Efficacy of Feed Deprivation During Juvenile Rearing to Reduce Precocious Maturation of Age 1+ Male Spring Chinook Salmon Smolts PDF Download
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Author: Peter F. Galbreath (Fisheries biologist)
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Category : Chinook salmon
Languages : en
Pages : 22
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High feeding and growth, relative to wild fish, can induce substantial proportions of hatchery reared male spring Chinook Salmon juveniles to mature precociously as age-2 minijacks. Released as smolts, these fish do not migrate to the ocean for rearing, and thus do not reach the adult age and size at which they can contribute to harvest mitigation fisheries and natural population supplementation. Initiation of maturation is thought to occur during a critical time period approximately one year prior to spawning. We performed a study with broodyear 2018 juveniles involving total feed deprivation over two different time periods (Early - August 8 through September 11, 2019; and Late - September 11 through October 24, 2019), to determine whether the rate of precocious maturation of the hatchery reared juveniles could be significantly reduced, while also allowing time post-treatment for the fish to achieve an adequate final smolt size through compensatory growth. At termination of the study in July 2020, the probabilities of precocious maturation of male smolts as minijacks in the Early and Late treatment tanks, as determined by logistic regression analyses, averaged 24.7% and 24.2%, respectively, which were significantly lower than the 38.1% rate for continuously fed fish in the Control tanks. Because the fish had to be pooled from their replicate tanks into a single subdivided concrete raceway for overwintering, fish from each tank were stocked into a particular section of the raceway after receiving an identifying adipose and/or pelvic fin clip combination. Unfortunately, there was some level of misidentification of fish to their original rearing tank, due primarily to regrowth of clipped pelvic fins. Errors in identification were such that the actual reduction in minijack rate was likely even larger, in particular for the Early treatment fish, for which the actual minijack rate was likely closer to 20%. In both May and July 2020, the treatment fish were similar in size to Control fish. Further study of the effects of timing and duration of the food deprivation period on precocious maturation rate and growth is recommended in order to develop a protocol for hatchery rearing of spring Chinook Salmon smolts for consideration by regional fisheries and hatchery managers.
Author: Peter F. Galbreath (Fisheries biologist)
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 22
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High feeding and growth, relative to wild fish, can induce substantial proportions of hatchery reared male spring Chinook Salmon juveniles to mature precociously as age-2 minijacks. Released as smolts, these fish do not migrate to the ocean for rearing, and thus do not reach the adult age and size at which they can contribute to harvest mitigation fisheries and natural population supplementation. Initiation of maturation is thought to occur during a critical time period approximately one year prior to spawning. We performed a study with broodyear 2018 juveniles involving total feed deprivation over two different time periods (Early - August 8 through September 11, 2019; and Late - September 11 through October 24, 2019), to determine whether the rate of precocious maturation of the hatchery reared juveniles could be significantly reduced, while also allowing time post-treatment for the fish to achieve an adequate final smolt size through compensatory growth. At termination of the study in July 2020, the probabilities of precocious maturation of male smolts as minijacks in the Early and Late treatment tanks, as determined by logistic regression analyses, averaged 24.7% and 24.2%, respectively, which were significantly lower than the 38.1% rate for continuously fed fish in the Control tanks. Because the fish had to be pooled from their replicate tanks into a single subdivided concrete raceway for overwintering, fish from each tank were stocked into a particular section of the raceway after receiving an identifying adipose and/or pelvic fin clip combination. Unfortunately, there was some level of misidentification of fish to their original rearing tank, due primarily to regrowth of clipped pelvic fins. Errors in identification were such that the actual reduction in minijack rate was likely even larger, in particular for the Early treatment fish, for which the actual minijack rate was likely closer to 20%. In both May and July 2020, the treatment fish were similar in size to Control fish. Further study of the effects of timing and duration of the food deprivation period on precocious maturation rate and growth is recommended in order to develop a protocol for hatchery rearing of spring Chinook Salmon smolts for consideration by regional fisheries and hatchery managers.
