Migratory Behavior and Physiological Development as Potential Determinants of Life History Diversity in Fall Chinook Salmon in the Clearwater River

In light of recent recoveries of marine mammal populations worldwide and heightened concern about their impacts on marine food webs and global fisheries, it has become increasingly important to understand the potential impacts of large marine mammal predators on prey populations and their life-history traits. In coastal waters of the northeast Pacific Ocean, marine mammals have increased in abundance over the past 40 to 50 y, including fish-eating killer whales that feed primarily on Chinook salmon. Chinook salmon, a species of high cultural and economic value, have exhibited marked declines in average size and age throughout most of their North American range. This raises the question of whether size-selective predation by marine mammals is generating these trends in life-history characteristics. Here we show that increased predation since the 1970s, but not fishery selection alone, can explain the changes in age and size structure observed for Chinook salmon populations along the west coast of North America. Simulations suggest that the decline in mean size results from the selective removal of large fish and an evolutionary shift toward faster growth and earlier maturation caused by selection. Our conclusion that intensifying predation by fish-eating killer whales contributes to the continuing decline in Chinook salmon body size points to conflicting management and conservation objectives for these two iconic species.

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Short-term exposure of Chinook salmon (Oncoryhnchus tshawytscha) to o,p-DDE or DMSO during early life-history stages causes long-term humoral immunosuppression.

Environmental Health Perspectives ◽

10.1289/ehp.6171 ◽

2003 ◽

Vol 111 (13) ◽

pp. 1601-1607 ◽

Cited By ~ 41

Author(s):

Ruth H Milston ◽

Martin S Fitzpatrick ◽

Anthony T Vella ◽

Shaun Clements ◽

Deke Gundersen ◽

...

Keyword(s):

Life History ◽

Chinook Salmon ◽

Early Life ◽

Early Life History ◽

Short Term ◽

Life History Stages ◽

Short Term Exposure

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Contrasting the migratory behavior and stranding risk of White Sturgeon and Chinook Salmon in a modified floodplain of California

Environmental Biology of Fishes ◽

10.1007/s10641-020-00974-9 ◽

2020 ◽

Vol 103 (5) ◽

pp. 481-493

Author(s):

Myfanwy Johnston ◽

Jared Frantzich ◽

Matthew B. Espe ◽

Pascale Goertler ◽

Gabriel Singer ◽

...

Keyword(s):

Chinook Salmon ◽

White Sturgeon ◽

Migratory Behavior

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Precocial male maturation in laboratory-reared populations of chinook salmon, Oncorhynchus tshawytscha

Canadian Journal of Zoology ◽

10.1139/z89-239 ◽

1989 ◽

Vol 67 (7) ◽

pp. 1665-1669 ◽

Cited By ~ 19

Author(s):

Eric B. Taylor

Keyword(s):

Life History ◽

Chinook Salmon ◽

Oncorhynchus Tshawytscha ◽

Evolutionary Ecology ◽

Migration Distance ◽

Pacific Salmonids

The incidence of precocial male maturation in yearling chinook salmon, Oncorhynchus tshawytscha, was examined in four laboratory-reared populations. Slim Creek and Bowron River chinook salmon were about 4 weeks older than Harrison and Nanaimo river chinook salmon when sampled (14 vs. 13 months of age), but were also 20–40 g smaller. Approximately 29, 12, 0, and 0% of all males were precocious in Bowron River, Slim Creek, Harrison River, and Nanaimo River chinook salmon, respectively. Precocial male chinook salmon had gonadosomatic indices of about 5–6%, whereas immature salmon from all populations had indices under 1%. Precocial male chinook salmon were more robust bodied than immature salmon; precocial males had deeper bodies, deeper heads, and larger adipose fins. Variation among the study populations in the incidence of precocial male maturation may be related to differences among the populations in migration distance to the sea or in juvenile freshwater rearing life history. The chinook salmon would probably be a productive species with which to study the evolutionary ecology of precocial maturity in Pacific salmonids.

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Extreme life history change of white-spotted char (Salvelinus leucomaenis) after damming

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-050 ◽

2000 ◽

Vol 57 (6) ◽

pp. 1300-1306 ◽

Cited By ~ 61

Author(s):

Kentaro Morita ◽

Shoichiro Yamamoto ◽

Noboru Hoshino

Keyword(s):

Life History ◽

High Growth ◽

Migratory Behavior ◽

Transplant Experiment ◽

Dam Construction ◽

Low Density ◽

Salvelinus Leucomaenis ◽

Migration Barriers ◽

Potential Migrant ◽

White Spotted Char

Dam construction has serious consequences for anadromous fishes. We examined the effects of migration barriers formed following dam construction on the migratory behavior of white-spotted char (Salvelinus leucomaenis) by comparing migrants in accessible below-dam river sections with migrants in inaccessible above-dam river sections. The frequency of smolts (i.e., potential migrant) was higher for the below-dam sections than for the above-dam sections, and in contrast, the frequency of residents was higher for the above-dam sections. Above-dam sections had lower fry (age 0+) densities and consequently had higher growth rates compared with below-dam sections. A transplant experiment revealed that the majority of the below-dam fish adopted a resident strategy, as well as above-dam fish, when both had experienced the above-dam environment. We conclude that high growth as a result of low density promotes residency in the above-dam sections.

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