Papers by Yvette Heimbrand
Age is a fundamental parameter in biology and fishery science to estimate growth and population p... more Age is a fundamental parameter in biology and fishery science to estimate growth and population parameters. Losing track of time, in the sense of lacking reliable estimates of age and growth creates substantial problems for managing difficult-to-age-species. This thesis explores the use of fish otolith chemistry to improve age determination. Otoliths produce annual growth zones in the form of alternating opaque and translucent rings, corresponding to fast growth in summer and autumn and slow to no growth in winter. For the eastern Baltic cod (EBC), degraded environmental conditions led to a worsening of visual contrast in their otoliths. The EBC served as a model species to test new methods of aging, taking advantage of seasonally driven patterns in otolith chemical constituents. Experiments demonstrated that patterns of physiologically regulated elements significantly improved agreement among untrained chemical readers when compared to experienced readers using standard visual tech...
Fisheries Management and Ecology, 2021
Front cover: A Baltic cod (Gadus morhua), a cod otolith and the rings of daily growth in an otoli... more Front cover: A Baltic cod (Gadus morhua), a cod otolith and the rings of daily growth in an otolith. Photo montage: Y. Heimbrand Back cover: Baltic herring (Clupea harengus membras). Photo: Y. Heimbrand. Cod (Gadus morhua) is a key fish species of the Baltic Sea, economically as well as ecologically. Stocks declined during recent decades due to factors such as high fishing pressure, loss of spawning and feeding habitats caused by eutrophication, changing climate and widespread hypoxia. The growing seal population preys on cod and increased contact has resulted in the trans-mittance of parasites to cod, causing additional stress. In order to manage fisheries, age distribution and growth history of fish are needed to run stock assessment models. Based on these biological references, decisions are made for fishing quotas and restricting catches. Fish age is usually determined from counting annual growth zones in otoliths, calcium carbonate structures situated in the skull of the fish. ...
Front cover: A Baltic cod (Gadus morhua), a cod otolith and the rings of daily growth in an otoli... more Front cover: A Baltic cod (Gadus morhua), a cod otolith and the rings of daily growth in an otolith. Photo montage: Y. Heimbrand Back cover: Baltic herring (Clupea harengus membras). Photo: Y. Heimbrand. Cod (Gadus morhua) is a key fish species of the Baltic Sea, economically as well as ecologically. Stocks declined during recent decades due to factors such as high fishing pressure, loss of spawning and feeding habitats caused by eutrophication, changing climate and widespread hypoxia. The growing seal population preys on cod and increased contact has resulted in the transmittance of parasites to cod, causing additional stress. In order to manage fisheries, age distribution and growth history of fish are needed to run stock assessment models. Based on these biological references, decisions are made for fishing quotas and restricting catches. Fish age is usually determined from counting annual growth zones in otoliths, calcium carbonate structures situated in the skull of the fish. Otoliths grow incrementally, depositing layers of material, forming annual rings reflecting growth, like a tree's rings. Baltic cod otolith readability has always been somewhat difficult; today the poor condition of Baltic cod has worsened the problem. Unclear seasonal growth zones in otoliths have made age data unreliable, resulting in an uncertain forecast for stock size and suspended Marine Stewardship Council (MSC) certificate for sustainable seafood. However, invisible to the eye, the chemistry of the otolith contains a "hidden code" that could validate conventional ageing methods. The otolith takes up trace elements and isotopes from the surrounding water; hence the fish's seasonal migration among areas with different environmental conditions is recorded in the otolith. Microchemical analyses enable us to track seasonal changes in trace elemental and isotopic composition in the otolith throughout the fish's life. The aim of this thesis is to (1) explore the potential use of otolith chemistry as an age validating tool, (2) provide alternative ways to age fishes when other methods fail, as well as (3) provide novel information for aquatic monitoring.