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Languages : en
Pages : 41
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The Yakima River Spring Chinook Salmon Supplementation Project in Washington State is currently one of the most ambitious efforts to enhance a natural salmon population in the United States. Over the past five years we have conducted research to characterize the developmental physiology of naturally- and hatchery-reared wild progeny spring chinook salmon (Oncorhynchus tshawytscha) in the Yakima River basin. Fish were sampled at the main hatchery in Cle Elum, at remote acclimation sites and, during smolt migration, at downstream dams. Throughout these studies the maturational state of all fish was characterized using combinations of visual and histological analysis of testes, gonadosomatic index (GSI), and measurement of plasma 11-ketotestosterone (11-KT). We established that a plasma 11-KT threshold of 0.8 ng/ml could be used to designate male fish as either immature or precociously maturing approximately 8 months prior to final maturation (1-2 months prior to release as 'smolts'). Our analyses revealed that 37-49% of the hatchery-reared males from this program undergo precocious maturation at 2 years of age and a proportion of these fish appear to residualize in the upper Yakima River basin throughout the summer. An unnaturally high incidence of precocious male maturation may result in loss of potential returning anadromous adults, skewing of female: male sex ratios, ecological, and genetic impacts on wild populations and other native species. Precocious male maturation is significantly influenced by growth rate at specific times of year and future studies will be conducted to alter maturation rates through seasonal growth rate manipulations.
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Languages : en
Pages : 51
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This project was developed to conduct research to improve the efficacy of captive broodstock programs and advance hatchery reform throughout the Columbia river basin. The project has three objectives: (1) maintain adaptive life history characteristics in Chinook salmon, (2) improve imprinting in juvenile sockeye salmon, and (3) match wild phenotypes in Chinook and sockeye salmon reared in hatcheries. A summary of the results are as follows: Objective 1: Adult and jack Chinook salmon males were stocked into four replicate spawning channels at a constant density (N = 16 per breeding group), but different ratios, and were left to spawn naturally with a fixed number of females (N = 6 per breeding group). Adult males obtained primary access to females and were first to enter the nest at the time of spawning. Jack male spawning occurred primarily by establishing satellite positions downstream of the courting pair, and 'sneaking' into the nest at the time of spawning. Male dominance hierarchies were fairly stable and strongly correlated with the order of nest entry at the time of spawning. Spawning participation by jack and adult males is consistent with a negative frequency dependent selection model, which means that selection during spawning favors the rarer life history form. Results of DNA parentage assignments will be analyzed to estimate adult-to-fry fitness of each male. Objective 2: To determine the critical period(s) for imprinting for sockeye salmon, juvenile salmon were exposed to known odorants at key developmental stages. Molecular assessments of imprinting-induced changes in odorant receptor gene expression indicated that regulation of odorant expression is influenced by developmental status and odor exposure history. The results suggest that sockeye salmon are capable of imprinting to homing cues during the developmental periods that correspond to several of current release strategies employed as part of the Captive Broodstock program (specifically, planting eyed eggs, fall and smolt releases into the lake) appear to be appropriate for successful homing of sockeye in Redfish Lake. Also, our findings indicated that sockeye salmon were capable of olfactory imprinting at multiple life stages and over varying exposure durations. Fish exposed to odors just prior to smolting showed the strongest attraction to the imprinting odor arginine and this period corresponds to the period of highest plasma thyroxine levels and increased BAAR receptor mRNA in juveniles. Objective 3: Spring Chinook salmon were exposed to three different photoperiods and three feed rations at the button-up stage of development. Both photoperiod at emergence and ration post-ponding affected the number of males maturing at age one. Nearly 70% of the males in the early emergence and satiation fed group matured after the first year of rearing, while none of the fish reared on late emergence photoperiod (equivalent to emergence on May 1) matured during this time irrespective of ration treatment. Within the early emergence groups, reducing growth using ration (low or high) appeared to reduce the number of males maturing at age one from 70% to 40-50%. Maturation rates of fish that emerged in a photoperiod equivalent to mid-February (middle emergence) ranged from 10-25%. Together these data indicate that the seasonal timing of fry emergence and growth after ponding can alter life history patterns in spring Chinook salmon. The results imply that hatchery rearing practices that alter seasonal timing of fry emergence can have drastic effects on life history patterns in juvenile Chinook salmon. All three objectives are on-going and will result in recommendations (at the end of the FY 2009 performance period) to advance hatchery reforms in conventional and captive broodstock programs.
