Pub Date : 1998-03-01DOI: 10.1577/1548-8640(1998)060<0152:ALFSCD>2.0.CO;2
Daniel S. Hagopian, J. Riley
Abstract A float–stopper mechanism was designed to drain fish holding tanks directly from the bottom. Unlike traditional, top-drawn standpipe systems, it allows continuous flushing of settled solid waste. It also prevents the accumulation of these wastes between the two standpipes that are used in bottom-drawn, double-walled standpipe systems. When suspended solids are forced upward between the outer and inner standpipes of such systems, a minimum velocity must be maintained to prevent sediment accumulation. This minimum velocity determines the minimum flow rate through the tank. The system described in this report flushes well over a wide range of flow rates.
{"title":"A Low-Flow Self-Cleaning Drainage System for Fish Rearing Tanks","authors":"Daniel S. Hagopian, J. Riley","doi":"10.1577/1548-8640(1998)060<0152:ALFSCD>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0152:ALFSCD>2.0.CO;2","url":null,"abstract":"Abstract A float–stopper mechanism was designed to drain fish holding tanks directly from the bottom. Unlike traditional, top-drawn standpipe systems, it allows continuous flushing of settled solid waste. It also prevents the accumulation of these wastes between the two standpipes that are used in bottom-drawn, double-walled standpipe systems. When suspended solids are forced upward between the outer and inner standpipes of such systems, a minimum velocity must be maintained to prevent sediment accumulation. This minimum velocity determines the minimum flow rate through the tank. The system described in this report flushes well over a wide range of flow rates.","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"17 1","pages":"152-155"},"PeriodicalIF":0.0,"publicationDate":"1998-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74996314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0025:FTWHPG>2.0.CO;2
R. Bardi, F. Chapman, F. Barrows
Abstract Survival and growth in larval Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi fed live and formulated diets were evaluated. Live foods consisted of brine shrimp Artemia sp. and California blackworms Lumbriculus variegatus. Formulated diets consisted of commercially produced pellets and two experimentally formulated sturgeon starter diets (SS). Feeds were first offered at 5 d posthatch, 2 d before initiation of exogenous feeding. Significant differences (P 95%) and specific growth rate (12%; SGR, logarithmic growth per unit time). In contrast, commercially formulated feeds were poorly accepted at the onset of feeding, and their use resulted in nearly complete mortality (>99%) by 3 weeks. First-feeding larvae, however, displayed preference for an experimentally formulated sturgeon ...
{"title":"Feeding Trials with Hatchery-Produced Gulf of Mexico Sturgeon Larvae","authors":"R. Bardi, F. Chapman, F. Barrows","doi":"10.1577/1548-8640(1998)060<0025:FTWHPG>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0025:FTWHPG>2.0.CO;2","url":null,"abstract":"Abstract Survival and growth in larval Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi fed live and formulated diets were evaluated. Live foods consisted of brine shrimp Artemia sp. and California blackworms Lumbriculus variegatus. Formulated diets consisted of commercially produced pellets and two experimentally formulated sturgeon starter diets (SS). Feeds were first offered at 5 d posthatch, 2 d before initiation of exogenous feeding. Significant differences (P 95%) and specific growth rate (12%; SGR, logarithmic growth per unit time). In contrast, commercially formulated feeds were poorly accepted at the onset of feeding, and their use resulted in nearly complete mortality (>99%) by 3 weeks. First-feeding larvae, however, displayed preference for an experimentally formulated sturgeon ...","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"57 1","pages":"25-31"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76903182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0032:CSOTNT>2.0.CO;2
F. Chapman, D. Colle, R. Rottmann, J. Shireman
Abstract The neon tetra Paracheirodon innesi is one of the most valuable species in the ornamental fish trade. Most neon tetras available in the United States are imported from Southeast Asia, where they are farm raised, or from South America, where they are collected from the wild. In this study, we describe a method for artificially breeding the neon tetra that can be adapted to domestic commercial production. Broodfish pairs were routinely spawned in acidified, soft water at 25°C (pH, 5.5–6.5, adjusted with phosphoric acid; total alkalinity, 3.2 mg/L, and total hardness, 6.0 mg/L, as CaCO3). The water was also conditioned with humic acids (0.04%). A spawning substrate (nylon brush) was available for egg deposition. Fish reared in the laboratory had a significantly higher number of larvae (82 larvae/female) than broodstock collected from the wild or cultured abroad (28 larvae/female). The domestic population reached sexual maturity at 5–6 months of age, and broodfish pairs produced an average of 82 larv...