Cod (Gadus morhua) is a key fish species of the Baltic Sea, economically as well as ecologically.... more Cod (Gadus morhua) is a key fish species of the Baltic Sea, economically as well as ecologically. Stocks declined during recent decades due to factors such as high fishing pressure, loss of spawning and feeding habitats caused by eutrophication, changing climate and widespread hypoxia. The growing seal population preys on cod and increased contact has resulted in the transmittance of parasites to cod, causing additional stress. In order to manage fisheries, age distribution and growth history of fish are needed to run stock assessment models. Based on these biological references, decisions are made for fishing quotas and restricting catches. Fish age is usually determined from counting annual growth zones in otoliths, calcium carbonate structures situated in the skull of the fish. Otoliths grow incrementally, depositing layers of material, forming annual rings reflecting growth, like a tree’s rings. Baltic cod otolith readability has always been somewhat difficult; today the poor co...
The ICES Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD2) met at ICES Headquarters in Copenha... more The ICES Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD2) met at ICES Headquarters in Copenhagen, Denmark on 4–8 February 2019, following a data evaluation workshop (Chair Johan Lovgren) and several preparatory web conference meetings. The meeting, cochaired by Meaghan Bryan, USA (External Chair) and Michele Casini, Sweden (ICES Chair), was attended by two invited external experts, Vladlena Gertseva, USA, and Verena Trenkel, France, and 47 participants from 10 countries. Participants represented a diversity of groups including industry, NGOs, managers, and scientists. The objectives of WKBALTCOD2 were to evaluate the appropriateness of the data and the assessment methods to determine stock status for the Western Baltic cod (SD 22-24) and the Eastern Baltic cod (SD 24-32) stocks, evaluate the short-term forecasting methods, re-examine and update the reference points, and update the stock annex as appropriate to these stocks. The workshop started with a group discussion of data is...
Denna rapport ar en utvardering av artificiella substrat som metod for att overvaka bottenfauna p... more Denna rapport ar en utvardering av artificiella substrat som metod for att overvaka bottenfauna pa bottnar som saknar sediment. Undersokningarna utfordes under aren 2010-2014 i Forsmarks skargard. Rapporten redogor for metodutveckligen och de biologiska resultaten av undersokningarna. Den syftar dessutom till att grundligt beskriva metodiken for de artificiella substraten, for att mojliggora en standardiserad och upprepningsbar framtida langtidsovervakning av hardbottenfauna i kustnara vattenomraden. De artificiella substraten, som gar under namnet Landforsplattor, konstruerades utgaende fran en motsvarande metod som anvands i vattendrag och sjoar och anpassade sarskilt for kustnara forhallanden. Undersokningarna genomfordes pa fyra lokaler i Forsmarks skargard, namligen i utslappsomradet fran Biotestsjon, referensomradet Borgarna, intagsomradet for kylvatten i Asphallafjarden och inne i Biotestsjon. Plattorna sattes ut i slutet av maj och togs upp i mitten av september. Utformninge...
Journal of Applied Ichthyology, 2017
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Journal of Fish Biology, 2020
Fish otoliths' chronometric properties make them useful for age and growth rate estimation in fis... more Fish otoliths' chronometric properties make them useful for age and growth rate estimation in fisheries management. For the Eastern Baltic Sea cod stock (Gadus morhua), unclear seasonal growth zones in otoliths have resulted in unreliable age and growth information. Here, a new age estimation method based on seasonal patterns in trace elemental otolith incorporation was tested for the first time and compared with the traditional method of visually counting growth zones, using otoliths from the Baltic and North seas. Various trace elemental ratios, linked to fish metabolic activity (higher in summer) or external environment (migration to colder, deeper habitats with higher salinity in winter), were tested for age estimation based on assessing their seasonal variations in concentration. Mg:Ca and P:Ca, both proxies for growth and metabolic activity, showed greatest seasonality and therefore have the best potential to be used as chemical clocks. Otolith image readability was significantly lower in the Baltic than in the North Sea. The chemical (novel) method had an overall greater precision and percentage agreement among readers (11.2%, 74.0%) than the visual (traditional) method (23.1%, 51.0%). Visual readers generally selected more highly contrasting zones as annuli whereas the chemical readers identified brighter regions within the first two annuli and darker zones thereafter. Visual estimates produced significantly higher, more variable ages than did the chemical ones. Based on the analyses in our study, we suggest that otolith microchemistry is a promising alternative ageing method for fish populations difficult to age, such as the Eastern Baltic cod.
