Yellow perch (Perca flavescens), a native species of the Great Lakes, has experienced a significant decline in wild harvest since the 1990s, leading to an increased reliance on aquaculture. This study aimed to optimize feeding rate for yellow perch by evaluating the effects of various feeding rates (1.5%, 3.0%, 4.5%, 6.0%, and 7.5% body weight (BW)/day) on growth, nutrient retention, and heat shock protein 70 expression in perch fingerlings (initial BW: 1.73 ± 0.11 g) over a four-week period. Following the feeding trial, an acute heat shock was induced by raising the water temperature from 23 °C to 31 °C, followed by an 18 h recovery period. Results indicated that both growth rate and whole fish lipid content increased with higher feeding rates (p < 0.05), while nutrient retention decreased. Growth and energy retention did not significantly improve beyond 4.5%, with maximum energy retention observed at 3.9% BW/day. Heat shock protein 70 expression was highest in liver tissue at a feeding rate of 6.2% BW/day, indicating that higher feeding levels may enhance thermal stress response. These results indicate that a feeding rate of 4.5% BW/day supports optimal growth, while 6.2% BW/day may be necessary to improve heat shock tolerance. The study provides practical insights for refining feeding strategies in yellow perch aquaculture.

Cost-effective feeding management is required to support conservation hatcheries for lake sturgeon (Acipenser fulvescens), an ecologically important species in the Great Lakes region. This study investigated an approach to transition lake sturgeon larvae from live feed (Artemia) to formulated feed and its effect on growth performance, survival, and response to acute hypoxia stress. The first experiment showed that sturgeon had similar (p > 0.05) growth and survival when fed Artemia or the combined feeding of Artemia with the commercial diet (crude protein, 551 g/kg diet). Feeding solely on the commercial or lab-made (crude protein, 491 g/kg diet) diet significantly reduced growth and survival (p < 0.05). In the second experiment, the growth performance of sturgeon (14 days post-hatch, DPH) fed with either Artemia only or combined feeding different feeding durations of two, three, and four weeks followed by a complete transition to the commercial diet. At the end of six weeks, the 3- and 4-week combined feeding periods resulted in significantly higher body weight and survival compared to the 2-week combined and the Artemia only feeding treatments. In the last experiment, sturgeons (27 DPH) were fed only with Artemia or combined feeding of Artemia with the commercial diet for four weeks followed by the complete transition to the commercial diet for two weeks. Eighteen fish from each treatment were investigated the response to acute hypoxic conditions (gradual decrease in dissolved oxygen level from 8 to 2.3 mg/L at the rate of 1 mg/L per hour). When the dissolved oxygen was between 3 and 4 mg/L, the mortality rate of the combination-fed sturgeon (11.7%) was significantly lower than those fed only Artemia (83.3%). These results clearly demonstrate that a commercial diet can partially replace Artemia at early life stages to improve growth, survival, and hypoxia tolerance and thus its co-feeding with Artemia is recommended.

Behrents Hartney, Kristine, 105 Bematchez, Louis, 247 Breitburg, Denise L., 97 Brown, Larry R., 223 Carl, Leon M., 239 Christensen, V., 87 Cooper, Scott D., 285 Copp, Gordon H., 1 Dodson, Julian J., 247 Donaldson, Terry J., 295 Dudley, Tom L., 285 Dunson, William A., 303 Farr, James A., 39,119 Fox, Michael G., 129 Gonzalez, Richard J., 303 Gunnarsson, Karl, 159 Gutherz, Elmer J., 277 Hales, L. Stanton, Jr., 153 J&vi, Torbjiim, 149 Jones, Robert S., 277 Keast, J. Allen, 129 Kemp, Alain, 247 Kiorboe , T., 87 Kraft, Melvin, 239 Lammens, Eddy H.R.R., 63 Matlock, Gary C., 277 McManus, Michael, 119 Mikhail, Mansour Y., 49 Munk, Peter, 87 Nelson, Walter R., 277 Ochi, Haruki, 257 Pankhurst , Neville W., 201 Parrish, Julia K., 79 Petersen, Christopher W., 213 Power, Mary E., 285 Quinn, Thomas P., 311 Rhude, Larry, 239 Ruggerone, Gregory T., 143 Sale, Peter F., 77 Sigurj&sd&tir, Hrefna, 159 Smith, C. Lavett, 237 Smith, Marcus P.L., 29 Swainson, Robert J., 129 Travis, Joseph, 39, 119 Trexler, Joel C., 119 Visser, Jentsje T., 63 Welch, Harold E., 49 Winemiller, Kirk O., 177

