A hump-shaped relationship between migration distance and adult pink salmon morphology suggests interactive effects of migration costs and bear predation

2016 ◽  
Vol 73 (3) ◽  
pp. 427-435 ◽  
Author(s):  
Genki Sahashi ◽  
Taku Yoshiyama
Keyword(s):  
Body Shape ◽  
Pink Salmon ◽  
Interactive Effects ◽  
Head Size ◽  
Oncorhynchus Gorbuscha ◽  
Spawning Habitat ◽  
Selective Predation ◽  
Body Depth ◽  
Shape Selective ◽  
Migration Costs

We examined the relationship between environmental factors of a spawning habitat and body shape at maturity in 16 pink salmon (Oncorhynchus gorbuscha) populations. The divergence vector (indicator of body depth and head size development) in both sexes was significantly correlated with distance from the sea and was described by a hump-shaped relationship. An exaggerated body shape was most developed at mid-distance from the sea and less developed both near and far from the sea. The observed frequency of bears decreased significantly with distance from the sea, implying that bear predation on salmon is most intense near the sea. Therefore, our results imply that shape-selective predation by bears affects the shape of pink salmon in rivers where the spawning habitat is near the sea and that migration costs inhibit development of an exaggerated body depth and head size in salmon in rivers where the spawning habitat is far from the sea.

Species Selective Predation on Juvenile Pink (Oncorhynchus gorbuscha) and Chum Salmon (O. keta) by Coho Salmon (O. kisutch)

1985 ◽  
Vol 42 (4) ◽  
pp. 659-668 ◽  
Author(s):  
N. Brent Hargreaves ◽  
Robin J. Lebrasseur
Keyword(s):  
Chum Salmon ◽  
Prey Species ◽  
Coho Salmon ◽  
Prey Size ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Selective Predation ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Mixed Populations

Predation on juvenile pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta) by yearling coho (O. kisutch) was studied in marine enclosures in Masset Inlet, B.C. These experiments demonstrate that coho prey selectively upon pink salmon even when chums are both significantly smaller and more abundant than pink salmon. Reexamination of the results of similar experiments conducted in Burke Channel, B.C., also confirms that mortality was biased towards pink salmon. Prey species may be more important than prey size for coho that prey upon mixed populations of pink and chum salmon during early sea-life.

Variation in Length and Body Depth of Pink Salmon (Oncorhynchus gorbuscha) and Chum Salmon (O. keta) in Southern British Columbia

1985 ◽  
Vol 42 (2) ◽  
pp. 312-319 ◽  
Author(s):  
Terry D. Beacham ◽  
Clyde B. Murray
Keyword(s):  
British Columbia ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Body Depth ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Gain Access

The magnitude of within-stock variability of postorbital–hypural length and body depth was investigated for spawning pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta) stocks. Variability of postorbital–hypural length and body depth of male pink salmon, all maturing at 2 yr of age, was greater than that for male chum salmon, maturing at ages of 3–5 yr. Female pink salmon were less variable for the two characters than all ages of female chum salmon, equally variable when only age 3 or age 4 female chum salmon were considered, and more variable in comparison with age 5 female chum salmon. Males were more variable for each character than females for both species. Small males of both species tend to resemble females when body depths are compared. It is suggested that small males mimic females to reduce aggression from larger males and gain access to spawning females.

Determinants of stream life, spawning efficiency, and spawning habitat in pink salmon in the Auke Lake system, Alaska

1997 ◽  
Vol 54 (1) ◽  
pp. 96-104 ◽  
Author(s):  
M Fukushima ◽  
W W Smoker
Keyword(s):  
Linear Models ◽  
Pink Salmon ◽  
Stream Temperature ◽  
Oncorhynchus Gorbuscha ◽  
Spawning Habitat ◽  
Stream Discharge ◽  
Lake System ◽  
Inlet Stream ◽  
Lake Outlet ◽  
Outlet Stream

Variation in stream life, spawning efficiency, and spawning habitat among adult pink salmon (Oncorhynchus gorbuscha) in the Auke Lake system, southeastern Alaska, was best explained by stream discharge, stream temperature, and a combination of stream temperature and discharge. We estimated these attributes of female pink salmon spawners in samples of daily cohorts tagged as they entered fresh water and used generalized linear models to analyze variation in the attributes with respect to environmental factors. Spawners varied in stream life (5-11 days), spawning efficiency (30-70% of females in daily entry cohorts retained less than 500 eggs at death), and spawning habitat (30-70% spawned in the lake outlet stream rather than the lake inlet stream). Observed variation of habitat (proportionately more use of the cooler inlet stream early in the spawning season when stream temperatures are warm and development is rapid) would contribute to synchronicity of fry emigration, which is known to be positively correlated with subsequent survival in Auke Lake pink salmon.

Supplementary Checks on the Scales of Pink Salmon (Oncorhynchus gorbuscha) and Chum Salmon (O. keta)

1965 ◽  
Vol 22 (6) ◽  
pp. 1477-1489 ◽  
Author(s):  
H. T. Bilton ◽  
W. E. Ricker
Keyword(s):  
British Columbia ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Commercial Fisheries ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Clear Cut ◽  
Second Year Of Life ◽  
Second Year ◽  
Similar Incidence

Among 159 central British Columbia pink salmon that had been marked by removal of two fins as fry and had been recovered in commercial fisheries after one winter in the sea, the scales of about one-third showed a supplementary or "false" check near the centre of the scale, in addition to the single clear-cut annulus. This evidence from fish of known age confirms the prevailing opinion that such extra checks do not represent annuli, hence that the fish bearing them are in their second year of life rather than their third. Unmarked pink salmon from the same area, and some from southern British Columbia, had a generally similar incidence of supplementary checks. In both marked and unmarked fish the supplementary checks varied in distinctness from faint to quite clear. In a sample of scales of 14 double-fin marked chum salmon which were known to be in their 4th year, all fish had the expected 3 annuli, and 12 fish had a supplementary check inside the first annulus.

Sign in / Sign up

Export Citation Format

Share Document