Reviews in Fisheries Science & Aquaculture, 2020
Please note that this is an author-produced PDF of an article accepted for publication following ... more Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. studies for either environmental or physiological tracers, presumably attributable to variable relationships between temperature and fish behavior and physiology (e.g., feeding rate, reproduction). Biomineralization thus has a controlling effect on otolith element concentrations for elements that are linked with somatic growth, but not for elements that substitute for Ca in the crystal lattice. Interpretation of the ecological significance of patterns from field samples therefore needs to consider the impact of the underlying biomineralization processes of the element in question as well as physiological processes regulating the availability of ions for inclusion in the growing crystal lattice. Such understanding will enhance the utility of this technique to address fisheries management questions.
Ecology of Freshwater Fish, 2016
To manage anadromous river-spawning whitefish (Coregonus lavaretus L.) populations in the Gulf of... more To manage anadromous river-spawning whitefish (Coregonus lavaretus L.) populations in the Gulf of Bothnia, the Baltic Sea, understanding of their biology including feeding migration distribution is valuable. Tagging studies have shown that river-spawning whitefish originating from the rivers flowing into the northern Gulf of Bothnia can undertake long-distance feeding and spawning migrations between their home rivers and the feeding grounds in the south, the southernmost areas being around Åland Islands (>700 km) (Leh
Metodik 2.1 Effekter av ökat vattenflöde 2.1.1 Fiskrekrytering i Asphällafjärden 2.1.2 Fiskförlus... more Metodik 2.1 Effekter av ökat vattenflöde 2.1.1 Fiskrekrytering i Asphällafjärden 2.1.2 Fiskförluster i silstationer 2.1.3 Rekrytering av abborre i Biotestsjön 2.2 Effekter av ökad temperatur 2.2.1 Ålder och tillväxt hos abborre 2.2.2 Strömming-ekointegrering och artificiella substrat 2.2.3 Rekrytering sik 3 Resultat 3.1 Effekter av ökat vattenflöde 3.1.1 Fiskrekrytering-Asphällafjärden 3.1.2 Fiskförluster i silstationer 3.1.3 Rekrytering abborre 3.2 Effekter av ökad temperatur 3.2.1 Ålder och tillväxt hos abborre 3.2.2 Strömming-ekointegrering och artificiella substrat 3.2.3 Rekrytering sik 4 Diskussion 4.1 Utvecklingen av fisksamhället i Forsmarksområdet 4.2 Effekter av ökat vattenflöde och höjda temperaturer 4.3 Fiskrekrytering-Asphällafjärden 4.4 Fiskförluster i silstationer 4.5 Rekrytering abborre 4.6 Strömming 4.7 Rekrytering sik 5 Referenslista
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015
ABSTRACT In this work we describe an application of particle-induced X-ray emission (PIXE) to the... more ABSTRACT In this work we describe an application of particle-induced X-ray emission (PIXE) to the elemental analysis of polished otoliths of whitefish. Two spots on polished otoliths were irradiated; one spot in the core region of the otolith and another one close to the edge. The irradiations were performed in air with a collimated 0.5 mm proton beam. The ratio of the strontium concentrations in the two spots was used to distinguish between different ecotypes (river, sea, lake) of whitefish. Criteria on the ratios were suggested for identification of the whitefish forms. The results were compared to results of μ-beam PIXE scans as well as multi-point scans with the 0.5 mm proton beam. The measuring setup and the results are discussed.
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Papers by Yvette Heimbrand