The sperm of Yellow Perch Perca flavescens of two different age-classes, age 0 and 3, were cryopreserved using two different cryoprotectants (dimethylsulfoxide [DMSO] and methanol [MetOH]) with two freezing methods (pellet and vial). The viability and quality of the progenies obtained from fertilization with cryopreserved sperm were then examined. The motility of Walleye Sander vitreus sperm was examined following cryopreservation and ultraviolet (UV) irradiation, with the aim of using heterologous cryopreserved sperm to inseminate Yellow Perch eggs to ensure gynogenesis. The first experiment compared the motility of fresh sperm and pellet method cryopreserved sperm devoid of salmon seminal plasma. Despite the high motility of fresh sperm-75% and 100%-of males age 0 and 3, respectively, the postthaw motility of seminal plasma devoid cryopreserved sperm was 0%. The second experiment addressed the efficiency of pellet and vial freezing methods with DMSO and MetOH supplemented with salmon seminal plasma. Cryopreserved sperm was thawed and motility measured. Sperm motility was not significantly different between pellet (13.3 ± 10.4%) and vial (10.3 ± 12.9%) methods in the absence of sperm extender; however, sperm motility of the pellet method was further improved (20 ± 8.7%) with the addition of sperm extender after thawing, while motility of the vial method sperm (10 ± 7.1%) was not. Cryopreserved sperm was further evaluated based on fertilization rate and ultimate survival and growth of larvae and juveniles through 14 d posthatch. Effects of UV exposure on fresh and pellet method cryopreserved sperm following UV irradiation were also examined. The motility of control sperm cryopreserved with DMSO and MetOH, and UV-exposed sperm cryopreserved with DMSO decreased from 100% motility before cryopreservation (fresh sperm) to 75% following cryopreservation, while UV-exposed sperm cryopreserved with MetOH decreased from 100% to 50%. This experiment provides significant new data to improve the effectiveness of straightforward cryopreservation techniques for Yellow Perch.Yellow Perch Perca flavescens is a North American game fish as well as an important species to aquaculturists. Advancements in artificial spawning, incubation and hatching of perch embryos, and larviculture over the past few decades have promoted the development of Yellow Perch aquaculture; however, several challenges and

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Challenges associated with first feeding have impeded the intensive culture of larval Yellow Perch Perca flavescens. Live-food enrichment with polyunsaturated fatty acids (PUFAs) can increase the growth and survival of larval fish, but this method has not been tested with Yellow Perch. This study includes two experiments that were meant to evaluate (1) the relative proportion of docosahexaenoic acid (DHA; 22:6[n-3]) and arachidonic acid (ARA; 20:4[n-6]) in enrichment emulsions and (2) the provision of PUFA emulsions in ethyl ester (EE) or triacylglycerol (TG) form on Yellow Perch growth and survival. Fish were provided with live rotifers Brachionus plicatilis and brine shrimp Artemia nauplii for the first 10 d of exogenous feeding within a specialized recirculating system (phase I). Fish were then transferred to flow-through tanks and were fed Artemia nauplii for 3 d before gradually transitioning to a formulated starter diet (5-7 d; phase II). Fish size, growth, survival, swim bladder inflation rates, and lipid/fatty acid concentrations were evaluated after each phase. Overall, rotifers assimilated ARA in higher concentrations (23.3% of total fatty acids) than Artemia (0.6-0.7% of total fatty acids). Rotifers also tended to assimilate PUFAs better in EE form than in TG form (71.3% versus 66.5% Σn-3 + n-6 fatty acids). In the first experiment, fish from the ARA-and DHAenriched diet groups had greater swim bladder inflation rates (phase I) and growth rates (phase II) than the unenriched control group. In phase I of the second experiment, the EE enrichment group had a significantly faster growth rate than the TG enrichment group (specific growth rate: mean AE SD = 40.5 AE 0.9% and 36.6 AE 1.8%, respectively). Fatty acid composition of zooplankton was heavily influenced by enrichments, and fatty acid composition of larvae/ juveniles reflected that of their live prey. The results of this study suggest that PUFA enrichment of live feeds can accelerate Yellow Perch growth and reduce the time spent in the critical period of early development.

The tolerance of eyed‐stage embryos of Walleye Sander vitreus to cooling at melting‐ice temperatures and their subsequent hatching and rearing to advanced juveniles were examined. Embryos (71% viable; 8 d after fertilization) were refrigerated in an insulated transportation Styrofoam box between wet cheesecloth layers and melting ice (1.4°C) for 25, 48, 72, and 120 h. Embryos were then acclimated to 14°C aquaria for hatching and rearing (20°C). The hatching of embryos and their ability to continue development (swim bladder inflation), food acceptance (live nauplii of brine shrimp Artemia spp.), and growth were monitored for 14 d. The duration of exposure to cold storage stress resulted in no significant differences in mean ± SD survival (46.8 ± 8.0, 38.7 ± 8.6, 41.0 ± 4.9, and 36.9 ± 12.5% for 25‐, 48‐, 72‐, 120‐h treatments, respectively) at the end of the rearing and feeding period. However, the proportion of fish with inflated swim bladders was the highest in the 120‐h cold‐delayed fish (mean ± SD = 61 ± 18, 54 ± 8, 64 ± 3.8, and 90.5 ± 8%, respectively). The mean weight of fish was not significantly influenced by cold storage treatments but was significantly influenced by swim bladder status (9.2–11.8 mg, 7.0–9.8 mg, and 5.7–9.5 mg for fully inflated, partially inflated, and uninflated groups, respectively). This experiment provides significant new data to fish culturists regarding the storage of Walleye embryos prior to hatching and the possibility of convenient transportation or delayed stocking of larvae into prepared nursing ponds or indoor rearing tanks for intensive culture.

Climate‐induced shifts in plankton blooms may alter fish recruitment by affecting the fatty acid composition of early‐life diets and corresponding performance. Early‐life nutrition may immediately affect survival but may also have a lingering influence on size and growth via experiential legacies. We explored the short‐ and longer‐term performance consequences of different concentrations of polyunsaturated fatty acids (PUFA) for juvenile Walleye (Sander vitreus, Mitchill 1818). For the first 10 days of feeding, juveniles were provided Artemia enriched with: oleic acid (low PUFA), high docosahexaenoic acid and high eicosapentaenoic acid (high PUFA), or high PUFA and a form of vitamin E (high PUFA + E). After 10 days, all fish were fed a high‐quality diet and reared for an additional 27 days. Juveniles fed either high PUFA diet were 1.15‐fold larger (PUFA mean ± SD = 20.0 ± 3.3 mg; PUFA + E = 19.8 ± 3.3 mg) than those fed the low PUFA (17.3 ± 2.8 mg) diet after 10 days of feeding. After 27 days, juveniles initially fed the high PUFA diet were still 1.10‐ to 1.20‐fold larger (PUFA = 407.0 ± 61.6 mg; PUFA + E = 422.7 ± 58.7 mg) than those initially fed the low PUFA diet (356.5.0 ± 39.5 mg). Our findings demonstrate that fatty acid composition of juvenile Walleye diets has immediate and lingering size effects. As changes in climate continue to alter lower trophic levels, fish management and conservation may need to consider short‐ and long‐term effects of temporal or spatial differences in early‐life diet quality.

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