{"title":"Controlled Spawning of the Neon Tetra","authors":"F. Chapman, D. Colle, R. Rottmann, J. Shireman","doi":"10.1577/1548-8640(1998)060<0032:CSOTNT>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0032:CSOTNT>2.0.CO;2","url":null,"abstract":"Abstract The neon tetra Paracheirodon innesi is one of the most valuable species in the ornamental fish trade. Most neon tetras available in the United States are imported from Southeast Asia, where they are farm raised, or from South America, where they are collected from the wild. In this study, we describe a method for artificially breeding the neon tetra that can be adapted to domestic commercial production. Broodfish pairs were routinely spawned in acidified, soft water at 25°C (pH, 5.5–6.5, adjusted with phosphoric acid; total alkalinity, 3.2 mg/L, and total hardness, 6.0 mg/L, as CaCO3). The water was also conditioned with humic acids (0.04%). A spawning substrate (nylon brush) was available for egg deposition. Fish reared in the laboratory had a significantly higher number of larvae (82 larvae/female) than broodstock collected from the wild or cultured abroad (28 larvae/female). The domestic population reached sexual maturity at 5–6 months of age, and broodfish pairs produced an average of 82 larv...","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"145 1","pages":"32-37"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88632004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0059:SBOFLB>2.0.CO;2
Jacob Isaac, T. Kimmel, R. Bagley, V. Staats, Aaron Barkoh
Abstract Florida largemouth bass Micropterus salmoides floridanus were tagged and placed into an indoor raceway to document time of spawning, duration of spawning episodes, number of fish contributing to spawns, number of fish spawning multiple times, and percent of fish that spawned. In 8 d of observation, 16 spawns were initiated from 1500 to 1850 hours (lights on at 0700 hours, off at 1900 hours), and 3 spawns occurred during the night. Spawning episodes lasted from 110 to more than 240 min. Two spawns included participation by more than one male or female, but in both cases, activity of the third fish was brief and did not appear to contribute gametes. Five males (25%) and three females (15%) spawned more than once, and multiple-spawning males always used the same nest. Fifty percent of the males and 65% of the females spawned at 10 mat locations during observations. Six mat locations were used after observations ceased, which added to the 10 confirmed locations and 2 mat sites from night spawns, indi...
{"title":"Spawning Behavior of Florida Largemouth Bass in an Indoor Raceway","authors":"Jacob Isaac, T. Kimmel, R. Bagley, V. Staats, Aaron Barkoh","doi":"10.1577/1548-8640(1998)060<0059:SBOFLB>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0059:SBOFLB>2.0.CO;2","url":null,"abstract":"Abstract Florida largemouth bass Micropterus salmoides floridanus were tagged and placed into an indoor raceway to document time of spawning, duration of spawning episodes, number of fish contributing to spawns, number of fish spawning multiple times, and percent of fish that spawned. In 8 d of observation, 16 spawns were initiated from 1500 to 1850 hours (lights on at 0700 hours, off at 1900 hours), and 3 spawns occurred during the night. Spawning episodes lasted from 110 to more than 240 min. Two spawns included participation by more than one male or female, but in both cases, activity of the third fish was brief and did not appear to contribute gametes. Five males (25%) and three females (15%) spawned more than once, and multiple-spawning males always used the same nest. Fifty percent of the males and 65% of the females spawned at 10 mat locations during observations. Six mat locations were used after observations ceased, which added to the 10 confirmed locations and 2 mat sites from night spawns, indi...","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"52 1","pages":"59-62"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86992772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0067:OOHPCO>2.0.CO;2
M. E. Barnes, D. Ewing, Rick J. Cordes, Gregorio Young
Abstract Daily treatments of 250, 500, and 1,000 mg hydrogen peroxide/L for 15 min were evaluated for fungal control on incubating eggs from two strains of rainbow trout Oncorhynchus mykiss. Observed infection rates and egg clumping were extensive enough in incubator trays receiving treatments of 250 or 500 mg hydrogen peroxide/L to make egg and fry handling difficult. The 1,000 mg/L treatment provided fungal control similar to daily formalin treatments of 1,667 mg/L for 15 min. Despite the differences in infection rates and clumping, egg survival was not affected by any of the treatments used.
