Relationship of water column stability to the growth, condition, and survival of pink salmon (Oncorhynchus gorbuscha) in the northern coastal Gulf of Alaska and Prince William Sound

Water column stability has been hypothesized to affect growth and ultimately survival of juvenile fish. We estimated the relationships between stability and the growth, condition, and marine survival of several stocks of pink salmon ( Oncorhynchus gorbuscha ) within Prince William Sound (PWS), Alaska, USA, and the northern coastal Gulf of Alaska (GOA) shelf. There was a stronger correlation among the biological parameters of the fish than between the biological parameters and physical conditions. While stability and fish condition during early marine residence in PWS were important to year-class survival, stability of the water column that juveniles experienced as they migrated to the open waters of the GOA did not play a key role in determining survival to adulthood. Below-average stability just prior to capture within PWS combined with positive fish condition was related to increased year-class survival. Our results are similar to previous studies that concluded that slower and weaker development of stratification with a deeper mixed layer depth may be important for juvenile pink salmon survival in PWS.

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Diel vertical distribution of early marine phase juvenile pink salmon (Oncorhynchus gorbuscha) and behaviour when exposed to salmon louse (Lepeophtheirus salmonis)

Canadian Journal of Zoology ◽

10.1139/z11-049 ◽

2011 ◽

Vol 89 (9) ◽

pp. 796-807 ◽

Cited By ~ 5

Author(s):

S. Tang ◽

A.G. Lewis ◽

M. Sackville ◽

L. Nendick ◽

C. DiBacco ◽

...

Keyword(s):

Vertical Distribution ◽

Water Column ◽

Pink Salmon ◽

Distribution Patterns ◽

Oncorhynchus Gorbuscha ◽

Lepeophtheirus Salmonis ◽

Night Time ◽

Pink Salmon Oncorhynchus Gorbuscha ◽

Salmon Louse ◽

Seawater Acclimation

We observed diel vertical migration patterns in juvenile pink salmon ( Oncorhynchus gorbuscha (Walbaum, 1792)) and tested the hypothesis that fish behaviour is altered by exposure to sea lice copepodids. Experiments involved replicated field deployments of a large (9 m) plankton column, which provided a vertical distribution enclosure under natural light and salinity conditions. Diel vertical distributions of juvenile pink salmon were observed during the first 3 weeks of seawater acclimation in both the presence and the absence of the ectoparasitic salmon louse ( Lepeophtheirus salmonis (Krøyer, 1838)). Immediately upon entering seawater, juvenile pink salmon preferred the top 1 m of the water column, but they moved significantly deeper down the vertical water column as seawater acclimation time increased. A significant diel migration pattern was observed, which involved a preference for the surface at night-time, compared with daytime. When fish in the column were exposed to L. salmonis copepodids for 3 h, 43%–62% of fish became infected, fish expanded their vertical distribution range, and significant changes in vertical distribution patterns were observed.

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Resolving allegations of oil damage to incubating pink salmon eggs in Prince William Sound

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f01-055 ◽

2001 ◽

Vol 58 (6) ◽

pp. 1070-1076 ◽

Cited By ~ 4

Author(s):

Ernest L Brannon ◽

Keya CM Collins ◽

Lawrence L Moulton ◽

Keith R Parker

Keyword(s):

Oil Spill ◽

Pink Salmon ◽

Oncorhynchus Gorbuscha ◽

Sensitive Period ◽

Time Sampling ◽

Prince William Sound ◽

Pink Salmon Oncorhynchus Gorbuscha ◽

Salmon Eggs ◽

Original Survey ◽

Oil Exposure

The Exxon Valdez Oil Spill Trustee Council concluded that oil caused mortality of pink salmon (Oncorhynchus gorbuscha) eggs in Prince William Sound streams. Their conclusion was based primarily on Alaska Department of Fish and Game (ADF&G) studies which reported that mean mortality of embryos in eggs was higher in oiled than non-oiled streams when sampled shortly after spawning completion. However, developing embryos are vulnerable to shock mortality for a period of 20 days after fertilization, and the embryos in eggs from the latest spawners were still in the sensitive period at the time sampling took place. We argue that the original ADF&G analysis should have included sample timing in statistical comparisons of mortality between streams. Analysis of a subset of the ADF&G data showed that sampling shock was a major source of embryo mortality in these samples, and that source of mortality in the original survey would likely have been mistakenly interpreted as an oiling effect. Compensating for sample timing removed all statistical evidence for an oiling effect in the data subset. We conclude that the ADF&G study design confounded the ability to assess for the effect of oil exposure on pink salmon eggs.

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