Lake Michigan Chinook Salmon Research Articles

Examining the potential of otolith chemistry to determine natal origins of wild Lake Michigan Chinook salmon

Previous research has demonstrated a large movement of hatchery-reared Chinook salmon (Oncorhynchus tshawytscha) from Lake Huron to Lake Michigan, suggesting the potential for wild fish to exhibit similar movement patterns. We assessed the feasibility of using otolith microchemistry to estimate the natal source composition of wild Chinook salmon in Lake Michigan and evaluate interbasin movement. Otolith pairs were extracted from juvenile and adult fish collected in 2015 and 2016 from Great Lakes tributaries. Otoliths were analyzed using laser ablation inductively coupled plasma mass spectrometry to determine trace element concentrations, and four multivariate classification algorithms were evaluated for classification accuracy. Juvenile data reclassified to their natal regions with up to 89% success on a basin level, with a random forest approach performing the best among all models. Assigning adults to their natal origins resulted in more success on a basin-wide scale (74% to 88%) compared with a regional scale (32% to 51%), but success was still below juvenile reclassification accuracy. Our findings suggest that otolith microchemistry can be used to estimate wild Chinook salmon interbasin movement and that classification accuracy can be improved by matching juvenile and adult year classes in our assessment samples. Ultimately, we intend to use these models to assess the effects of wild Chinook salmon interbasin movement on Lake Michigan predatory demand and evaluate the risks of various stocking alternatives.

Genetic Variation in Bacterial Kidney Disease (BKD) Susceptibility in Lake Michigan Chinook Salmon and Its Progenitor Population from the Puget Sound

Mass mortality events in wild fish due to infectious diseases are troubling, especially given the potential for long-term, population-level consequences. Evolutionary theory predicts that populations with sufficient genetic variation will adapt in response to pathogen pressure. Chinook Salmon Oncorhynchus tshawytscha were introduced into Lake Michigan in the late 1960s from a Washington State hatchery population. In the late 1980s, collapse of the forage base and nutritional stress in Lake Michigan were thought to contribute to die-offs of Chinook Salmon due to bacterial kidney disease (BKD). Previously, we demonstrated that Lake Michigan Chinook Salmon from a Wisconsin hatchery have greater survival following BKD challenge relative to their progenitor population. Here, we evaluated whether the phenotypic divergence of these populations in BKD susceptibility was due to selection rather than genetic drift. Comparison of the overall magnitude of quantitative trait to neutral marker divergence between the populations suggested selection had occurred but a direct test of quantitative trait divergence was not significant, preventing the rejection of the null hypothesis of differentiation through genetic drift. Estimates of phenotypic variation (VP ), additive genetic variation (VA ) and narrow-sense heritability (h (2)) were consistently higher in the Wisconsin relative to the Washington population. If selection had acted on the Wisconsin population there was no evidence of a concomitant loss of genetic variation in BKD susceptibility. The Renibacterium salmoninarum exposures were conducted at both 14°C and 9°C; the warmer temperature accelerated time to death in both populations and there was no evidence of phenotypic plasticity or a genotype-by-environment (G × E) interaction. High h (2) estimates for BKD susceptibility in the Wisconsin population, combined with a lack of phenotypic plasticity, predicts that future adaptive gains in BKD resistance are still possible and that these adaptive gains would be stable under the temperature range evaluated here.

Thiamine and Fatty Acid Content of Lake Michigan Chinook Salmon

Nutritional status of Lake Michigan Chinook salmon (Oncorhynchus tshawytscha) is inadequately documented. An investigation was conducted to determine muscle and liver thiamine content and whole body fatty acid composition in small, medium and large Chinook salmon. Muscle and liver thiamine concentrations were highest in small salmon, and tended to decrease with increasing fish size. Muscle thiamine was higher in fall than spring in large salmon. The high percentage of Chinook salmon (24–32% in fall and 58–71% in spring) with muscle thiamine concentration below 500 pmol/g, which has been associated with loss of equilibrium and death in other Great Lake salmonines, suggest that Chinook appear to rely less on thiamine than other Great Lakes species for which such low concentrations would be associated with thiamine deficiency (Brown et al. 2005b). A positive correlation was observed between liver total thiamine and percent liver lipids (r = 0.53, P < 0.0001, n = 119). In medium and large salmon, liver lipids were observed to be low in fish with less than 4,000 pmol/g liver total thiamine. In individuals with greater than 4,000 pmol/g liver thiamine, liver lipid increased with thiamine concentration. Individual fatty acids declined between fall and spring. Essential omega-3 fatty acids appear to be conserved as lipid content declined. Arachidonic acid (C20:4n6), an essential omega-6 fatty acid was not different between fall and spring, although the sum of omega-6 (Sw6) fatty acids declined over winter. Elevated concentrations of saturated fatty acids (sum) were observed in whole body tissue lipid. In summary, thiamine, a dietary essential vitamin, and individual fatty acids were found to vary in Lake Michigan Chinook salmon by fish size and season of the year.

