Long-term Population Dynamics Research Articles

Longitudinal population dynamics of Mediterranean-Atlantic Arbutus during the last 30 ka

The current distribution of the genus Arbutus in the Old World prompts questions about its long-term population dynamics, location and extent of refuge areas, and modern vulnerability in relation to climate change and human activity. Our work aims to address these questions by combining modern occurrence data with a comprehensive survey of pollen and macrofossil records. Range maps of past distribution have been produced for the last 32 ka to investigate geographical trends in population dynamics and the timing of the appearance of Arbutus across different biogeographical regions. In the Atlantic domain, Arbutus has been consistently present during the last 32 ka, even during the Last Glacial Maximum. In the central and eastern Mediterranean regions, it progressively increased since the beginning of the Holocene, appearing along the coasts of the Black Sea and in the Levant during the Middle Holocene. In addition, the dynamics of Arbutus in a number of peripherals stands (Ireland, Canary Islands, Cyrenaica, Crimea, and Black Sea coasts) is discussed. The palaeobotanical evidence suggests that the delayed emergence of eastern populations and peripheral stands in the fossil record may be ascribed to a very low population density, rather than to a sequential migration process from the western sectors of the range. The comparison of fossil records and modern occurrences highlights an overall temporal continuity between long-term persistence areas and current centers of gravity and calls for density-weighted ecological models that may contribute to an informed assessment of conservation actions and strategies.

An individual-based model for direct and indirect transmission of chronic wasting disease in free-ranging white-tailed deer

Chronic wasting disease (CWD) is an infectious prion disease that infects members of the Cervidae family (i.e., deer) resulting in widespread ecological, economic, and recreational ramifications. We introduce a spatially explicit individual-based model (IBM) that integrates individual deer movement and behavior with population and disease dynamics to forecast CWD in populations of free-ranging white-tailed deer (Odocoileus virginianus). We use a Susceptible-Exposed-Infectious-Dead (S-E-I-D) epidemiological framework to explore spatiotemporal dynamics of CWD within an agriculturally dominated area in Michigan, USA. The IBM results closely mimicked documented short- and long-term dynamics of white-tailed deer populations and CWD in the Midwestern, USA. We applied pattern-oriented modeling using annual apparent CWD prevalence rates reported by Midwestern state wildlife agencies to validate the disease model. The introduction of a single infected deer to the modeled landscape (93 km2) led to an outbreak of CWD in 100 out of 350 model simulations (29 %); prevalence never exceeded 1.47 % for repetitions where the outbreak ended. For the 100 simulations where disease persisted, the deer population declined by 87 % by year 50 following initial introduction of CWD. Mean (±SD) prevalence after 5, 10, 25, and 50 years was 1.1 % (±1.0 %), 3.4 % (±3.3 %), 46.5 % (±18.8 %), and 51.8 % (±18.1 %), respectively, which highly correlated (r = 0.99) with annual CWD prevalence reported in Wisconsin white-tailed deer populations for years 1–21 post initial detection. Combined with a global sensitivity analysis, the IBM indicated that prevalence of CWD at year 20 was most sensitive to harvest rate of yearling and adult female deer and least sensitive to prion shedding rate, prion half-life, and deer group numbers, indicating that deer population parameters were more influential than disease parameters on CWD dynamics. Our IBM serves as a tool to explore and better understand indirect and direct transmission of CWD within free-ranging cervid populations. Users of this model can adjust parameter values to explore how interactions among individual deer and between deer and their environment affect CWD dynamics. This IBM also serves as a framework for applying and assessing spatially and temporally explicit management scenarios.

