Changes in life history parameters in a naturally spawning population of chinook salmon (Oncorhynchus tshawytscha) associated with releases of hatchery-reared fish

1997 ◽  
Vol 54 (6) ◽  
pp. 1235-1245 ◽  
Author(s):  
M J Unwin ◽  
G J Glova
Keyword(s):  
Life History ◽  
New Zealand ◽  
Chinook Salmon ◽  
Life History Traits ◽  
Oncorhynchus Tshawytscha ◽  
Fork Length ◽  
Age At Maturity ◽  
Natural Origin ◽  
Parent Stock ◽  
Stream Type

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.

Life History of Juvenile Ocean-type Chinook Salmon (Oncorhynchus tshawytscha) in the Situk River, Alaska

1992 ◽  
Vol 49 (12) ◽  
pp. 2621-2629 ◽  
Author(s):  
S. W. Johnson ◽  
J. F. Thedinga ◽  
K. V. Koski
Keyword(s):  
Life History ◽  
Chinook Salmon ◽  
Habitat Preference ◽  
Oncorhynchus Tshawytscha ◽  
Fork Length ◽  
Main Stem ◽  
Seawater Tolerance ◽  
History Of ◽  
Two Phases ◽  
Stream Type

Distribution, abundance, habitat preference, migration and residence timing, seawater tolerance, and size were determined for juvenile ocean-type (age 0) chinook salmon (Oncorhynchus tshawytscha) in the Situk River, Alaska. Chinook primarily occupied main-stem habitats (channel edges in spring, pools and willow edges in summer). Peak chinook densities in the upper and lower main stem were 96 and 76 fish/100 m2, respectively. Chinook migrated downstream in two phases: a spring dispersal of emergent fry and a summer migration. Chinook marked in the upper river in late June and early July were recaptured 20 km downstream in the lower river in late July. Marked chinook resided in the lower river up to 34 d. Mean fork length of chinook in the lower river increased from 40 mm in May to 80 mm in early August. By late August, chinook had emigrated from the lower river at a size of approximately 80 mm. Fish this size were seawater tolerant and had the physical appearance of smolts. Ocean-type chinook in the Situk River are unique because in most Alaskan streams, chinook are stream-type (rear in freshwater at least 1 yr).

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

1993 ◽  
Vol 50 (7) ◽  
pp. 1414-1421 ◽  
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.

Homing and Straying Patterns of Chinook Salmon (Oncorhynchus tshawytscha) from a New Zealand Hatchery: Spatial Distribution of Strays and Effects of Release Date

1993 ◽  
Vol 50 (6) ◽  
pp. 1168-1175 ◽  
Author(s):  
Martin J. Unwin ◽  
Thomas P. Quinn
Keyword(s):  
Spatial Distribution ◽  
New Zealand ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Complex Interaction ◽  
Research Station ◽  
Age At Maturity ◽  
Release Date

Homing and straying patterns of fall chinook salmon (Oncorhynchus tshawytscha) released from the Glenariffe Salmon Research Station on the Rakaia River, New Zealand, are reported, based on coded-wire tag recoveries from the 1978–84 brood years. Of 17 671 tagged adults recovered, 87.9% returned to the Rakaia, and the rest were recovered from 12 other catchments up to 500 km away. The number of strays entering a given river increased with discharge and with proximity to the Rakaia, but most strays were recorded in catchments north of the Rakaia. A higher proportion of salmon released in winter, when the downriver migration of naturally produced chinook is a minimum, strayed to other catchments (14.9–20.6%) than did those released at other times of the year (3.6–7.6%). However, straying within the Rakaia catchment was largely unaffected by release date, suggesting that imprinting by fry to the natal tributary is separate from imprinting by smolts to the mainstem river. There was a complex interaction between age at maturity, release date, and straying rates; straying of 4-yr-old fish was more strongly influenced by release date than straying of younger fish. Notwithstanding this interaction, straying was more prevalent among older fish.

Scale Characteristics of Wild and Hatchery Chinook Salmon (Oncorhynchus tshawytscha) in the Rakaia River, New Zealand, and Their Use in Stock Identification

1993 ◽  
Vol 50 (11) ◽  
pp. 2475-2484 ◽  
Author(s):  
M. J. Unwin ◽  
D. H. Lucas
Keyword(s):  
New Zealand ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Function Analysis ◽  
Adult Population ◽  
Fork Length ◽  
Genetic Traits ◽  
Linear Discriminant ◽  
Scale Characteristics ◽  
Freshwater Zone

To distinguish between fish with potentially desirable behavioural or genetic traits, we examined scales from wild and hatchery chinook salmon (Oncorhynchus tshawytscha) in the Rakaia River, New Zealand, and a tributary, Glenariffe Stream. Scales from wild chinook with a "stream-type" life history corresponded closely to those from 1+ juveniles, but the mean size of the freshwater zone for scales from "ocean-type" adults was significantly larger than for age 0+ juveniles. Scales from fish of hatchery origin lacked a distinct freshwater zone but were distinguishable from scales from wild fish by the location of the first annulus. Linear discriminant function analysis (DFA) based on the location of the first annulus correctly identified 82–90% of the fish in a mixed adult population, increasing to 88–92% when fork length and age were included. Estimates of the number of hatchery fish entering Glenariffe Stream from 1989 to 1992, based on DFA, were consistent with independent estimates derived from coded-wire tag returns.

Adaptive Variation in Rheotactic and Agonistic Behavior in Newly Emerged Fry of Chinook Salmon, Oncorhynchus tshawytscha, from Ocean- and Stream-Type Populations

1988 ◽  
Vol 45 (2) ◽  
pp. 237-243 ◽  
Author(s):  
Eric B. Taylor
Keyword(s):  
Life History ◽  
Chinook Salmon ◽  
Agonistic Behavior ◽  
Oncorhynchus Tshawytscha ◽  
Genetic Difference ◽  
Current Response ◽  
Body Morphology ◽  
Local Adaptations ◽  
Stream Type ◽  
Downstream Movement

Agonistic and rheotactic behavior and body morphology were compared in recently emerged, laboratory-reared chinook salmon (Oncorhynchus tshawytscha) from two "stream-type" and two "ocean-type" populations. Newly emerged chinook fry from the stream-type populations (Slim Creek and the Eagle River) were more aggressive than fry from the ocean-type populations (the Nanaimo and Harrison rivers). Slim Creek fry were consistently the most aggressive. There was no clear distinction in rheotactic behavior between stream- and ocean-type chinook; Harrison River, ocean-type chinook fry had the strongest downstream movement in "dark" current response tests, but fry from the other three populations had similar movement scores in both light and dark tests. Fry from the four populations were morphologically distinct; however, there was no clear separation in body morphology or coloration based on life history type. These differences exhibited in laboratory-reared fry indicate that they are, at least in part, inherited. I conclude that a fundamental genetic difference in agonistic behavior exists between stream- and ocean-type chinook juveniles. A genetic dichotomy between stream- and ocean-type chinook in rheotactic behavior and morphology, however, may be overidden by population-specific local adaptations, independent of life history type.

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