This study determined whether accumulated liver and visceral lipid in yellow perch can be alleviated by feeding an appropriate starch source. We compared the growth performance, nutritional composition and health of yellow perch fed a control diet (no added starch) and three diets with corn, potato or wheat starch (200 g/kg diet) to replace an equal proportion of fishmeal in the control diet. Dietary starch led to increased bulk density, hardness and gelatinization levels of feed pellets compared with the control diet. At the end of an 8-week feeding, all fish fed the test diets had similar growth rates (p > .05). However, the wheat starch diet resulted in significantly enlarged livers and increased accumulation of lipid in the liver, viscera and whole body (p < .05). This diet also caused significantly higher levels of fasting glucose, aspartate aminotransferase and alkaline phosphatase activities in serum than the control diet. Liver cell diameters were larger, and Kupffer cell numbers were lower in the fish fed the wheat starch than those fed the control diet. Potato or corn starch had less impact on fish health and is considered to be an appropriate carbohydrate sources for yellow perch under the current testing conditions.

Two 3-week growth trials were performed to determine the optimum feeding rate of juvenile lake sturgeon (Acipenser fulvescens) fed with a semi-purified dry diet (protein, 440 g; lipid, 130 g/kg) at different feeding rates: 5, 10, 20, 30, and 40 g/kg body weight per day (BW/.d-1), for 36 g-sized fish; and 2.5, 5, 10, 20, and 30 g/kg BW/.d-1, for 80 g sized fish. Feeding rates significantly influenced growth performances, feed conversion ratio, wholebody lipid and moisture contents, energy and protein retention, and fasted blood glucose levels (p < 0.05). The ratio of total C/total N measured in whole fish was positively correlated to the feeding rates and the lipid contents of whole fish. Suboptimal feeding significantly depressed growth performance and protein synthesis based on the measurement of RNA/DNA ratio in white muscle. Based on polynomial regression models, an optimal feeding rate to support the maximum growth, protein and energy retention was 34.5, 22 and 27.3 g/kg BW/.d-1, respectively, for fish sized at 36-72 g; and 29.0, 16.9 and 19.9 g/kg BW/.d-1, respectively for fish sized at 80-140 g. Results of this study will benefit future research to develop practical feeds to replace frozen live feed and feed management for lake sturgeon.

The present study was conducted to assess an optimal dose of tricaine methansulfonate (MS-222) for rapid anesthesia and recovery in juvenile Yellow perch Perca flavescens. Yellow perch (≈7.0 g/fish) exposed to increasing concentrations of MS-222 (100, 150, 200, 250 and 300 mg/L) showed significant (P<0.05) decreased anesthetic induction and increased recovery time with increasing MS-222 dose. Among the doses tested, the 250 mg/L MS-222 dose showed the shortest anesthetic induction and recovery times. Blood glucose and hematocrit levels were significantly (P<0.05) lower in juvenile yellow perch exposed to the 250 mg/L MS-222 dose than the other MS-222 doses tested. Juvenile yellow perch (about 9.7 g/fish) exposed to 250/mg MS-222 combined with bicarbonate buffer at three ratios (w/w: 1:0.5, 1:1 and 1:2) showed significantly (P<0.05) reduced anesthesia induction and recovery times. The shortest times of anesthesia induction and recover were observed in treatments using the 1:1 MS-222 to buffer ratio. Analysis on serum biochemical parameters (e.g., osmolality, glucose, albumin, calcium, alanine transaminase, total protein and calcium) showed that use of sodium bicarbonate with MS-222 did not have any significant effect on the above measurements compared with those determined in fish exposed to MS-222 only. Anesthesia induction time and recovery time of yellow perch were significantly affected by body sizes. These results suggest that a brief exposure to a 250 mg/L MS-222: sodium bicarbonate dose may be optimal for minimizing handling disturbance in juvenile yellow perch.

