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1.
Increasing concern has been expressed about the genetic effects of cultured salmonid fishes on natural populations. Avoidance of extreme negative outcomes was one reason for the establishment of a genetic management policy for the State of Alaska. However, domestication within the hatchery may still cause divergence from the wild donor population. This divergence could potentially lead to adverse impacts on wild stocks through straying and introgression. This study examines potential domestication in two Alaskan chinook salmon stocks. The Little Port Walter (LPW) Hatchery Chickamin River stock resulted from a small collection of wild broodstock in 1976. The LPW Unuk stock was founded with a larger number of individuals in 1976 and has had subsequent infusion of wild gametes. These lines have been maintained at LPW through ocean ranching of tagged smolts. Comparisons are made between the hatchery lines, progeny of wild chinook collected from the Chickamin and Unuk Rivers, and hybrids between the hatchery and wild groups. Mature ocean‐ranched female chinook salmon returning to the facility were periodically graded for ripeness and spawned. Body size and meristic measurements were collected from these mature spawners. Maturation timing, fecundity, and individual egg size of these fourth generation hatchery fish are compared with that of offspring of wild fish from the same donor stock. Stock of origin is confirmed for all spawners and offspring using microsatellite DNA analysis. 相似文献
2.
R. J. Beamish R. M. Sweeting C. M. Neville K. L. Lange T. D. Beacham D. Preikshot 《Environmental Biology of Fishes》2012,94(1):135-148
The population dynamics of chinook salmon (Oncorhynchus tshawytscha) from the Cowichan River on Vancouver Island, British Columbia, Canada are used by the Pacific Salmon Commission as an index
of the general state of chinook salmon coast wide. In recent years the production declined to very low levels despite the
use of a hatchery that was intended to increase production by improving the number of smolts entering the ocean. In 2008,
we carried out an extensive study of the early marine survival of the hatchery and wild juvenile chinook salmon. We found
that both rearing types mostly remained within the Gulf Islands study area during the period when most of the marine mortality
occurred for the hatchery fish. By mid September, approximately 1.3% of all hatchery fish survived, compared to 7.8%–31.5%
for wild fish. This six to 24 times difference in survival could negate an estimated increased egg-to-smolt survival of about
13% that is theorized to result through the use of a hatchery. Estimates of the early marine survival are approximate, but
sufficient to show a dramatic difference in the response of the two rearing types to the marine nursery area. If the declining
trend in production continues for both rearing types, modifications to the hatchery program are needed to improve survival
or an emphasis on improving the abundances of wild stocks is necessary, or both. The discovery that the juvenile Cowichan
River chinook salmon remain within a relatively confined area of the Gulf Islands within the Strait of Georgia offers an excellent
opportunity to research the mechanisms that cause the early marine mortalities and hopefully contribute to a management that
improves the production. 相似文献
3.
The impact of supplementation in winter-run chinook salmon on effective population size 总被引:1,自引:0,他引:1
Supplementation of young raised at a protected site, such as a hatchery, may influence the effective population size of an endangered species. A supplementation program for the endangered winter-run chinook salmon from the Sacramento River, California, has been releasing fish since 1991. A breeding protocol, instituted in 1992, seeks to maximize the effective population size from the captive spawners by equaling their contributions to the released progeny. As a result, the releases in 1994 and 1995 appear not to have decreased the overall effective population size and may have increased it somewhat. However, mistaken use of non-winter-run chinook spawners resulted in artificial crosses between runs with a potential reduction in effective population size, and imprinting of the released fish on Battle Creek, the site of the hatchery, resulted in limiting the contribution of the released fish to the target mainstem population. Rapid genetic analysis of captured spawners and a new rearing facility on the Sacramento River should alleviate these problems and their negative effect on the effective population size in future years. 相似文献
4.