Decreased Mortality of Lake Michigan Chinook Salmon after Bacterial Kidney Disease Challenge: Evidence for Pathogen‐Driven Selection?

In the late 1960s, Chinook salmon Oncorhynchus tshawytscha from the Green River, Washington, were successfully introduced into Lake Michigan. During spring from 1988 to 1992, large fish die-offs affecting Chinook salmon occurred in the lake. Multiple ecological factors probably contributed to the severity of the fish kills, but the only disease agent found regularly was Renibacterium salmoninarum, the causative agent of bacterial kidney disease. In this study, survival after challenge by R. salmoninarum was compared between two Chinook salmon stocks: a Lake Michigan stock from Wisconsin (WI) and the progenitor stock from the Green River. We found that the WI stock had significantly greater survival than the Green River stock. Next, the WI and Green River stocks were exposed to the marine pathogen Listonella anguillarum (formerly Vibrio anguillarum), one of the causative agents of vibriosis; survival after this challenge was significantly poorer for the WI stock than for the Green River stock. A close genetic relationship between the Green River and WI stocks was confirmed by analyzing 13 microsatellite loci. These results collectively suggest that disease susceptibility of Lake Michigan Chinook salmon has diverged from that of the source population, possibly in response to pathogen-driven selection.

Thiamine and Fatty Acid Content of Lake Michigan Chinook Salmon

Nutritional status of Lake Michigan Chinook salmon (Oncorhynchus tshawytscha) is inadequately documented. An investigation was conducted to determine muscle and liver thiamine content and whole body fatty acid composition in small, medium and large Chinook salmon. Muscle and liver thiamine concentrations were highest in small salmon, and tended to decrease with increasing fish size. Muscle thiamine was higher in fall than spring in large salmon. The high percentage of Chinook salmon (24–32% in fall and 58–71% in spring) with muscle thiamine concentration below 500 pmol/g, which has been associated with loss of equilibrium and death in other Great Lake salmonines, suggest that Chinook appear to rely less on thiamine than other Great Lakes species for which such low concentrations would be associated with thiamine deficiency (Brown et al. 2005b). A positive correlation was observed between liver total thiamine and percent liver lipids (r = 0.53, P < 0.0001, n = 119). In medium and large salmon, liver lipids were observed to be low in fish with less than 4,000 pmol/g liver total thiamine. In individuals with greater than 4,000 pmol/g liver thiamine, liver lipid increased with thiamine concentration. Individual fatty acids declined between fall and spring. Essential omega-3 fatty acids appear to be conserved as lipid content declined. Arachidonic acid (C20:4n6), an essential omega-6 fatty acid was not different between fall and spring, although the sum of omega-6 (Sw6) fatty acids declined over winter. Elevated concentrations of saturated fatty acids (sum) were observed in whole body tissue lipid. In summary, thiamine, a dietary essential vitamin, and individual fatty acids were found to vary in Lake Michigan Chinook salmon by fish size and season of the year.

Monitoring Energetic Status of Lake Michigan Chinook Salmon Using Water Content as a Predictor of Whole-fish Lipid Content

Monitoring health indicators of fish populations can be an expensive and time consuming process. This study analyzed energy dynamics of Lake Michigan Chinook salmon using proximate composition analysis with the goal of determining an efficient method for monitoring the nutritional status of the population. Condition factor performed poorly as an indicator of whole-fish lipids (r 2 = 0.07). Water content in a dorsal muscle plug was found to be correlated with whole-fish lipids (r 2 = 0.50) for all samples. For the subset of samples that included small fish collected in the spring, the strength of the relationship between water content in a dorsal muscle plug and whole-fish lipids increased (r 2 = 0.70). The metric of water content in a dorsal muscle plug was determined to provide an adequate surrogate of whole-fish lipid content and, therefore, overall nutritional status. We propose a monitoring program that involves collecting small individuals in the spring and reporting the proportion of samples with over 78% water content in muscle tissue. Small individuals collected in the spring had the lowest whole-fish lipid levels of any segment of the population and would be the most prone to nutritional stress; therefore we recommend focusing on them for monitoring.