Proximity to natural forests failed to rescue a declining agroforestry tree species

The conservation of species in human-modified landscapes such as agroforestry systems is central to global conservation and sustainable use of biodiversity. Understanding the dynamics of key species in agroforestry systems is important for predicting the sustainability of these systems. However, the population dynamics of agroforestry tree species are often unknown, and planning for the management of these systems is generally grounded on the untested assumption that the tree component will persist over time. Here, we developed an integral projection model for Vitellaria paradoxa (Sapotaceae), one of the most important tree species in traditional agroforestry systems in West Africa. We collected three years of demographic data from six populations around the Pendjari Biosphere Reserve in Benin to parameterize this model and test the effect of populations’ proximity to natural habitats on the short- and long-term dynamics of V. paradoxa. However, models suggest that V. paradoxa populations are projected to decline at a yearly rate of 10.6% and within the next two decades, this tree will be locally extinct. We found a significant positive effect of proximity to natural forest on the long-term population dynamics, but this failed to save populations from decline. Elasticity analyses show that the best strategy to slow down such a decline includes preserving the largest mature trees. However, traditional management systems that protect shea butter trees in agroforestry systems are now replaced by increasing tree cutting to produce firewood, charcoal and carve out mortars and pestles. The decline of this key agroforestry tree poses a broader threat to long-term sustainability of agroforestry systems.

Alternative vegetation trajectories through passive habitat rewilding: opposite effects for animal conservation

ContextPassive habitat rewilding after rural abandonment can affect wildlife differently depending on the type of habitats that it generates.ObjectiveEvaluate and compare the effects of two alternative vegetation trajectories that occur through passive habitat rewilding in Mediterranean ecotone areas (crop-scrub and crop-pine forest transitions) on the long-term population dynamics of animal species.MethodsWe used the spur-thighed tortoise (Testudo graeca), a characteristic long-lived species of cultural landscapes, as study species. We applied a spatially explicit and individual-based model (STEPLAND) to simulate the movement and demographic processes in a long-term period, by comparing an “impact scenario” (i.e., historical land-use changes) to a “control scenario” (no land-use changes).ResultsThe two landscape scenarios resulted in different population trends. In the crop-scrub scenarios (control and impact), population densities increased similarly over time. However, the crop-pine forest scenario negatively affected population density throughout the simulation period, and showed a time-lag response of three decades. The extinction risk was 55% with a time-lag response of approximately 110 years.ConclusionsOur study highlights the need to analyse the legacy effects on long-lived ectotherms, using them as a proxy to understand the future effects of dynamic landscapes created by “passive habitat rewilding”. Our results showed how traditional agriculture in Mediterranean ecotone areas may generate “ecotone effects” (i.e. increase in demographical parameters), but also population extinction on long-lived ectotherms. Therefore, we consider it relevant to maintain traditional agricultural areas in Mediterranean landscapes, especially in ecotone areas associated with pine forests (generating mosaics with open habitats).

A comparison of two snapshot studies half a century apart suggests stability in a Pacific Northwest winter forest bird community

Populations of many North American bird species have declined throughout the past half century. The majority of studies quantifying these declines have analyzed counts of birds taken during spring and summer, not during the season of scarcity, winter. We re-surveyed seven large study plots in Douglas fir (Pseudotsuga menziesii) forests initially surveyed in winter during the late 1960s in the Oregon Coast Range, USA. We compared density estimates, observed species richness and vegetation structure within plots, and inspected aerial photography to describe changes in landscape-level landcover. To assess potential drivers of change, we reviewed historical climate data and explored patterns of abundance associated with forest age. Observed species richness was greater in the modern surveys. Abundances of four of the six most common bird species appeared to be similar to or slightly lower than 50 years ago as the historical point estimates usually fell within or above 95% confidence intervals generated from our analyses. We found no clear associations with changes in bird communities and forest structure, climate, or forest age. The historical data are unique in providing point estimates of abundance for the entire bird community on each study plot. Yet, some uncertainties in accuracy of the historic counting methods could still influence interpretation of multi-decadal changes in apparent abundance. We conclude that this Pacific Northwest bird community was relatively stable in its abundances of the most common forest-dwelling species and that largely the communities are still intact. Additional production of precisely repeatable surveys of winter bird communities are needed in all habitats to adequately characterize long-term population dynamics during the season of scarcity.