For over a century, Washington State Department of Fish and Wildlife has implemented hatchery programs as a means to boost salmon abundance. Concerns have developed that native populations may be replaced by hatchery strains, decreasing the genetic diversity required to respond to environmental changes. We report a comparison of microsatellite DNA variation in wild-spawning and hatchery-strain coho salmon from the Nooksack and Samish rivers in northern Puget Sound. Significant heterogeneity in genotype frequencies was detected between wild-spawning coho salmon from the upper North Fork (NF) Nooksack River and hatchery-strain coho salmon from the Nooksack River (descendants of primarily Nooksack River broodstock). Little difference in genotype frequencies was detected between wild-spawning coho salmon from the Samish River and hatchery-strain coho salmon from the Nooksack River. The 13-locus suite provided high resolution: in assignment tests over 85% of wild-spawning coho salmon from the upper NF Nooksack River were assigned to source. Wild-spawning coho salmon collected below hatcheries in the Nooksack River and 50% of wild-spawning Samish River coho salmon were assigned to hatchery collections. The genetic divergence of wild-spawning coho salmon in the upper NF Nooksack River is remarkable given the extensive stocking history and proximity of a hatchery. We suggest that these upper river fish are native coho salmon and that wild spawners in the lower Nooksack and Samish River are descendants of hatchery productions. We attribute divergence to earlier run timing in upper NF Nooksack River wild spawners, availability of extensive spawning and rearing habitat upstream of a hatchery in the upper NF Nooksack River, and a longer stocking history in the Samish River. 相似文献
5.
Levin PS Zabel RW Williams JG 《Proceedings. Biological sciences / The Royal Society》2001,268(1472):1153-1158
Hatchery programmes for supplementing depleted populations of fish are undergoing a worldwide expansion and have provoked concern about their ramifications for populations of wild fish. In particular, Pacific salmon are artificially propagated in enormous numbers in order to compensate for numerous human insults to their populations, yet the ecological impacts of this massive hatchery effort are poorly understood. Here we test the hypothesis that massive numbers of hatchery-raised chinook salmon reduce the marine survival of wild Snake River spring chinook, a threatened species in the USA. Based on a unique 25-year time-series, we demonstrated a strong, negative relationship between the survival of chinook salmon and the number of hatchery fish released, particularly during years of poor ocean conditions. Our results suggest that hatchery programmes that produce increasingly higher numbers of fish may hinder the recovery of depleted wild populations. 相似文献
6.
Palm S Dannewitz J Järvi T Petersson E Prestegaard T Ryman N 《Molecular ecology》2003,12(8):2057-2071
The supportive breeding programme for sea trout (Salmo trutta) in the River Dalälven, Sweden, is based on a sea‐ranched hatchery stock of local origin that has been kept ‘closed’ to the immigration of wild genes since the late 1960s (about seven generations). In spite of an apparent potential for substantial uni directional gene flow from sea‐ranched to wild (naturally produced) trout, phenotypic differences with a presumed genetic basis have previously been observed between the two ‘stocks’. Likewise, two previous studies of allozyme and mitochondrial DNA variation based on a single year of sampling have indicated genetic differentiation. In the present study we used microsatellite and allozyme data collected over four consecutive years, and tested for the existence of overall genetic stock divergence while accounting for temporal heterogeneity. Statistical analyses of allele frequency variation (F‐statistics) and multilocus genotypes (assignment tests) revealed that wild and sea‐ranched trout were significantly different in three of four years, whereas no overall genetic divergence could be found when temporal heterogeneity among years within stocks was accounted for. On the basis of estimates of effective population size in the two stocks, and of FST between them, we also assessed the level of gene flow from sea‐ranched to wild trout to be ≈ 80% per generation (with a lower confidence limit of ≈ 20%). The results suggest that the reproductive success of hatchery and naturally produced trout may be quite similar in the wild, and that the genetic characteristics of the wild stock are largely determined by introgressed genes from sea‐ranched fish. 相似文献
7.
8.
Early marine trophic interactions of wild and hatchery chum salmon (Oncorhynchus keta) were examined as a potential cause for the decline in harvests of adult wild chum salmon in Taku Inlet, Southeast Alaska.
