Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish
Many lakes of the pre-Alpine region suffered from severe eutrophication that affected the natural reproduction of whitefish (Coregonus spp.) and necessitated large-scale supportive breeding programs. With the advanced reoligotrophication, it is now important to evaluate the relevance of continued ar...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2022-10-01
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| Series: | Global Ecology and Conservation |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2351989422002219 |
| _version_ | 1818114880023035904 |
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| author | Claus Wedekind Pascal Vonlanthen Christian de Guttry Richard Stadelmann Noah Stadelmann Aurélien Pirat Giulia Perroud |
| author_facet | Claus Wedekind Pascal Vonlanthen Christian de Guttry Richard Stadelmann Noah Stadelmann Aurélien Pirat Giulia Perroud |
| author_sort | Claus Wedekind |
| collection | DOAJ |
| description | Many lakes of the pre-Alpine region suffered from severe eutrophication that affected the natural reproduction of whitefish (Coregonus spp.) and necessitated large-scale supportive breeding programs. With the advanced reoligotrophication, it is now important to evaluate the relevance of continued artificial breeding for population dynamics. We focused on a whitefish population of a lake that has reached phase III of the reoligotrophication, i.e., lake biomass production is declining since 2012 in response to low phosphorus concentrations. We show that most eggs are naturally spawned, the observed oxygen concentrations would again support embryo development at all depths, and ready-to-hatch embryos can indeed be found on spawning grounds. We marked all hatchery-produced eggs of the 2014 cohort with Alizarin red, stocked them as usual (at larval or early juvenile stages), and recaptured them over a period of five years. Fish were aged from yearly growth rings on scales, and otoliths were checked for marks. We found 90.3 % of the 2014 cohort to be hatchery-born. This ratio did not decline with fish age. We also determined juvenile growth of the cohorts 2012–2020 (based on the first annual ring on scales) and found that stocking intensity predicted juvenile growth (r2 = 0.67). This strong density dependence of individual growth suggests that stocking has largely determined cohort size over the first nine years of reoligotrophication phase III. We conclude that large areas of spawning grounds allow again for successful embryogenesis, that large quantities of eggs are naturally spawned, but that natural recruitment is significantly reduced by ecological or evolutionary factors, e.g., competition with hatchery-born fish, desynchronization of trophic interactions, or long-term effects of fishing- or hatchery-induced evolution. |
| first_indexed | 2024-12-11T03:57:45Z |
| format | Article |
| id | doaj.art-ad78c016fce74b6e922c3f0fc4f70743 |
| institution | Directory Open Access Journal |
| issn | 2351-9894 |
| language | English |
| last_indexed | 2024-12-11T03:57:45Z |
| publishDate | 2022-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Global Ecology and Conservation |
| spelling | doaj.art-ad78c016fce74b6e922c3f0fc4f707432022-12-22T01:21:44ZengElsevierGlobal Ecology and Conservation2351-98942022-10-0138e02219Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefishClaus Wedekind0Pascal Vonlanthen1Christian de Guttry2Richard Stadelmann3Noah Stadelmann4Aurélien Pirat5Giulia Perroud6Department of Ecology & Evolution, University of Lausanne, Lausanne, Switzerland; Correspondence to: Department of Ecology & Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland.Aquabios GmbH, Cordast, SwitzerlandDepartment of Ecology & Evolution, University of Lausanne, Lausanne, SwitzerlandFischerei Hallwilersee, Birrwil, SwitzerlandFischerei Hallwilersee, Birrwil, SwitzerlandDepartment of Ecology & Evolution, University of Lausanne, Lausanne, SwitzerlandDepartment of Ecology & Evolution, University of Lausanne, Lausanne, SwitzerlandMany lakes of the pre-Alpine region suffered from severe eutrophication that affected the natural reproduction of whitefish (Coregonus spp.) and necessitated large-scale supportive breeding programs. With the advanced reoligotrophication, it is now important to evaluate the relevance of continued artificial breeding for population dynamics. We focused on a whitefish population of a lake that has reached phase III of the reoligotrophication, i.e., lake biomass production is declining since 2012 in response to low phosphorus concentrations. We show that most eggs are naturally spawned, the observed oxygen concentrations would again support embryo development at all depths, and ready-to-hatch embryos can indeed be found on spawning grounds. We marked all hatchery-produced eggs of the 2014 cohort with Alizarin red, stocked them as usual (at larval or early juvenile stages), and recaptured them over a period of five years. Fish were aged from yearly growth rings on scales, and otoliths were checked for marks. We found 90.3 % of the 2014 cohort to be hatchery-born. This ratio did not decline with fish age. We also determined juvenile growth of the cohorts 2012–2020 (based on the first annual ring on scales) and found that stocking intensity predicted juvenile growth (r2 = 0.67). This strong density dependence of individual growth suggests that stocking has largely determined cohort size over the first nine years of reoligotrophication phase III. We conclude that large areas of spawning grounds allow again for successful embryogenesis, that large quantities of eggs are naturally spawned, but that natural recruitment is significantly reduced by ecological or evolutionary factors, e.g., competition with hatchery-born fish, desynchronization of trophic interactions, or long-term effects of fishing- or hatchery-induced evolution.http://www.sciencedirect.com/science/article/pii/S2351989422002219EutrophicationSupplementary breedingSalmonidFish growthDensity dependenceSediment memory effect |
| spellingShingle | Claus Wedekind Pascal Vonlanthen Christian de Guttry Richard Stadelmann Noah Stadelmann Aurélien Pirat Giulia Perroud Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish Global Ecology and Conservation Eutrophication Supplementary breeding Salmonid Fish growth Density dependence Sediment memory effect |
| title | Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| title_full | Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| title_fullStr | Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| title_full_unstemmed | Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| title_short | Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| title_sort | persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish |
| topic | Eutrophication Supplementary breeding Salmonid Fish growth Density dependence Sediment memory effect |
| url | http://www.sciencedirect.com/science/article/pii/S2351989422002219 |
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