Temporal and Spatial Variation of Early Mortality Syndrome in Salmonids from Lakes Michigan and Huron

AbstractTo assess the extent that early mortality syndrome (EMS) impacts different Pacific salmonid stocks and the association of EMS with thiamine, we collected eggs of coho salmon Oncorhynchus kisutch from three Lake Michigan tributaries (Platte River, Thompson Creek, and Root River) in 1996–2001. We also obtained eggs of Chinook salmon O. tshawytscha from Lake Michigan (Little Manistee River) and Lake Huron (Swan River) in 1998–2001. Unfertilized eggs from individual females were frozen for thiamine analysis, and the remainder were fertilized and reared until first feeding. We observed a high incidence of EMS in offspring when total egg thiamine levels were less than 1.7 nmol/g in both coho and Chinook salmon. In Lake Michigan strain coho salmon from the Platte River, EMS occurred in more than 70% of monitored families in 1996, 1999, 2000, and 2001, while 1997 and 1998 were years when EMS was low (&lt;25%). Hinchenbrooke strain coho salmon from Thompson Creek exhibited greater impacts from EMS in the years when EMS was low in the Lake Michigan strain coho salmon from the Platte River. Similar to coho salmon, Lake Michigan Chinook salmon also exhibited EMS (&gt;70%) in 1999, 2000, and 2001. Chinook salmon from Lake Huron exhibited high (&gt;70%) EMS in 2001, moderate (40–60%) EMS in 1999, and low (&lt;25%) EMS in 1998. Our data suggest that the incidence of EMS in salmonids varies by species, location, and year. The data support the general contention that EMS in salmonids is associated with low egg thiamine content.

Field estimate of net trophic transfer efficiency of PCBs to Lake Michigan chinook salmon from their prey.

Chinook salmon (Oncorhynchus tshawytscha) has been the predominant piscivore in Lakes Michigan, Huron, and Ontario since the 1970s, and therefore accurate quantification of its energy budget is needed for effective management of Great Lakes fisheries. A new approach of evaluating a fish bioenergetics model in the field involves field estimation of the efficiency with which the fish retains PCBs from its food. We used diet information, PCB determinations in both chinook salmon and their prey, and bioenergetics modeling to generate a field estimate of the efficiency with which Lake Michigan chinook salmon retain PCBs from their food. Our field estimate is the most reliable field estimate to date because (a) the estimate was based on a relatively high number (N = 142) of PCB determinations for chinook salmon from Wisconsin waters of Lake Michigan in 1985, (b) a relatively long time series (1978-1988) of detailed observations on chinook salmon diet in Lake Michigan was available, and (c) the estimate incorporated new information from analyses of chinook salmon age and growth during the 1980s and 1990s in Lake Michigan. We estimated that chinook salmon from Lake Michigan retain 53% of the PCBs that are contained within their food.

Organochlorine concentration dynamics in Lake Michigan chinook salmon (Oncorhynchus tshawytscha)

To investigate how trophic level and physiological processes influence organochlorine (OC) chemical concentrations in chinook salmon (Oncorhynchus tshawytscha) and their offspring, data on polychlorinated biphenyl (PCB), and OC pesticides and metabolite concentrations in Lake Michigan chinook salmon muscle tissue, eggs, sac fry, and prey fish were analyzed. Total concentrations of PCBs in chinook salmon decreased exponentially from the mid-1970s to mid-1980s, but the concentrations have since shown an asymptotic response, a trend also seen in alewife (Alosa pseudoharengus), an exotic planktivore that is the principal prey of chinook salmon in western Lake Michigan, and bloater (Coregonus hoyi) an endemic planktivore. The total concentration of PCBs in chinook salmon were positively correlated with fish length. OC concentrations in chinook salmon eggs were positively correlated with the concentrations of these compounds in the muscle tissue of the gravid fish. Egg and sac fry OC concentrations were also positively correlated. Estimates of the quantities of various OCs in chinook salmon muscle tissue and eggs, reveal that between 22% and 40% of the quantities of these compounds are eliminated through spawning.

Prediction of Concentrations of 2,3,7,8-Tetrachlorodibenzo-p-dioxin Equivalents from Total Concentrations of Polychlorinated Biphenyls in Fish Fillets

Concentrations of PCBs result in the most restrictive risk assessments for fish consumption advisories, yet total concentrations of PCBs may not accurately represent toxicity. The objective of this study was to determine the relationship between concentrations of AHH-active PCB congeners, 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent (TCDD-EQ), total PCBs, and fish size for trimmed fillets of Lake Michigan chinook salmon. Total concentrations of PCBs ranged from 0.14 to 2.1 μg /g

Relationships Among Concentrations of Individual Polychlorinated Biphenyl (PCB) Congeners, 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Equivalents (TCDD-EQ), and Rearing Mortality of Chinook Salmon (Oncorhynchus Tshawytscha) Eggs from Lake Michigan