In 2004 and 2005, outmigrating juvenile chum salmon were sampled in nearshore habitats of the inlet (spring) and in epipelagic
habitat at Icy Strait (summer) as they approached the Gulf of Alaska. Fish were frozen for energy density determination or
preserved for diet analyses, and hatchery stocks were identified from the presence of thermal marks on otoliths. We compared
feeding intensity, diets, energy density, and size relationships of wild and hatchery stocks (n = 3123) across locations and weeks. Only hatchery fish feeding intensity was negatively correlated with fish abundance. In
both years, hatchery chum salmon were initially larger and had greater energy density than wild fish, but lost condition in
early weeks after release as they adapted to feeding on wild prey assemblages. Diets differed between the stocks at all inlet
locations, but did not differ for hatchery salmon between littoral and neritic habitats in the outer inlet, where the stocks
overlapped most. Both diets and energy density converged by late June. Therefore, if density-dependent interactions affect
wild chum salmon, these effects must be very rapid because survivors in Icy Strait showed few differences. Our study also
demonstrates that hatchery release strategies used near Taku Inlet successfully promote early spatial segregation and prey
partitioning, which reduce the probability of competition between wild and hatchery chum salmon stocks. 相似文献
9.
Jennifer E. McLean Paul Bentzen Thomas P. Quinn 《Environmental Biology of Fishes》2004,69(1-4):359-369
Hatchery propagation of salmonids has been practiced in western North America for over a century. However, recent declines in wild salmon abundance and efforts to mitigate these declines through hatcheries have greatly increased the relative abundance of fish produced in hatcheries. The over-harvest of wild salmon by fishing mixed hatchery and wild stocks has been of concern for many years but genetic interactions between populations, such as hybridization, introgression and outbreeding depression, may also compromise the sustainability of wild populations. Our goal was to examine whether a newly established hatchery population of steelhead trout successfully reproduced in the wild and to compare their rate of reproductive success to that of sympatrically spawning native steelhead. We used eight microsatellite loci to create allele frequency profiles for baseline hatchery and wild populations and assigned the smolt (age 2) offspring of this parental generation to a population of origin. Adults originating from a generalized hatchery stock artificially selected for early return and spawning date were successful at reproducing in Forks Creek, Washington. Although hatchery females (N = 90 and 73 in the two consecutive years of the study) produced offspring that survived to emigrate as smolts, they produced only 4.4–7.0% the number produced per wild female (N = 11 and 10). This deficit in reproductive success implies that the proportion of hatchery genes in the mixed population may diminish since deliberate releases into the river have ceased. This hypothesis is being tested in a long-term study at Forks Creek. 相似文献
10.
Gregory T. Ruggerone Beverly A. Agler Jennifer L. Nielsen 《Environmental Biology of Fishes》2012,94(1):149-163
Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects
on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap
in the ocean, and wild salmon populations having low productivity may compete for food with abundant hatchery populations.
We tested the hypothesis that adult length-at-age, age-at-maturation, productivity, and abundance of a Norton Sound, Alaska,
chum salmon population were influenced by Asian hatchery chum salmon, which have become exceptionally abundant and surpassed
the abundance of wild chum salmon in the North Pacific beginning in the early 1980s. We found that smaller adult length-at-age,
delayed age-at-maturation, and reduced productivity and abundance of the Norton Sound salmon population were associated with
greater production of Asian hatchery chum salmon since 1965. Modeling of the density-dependent relationship, while controlling
for other influential variables, indicated that an increase in adult hatchery chum salmon abundance from 10 million to 80
million adult fish led to a 72% reduction in the abundance of the wild chum salmon population. These findings indicate that
competition with hatchery chum salmon contributed to the low productivity and abundance of Norton Sound chum salmon, which
includes several stocks that are classified as Stocks of Concern by the State of Alaska. This study provides new evidence
indicating that large-scale hatchery production may influence body size, age-at-maturation, productivity and abundance of
a distant wild salmon population. 相似文献
11.