This study evaluated the potential of feeding formulated feed to juvenile Lake Sturgeon Acipenser fulvescens and determined the optimal feeding rate of a soft-moist feed on the growth performance and whole-body composition of the fish. Six feeding rates (% body weight [BW]/d) of the soft-moist feed were assigned to each of the 1-week feeding trials: 2%, 4%, 6%, 8%, 10%, and 12%BW/d for trial I; and 0.5%, 2%, 3.5%, 5%, 6.5%, and 8%BW/d for trial II. As reference diets, frozen bloodworms and a dry formulated feed were administered to the fish at feeding rates of 8% and 5%BW/d for trials I and II, respectively. Each treatment was assigned to three tanks, with either 18 fish (trial I; initial BW [mean +/- SD]=3.5 +/- 0.05g) or 15 fish (trial II; initial BW=7.8 +/- 0.1g) per tank. No mortality was observed during the two trials. Weight gain and feed conversation ratio were significantly better for fish that received the soft-moist feed than for those fed the bloodworms. The dry diet and soft-moist diet resulted in similar growth rates. Growth performance and whole-body lipid and moisture content were significantly influenced by feeding rates in both trials. The tyrosine, isoleucine, lysine, phenylalanine, and valine levels in whole fish were significantly altered by the feeding rates in trial I, whereas only the glycine level was altered in trial II. Optimum feeding rates based on the specific growth rate were estimated to be 7.6% and 6.2%BW/d (or 1.47and 1.19MJkgBW(-1)d(-1)) for Lake Sturgeon weighing 3.5 and 7.8g, respectively. These results indicate that Lake Sturgeon can be given formulated feed after previous acclimation to the formulated feed during the early life stage.

Spring viremia of carp virus (SVCV) is a rhabdoviral pathogen associated with disease outbreaks in cultured and wild fish worldwide. Common carp (Cyprinus carpio carp), and koi (C. carpio koi) suffer the highest mortalities from SVCV infections, while other cyprinid fish species have varying susceptibility. Although salmonid fish typically are considered refractory to infection by SVCV, there have been a few reports suggesting infection has occurred in rainbow trout (Oncorhynchus mykiss). There have been no reports of Percid fish being infected with SVCV. Since the first North American outbreak of SVCV at a North Carolina koi farm in 2002 there have been eight subsequent detections or outbreaks of SVCV among fish species from the families of Cyprinidae and Centrarchidae within the US and Canada. Thus, this exotic virus is considered a potential threat to native and cultured fish populations in North America. We performed multiple experimental challenges with fish species from three families (Salmonidae, Cyprinidae, and Percidae) to identify the potential risk associated with SVCV exposure of resident fish populations in North America.Three salmonid species, rainbow and steelhead trout (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha), and sockeye salmon (O. nerka), were challenged by immersion or injection with the North Carolina SVCV isolate. Two cyprinid species, koi and fathead minnow(Pimephales promelas) and one percid species, yellow perch (Perca flavescens) were also challenged. Koi were highly susceptible to SVCV up to 11 months of age and fathead minnows had chronic disease expression with moderate mortality (29%). SVCV also induced moderate mortalities (33%) in yellow perch fry. Virus challenged salmonid fish had cumulative percent mortalities ranging from 0 to 100%, with sockeye salmon fry being the most vulnerable. A sub-sample of mortalities and survivors were screened for virus by plaque assay and reverse transcription polymerase chain reaction. In general, all mortalities tested positive for SVCV with high viral titers while survivors had variable persistence of SVCV with overall lower virus titers. Our SVCV challenges of multiple North American fish species suggested that host age is a key factor in determining disease outcome. Other factors, such as fish broodstock, virus strain, water temperature, and rearing conditions in association with the intrinsic level of species susceptibility may also impact infection dynamics. This is the first report of SVCV infecting a species (yellow perch) in the family Percidae and that sockeye salmon fry can suffer similarly high mortalities as the primary SVCV host species. Published by Elsevier B. V.