{"title":"Observations on Hydrogen Peroxide Control of Saprolegnia spp. during Rainbow Trout Egg Incubation","authors":"M. E. Barnes, D. Ewing, Rick J. Cordes, Gregorio Young","doi":"10.1577/1548-8640(1998)060<0067:OOHPCO>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0067:OOHPCO>2.0.CO;2","url":null,"abstract":"Abstract Daily treatments of 250, 500, and 1,000 mg hydrogen peroxide/L for 15 min were evaluated for fungal control on incubating eggs from two strains of rainbow trout Oncorhynchus mykiss. Observed infection rates and egg clumping were extensive enough in incubator trays receiving treatments of 250 or 500 mg hydrogen peroxide/L to make egg and fry handling difficult. The 1,000 mg/L treatment provided fungal control similar to daily formalin treatments of 1,667 mg/L for 15 min. Despite the differences in infection rates and clumping, egg survival was not affected by any of the treatments used.","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"155 1","pages":"67-70"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76434045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0044:EOIBEA>2.0.CO;2
S. Redman, J. Meinertz, M. Gaikowski
Abstract To determine the effects of electrically and chemically induced immobilization on postspawn broodstock and their progeny, age-2 and age-3 female broodstock and age-2 male broodstock of brown trout Salmo trutta were immobilized with electricity or tricaine methanesulfonate (MS-222), stripped of their eggs or milt, and weighed. Eggs taken from electrically immobilized females were fertilized with milt taken from age-2 males that were immobilized with electricity, and eggs taken from females immobilized with MS-222 were fertilized with milt taken from age-2 males that were immobilized with MS-222. After spawning, the mortality and weight of broodstock were compared twice over a 6-month period. Egg viability and growth of offspring fry from each treatment group were also compared. Electricity induced complete and consistent immobilization in brown trout broodstock. Electrically immobilized fish were more easily handled than fish immobilized with MS-222; however, electrically immobilized fish survival...
{"title":"Effects of Immobilization by Electricity and MS‐222 on Brown Trout Broodstock and Their Progeny","authors":"S. Redman, J. Meinertz, M. Gaikowski","doi":"10.1577/1548-8640(1998)060<0044:EOIBEA>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0044:EOIBEA>2.0.CO;2","url":null,"abstract":"Abstract To determine the effects of electrically and chemically induced immobilization on postspawn broodstock and their progeny, age-2 and age-3 female broodstock and age-2 male broodstock of brown trout Salmo trutta were immobilized with electricity or tricaine methanesulfonate (MS-222), stripped of their eggs or milt, and weighed. Eggs taken from electrically immobilized females were fertilized with milt taken from age-2 males that were immobilized with electricity, and eggs taken from females immobilized with MS-222 were fertilized with milt taken from age-2 males that were immobilized with MS-222. After spawning, the mortality and weight of broodstock were compared twice over a 6-month period. Egg viability and growth of offspring fry from each treatment group were also compared. Electricity induced complete and consistent immobilization in brown trout broodstock. Electrically immobilized fish were more easily handled than fish immobilized with MS-222; however, electrically immobilized fish survival...","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"35 1","pages":"44-49"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73334091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0050:LCOT>2.0.CO;2
D. Perry, R. Mercaldo-Allen, C. Kuropat, J. B. Hughes
Abstract Spawning of field-captured adult tautog Tautoga onitis was accomplished under laboratory conditions. Natural spawning of tautog produced more viable embryos and larvae than did strip-spawning. Embryos were cultured to hatching and raised successfully through the larval stage to juveniles. Newly hatched larvae were fed protozoans from day 0 to day 6 posthatch, rotifers from day 2 to day 20 posthatch, and brine shrimp Artemia salina from day 7 to several months posthatch. Rotifers and brine shrimp were enriched with highly unsaturated fatty acids. Supplementing cultured foods with natural plankton enhanced larval survival. Slow flow-through green-water culture proved superior to static culture methods. Handling resulted in high larval mortality. Laboratory-cultured brine shrimp and a commercial food provided an adequate diet for juvenile tautog.
{"title":"Laboratory Culture of Tautog","authors":"D. Perry, R. Mercaldo-Allen, C. Kuropat, J. B. Hughes","doi":"10.1577/1548-8640(1998)060<0050:LCOT>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0050:LCOT>2.0.CO;2","url":null,"abstract":"Abstract Spawning of field-captured adult tautog Tautoga onitis was accomplished under laboratory conditions. Natural spawning of tautog produced more viable embryos and larvae than did strip-spawning. Embryos were cultured to hatching and raised successfully through the larval stage to juveniles. Newly hatched larvae were fed protozoans from day 0 to day 6 posthatch, rotifers from day 2 to day 20 posthatch, and brine shrimp Artemia salina from day 7 to several months posthatch. Rotifers and brine shrimp were enriched with highly unsaturated fatty acids. Supplementing cultured foods with natural plankton enhanced larval survival. Slow flow-through green-water culture proved superior to static culture methods. Handling resulted in high larval mortality. Laboratory-cultured brine shrimp and a commercial food provided an adequate diet for juvenile tautog.","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"107 1","pages":"50-54"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74882472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0055:PFCORS>2.0.CO;2
S. Cook, G. D. Scurlock
Abstract Intensive culture of redear sunfish Lepomis microlophus has been difficult because these fish do not readily accept formulated diets. Many fish culturists have continued to raise redear sunfish in ponds on formulated diets, but it is uncertain whether the fish are effectively using the provided feed or the feed is simply adding nutrients to the pond. We examined the feed conversion, relative condition, and body composition of redear sunfish fingerlings fed three nutritionally complete commercial formulated diets in recirculating-water, biofiltered aquaculture systems. Redear sunfish accepted all three diets after an initial training period of 3 weeks. Increases in total length and weight were noted for all three diets; however, condition factors only increased for fish fed two of the diets. Proximate body composition appeared to be related to composition and particle size of the diets. Feed conversion ratios for fish fed one of the diets were similar to those reported for hybrid sunfish (bluegill...