Genetic hazards associated with the stocking of fish juveniles produced in hatcheries were studied with simple mathematical
models. Domestication is the process of acquiring a genetic characteristics that are advantageous in a hatchery environment
but that are disadvantageous in a natural environment due to the selection pressure in the hatchery differing from that in
the natural environment. Conditions for the propagation of mutants enhancing domestication were obtained for a variety of
stocking strategies specified by parameters related to hatchery productivity and kind of brood stock used. By using this,
the possibility of reducing the risk of domestication was studied. As a means of reducing the risk, selective use of wild-born
individuals for brood stock was considered. The effectiveness of this was analyzed for both the cases where all brood stock
is collected from the wild, and the male brood stock is collected from the wild and the female brood stock is born and reared
in a hatchery. We also estimate how much hatchery release can be increased without increasing the risk by employing these
means. It is concluded that the use of only male brood stock from the wild is not very effective in reducing the risk of domestication.
Further, it is concluded that selective use of the wild-born individuals of both sexes for brood stock is highly desirable
if the contribution of released individuals to the natural reproduction is high. In other words, substantial increase of hatchery
release may be possible while keeping risk at a level comparable to that under moderate hatchery release, if it is accompanied
by the selective use of wild-born individuals for brood stock. 相似文献
12.
Evolution of temporal isolation in the wild: genetic divergence in timing of migration and breeding by introduced chinook salmon populations 总被引:3,自引:0,他引:3
Quinn TP Unwin MJ Kinnison MT 《Evolution; international journal of organic evolution》2000,54(4):1372-1385
Abstract. The timing of migration and breeding are key life-history traits; they are not only adaptations of populations to their environments, but can serve to increase reproductive isolation, facilitating further divergence among populations. As part of a study of divergence of chinook salmon, Oncorhynchus tshawytscha , populations, established in New Zealand from a common source in the early 1900s, we tested the hypotheses that the timing of migration and breeding are under genetic control and that the populations genetically differ in these traits despite phenotypic overlap in timing in the wild. Representatives of families from two populations were collected within a day or two of each other, reared in a common environment, and then released to sea from each of two different rivers, while other family representatives were retained in fresh water to maturity. The date of maturation of fish held in fresh water and the dates of return from the ocean and maturation of fish released to sea all showed significant differences between the two populations and among families within populations. The very high heritabilities and genetic correlations estimated for migration and maturation date indicated that these traits would respond rapidly to selection. Combined with the results of related studies on these chinook salmon populations, it appears that spawning time may not only evolve during the initial phases of divergence, but it may play an important role in accelerating divergence in other traits. 相似文献
13.
Overview of salmon stock enhancement in southeast Alaska and compatibility with maintenance of hatchery and wild stocks 总被引:1,自引:0,他引:1
Modern salmon hatcheries in Southeast Alaska were established in the 1970s when wild runs were at record low levels. Enhancement
programs were designed to help rehabilitate depressed fisheries and to protect wild salmon stocks through detailed planning
and permitting processes that included focused policies on genetics, pathology, and management. Hatcheries were located away
from significant wild stocks, local sources were used to develop hatchery broodstocks, and juveniles are marked so management
can target fisheries on hatchery fish. Initially conceived as a state-run system, the Southeast Alaska (SEAK) program has
evolved into a private, non-profit concept centered around regional aquaculture associations run by fishermen and other stakeholders
that pay for hatchery operations through landing fees and sale of fish. Today there are 15 production hatcheries and 2 research
hatcheries in SEAK that between 2005 and 2009 released from 474 to 580 million (average 517 million) juvenile salmon per year.
During this same period commercial harvest of salmon in the region ranged from 28 to 71 million salmon per year (average 49
million). Contributions of hatchery-origin fish to this harvest respectively averaged 2%, 9%, 19%, 20%, and 78% for pink,
sockeye, Chinook, coho, and chum salmon. Both hatchery and wild salmon stocks throughout much of Alaska have experienced high
marine survivals since the 1980s and 1990s resulting in record harvests over the past two decades. Although some interactions
between hatchery salmon and wild salmon are unavoidable including increasing concerns over straying of hatchery fish into
wild salmon streams, obvious adverse impacts from hatcheries on production of wild salmon populations in this region are not
readily evident. 相似文献
14.