Long-Term Population Dynamics of Seabirds Breeding in the Western Part of the White Sea

Long-Term Population Dynamics of Seabirds Breeding in the Western Part of the White Sea

Unraveling population trends in Italy (1921–2021) with spatial econometrics

Testing density-dependence and path-dependence in long-term population dynamics under differentiated local contexts contributes to delineate the changing role of socioeconomic forces at the base of regional disparities. Despite a millenary settlement history, such issue has been rarely investigated in Europe, and especially in highly divided countries such as those in the Mediterranean region. Using econometric modeling to manage spatial heterogeneity, our study verifies the role of selected drivers of population growth at ten times between 1921 and 2021 in more than 8000 Italian municipalities verifying density-dependent and path-dependent dynamics. Results of global and quantile (spatial) regressions highlight a differential impact of density and (lagged) population growth on demographic dynamics along the urban cycle in Italy. Being weakly significant in the inter-war period (1921–1951), econometric models totalized a high goodness-of-fit in correspondence with compact urbanization (1951–1981). Model’s fit declined in the following decades (1981–2021) reflecting suburbanization and counter-urbanization. Density-dependence and path-dependence were found significant and, respectively, positive or negative, with compact urbanization, and much less intense with suburbanization and counter-urbanization. A spatial econometric investigation of density-dependent and path-dependent mechanisms of population dynamics provided an original explanation of metropolitan cycles, delineating the evolution of socioeconomic (local) systems along the urban-rural gradient.

Features of development and harmfulness of the berry bug in grain crops in the north-west of Russia

In 2022, a mass propagation of the berry bug occurred in the North-West of Russia, which had no analogues over the past decade. This made it possible to study in detail some issues of its biology and harmfulness on grain crops. The purpose of the current study was to determine food specialization, long-term population dynamics, seasonal development, and harmfulness of the berry bug in grain crops in the North-West of the Russian Federation. For this purpose, there was carried out regular mowing with an entomological net, timed to coincide with the phonological development of cultivated plants, the total number of which was 2544, of which 1380 were on grain crops. The estimation of the harmfulness of the berry bug was carried out on winter triticale by simply comparing the mass of damaged and undamaged caryopses. According to the study results, there has been revealed that grain crops were populated to a greater extent than agrocenoses of other crops. Among grain crops, winter triticale turned out to be the most populated crop, and winter rye was the least populated. The maximum number of berry bug occurred during the period of maturation of grain crops, when larvae of different ages feeding on caryopses were predominantly found in the crops. The study of topical confinement showed that the largest number of bugs’ pricks were located in the middle part of the caryopsis and mainly on the sides (75.0 %). Analysis of the harvested crop of winter triticale revealed that damage to the grain caused by berry bug was 6.4 %, 5.0 % of which 1–2 points, 1.4 % of which 3 points. Depending on the damage scale, the decrease in 1 caryopses weight was from 6.6 to 18.2 mg (13.2–36.5 %), the yield was 0.061 ton/ha (1.2 %). Thus, despite the high density of winter triticale crops with berry bug in the conditions of 2022, the proportion of damaged caryopses and their damage degree, as well as the total yield loss, turned out to be low, which means that the use of insecticides was inappropriate.

Social housing and the spread of population: Evidence from twentieth century Ireland

How does housing policy influence the long-run distribution of population? We examine the impact on long-term population dynamics of the world’s first large-scale rural public housing scheme, specifically the case of Ireland’s Labourers Acts. We link detailed data on the location of over 45,000 heavily subsidized cottages for agricultural laborers built 1883–1915 in over 200 districts to decennial Censuses between 1841 and 2002. We examine how the density of this social housing affected subsequent population change and find significant persistence in the effect of this treatment on the population. These findings are from specifications that include other factors plausibly related to future population growth, including initial housing stock, land values and population density, as well as distance to urban centres. A causal interpretation is supported by an assessment of pre-trends, by no effect of cottages authorized but not built and by an IV approach that exploits a 1906 limit on legal costs. We also highlight the role of agglomeration in amplifying the impact of the initial investment. Mediation analysis suggests that schooling was a key factor, with districts receiving more cottages less likely to lose primary schools, thus further influencing population growth.

