{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T16:19:35Z","timestamp":1764692375895,"version":"3.46.0"},"reference-count":49,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,12,1]],"date-time":"2025-12-01T00:00:00Z","timestamp":1764547200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia"},{"name":"European Commission\u2019s Recovery and Resilience Facility","award":["UID\/04423\/2025","UID\/PRR\/04423\/2025","LA\/P\/0101\/2020"],"award-info":[{"award-number":["UID\/04423\/2025","UID\/PRR\/04423\/2025","LA\/P\/0101\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Hydrobiology"],"abstract":"<jats:p>The Ohrid trout (Salmo letnica) is a species endemic to Lake Ohrid (shared by Albania and North Macedonia), which is internationally recognized for its geological longevity and unique natural features. Given that the species has distinctive biological, ecological, and evolutionary characteristics, as well as significant economic value, the decline in this trout\u2019s population is a serious and urgent problem, deserving continuous, scientifically based management. Yet, although it is considered a \u201cFossil Trout\u201d, research on this species remains limited in relation to science and conservation. To understand the current state of the art, we conducted a systematic review in Web of Science, analyzing 31 indexed articles about the Ohrid trout. These studies primarily focused on the seasonal morphological characteristics of specific organs, phylogenetics, and, to a lesser extent, the impacts of environmental contamination. However, notable gaps exist in understanding sex- and stage-specific physiology, morphotype diversity, and pollutant bioaccumulation. To address these limitations, integrative strategies that combine multi-omics biomarker development, genetic screening of broodstock, and systematic monitoring of pollution and climate-related stressors are crucial. Regional authorities should work with international organizations to establish long-term monitoring of S. letnica. This review aims to provide a critical foundation for overcoming the \u201cLiving Fossil Left Behind by Science\u201d paradigm and to foster global initiatives to preserve the long-term survival and evolutionary legacy of this endangered species.<\/jats:p>","DOI":"10.3390\/hydrobiology4040032","type":"journal-article","created":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T15:31:46Z","timestamp":1764689506000},"page":"32","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Ohrid Trout: A \u201cLiving Fossil\u201d Endemic to Lake Ohrid Left Behind by Science"],"prefix":"10.3390","volume":"4","author":[{"given":"T\u00e2nia Vieira","family":"Madureira","sequence":"first","affiliation":[{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR\/CIMAR), University of Porto (U.Porto), 4450-208 Matosinhos, Portugal"},{"name":"School of Medicine and Biomedical Sciences (ICBAS), University of Porto (U.Porto), 4050-313 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8688-8033","authenticated-orcid":false,"given":"Maria Jo\u00e3o","family":"Rocha","sequence":"additional","affiliation":[{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR\/CIMAR), University of Porto (U.Porto), 4450-208 Matosinhos, Portugal"},{"name":"School of Medicine and Biomedical Sciences (ICBAS), University of Porto (U.Porto), 4050-313 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9813-4389","authenticated-orcid":false,"given":"Eduardo","family":"Rocha","sequence":"additional","affiliation":[{"name":"Interdisciplinary Centre of Marine and Environmental Research (CIIMAR\/CIMAR), University of Porto (U.Porto), 4450-208 Matosinhos, Portugal"},{"name":"School of Medicine and Biomedical Sciences (ICBAS), University of Porto (U.Porto), 4050-313 Porto, Portugal"}]},{"given":"Maja","family":"Jordanova","sequence":"additional","affiliation":[{"name":"Faculty of Natural Sciences and Mathematics, Ss. Cyril & Methodius University in Skopje, 1000 Skopje, North Macedonia"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1111\/bre.12063","article-title":"Sedimentary and tectonic evolution of Lake Ohrid (Macedonia\/Albania)","volume":"27","author":"Lindhorst","year":"2015","journal-title":"Basin Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1007\/s10750-008-9558-y","article-title":"Ancient Lake Ohrid: Biodiversity and evolution","volume":"615","author":"Albrecht","year":"2008","journal-title":"Hydrobiologia"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"158","DOI":"10.3394\/0380-1330(2006)32[158:SOALOT]2.0.CO;2","article-title":"Sensitivity of ancient Lake Ohrid to local anthropogenic impacts and global warming","volume":"32","author":"Matzinger","year":"2006","journal-title":"J. Great Lakes Res."