Juvenile brown trout Salmo trutta from natural populations reacted to the presence of piscivorous brown trout by increasing the use of refuges. In contrast, second‐generation hatchery fish and the offspring of wild fish raised under hatchery conditions were insensitive to predation risk. The diel pattern of activity also differed between wild and hatchery brown trout. Second‐generation hatchery fish were predominantly active during daytime regardless of risk levels. Wild fish, however, showed a shift towards nocturnal activity in the presence of predators. These findings emphasize the potential role of domestication in weakening behavioural defences. They support the idea that the behavioural divergence between wild and domesticated individuals can arise from a process of direct or indirect selection on reduced responsiveness to predation risk, or as a lack of previous experience with predators. 相似文献
15.
The use of developmental instability (an individual's failure to produce a consistent phenotype in a given environment) was evaluated to detect the effects of outplanting hatchery fish on wild salmon. Juvenile chinook salmon were collected in 1989, 1990, and 1991 from five drainages in the Snake River Basin. In each drainage we attempted to collect fish from streams with no hatchery supplementation (wild), naturally spawning fish from streams with hatchery supplementation (natural), and fish collected at a hatchery. Forty fish were collected per site and the number of elements in bilateral characters were counted on each side of the fish. Indices of fluctuating asymmetry (FA), a measure of minor, random deviations in perfect symmetry of bilateral counts, were calculated as an estimator of developmental instability. Analysis of character counts from seven paired characters revealed normal distributions. Only one of the characters displayed counts that were statistically larger on one side than the other, indicating that directional asymmetry (DA) or antisymmetry was not a major bias of FA. However, the means of all individual characters revealed a non-statistically significant left side bias. We analyzed our data using two indices of FA (FA1 and FA5) with different levels of sensitivity to DA. Differences in both FA indices were found among years, with collection sites in 1989 having significantly larger FA values than in 1991 (FA p < 0.01). Levels of FA among wild, natural, and hatchery fish were comparatively small (FA1 p = 0.17). This suggests developmental conditions were different in the first year of the study than in the last. The cause of these differences may be linked to either genetic or environmental variation or to gene—environment interactions, but the general population declines of salmon that occurred during this time obscures more specific conclusions. 相似文献
16.
Genetic homogenization has been recognized as a serious threat in an increasing number of species, including many salmonid fishes. We assessed the rate and impact of immigration from the main hatchery stocks of Atlantic salmon in the Gulf of Bothnia into one of the largest wild salmon populations in the Baltic Sea, the River Vindel?lven, within a temporal framework of 18 years (from 1985-2003). We provide genetic evidence based on mtDNA and microsatellite markers, using mixed-stock analysis, that a large proportion (66%) of fin-damaged spawners (n=181) caught in the Ume/Vindel?lven during 1997-2003 originated from the hatcheries in the Rivers Angerman?lven, Lule?lven and Ljusnan. The maximum-likelihood estimate of immigration rate from these hatcheries into the wild Vindel?lven population was 0.068 (95% CI 0.021-0.128) over the studied time period (1985-2003) and reached up to a quarter (m=0.249, 95% CI 0.106-0.419) of the total population during 1993-2000. This resulted in significant (P<0.01) genetic homogenization trend between the wild Vindel?lven population and hatchery stocks of the Angerman?lven and Lule?lven. Our results demonstrate extensive straying from geographically distant hatchery releases into wild salmon population and emphasize the genetic risks associated with current large-scale stocking practices in the Baltic Sea. 相似文献
17.
For conserving the unique representative of salmonids—the Black Sea salmon Salmo trutta labrax—its hatchery rearing was initiated in 1998 at the Adler trout hatchery farm (Northern Caucasia). Fish were kept in concrete tanks. The comparative assessment of hatchery-reared fish and salmon from natural populations revealed their similarity by dates of the onset of smoltification, ratio of spawners maturing at different ages, and the weight, sizes, and fecundity of females. The quality of sexual products and progeny obtained from spawners of the initial brood stock was high. The data obtained indicate that the method of hatchery rearing the Black Sea salmon is promising. 相似文献
18.