{"title":"Potential Feed Conversion of Redear Sunfish Fed Nutritionally Complete Formulated Diets","authors":"S. Cook, G. D. Scurlock","doi":"10.1577/1548-8640(1998)060<0055:PFCORS>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0055:PFCORS>2.0.CO;2","url":null,"abstract":"Abstract Intensive culture of redear sunfish Lepomis microlophus has been difficult because these fish do not readily accept formulated diets. Many fish culturists have continued to raise redear sunfish in ponds on formulated diets, but it is uncertain whether the fish are effectively using the provided feed or the feed is simply adding nutrients to the pond. We examined the feed conversion, relative condition, and body composition of redear sunfish fingerlings fed three nutritionally complete commercial formulated diets in recirculating-water, biofiltered aquaculture systems. Redear sunfish accepted all three diets after an initial training period of 3 weeks. Increases in total length and weight were noted for all three diets; however, condition factors only increased for fish fed two of the diets. Proximate body composition appeared to be related to composition and particle size of the diets. Feed conversion ratios for fish fed one of the diets were similar to those reported for hybrid sunfish (bluegill...","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"16 1","pages":"55-58"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89915281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0072:>2.0.CO;2
R. Stickney
{"title":"Physiology of Fish in Intensive Culture Systems","authors":"R. Stickney","doi":"10.1577/1548-8640(1998)060<0072:>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0072:>2.0.CO;2","url":null,"abstract":"","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"1 1","pages":"73-75"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88664627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.1577/1548-8640(1998)060<0020:POMFPO>2.0.CO;2
J. Malison, J. Held, L. S. Procarione, M. Garcia-Abiado
Abstract Monosex female populations of walleye Stizostedion vitreum were produced by fertilizing eggs with sperm obtained from intersex genetic female broodstock. To produce these broodstock, groups of walleyes at mean sizes of 50, 70, and 90 mm total length (TL) were fed a diet containing 17α-methyltestosterone at 15 mg/kg of food for 60 consecutive days. At age 2, three masculinized females from the 50-mm TL group were identified by the presence of both ovarian and testicular tissue. Mature spermatozoa were collected from these fish and used to fertilize eggs collected from normal females. Approximately 200 of the resultant progeny were reared to 145 mm TL. Morphological and histological examination of the gonads from a subsample of 35 of these fish confirmed that all were normal females. The potential uses of monosex female populations of walleye and the advantages of this indirect hormonal method of producing monosex female populations are discussed.
{"title":"Production of Monosex Female Populations of Walleye from Intersex Broodstock","authors":"J. Malison, J. Held, L. S. Procarione, M. Garcia-Abiado","doi":"10.1577/1548-8640(1998)060<0020:POMFPO>2.0.CO;2","DOIUrl":"https://doi.org/10.1577/1548-8640(1998)060<0020:POMFPO>2.0.CO;2","url":null,"abstract":"Abstract Monosex female populations of walleye Stizostedion vitreum were produced by fertilizing eggs with sperm obtained from intersex genetic female broodstock. To produce these broodstock, groups of walleyes at mean sizes of 50, 70, and 90 mm total length (TL) were fed a diet containing 17α-methyltestosterone at 15 mg/kg of food for 60 consecutive days. At age 2, three masculinized females from the 50-mm TL group were identified by the presence of both ovarian and testicular tissue. Mature spermatozoa were collected from these fish and used to fertilize eggs collected from normal females. Approximately 200 of the resultant progeny were reared to 145 mm TL. Morphological and histological examination of the gonads from a subsample of 35 of these fish confirmed that all were normal females. The potential uses of monosex female populations of walleye and the advantages of this indirect hormonal method of producing monosex female populations are discussed.","PeriodicalId":22850,"journal":{"name":"The Progressive Fish-culturist","volume":"53 1","pages":"20-24"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90361208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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