Long-term responses of Icelandic Arctic foxes to changes in marine and terrestrial ecosystems.

The long-term dynamics of predator populations may be driven by fluctuations in resource availability and reflect ecosystem changes such as those induced by climate change. The Icelandic Arctic fox (Vulpes lagopus) population has known major fluctuations in size since the 1950s. Using stable isotopes analysis of bone collagen over a long-time series (1979-2018), we aimed at identifying the main resources used by Icelandic Arctic foxes during periods of growth and decline to assess if the variations in their population size are linked to fluctuations in the availability of resources. We hypothesized that (1) the decline in Seabird abundance was responsible for the decrease in the fox population; and (2) that the growth in the fox population combined to fluctuations in main resources would lead to an increase in intra-specific competition, ultimately leading to variations in their isotopic niches at the population scale. The isotopic composition of Arctic fox bones differed clearly between inland and coast. Stable isotopes mixing models suggested that marine resources and rock ptarmigans were the most important food source and highlighted a rather stable diet in coastal habitats compared to inland habitats where more fluctuations in dietary composition were observed. Coastal foxes had a broader niche than inland foxes, and there was more variation in niche size in the inland habitat. Our results tend to confirm that a general decline in seabird populations drove the decline in Arctic foxes, especially in coastal habitats. For the inland foxes, our results suggest that the lack of marine resources might have led to an increased use of ptarmigans especially during the most recent period.

Periodic temporal environmental variations induce coexistence in resource competition models.

Natural ecosystems, in particular on the microbial scale, are inhabited by a large number of species. The population size of each species is affected by interactions of individuals with each other and by spatial and temporal changes in environmental conditions, such as resource abundance. Here, we use a generic population dynamics model to study how, and under what conditions, a periodic temporal environmental variation can alter an ecosystem's composition and biodiversity. We demonstrate that using timescale separation allows one to qualitatively predict the long-term population dynamics of interacting species in varying environments. We show that the notion of Tilman's R* rule, a well-known principle that applies for constant environments, can be extended to periodically varying environments if the timescale of environmental changes (e.g., seasonal variations) is much faster than the timescale of population growth (doubling time in bacteria). When these timescales are similar, our analysis shows that a varying environment deters the system from reaching a steady state, and stable coexistence between multiple species becomes possible. Our results posit that biodiversity can in part be attributed to natural environmental variations.

Enhancing population persistence by a protection zone in a reaction–diffusion model with strong Allee effect

Protecting native species or endangered species has been an important issue in ecology. We derive a reaction–diffusion model for a population in a one-dimensional bounded habitat, where the population is subjected to a strong Allee effect in its natural domain but obeys a logistic growth in a protection zone. We establish threshold conditions for population persistence and extinction via the principal eigenvalue of an associated eigenvalue problem. We then obtain the influences of the protection zone on the long-term population dynamics under different boundary conditions and propose strategies for designing the optimal location of the protection zone (i.e., the starting point and the length) in order for the population to persist in the long run.

