?

2014 ◽  
Vol 71 (1) ◽  
pp. 162-180 ◽  
Author(s):  
James P. Meador
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Coho Salmon ◽  
Life Stage ◽  
Puget Sound ◽  
Adult Life ◽  
Parallel Analysis ◽  
Differential Survival ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

This study examined the rate of survival for hatchery-reared, ocean-type juvenile Chinook salmon (Oncorhynchus tshawytscha) to the adult life stage in relation to contamination status for estuaries where they temporarily reside. The hypothesis tested here is that juvenile Chinook from Puget Sound (Washington, USA) area hatcheries exhibit differential survival as categorized by the state of contamination in their respective natal estuaries. Data were examined from 20 hatcheries that released fish to 14 local estuaries in the Greater Puget Sound area over 37 years (1972–2008). A parallel analysis was also conducted for coho salmon (Oncorhynchus kisutch) outmigrating from many of the same hatcheries. For all years combined, juvenile Chinook transiting contaminated estuaries exhibited an overall rate of survival that was 45% lower than that for Chinook moving through uncontaminated estuaries, which was confirmed when tested year by year. The results for coho originating from the same hatcheries and sharing a similar marine distribution indicated no substantial differences among estuaries. These observations have important implications for wild juvenile Chinook that spend more time in the estuary compared with hatchery-reared fish.

scholarly journals A comparison of infectious agents between hatchery-enhanced and wild out-migrating juvenile chinook salmon (Oncorhynchus tshawytscha) from Cowichan River, British Columbia

FACETS ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 695-721 ◽  
Author(s):  
Krishna K. Thakur ◽  
Raphaël Vanderstichel ◽  
Shaorong Li ◽  
Emilie Laurin ◽  
Strahan Tucker ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
River System ◽  
Infectious Agents ◽  
Juvenile Chinook Salmon ◽  
Hatchery Fish ◽  
Juvenile Chinook

Infectious diseases are likely contributing to large-scale declines in chinook salmon stocks in the Pacific Northwest, but the specific agents and diseases involved, and the prevalences in migratory salmon, are mostly unknown. We applied a high-throughput microfluidics platform to screen for 45 infectious agents in 556 out-migrating juvenile chinook salmon, collected from freshwater (FW) and saltwater (SW) locations in the Cowichan River system on Vancouver Island, Canada, during 2014. Nineteen agents (5 bacterial, 2 viral, and 12 parasitic) were detected, with prevalences ranging from 0.2% to 57.6%. Co-infections between Candidatus Branchiomonas cysticola Toenshoff, Kvellestad, Mitchell, Steinum, Falk, Colquhoun & Horn, 2012, Paranucleospora theridion Nylund, Nylund, Watanabe, Arnesen & Kalrsbakk, 2010, and gill chlamydia, all associated with gill disease, were observed in SW samples. We detected agents known to cause large-scale mortalities in Pacific salmon ( Ceratonova shasta (Noble, 1950), Parvicapsula minibicornis Kent, Whitaker & Dawe, 1977), and agents only recently reported in Pacific salmon in BC ( Ca. B. cysticola, P. theridion, Facilispora margolisi Jones, Prosperi-Porta & Kim, 2012 and Parvicapsula pseudobranchicola Karlsbakk, Saether, Hostlund, Fjellsoy & Nylund, 2002). Wild and hatchery fish were most divergent in agent profiles in FW, with higher agent diversity in wild fish. Differences in prevalence largely dissipated once they converged in the marine environment, although hatchery fish may be infected by a greater diversity of agents sooner after ocean entry by virtue of their more rapid migration from nearshore to offshore environments.

Differences in acquired and innate resistance among Pacific salmon (Oncorhynchus spp.) against the haemoflagellate Cryptobia salmositica and numbers delivered by the leech vector Piscicola salmositica

1995 ◽  
Vol 52 (S1) ◽  
pp. 1-6 ◽  
Author(s):  
S.M. Bower
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Elevated Temperatures ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Lytic Activity ◽  
Juvenile Chinook Salmon ◽  
Elevated Water ◽  
Plasma Factors

Susceptible juvenile chinook salmon (Oncorhynchus tshawytscha) were protected from otherwise lethal challenges with the haemoflagellate Cryptobia salmositica by acclimation to an elevated water temperature (20 °C). Following challenge at temperatures advantageous to the haemoflagellate (9–11 °C), surviving fish had plasma with enhanced acquired lytic activity against the parasite. In contrast, most coho salmon (Oncorhynchus kisutch) from a resistant stock survived up to three challenges with C. salmositica, without "immunization" at elevated temperatures. However, they acquired little or no lytic activity against the parasite, which survived in low numbers in some fish. Also, the chinook and coho salmon did not have innate plasma factors that lysed the parasite under in vitro conditions like those demonstrated in other salmonids. Thus, the mechanism(s) that protect the resistant O. kisutch from the pathogenic affects of C. salmositica are different from those identified in other fishes that are resistant to Cryptobia spp. A challenge of 105 flagellates per fish was suggested to be representative of the number of C. salmositica inoculated into a fish by one infected leech vector (Piscicola salmositica).

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