Two brood stocks of brook charr, Sulvelinus fontinalis , are currently maintained by the Ontario Ministry of Natural Resources. The Nipigon brood stock originated from Lake Nipigon, in north-central Ontario, while the Hills Lake stock is believed to have been produced by hybridizing several strains (including charr from a Pennsylvania hatchery as well as charr from Ontario) in the past. The mitochondrial DNA (mtDNA) variability of these brood stocks was characterized using 51 hexanucleotide restriction enzymes. Eleven restriction enzymes, Acc I, Am I, Bun I, Bun II, Hind III, Nco I, Nde I, Nhe I, Nsi I, Pst I and Sph I, were polymorphic between the two brood stocks. Eight hatchery mtDNA haplotypes were detected showing a maximum of 0.41 % sequence divergence. Seven haplotypes are present in the Hills Lake strain, and two in the Nipigon strain. These mtDNA haplotypes are useful markers to determine the degree of reproductive success between planted and native fish. In one comparison in southern Ontario, less than 20% of the wild fish sampled from the head water regions of a small drainage entering Lake Erie could have resulted from random introgression with hatchery fish planted further downstream, because most of these fish possessed a unique Acc 1 cut site. This is one of the few examples in stock analysis studies where such a high degree of genetic discrimination is evident between hatchery and native fish. 相似文献
19.
A. Yurtseva D. Lajus V. Artamonova A. Makhrov 《Zeitschrift fur angewandte Ichthyologie》2010,26(2):307-314
The study addresses the effect of hatchery rearing on morphological variation and developmental stability of Atlantic salmon parr from North‐West Russia. Totally, we collected nine samples. Four wild samples were collected from each of the rivers Kola, Umba, Keret’ and Shuia. Five samples of hatchery‐reared parr were the first‐generation progeny of wild adults from these rivers reared separately at the four hatcheries (one hatchery was represented by two samples). Ten meristic and 48 morphometric cranial characters were analysed. We studied the morphological divergence between wild and hatchery fishes of the same river of origin. To analyze developmental stability we used fluctuating asymmetry (random deviations from perfect bilateral symmetry). It was found that hatchery‐reared parr significantly differ from wild parr in both meristic characters and the shape of cranial bones. Different hatcheries caused similar effect on morphological variation in all populations. Fluctuating asymmetry in morphometric characters was significantly higher in hatchery fish than in wild from the Shuia River, indicating a higher level of developmental instability. However, wild parr from the Keret’ River had significantly higher fluctuating asymmetry than cultivated parr of the same origin, possible due to a high infection pressure of the parasite Gyrodactylus salaris Malmberg which has led to significant decline of the wild salmon population in this river, or from genetic changes caused by cultivation. The obtained results indicate a notable effect of hatchery environment on Atlantic salmon’s phenotype. 相似文献
20.
Teppo Vehanen 《Environmental Biology of Fishes》2006,76(2-4):255-264
I studied inter- and intraspecific competition in two hatchery stocks: landlocked salmon with long-hatchery background and a heterogenic brown trout stock. These species are potential competitors in the natural environment when landlocked salmon is being restored to wild by stocking hatchery juveniles. Behavioural responses were studied in four indoor laboratory flumes (400 cm long and 37 cm wide) and habitat use in six semi-natural outdoor streams (26 m long and 1.5 m long). Video recordings were used to monitor fish behaviour and electrofishing for fish positioning in the outdoor channels. The study design included five treatments: two densities of brown trout and salmon in solitary and both species together. The results of the study demonstrated that juvenile brown trout changed their behaviour in laboratory streams in response to presence of the landlocked salmon and the density of the conspecifics also tended to alter the habitat use by brown trout in semi-natural streams. Landlocked salmon juveniles showed no response to treatments. I conclude that possible poor adaptive ability to conditions outside hatchery by the hatchery salmon together and more competitive brown trout stocks may limit the success of management action in restoring landlocked salmon back to their natural streams of stocking. 相似文献