МОДЕЛЮВАННЯ ЧИСЕЛЬНОСТІ ГРИЗУНІВ У ЛІСОВИХ БІОТОПАХ ЗАХІДНОГО ПОДІЛЛЯ (НА ПРИКЛАДІ MYODES GLAREOLUS)

Monitoring and predicting the dynamics of abundance of species living in natural habitats is an important component stability analysis of ecosystem as well as dynamics and direction of change of biotic communities under global climate change and pressure of the alien species. The aim of the work was to build a matrix model and study the state of stabilisation of the dynamics of the bank vole population within the Leslie model. The object of the study was the population dynamics of Myodes glareolus Schreber, 1780 = Clethrionomys glareolus auct. The study is based on materials obtained during 2017–2019. This period covered one phase of the long-term population dynamics of the bank vole, named “population growth”. The research was carried out according to generally accepted methods. A total of 6400 trap-days were processed, and 358 forest fistulas were collected and studied. The intensity of harmful activity of rodents is due to the variability of the number of animals in the population. The quantitative population changes are the result of three factors: births, deaths, and migrations. The main condition for the existence of the species is the stability of the population, which is determined by the action of thecompensatory mechanisms. The growth phase of the bank vole lasted all three years of the research, the quantitative indicators were respectively: 2017 – 1.8 individuals per 100 trap-days; 2018 – 2.0 individuals per 100 trap-days; 2019 – 2.7 individuals per 100 trap-days. Low levels of the abundance in the spring of each year of the study, namely at the beginning of the breeding season (3.7 – 2.6 – 8.9 individuals per 100 trap-days). Favourable for the abundance growth was the sex ratio of the population (approximately 1:1), with some rise in the share of females, which decreases on the period of spring 2018 to autumn 2019). Some decrease in the share of immature individuals (4.5 – 3.9 – 3.1 %) is an indirect confirmation of the stability of puberty of animals with subsequent replenishment of the "stock", which led to accelerated reproduction and, consequently, provided prerequisites for further population growth. The causal mechanisms of population control established by us, without a doubt, can serve as a basis for further prognosis, of the number of pests in natural habitats. To predict population changes, the Leslie model, which is widely used in mathematical analyses of the abundance of both plant and animal groups, was chosen. The algorithm for building a matrix model, detailed in the article, has five following steps. The exponential nature of the actual and projected growth of the bank vole population during the five-year cycle (2017–2019 with a prognosis until 2023) revealed in the analysis can be explained not so much by the power of the species' reproductive potential as by the lack of the significant changes in habitat, caused by constant weather conditions, low individual mortality from predators and non-communicable diseases or other accidents. The application of the matrix model allowed to confirm the key role of the main compensatory mechanisms of population dynamics, as they contribute to the stabilisation of the population and, as a consequence, are an important condition for the existence of the species.

Veliger density and environmental conditions control quagga mussel colonization rates in two perialpine lakes

Quagga and zebra mussels (Dreissena bugensis and D. polymorpha) are spreading across lakes in Europe and North America. In particular, quagga mussels colonize lakes to great depths (>200 m). To better understand the colonization pattern of quagga mussels in deep lakes, we studied the settlement of quagga mussels along a depth gradient on colonization plates at multiple depths (1–140 m) in the pelagic zone of two recently invaded perialpine lakes, Lake Constance and Lake Geneva. We measured colonization rates every three months over one year on colonization plates deployed in both lakes at defined depths. We also assessed long-term population dynamics from abundance and size distribution using repeated photogrammetry of colonization plates. Highest colonization rates and largest mussel sizes occurred above 8 m depth, and almost no zebra mussels were found. Colonization rates decreased to almost zero below 30 m. Colonization rates on plates were associated with variation in environmental conditions as well as veliger densities in the plankton across season and depth. Temperature was the most important environmental parameter that influenced colonization. Our results will help to better understand the seasonal colonization patterns of invasive quagga mussels in deep lakes.

