Changes in the life history traits of Song Thrushes Turdus philomelos introduced to New Zealand

Chinook salmon (Oncorhynchus tshawytscha) spawning runs in Glenariffe Stream, New Zealand, exhibited significant changes in life history traits following supplementation releases of hatchery-reared juveniles. Total run strength did not change but the proportion of naturally produced fish declined to 34%. Attempts to separate spawners of natural and hatchery origin were unsuccessful, and 31-48% of natural spawners are now of hatchery origin. Hatchery males were smaller at age 2 and 3 than males of natural origin, and more often matured as jacks, producing an 86-mm decrease in mean fork length over 28 years. There was no change in length at age or age at maturity for female spawners. The proportion of jacks entering Glenariffe Stream each year was positively correlated with the proportion of jacks in the ensuing cohort. Most differences between fish of natural and hatchery origin were related to hatchery rearing practices, but the decline in age at maturity among naturally produced males appears to reflect traits inherited from parent stock of hatchery origin. Hatchery releases may also favour the survival of ocean-type fry over stream-type fry, possibly reversing a tendency for stream-type behaviour to evolve in response to the lack of estuaries on most New Zealand chinook salmon rivers.

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Using life-history traits of New Zealand sea lions, Auckland Islands to clarify potential causes of decline

Journal of Zoology ◽

10.1111/j.1469-7998.2012.00910.x ◽

2012 ◽

Vol 287 (4) ◽

pp. 240-249 ◽

Cited By ~ 9

Author(s):

B. L. Chilvers

Keyword(s):

Life History ◽

New Zealand ◽

Life History Traits ◽

Sea Lions

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Erratum: Correlated contemporary evolution of life-history traits in New Zealand Chinook salmon, Onchorhynchus tshawytscha

Heredity ◽

10.1038/hdy.2011.28 ◽

2011 ◽

Vol 106 (5) ◽

pp. 906-906

Author(s):

M T Kinnison ◽

T P Quinn ◽

M J Unwin

Keyword(s):

Life History ◽

New Zealand ◽

Chinook Salmon ◽

Life History Traits ◽

Contemporary Evolution ◽

Evolution Of Life

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Variation in Life History Patterns among New Zealand Chinook Salmon (Oncorhynchus tshawytscha) Populations

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-162 ◽

1993 ◽

Vol 50 (7) ◽

pp. 1414-1421 ◽

Cited By ~ 47

Author(s):

Thomas P. Quinn ◽

Martin J. Unwin

Keyword(s):

Life History ◽

New Zealand ◽

Chinook Salmon ◽

Life History Traits ◽

Oncorhynchus Tshawytscha ◽

Local Conditions ◽

Median Date ◽

Timing Of Entry ◽

Genetic And Environmental Factors ◽

Size At Age

Chinook salmon (Oncorhynchus tshawytscha) were introduced to New Zealand, apparently from a single California population, and have been self-sustaining since about 1905. Salmon from the Waimakariri, Rakaia, Rangitata, and Waitaki rivers differed in various life history traits. The proportion of stream-type adults ranged from 29.1 to 75.6% in Rakaia and Waimakariri tributaries, respectively. Average age at maturity not only differed among the major rivers but also between two tributaries within the Rakaia River catchment. Length at age varied among rivers, the differences being most pronounced in older fish. Age structure and size at age combined to produce 91-, and 73-mm differences in mean length of males and females, respectively, among populations. Waitaki River salmon were not only long at age but also heavier for their length than other populations. The timing of entry into freshwater varied by over 1 mo between the Rakaia and Waitaki rivers, and median date of arrival on spawning grounds varied by 16 d between Rakaia and Waimakariri river tributaries. These life history traits are influenced, to varying degrees, by genetic and environmental factors. However, the suite of differences indicates that considerable adaptation to local conditions has occurred in about 20 generations.

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