},{"key":"ref_4","unstructured":"UNESCO\u2013World Heritage Convention (2025, September 29). Protecting Lake Ohrid Region. Available online: https:\/\/whc.unesco.org\/en\/lake-ohrid-region\/."},{"key":"ref_5","unstructured":"Spirkovski, Z. (2004, January 25\u201329). The past and present state of the environment of three Balkan transboundary lakes: Dojran, Prespa and Ohrid. Proceedings of the BALWOIS 2004, Ohrid, North Macedonia."},{"key":"ref_6","unstructured":"Stefanovi\u0107, D. (1948). Rasna i Ekolo\u0161ka Ispitivanja na Ohridskim Salmonidama, Srpska Akademija Nauka. Posebna izdanja, knjiga CXXXIX (139)."},{"key":"ref_7","unstructured":"Ford, M. (2025, September 29). Salmo letnica. The IUCN Red List of Threatened Species 2024: e.T19858A137328386. Available online: https:\/\/www.iucnredlist.org\/species\/19858\/137328386."},{"key":"ref_8","unstructured":"Spirkovski, Z. (2003, January 25\u201329). Changes in the spawning ecology of the Lake Ohrid trout Salmo letnica (Karaman). Proceedings of the 2nd Congress of Ecologists of Macedonia. Special issues of Macedonian Ecological Society, Ohrid, North Macedonia."},{"key":"ref_9","unstructured":"Owen, J. (2025, September 29). Fossil Trout Faces Extinction in Balkans, Experts Warn. National Geographic News. National Geographic Society. Available online: https:\/\/web.archive.org\/web\/20030919012630\/http:\/\/news.nationalgeographic.com\/news\/2003\/09\/0915_030915_ohridtrout.html#main."},{"key":"ref_10","unstructured":"Brown, P. (2025, September 29). Ohrid Fate Awaits Ancient Trout in the Balkans. The Guardian. Available online: https:\/\/www.theguardian.com\/environment\/2003\/jul\/28\/endangeredspecies.sciencenews."},{"key":"ref_11","first-page":"342","article-title":"Artificial fertilization of the Ohrid Trout and the presence of its summer form in the lake","volume":"LIX","author":"Prifti","year":"2016","journal-title":"Sci. Papers Ser. D Anim. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"161","DOI":"10.3750\/AIP2015.45.2.06","article-title":"Risks to stocks of native trout of the genus Salmo (Actinopterygii: Salmoniformes: Salmonidae) of Serbia and management for their recovery","volume":"45","year":"2015","journal-title":"Acta Ichthyol. Piscat."},{"key":"ref_13","unstructured":"World Bank (2005). Albania and Former Yugoslav Republic of Macedonia\u2014Lake Ohrid Conservation Project (English), World Bank. Available online: http:\/\/documents.worldbank.org\/curated\/en\/789991468300543534."},{"key":"ref_14","unstructured":"Zdraveski, K., Petri, L., Trajanovski, S., Beqiraj, S., Gjoreska, B.B., Trajanovska, S., and Trichkova, T. (2019). First contingent valuation of the endemic species: Salmo letnica Karaman, 1924 (Actinopterygii: Salmonidae) and Gocea ohridana Hadzisce, 1956 (Gastropoda: Hydrobiidae) from Lake Ohrid. Acta Zool. Bulg., 99\u2013106."},{"key":"ref_15","first-page":"830","article-title":"How much can afford the south Adriatic and Ionian aquaculture development?","volume":"11","author":"Shumka","year":"2010","journal-title":"J. Environ. Prot. Ecol."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Pranckut\u0117, R. (2021). Web of Science (WoS) and Scopus: The titans of bibliographic information in today\u2019s academic world. Publications, 9.","DOI":"10.3390\/publications9010012"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1007\/s10228-012-0302-2","article-title":"Variations in the volumes of parenchyma and stroma of the liver and in the cytology of hepatocytes are associated with gonadal stages in female Ohrid trout (Salmo letnica)","volume":"60","author":"Jordanova","year":"2013","journal-title":"Ichthyol. Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"700","DOI":"10.1002\/jemt.22687","article-title":"Seasonal changes in hepatocytic lipid droplets, glycogen deposits, and rough endoplasmic reticulum along the natural breeding cycle of female ohrid trout (Salmo letnica Kar.)\u2014A semiquantitative ultrastructural study","volume":"79","author":"Jordanova","year":"2016","journal-title":"Microsc. Res. Tech."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1016\/j.tice.2008.12.005","article-title":"Crystalline inclusions in hepatocytes and associated interhepatocytic macrophages from female Ohrid trout (Salmo letnica Kar.)","volume":"41","author":"Jordanova","year":"2009","journal-title":"Tissue Cell"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"822","DOI":"10.1002\/jemt.20626","article-title":"A qualitative and quantitative study of the hepatic pigmented macrophage aggregates during the breeding cycle of Ohrid trout, Salmo letnica Kar. (Teloestei, Salmonidae)","volume":"71","author":"Jordanova","year":"2008","journal-title":"Microsc. Res. Tech."