External morphological criteria that enable the rapid determination of gender have been developed for Yellow Perch Perca flavescens. Criteria are based upon (1) shape of the urogenital papilla (UGP), (2) size of the UGP relative to the anal (AN) opening, and (3) coloration of the UGP. In females, the UGP appeared (1) rounded at the anterior margin, (2) pointed at the posterior margin and had a V or U shape (crescent shaped in mature animals), (3) generally lacked reddish coloration, and (4) narrower relative to the AN. In males, the UGP (1) appeared circular or oval around the entire margin, (2) typically displayed reddish coloration, and (3) was generally wider relative to the AN. To verify accuracy of these criteria, gender was verified internally in perch of various sizes, sex, and maturity from four domesticated geographic strains (n = 1,389). For all perch tested, accuracy was 97.3% for both sexes, 98.8% for females, and 95.9% for males. To experimentally verify accuracy of these criteria, juvenile Yellow Perch (n = 913) were treated with dietary 17-estradiol (E2; 15mg/kg diet) or a control diet. Accuracy was 97.7% for control females and 95.1% for control males, which diminished to 63.9% for the E2-treated females and 57.6% for E2-treated males. We developed a gender identification algorithm that will enable sorting of sexes for many uses including (1) collection of broodstock by new aquaculture producers, (2) management of broodstocks for existing producers, (3) improved selection criteria for genetic selection programs, (4) studies on gender-specific differences in Yellow Perch physiology, and (5) the unharmed release of fish in field and aquaculture settings. Uncoupling of external UGP morphology from actual gender in E2-treated perch can enable producers and biologists to detect exposure to estrogenic compounds in areas where endocrine disruption is suspected. Received October 11, 2012; accepted March 5, 2013

The suppressor of cytokine signaling (SOCS) proteins are a family of intracellular proteins that are centrally involved with vertebrate growth, development and immunity via their effects as negative feed-back regulators of cytokine (and hormone) signaling. The genes for SOCS-1 & -3 were cloned, sequences analyzed and expression patterns examined in the commercially-important teleost, yellow perch (Perca flavescens). The deduced (mature) proteins for yellow perch (yp)SOCS-1 and (yp)SOCS-3 consist of 211 and 205 amino acids, respectively. Functional domains such as the Src homology-2 (SH2) and SOCS-box were present in ypSOCS-1 and ypSOCS-3 and these domains were well conserved between teleost species. Sequence analysis showed that ypSOCS-1 & -3 share highest homology (among similar teleost sequences), to the stickleback (Gasterosteus aculatus) SOCS-1 & -3 protein homologs. To investigate sex-specific expression of the ypSOCS-1 and ypSOCS-3 mRNAs, juvenile male and female yellow perch were immunologically challenged with a single injection (10 μg/g bw) of lipopolysaccharide (LPS) and tissues (gill, head kidney, kidney, liver and spleen) were sampled over a 48-h time-course. Quantitative real-time PCR analysis showed that ypSOCS-1 & -3 were expressed in all tissues examined and at all sampling time-points. LPS injection significantly induced ypSOCS-1 & -3 mRNA levels in gill, head kidney, liver, kidney and spleen, with maximal induction occurring at 6 h post-injection in each tissue. By 48-h post-injection, expression levels for ypSOCS-1 & -3 mRNAs approached, or reached, control levels in all tissues examined. While there were statistical interactions among variables (treatment, time and sex) for ypSOCS-1, we only found a main effect of sex on SOCS-3 mRNA expression in head kidney with higher copy numbers occurring in males than in females treated with LPS. Sexually-dimorphic expression of SOCS-1 or -3 mRNA has not been examined, or described, in a teleost. Our findings suggest the involvement of the SOCS genes in the yellow perch immune response and that differences among the sexes are evident and should be explored further.

Recirculating Aquaculture Systems (RAS) use less water than open pond systems and the concentrated wastes generated by fish in RAS are easier to collect and reuse. High operating costs limit RAS use to high-value species production. One strategy to improve productivity and offset the high operating costs is to convert the solid waste from the aquaculture systems to more valuable byproducts.