A study was conducted to investigate possible correlations between concentrations of individual polychlorinated biphenyl congeners (PCBs) or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) and mortality in early life stages of Chinook salmon. Eggs were collected from adult Lake Michigan Chinook salmon in October, 1986, and were analyzed for concentrations of individual PCB congeners and total PCBs. Concentrations of mono- and non-ortho-substituted congeners were determined after fractionation of PCB-containing extracts with a carbon column. Three types of TCDD-EQ were calculated using an additive potency model by multiplying concentrations of individual PCB congeners by each of three different sets of toxic equivalency factors (TEFs) and summing the products. The mean total concentration of PCBs in the eggs was 7.02 μ/g, wet weight, and measured concentrations of the non-ortho-substituted PCB congeners ranged from 0.2 to 12 ng/g, wet weight. Mean concentrations of TCDD-EQ depended on the set of TEFS which were used in the calculations and ranged from 29 to 514 pg/g. Concentrations of TCDD-EQ were positively correlated with total concentrations of PCBs (r 2 = 0.60), although the magnitude of correlations between concentrations of individual non-ortho-substituted congeners and total PCBs were less than those for TCDD-EQ and total PCB. Mortality of eggs and fry differed significantly among clutches of eggs from different females but was not correlated with concentrations of TCDD-EQ, individual PCB congeners, or total PCBs in the eggs.

Maternal transfer of bioactive polychlorinated aromatic hydrocarbons in spawning chinook salmon ( Oncorhynchus tschawytscha)

The biological potency (relative to 2,3,7,8-tetrachlorodibenzo- p-dioxin. TCDD) of planar polychlorinated aromatic hydrocarbons (PCHs) in extracts of eggs and flesh from spawning female chinook salmon ( Oncorhynchus tschawytscha) from Lake Michigan was determined by measuring the induction of 7-ethoxyresorufin O-deethylase activity in H-4-II-E rat hepatoma cells. TCDD-equivalents in flesh and egg samples ranged from 0 to 115·8 pg/g, and were approximately 5-fold greater in eggs than in flesh. These results suggest that the maternal transfer of PCHs may play a role in determining the reproductive success of Lake Michigan chinook salmon.

Hepatic enzyme systems as biochemical indicators of the effects of contaminants on reproduction of chinook salmon ( Oncorhynchus tschawytscha)

1. The reproductive success of 30 female Lake Michigan chinook salmon ( Oncorhynchus tschawytscha) was evaluated and compared to the status of two hepatic enzyme systems proposed as sensitive biochemical indicators of exposure to planar polychlorinated aromatic hydrocarbons, including certain polychlorinated biphenyls, polychlorinated dibenzofurans and polychlorinated dibenzodioxins. 2. Fertilizability, hatchability and egg and fry mortality varied significantly among the fish. 3. Hepatic monooxygenase and glutathione S-transferase activities and cytochrome P-450E concentration also varied markedly among the fish. 4. There was, however, little correlation between reproductive success and the three biochemical indicators of contaminant exposure.

Relationships Between Chlorinated Hydrocarbon Concentrations and Rearing Mortality of Chinook Salmon ( Oncorhynchus Tshawytscha) Eggs from Lake Michigan

A study was conducted to investigate a possible correlation between chlorinated hydrocarbon concentrations and rearing mortality of chinook salmon. Eggs, collected from adult Lake Michigan chinook salmon in October, 1982, were analyzed for chlorinated hydrocarbon concentrations and rearing mortality. Polychlorinated biphenyls, toxaphene, and fifteen other chlorinated hydrocarbons were quantified. Also, concentrations of individual PCB congeners were quantified. We found 78 quantifiable PCB congeners, only three of which were non-ortho substituted. Mean concentrations of Arocloi ® 1242, 1254 and 1260 were 1.7, 5.4, and 1.1 μg/g, respectively. The concentration of toxaphene-like material was 3.3 μg/g, and the mean concentration of the total DDT complex was 1.0 μg/g. Concentrations of chlorinated hydrocarbons ranged approximately 10-fold among individual fish. An analysis of variance components demonstrated that this variability represented among-fish variation and was not due to errors in sampling or quantification. Duplicate studies of egg viability and fry mortality, conducted at 10, 11, and 15°C, correlated with residue concentrations. While some residue concentrations were significantly negatively correlated with egg viability and survival of fry, others were positively correlated. Thus, we observed no consistent trends in Pearson, pairwise-correlations between either egg viability or survival of fry to swim-up stage and individual residue concentrations. When the residues were classified into four principal components, two of the principal components which contained primarily the toxaphene and PCB concentrations were negatively correlated with survival of fry to the swim-up stage.

Survival of Lake Michigan Chinook Salmon Eggs and Fry Incubated at Three Temperatures

Survival of Lake Michigan Chinook Salmon Eggs and Fry Incubated at Three Temperatures