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Languages : en
Pages : 60
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This project was developed to conduct research to improve the efficacy of captive broodstock programs and advance hatchery reform throughout the Columbia River Basin. The project has three objectives: (1) maintain adaptive life history characteristics in Chinook salmon, (2) improve imprinting in juvenile sockeye salmon, and (3) match wild phenotypes in Chinook and sockeye salmon reared in hatcheries. A summary of the results are as follows: Objective 1: The ratio of jack to adult male Chinook salmon were varied in experimental breeding populations to test the hypothesis that reproductive success of the two male phenotypes would vary with their relative frequency in the population. Adult Chinook salmon males nearly always obtained primary access to nesting females and were first to enter the nest at the time of spawning. Jack male spawning occurred primarily by establishing satellite positions downstream of the courting pair, and 'sneaking' into the nest at the time of spawning. Male dominance hierarchies were fairly stable and strongly correlated with the order of nest entry at the time of spawning. Observed participation in spawning events and adult-to-fry reproductive success of jack and adult males was consistent with a negative frequency-dependent selection model. Overall, jack males sired an average of 21% of the offspring produced across a range of jack male frequencies. Implications of these and additional findings on Chinook salmon hatchery broodstock management will be presented in the FY 2009 Annual Report. Objective 2: To determine the critical period(s) for imprinting for sockeye salmon, juvenile salmon were exposed to known odorants at key developmental stages. Molecular assessments of imprinting-induced changes in odorant receptor gene expression indicated that regulation of odorant expression is influenced by developmental status and odor exposure history. Expression levels of basic amino acid receptor (BAAR) mRNA in the olfactory epithelium increased dramatically during final maturation in both Stanley Basin and Okanogan River sockeye. These increases appeared to be independent of odor exposure history, rising significantly in both arginine-naive and arginine-exposed fish. However, sockeye exposed to arginine during smolting demonstrated a larger increase in BAAR mRNA than arginine-naive fish. These results are consistent with the hypothesis that odorant receptors sensitive to home stream waters may be upregulated at the time of the homing migration and may afford opportunities to exploit this system to experimentally characterize imprinting success and ultimately identify hatchery practices that will minimize straying of artificially produced salmonids. Additional analysis of Sockeye salmon imprinting and further implications of these findings will be presented in the FY 2009 Annual Report. Objective 3: Photoperiod at emergence and ration after ponding were varied in Yakima River spring Chinook salmon to test the hypothesis that seasonal timing of emergence and growth during early stages of development alter seasonal timing of smoltification and age of male maturation. Fish reared under conditions to advance fry emergence and accelerate growth had the greatest variation in seasonal timing of smolting (fall, spring and summer) and highest rates of early male maturation with most males maturing at age 1 (35-40%). In contrast, fish with delayed emergence and slow growth had the least variation in phenotypes with most fish smolting as yearlings in the spring and no age-1 male maturation. Growth (not emergence timing) altered rates of age-2 male maturation. Results of this study demonstrate that altering fry development, as is often done in hatcheries, can profoundly affect later life history transitions and the range of phenotypes within a spring Chinook salmon population. Additional work in the next funding period will determine if these rearing regimes affected other aspects of smolt quality, which may affect ultimate survival upon ocean entry.
Author: Donald A. Larsen
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Category : Chinook salmon
Languages : en
Pages : 0
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Author:
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Category :
Languages : en
Pages : 131
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The success of captive broodstock programs depends on high in-culture survival, appropriate development of the reproductive system, and the behavior and survival of cultured salmon after release, either as adults or juveniles. Continuing captive broodstock research designed to improve technology is being conducted to cover all major life history stages of Pacific salmon. Accomplishments detailed in this report are listed below by major objective. Objective 1: This study documented that captively reared Chinook exhibited spawn timing similar to their founder anadromous population. An analysis of spawn timing data of captively reared Chinook salmon that had received different levels of antibiotic treatment did not suggest that antibiotic treatments during the freshwater or seawater phase of the life cycle affects final maturation timing. No effect of rearing density was found with respect to spawn timing or other reproductive behaviors. Objective 2: This study investigated the critical period(s) for imprinting for sockeye salmon by exposing juvenile salmon to known odorants at key developmental stages. Molecular assessments of imprinting-induced changes in odorant receptor gene expression indicated that regulation of odorant expression differs between coho and sockeye salmon. While temporal patterns differ between these species, exposure to arginine elicited increases in odorant receptor mRNA expression in sockeye salmon. Objective 3: This study: (i) identified the critical period when maturation is initiated in male spring Chinook salmon and when body growth affects onset of puberty, (ii) described changes in the reproductive endocrine system during onset of puberty and throughout spermatogenesis in male spring Chinook salmon, (iii) found that the rate of oocyte development prior to vitellogenesis is related to body growth in female spring Chinook, and (iv) demonstrated that growth regimes which reduce early (age 2) male maturation slow the rate of primary and early secondary oocyte growth, but do not alter number of oocytes at these stages of development. Objective 4 : This study, (1) determined that infected fish treated with oxytetracycline-medicated feed (as fry or as presmolts) had improved survival compared to nonmedicated fish, (2) determined that a single 14-day course of oral azithromycin at first feeding or at the start of smoltification is sufficient for significant azithromycin retention in internal tissues for at least a year, and (3) established that Renibacterium salmoninarum with an azithromycin-resistant phenotype can be isolated from Chinook salmon receiving macrolide antibiotic treatment. Objective 5: This study determined that for Chinook salmon rearing in similar, 'common environment' regimes in seawater, control fish have survived at a higher rate since seawater transfer than have experimentally inbred fish. However, in all groups, the variation among families in survival has been substantial, ranging from 0% to 100% over the entire year and from 0% to 40% since seawater transfer. The highly significant effect of variation among families within both stocks indicates that substantial genetic variation for size remains in these populations.