Evidence suggests larval yellow perch, Perca flavescens, utilize nearshore and offshore habitat during the 30–40 day period between hatch and transition from pelagic to demersal habitat. In a large, open system like Lake Michigan this represents a significant increase in available habitat and it is important to understand how this increase may impact our ability to sample larval yellow perch in an unbiased manner. We measured the vertical distribution of larval yellow perch in southern Lake Michigan as a function of size, age, and diel period. Larval yellow perch were collected from two zones (surface and epilimnion) from 1 to 32 km from shore in 2001 during the day; on four dates surface samples were also collected at night. Results indicate larval perch are more abundant at the surface at night han during the day. Larval yellow perch < 15 mm total length (TL) and younger than 18 days post hatch were found in both surface and epilimnion habitat during the day, but larvae > 15 mm TL were captured only in the epilimnion and farther than 5 km from shore, which suggests a different spatial distribution for larger, older larvae. Diel differences in larval abundance and size at the surface suggest more and larger larvae will be caught for a similar effort at night as compared to daytime sampling. Observed differences in larval distribution with size and age also suggest that sampling concentrated nearshore and/or at the surface has the potential to under-sample larger/older yellow perch larvae in Lake Michigan.

Growth and survivorship of larval yellow perch (Perca flavescens) have been examined in many systems but can conclusions from well-studied perch populations in smaller lakes be applied to populations in meso-oceanic systems like Lake Michigan, USA? Laboratory experiments were conducted with yellow perch (hatch to 35 mm total length) to develop an empirical selectivity function based on Chesson's α to describe larval diet as a function of changes in prey community composition. This function was used in an individual-based foraging and growth model (IBM) to describe changes in foraging decisions resulting from changes in prey composition between different systems. Larval perch made three selective transitions during ontogeny. Initial positive selection for rotifers and the relative selectivity for cladocerans vs. copepods in late-stage larvae were both dependent on prey composition. Larvae exposed to prey assemblages differing only in composition had different diets. The empirically based IBM accurately predicted these dietary differences and resulting differences in larval growth and likelihood of starvation between systems at equal prey density. The importance of feeding behavior to larval survival will differ between Lake Michigan and smaller lakes, and these results are important for comparisons of recruitment dynamics between large and small systems.

Yellow perch (Perca flavescens) in Lake Michigan have experienced sustained recruitment failure since 1990 as a result of increased mortality during the pelagic larval phase. Increased mortality of larval yellow perch has been tied indirectly to increased alewife (Alosa pseudoharengus) predation, but effects of predation on larval survival variability must be better understood. We compared the relative importance of predation by alewife and two other fish predators to larval survival in laboratory experiments and developed an individual-based predation model (IBM) to examine patterns in size-dependent predation vulnerability. Simulations exposing larval perch to predation by all predators suggest that larval mortality resulting from alewife predation is more size-dependent than mortality resulting from the other two predators, and the range of sizes vulnerable to alewife is smaller. Alewife predation may not be an important mortality source for larval yellow perch in Lake Michigan at present because of the narrow range of vulnerable sizes and low densities of larval perch in the open lake. Predation is more likely to be important in smaller, more productive systems where other predators are abundant. Modeling results also indicate IBM analysis of date of hatch distributions of surviving larvae is a valuable tool for identifying factors most important to larval survival.

Behrents Hartney, Kristine, 105 Bematchez, Louis, 247 Breitburg, Denise L., 97 Brown, Larry R., 223 Carl, Leon M., 239 Christensen, V., 87 Cooper, Scott D., 285 Copp, Gordon H., 1 Dodson, Julian J., 247 Donaldson, Terry J., 295 Dudley, Tom L., 285 Dunson, William A., 303 Farr, James A., 39,119 Fox, Michael G., 129 Gonzalez, Richard J., 303 Gunnarsson, Karl, 159 Gutherz, Elmer J., 277 Hales, L. Stanton, Jr., 153 J&vi, Torbjiim, 149 Jones, Robert S., 277 Keast, J. Allen, 129 Kemp, Alain, 247 Kiorboe , T., 87 Kraft, Melvin, 239 Lammens, Eddy H.R.R., 63 Matlock, Gary C., 277 McManus, Michael, 119 Mikhail, Mansour Y., 49 Munk, Peter, 87 Nelson, Walter R., 277 Ochi, Haruki, 257 Pankhurst , Neville W., 201 Parrish, Julia K., 79 Petersen, Christopher W., 213 Power, Mary E., 285 Quinn, Thomas P., 311 Rhude, Larry, 239 Ruggerone, Gregory T., 143 Sale, Peter F., 77 Sigurj&sd&tir, Hrefna, 159 Smith, C. Lavett, 237 Smith, Marcus P.L., 29 Swainson, Robert J., 129 Travis, Joseph, 39, 119 Trexler, Joel C., 119 Visser, Jentsje T., 63 Welch, Harold E., 49 Winemiller, Kirk O., 177