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"473","DOI":"10.1016\/j.fsi.2006.11.004","article-title":"A quantitative study of the hepatic eosinophilic granule cells and rodlet cells during the breeding cycle of Ohrid trout, Salmo letnica Kar. (Teloestei, Salmonidae)","volume":"23","author":"Jordanova","year":"2007","journal-title":"Fish Shellfish Immunol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1002\/jemt.21040","article-title":"Changes in the amount of kidney pigmented macrophage aggregates throughout the breeding cycle of female Ohrid trout, Salmo letnica Kar. (Teleostei, Salmonidae)","volume":"75","author":"Jordanova","year":"2012","journal-title":"Microsc. Res. Tech."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1023","DOI":"10.2298\/ABS1104023R","article-title":"Spleen histology in the female Ohrid trout, Salmo letnica (Kar.) (Teleostei, Salmonidae) during the reproductive cycle","volume":"63","author":"Rebok","year":"2011","journal-title":"Arch. Biol. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/0006-3207(94)00082-2","article-title":"Conservation status of freshwater fish of Albania","volume":"72","author":"Rakaj","year":"1995","journal-title":"Biol. Conserv."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Hoda, A., Locci, C., Azzena, I., Pascale, N., Deplano, I., Kristo, R., Demiri, A., Scarpa, F., Casu, M., and Sanna, D. (2025). Exploring mitochondrial evolutionary pathways: Insights into the origin of the endemic Ohrid Trout. Life, 15.","DOI":"10.3390\/life15010052"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3633","DOI":"10.1111\/j.1365-294X.2004.02362.x","article-title":"Mitochondrial DNA differentiation between two forms of trout Salmo letnica, endemic to the Balkan Lake Ohrid, reflects their reproductive isolation","volume":"13","author":"Sell","year":"2004","journal-title":"Mol. Ecol."},{"key":"ref_27","unstructured":"Georgievska, E., Sandjakoska, L., Kishore, C., Marina, N., and Ponraj, J.S. (2018, January 15\u201316). Phylogenetic analysis of endemic fish species of Ohrid Lake. Proceedings of the International Scientific Conference Geobalcanica, Ohrid, North Macedonia."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1111\/j.0022-1112.2006.00902.x","article-title":"Genetic and morphological characterization of a Lake Ohrid endemic, Salmo (Acantholingua) ohridanus with a comparison to sympatric Salmo trutta","volume":"68","author":"Knizhin","year":"2006","journal-title":"J. Fish Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.ympev.2006.08.021","article-title":"Historical demography of brown trout (Salmo trutta) in the Adriatic drainage including the putative S. letnica endemic to Lake Ohrid","volume":"44","author":"Snoj","year":"2007","journal-title":"Mol. Phylogenet. Evol."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Talarico, L., Rakaj, A., and Tancioni, L. (2024). Unveiling MHC-DAB polymorphism within the Western Balkan salmonid hotspot: Preliminary outcomes from native trouts of Ohrid Lake and the Drin-Skadar drainage (Albania). Biology, 13.","DOI":"10.3390\/biology13121060"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1186\/1297-9686-46-7","article-title":"Molecular phylogeny of Salmo of the western Balkans, based upon multiple nuclear loci","volume":"46","author":"Pustovrh","year":"2014","journal-title":"Genet. Sel. Evol."},{"key":"ref_32","first-page":"357","article-title":"Parasitofauna of the Ohrid trout (Salmo letnica Karaman, 1924) from Lake Ohrid (Macedonia)","volume":"48","author":"Stojanovski","year":"1998","journal-title":"Acta Vet."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"37","DOI":"10.2478\/macvetrev-2024-0013","article-title":"Distribution and genotyping of infectious hematopoietic necrosis virus in farmed rainbow trout and autochthonous salmonids in North Macedonia","volume":"47","author":"Trajchovski","year":"2024","journal-title":"Mac. Vet. Rev."},{"key":"ref_34","first-page":"241","article-title":"Liver pathology of female Ohrid Trout (Salmo letnica Kar.) from the Eastern coast of Lake Ohrid: Baseline data suggesting the presence of a pollution gradient","volume":"16","author":"Jordanova","year":"2016","journal-title":"Turk. J. Fish. Aquat. Sci."},{"key":"ref_35","first-page":"991","article-title":"A combined approach of principal component analysis and support vector machine for early development phase modeling of Ohrid","volume":"126","author":"Jha","year":"2021","journal-title":"Comput. Model. Eng. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1823","DOI":"10.1007\/s10661-011-2081-z","article-title":"Near-shore distribution of heavy metals in the Albanian part of Lake Ohrid","volume":"184","author":"Malaj","year":"2012","journal-title":"Environ. Monit. Assess."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1080\/02772248.2020.1781854","article-title":"Changes in copper load in hepatocytes of Ohrid trout in relation to the ovarian maturation cycle","volume":"102","author":"Jordanova","year":"2020","journal-title":"Toxicol. Environ. Chem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"137","DOI":"10.2478\/cjf-2024-0017","article-title":"Accumulation of toxic elements in fish from Ohrid Lake under the influence of anthropogenic activities","volume":"82","author":"Ukoski","year":"2024","journal-title":"Croat. J. Fish."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1543","DOI":"10.1071\/MF18419","article-title":"Heavy metals risk assessment in Salmo letnica from Lake Ohrid in Albania","volume":"70","author":"Marchetti","year":"2019","journal-title":"Mar. Freshw. Res."},{"key":"ref_40","unstructured":"Spirkovski, Z., Palluqi, A., Flloko, A., Miraku, T., Kapedani, E., Ilik-Boeva, D., Talevski, T., Trajchevski, B., Ritterbusch, D., and Br\u00e4mick, U. (2017). Technical report: Fish and fisheries Lake Ohrid. Implementing the EU Water Framework Directive in South-Eastern Europe, Deutsche Gesellschaft f\u00fcr Internationale Zusammenarbeit (GIZ) GmbH."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"106004","DOI":"10.1016\/j.applanim.2023.106004","article-title":"Evaluating blood, gill, and muscle biopsy methods on the behaviour, reproductive success, and survival of a wild freshwater fish","volume":"265","author":"Haniford","year":"2023","journal-title":"Appl. Anim. Behav. Sci."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Koeberle, A.L., Pearsall, W., Hammers, B.E., Mulhall, D., McKenna, J.E., Chalupnicki, M., and Sethi, S.A. (2023). Whole-lake acoustic telemetry to evaluate survival of stocked juvenile fish. Sci. Rep., 13.","DOI":"10.1038\/s41598-023-46330-6"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1002\/edn3.94","article-title":"Application of eDNA as a tool for assessing fish population abundance","volume":"3","author":"Spear","year":"2020","journal-title":"Environ. DNA"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1274","DOI":"10.1111\/1365-2664.14412","article-title":"Estimating abundance of fish associated with structured habitats by combining acoustics and optics","volume":"60","author":"Scoulding","year":"2023","journal-title":"J. Appl. Ecol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"163","DOI":"10.20450\/mjcce.2011.32","article-title":"Study of organochlorine pesticide residues in water, sediment and fish tissue in Lake Ohrid (Macedonia\/Albania)","volume":"30","author":"Jordanoski","year":"2011","journal-title":"Maced. J. Chem. Chem. Eng."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1021\/acs.chas.3c00071","article-title":"Pharmaceuticals and personal care products as emerging environmental contaminants: Prevalence, toxicity, and remedial approaches","volume":"30","author":"Chakraborty","year":"2023","journal-title":"ACS Chem. Health Saf."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1050","DOI":"10.1093\/biosci\/biac052","article-title":"Lakes in hot water: The impacts of a changing climate on aquatic ecosystems","volume":"72","author":"Woolway","year":"2022","journal-title":"BioScience"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"eadt5369","DOI":"10.1126\/sciadv.adt5369","article-title":"Climate warming and heatwaves accelerate global lake deoxygenation","volume":"11","author":"Zhang","year":"2025","journal-title":"Sci. Adv."},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Jonsson, B. (2023). Thermal effects on ecological traits of salmonids. Fishes, 8.","DOI":"10.3390\/fishes8070337"}],"container-title":["Hydrobiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2673-9917\/4\/4\/32\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T16:17:08Z","timestamp":1764692228000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2673-9917\/4\/4\/32"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,1]]},"references-count":49,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["hydrobiology4040032"],"URL":"https:\/\/doi.org\/10.3390\/hydrobiology4040032","relation":{},"ISSN":["2673-9917"],"issn-type":[{"value":"2673-9917","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,1]]}}}