Author: Roy E. Beaty
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Category : Chinook salmon
Languages : en
Pages : 540
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The average size and age of chinook salmon (Oncorhynchus tshawytscha) caught in commercial fisheries along the Pacific Coast of North America have decreased substantially in this century. These declines might be caused in part by changes in size and age at maturity within the stocks contributing to those fisheries. Upriver Brights (Brights), a stock of fall chinook salmon in the Columbia River, are one of those stocks. The purposes of this study were to (1) determine if average size and age at maturity of Brights have declined, (2) gain a better understanding of the factors that may contribute to such declines, and (3) describe potential consequences of these changes. Data from in-river fisheries suggest that the average weight of mature Brights returning to the Columbia River has decreased approximately 2.7 kg since the 1910s, an average rate of about 0.1 lb·yr−1 (45 g·yr−1). Most of the potential biases in these data tend to make this estimate conservative. Insufficient data were available to describe changes in average age at maturity. There are many potential causes for the decline in average size of mature Brights, including factors that affect very early life stages. Other researchers have determined that size at maturity appears to be highly influenced by inheritance, gender, and growth rate. I describe how maternal size can influence -- through time of spawning, choice of spawning site, and egg size -- the viability of the young, which carry the dam's genes for size. The size-related ability to produce viable offspring may have been changed by modifications in the environment. Very little is known about how changes in the natural environment for spawning, incubation, and rearing may have contributed to a decline in average size at maturity. Artificial propagation and rearing, such as at Priest Rapids Hatchery, seems to produce adult Brights that are smaller, younger, and more likely to be male than their natural counterparts. The net result is that the average hatchery fish may have only about 0.80 of the reproductive potential of the average natural fish. Changes in growth conditions in the ocean probably did not contribute to the change in size, although the ocean fisheries of Southeast Alaska and British Columbia appear to select, in the genetic sense, against large size and old age in Brights. Since 1978, in-river commercial fisheries have caught larger Brights and a higher proportion of females than are found in the escapement of the Priest Rapids Hatchery component of the stock, but the fisheries impact the two sexes differently by taking the larger males and the smaller females. The effect on the natural component may differ because of their apparently larger average size. I found no evidence that larger fish or more females were caught when 8-in. minimum restrictions were in effect on gillnet mesh size relative to periods when mesh size was not restricted. Impounding the mainstem during the last 50+ yr may have removed obstacles to migration (e.g., Celilo Falls) that selected for large size in Brights, but that hypothesis could not be tested. The perserverance of larger and older phenotypes in the Bright stock suggests that countervailing selection -- perhaps during spawning, incubation, and/or early rearing -- may have resisted the effects of a century of size- and age-selective fisheries. That resistance, however, may reduce the productivity of the stock. Declines in average size and age at maturity can have undesireable consequences. Lower average size means less biomass landed and lower commercial value. Lower average fecundity and a diminished ability to reproduce in some environments are also expected. Loss of size and age classes may reduce the ability of the stock to adapt to environmental variations. These results are relevant to several management practices. A holistic approach to fishery management issues is necessary to avoid erroneous conclusions based on narrow perspectives. Measuring reproductive potential of the catch and escapement would be superior to the conventional practice of simply counting numbers of fish. Many aspects of artificial propagation can be improved, including broodstock aquisition, mating regimes, and rearing practices. Stock abundance is a major factor in determining the effect of many management practices on the stock. In general, fisheries managers must be mindful that they manage very complex natural systems.