A karyotype analysis using several staining techniques was carried out on the North American lake sturgeon, Acipenser fulvescens. The chromosome number was found to be 2n = 262 +/- 6. A representative karyotype of 264 chromosomes was composed of 134 meta- and submetacentrics, 70 telo- and acrocentrics, and 60 microchromosomes. The constitutive heterochromatin, revealed by C banding, was localized in various positions on several chromosomes, including microchromosomes. The signals of fluorescent in situ hybridization (FISH) with a HindIII satellite DNA probe were visible as centromeric heterochromatin blocks on 48 chromosomes. The telomeric repeat (TTAGGG)n detected by FISH was localized at both ends of all chromosomes and two chromosomes were entirely marked. Fluorescent staining with GC-specific chromomycin A3 showed recognizable fluorescent regions, whereas a more uniform base composition was revealed by the AT-specific 4',6-diamidino-2-phenylindole (DAPI). After silver staining, the active nucleolar organizer regions (NORs) were detected on 12 chromosomes. FISH with the 5S probe showed four signals on four small chromosomes. Our data suggest that A. fulvescens is a tetraploid species.

Changes that occurred in the distribution of adult Lake Michigan yellow perch (Perca flavescens) phenotypic traits suggest that maternal effects on larval traits may be substantially influencing the recruitment of this heavily exploited species. We investigated maternal effects on yellow perch larvae at hatching in 10 maternal lines to test the null hypothesis of no effect of maternal phenotype on offspring phenotype and condition. Analyses lead to a rejection of the null hypothesis and indicated that the observed maternal effects likely resulted from differences among females in size, age, gonadosomatic index, and egg production. The observed maternal effects were expressed in the offspring by differences in larval total length, yolk volume, dry weight, and DNA quantity. Older, larger females were found to have high fecundity, yet low gonadosomatic index. Furthermore, older, larger females produced offspring that were, on average, short with large yolk sacs and high quantities of body reserves, as measured by dry weight and total DNA content. We conclude that the distribution of Lake Michigan yellow perch larval traits at hatching is linked to maternal influences and that this linkage may provide a mechanism through which managers can help rebuild the population.

Nous avons verifie l'hypothese qu'il n'y avait pas de differences entre les especes en ce qui a trait aux taux de consommation et de croissance chez trois especes de poisson du lac Michigan, la perchaude (Perca flavescens), le cisco de fumage (Coregonus hoyi), et le gaspareau (Alosa pseudoharengus), qui, a l'eclosion, presentent une gamme varie de tailles (3,5 a 9,5 mm). Les taux d'ingestion et de croissance differaient de maniere statistiquement significative entre les trois especes pour les poissons de 10 et 20 mm, bien que les differences etaient moins marquees dans le cas des taux de croissance chez les poissons de 10 mm. L'incorporation de ces valeurs estimees des taux de consommation et de croissance ainsi que des erreurs sur les parametriques qui les accompagnent dans un modele a revele que les differences de survie entre les especes pouvait etre determinees avec seulement trois echantillons (applications du modele) pour les poissons de 20 mm a densite de proies elevee et faible et pour les poissons de 10 mm a densite de proies faible, mais que 23 echantillons seraient necessaires pour deceler les differences pour les poissons de 10 mm a densite de proies elevee. Comparativement a nos valeurs estimees de 8 h, les valeurs estimees anterieures de la consommation a court terme (15-30 min) pour les trois memes especes entrainaient une surestimation des taux de consommation chez les poissons de 20 mm, mais une sous-estimation de ces derniers chez les poissons de 10 mm. Nos resultats laissent entendre que les differences dans la croissance et la consommation chez les trois especes sont vraisemblablement egales lorsque les poissons ont une longueur de 10 mm, mais que nous ne pourrions pas toujours etre en mesure de detecter les differences de survie chez les poissons plus petits.