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Languages : en
Pages : 115
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The physiological development and physiological condition of spring chinook salmon are being studied at several hatcheries in the Columbia River Basin. The purpose of the study is to determine whether any or several smolt indices can be related to adult recovery and be used to improve hatchery effectiveness. The tests conducted in 1989 on juvenile chinook salmon at Dworshak, Leavenworth, and Warm Springs National Fish Hatcheries, and the Oregon State Willamette Hatchery assessed saltwater tolerance, gill ATPase, cortisol, insulin, thyroid hormones, secondary stress, fish morphology, metabolic energy stores, immune response, blood cell numbers, and plasma ion concentrations. The study showed that smolt development may have occurred before the fish were released from the Willamette Hatchery, but not from the Dworshak, Leavenworth, or Warm Springs Hatcheries. These results will be compared to adult recovery data when they become available, to determine which smolt quality indices may be used to predict adult recovery. The relative rankings of smolt quality at the different hatcheries do not necessarily reflect the competency of the hatchery managers and staff, who have shown a high degree of professionalism and expertise in fish rearing. We believe that the differences in smolt quality are due to the interaction of genetic and environmental factors. One aim of this research is to identify factors that influence smolt development and that may be controlled through fish husbandry to regulate smolt development. 35 refs., 27 figs., 5 tabs.
Author: Stan P. Triebenbach
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Category : Chinook salmon
Languages : en
Pages : 152
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"This study investigated whether coho and Chinook smolts that experienced food deprivation during the winter would increase growth rates in the spring and attain the same physiological attributes as smolts fed to satiation twice per week during the winter. The treatment groups were deprived of food for 10 and 16 weeks, centered on the winter solstice. All groups were returned to daily satiation feeding at the end of the respective food reduction periods. Treatment fish were smaller than control fish after food deprivation but had higher growth rates after feeding resumed and the 10 week fish were not significantly different in size from the control fish at the end of the study. Protein and lipid content decreased during deprivation, while moisture and ash content increased, but all groups were not different by the end of the study. Gill ATPase activity was unaffected by deprivation. Hematocrit levels declined in response to deprivation but a consistent response was not observed after feeding resumed. Coho and Chinook smolts subjected to winter food deprivation grew faster in the spring, restored body composition, and did not lose osmoregulation ability but the long-term effects on body size are unknown"--Leaf iii.
Author: Christopher L. Johnson
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Category :
Languages : en
Pages : 121
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This report examines some of the factors that can influence the success of supplementation, which is currently being tested in the Yakima Basin using upper Yakima stock of spring chinook salmon. Supplementation success in the Yakima Basin is defined relative to four topic areas: natural production, genetics, ecological interactions, and harvest (Busack et al. 1997). The success of spring chinook salmon supplementation in the Yakima Basin is dependent, in part, upon fish culture practices and favorable physical and biological conditions in the natural environment (Busack et al. 1997; James et al. 1999; Pearsons et al., 2003; Pearsons et al. 2004). Shortfalls in either of these two topics (i.e., failure in culturing many fish that have high long-term fitness or environmental conditions that constrain spring chinook salmon production) will cause supplementation success to be limited. For example, inadvertent selection or propagation of spring chinook that residualize or precocially mature may hinder supplementation success. Spring chinook salmon that residualize (do not migrate during the normal migration period) may have lower survival rates than migrants and, additionally, may interact with wild fish and cause unacceptable impacts to non-target taxa. Large numbers of precocials (nonanadromous spawners) may increase competition for females and significantly skew ratios of offspring sired by nonanadromous males, which could result in more nonanadromous spring chinook in future generations. Conditions in the natural environment may also limit the success of spring chinook supplementation. For example, intra or interspecific competition may constrain spring chinook salmon production. Spring chinook salmon juveniles may compete with each other for food or space or compete with other species that have similar ecological requirements. Monitoring of spring chinook salmon residuals, precocials, prey abundance, carrying capacity, and competition will help researchers interpret why supplementation is working or not working (Busack et al. 1997). Monitoring ecological interactions will be accomplished using interactions indices. Interactions indices will be used to index the availability of prey and competition for food and space. The tasks described below represent various subject areas of juvenile spring chinook salmon monitoring but are treated together because they can be accomplished using similar methods and are therefore more cost efficient than if treated separately. Topics of investigation we pursued in this work were: (1) strong interactor monitoring (competition index and prey index), (2) carrying capacity monitoring (microhabitat monitoring); (3) residual and precocious male salmon monitoring (abundance); (4) performance of growth modulation in reducing precocious males during spawning; (5) incidence of predation by residualized chinook salmon; and (6) benefits of salmon carcasses to juvenile salmonids. This report is organized into six chapters to represent these topics of investigation. Data were collected during the summer and fall, 2004 in index sections of the upper Yakima Basin (Figure 1). Previous results on the topics in this report were reported in James et al. (1999), and Pearsons et al. (2003; 2004). Hatchery-reared spring chinook salmon were first released during the spring of 1999. The monitoring plan for the Yakima/Klickitat Fisheries Project calls for the continued monitoring of the variables covered in this report. All findings in this report should be considered preliminary and subject to further revision as more data and analytical results become available.