Status of Swamp Deer Rucervus duvaucelii duvaucelii (G. Cuvier, 1823) in grassland-wetland habitats in Dudhwa Tiger Reserve, India

Swamp Deer is an endemic species of the Indian subcontinent, mainly inhabiting tall grasslands in river floodplains. Populations of the northern subspecies (Rucervus duvaucelii duvaucelii), restricted to the Terai regions of northern India and western Nepal, have undergone dramatic declines over the past two─three decades. In this communication, we present results from systematic population counts conducted in Dudhwa Tiger Reserve between 2021─2022. These counts were conducted at 11 sites, each with two─three independent observers. The exercises covered summer, monsoon, post-monsoon, and winter seasons. We found the largest congregations of Swamp Deer in June during the summer and February in winter. In the monsoon months of July─September the Swamp Deer tend to use Sal woodlands along with farmlands adjoining the reserve edge. This is part of an ongoing research project on long-term monitoring and conservation of the threatened alluvial grasslands of the central Terai in Uttar Pradesh, India. Institutionalizing these monitoring practices for frontline forest staff is essential for understanding long-term population dynamics of the threatened Swamp Deer to develop conservation protocols for grasslands and their fauna.

Trait variation and long-term population dynamics of the invasive Alliaria petiolata (garlic mustard) across three microhabitats

Trait variation and long-term population dynamics of the invasive Alliaria petiolata (garlic mustard) across three microhabitats

Recruitment and mortality of Rhizophora mangle L. seedlings in the Tropical Southwestern Atlantic mangrove.

Studies in the long-term recruitment and mortality of mangrove seedlings can help to understand mangrove demography and its relationship with climatic variables, environmental restoration and advances in the ecology of this ecosystem. A seven-year population dynamics study of seedling recruitment and mortality in cohorts of Rhizophora mangle L. was carried out to identify expansion processes and patterns of survival in the understory of mangrove forests on the Atlantic coast of Brazil. The present study aimed to evaluate the relationship between recruitment and mortality R. mangle seedlings at the population level, salinity, and climatic variables (precipitation, temperature and humidity). On an annual scale, seedling recruitment was positively correlated with mean temperature. Seedling density was negatively correlated with the number of recruits and positively with the number of deaths. The number of recruits was associated with dead seedlings, temperature and precipitation considering a population scale, without grouping the data. The seedling density in the stands increased with the number of dead seedlings. Our findings described the relationship between climate variability (durability and magnitude of the dry/rainy season) and the long-term population dynamics of R. mangle seedlings in a poorly studied region and from what moment, on a monthly and annual time scale, did this relationship become significant and changes occur. The findings of this study provide information on the population dynamics of the species that will help in understanding mangrove demography. These results have important implications for projections about the recruitment and survival of the species thinking about to long-term climate change that will modify current weather patterns and mangrove conservation efforts.

Host tree species effects on long-term persistence of epiphytic orchid populations

The destinies of epiphytic orchids (about 70% of all orchids) are linked to their host trees. However, there is little information on if differences in host trees characteristics can affect the long-term persistence of orchid populations, and how this might vary under different climatic conditions. We compared the population dynamics of two epiphytic orchid species, Alamania punicea and Oncidium brachyandrum growing on two host trees with contrasting leaf phenologies: the deciduous Quercus martinezii and the semideciduous Q. rugosa, over 3 years with varying levels of rainfall, in a montane tropical oak forest in Oaxaca, Mexico. Using data from > 500 individuals growing on 63 host trees, we applied linear mixed effects models, Integral Projection Models, and Life Table Response Experiments to identify the effects of host tree on orchid vital rates and population growth rates. For both orchid species, survival and growth did not differ between host species during wettest year. However, during the driest year both vital rates were higher on the semi-deciduous host Q. rugosa than on the deciduous Q. martinezii. Host species did not affect fecundity for A. punicea, but for O. brachyandrum fecundity was higher on the deciduous host. For A. punicea, λ values were similar between hosts during the wettest and intermediate years, but significantly lower (Δ λ = 0.28) on the deciduous than on the semi-deciduous host during the driest year. This was due primarily to lower survival on the deciduous host. For O. brachyandrum, λ was slightly higher (Δ λ = 0.03) on the deciduous than the semideciduous host during the wettest year, due to higher growth and reproduction. However, during the intermediate and driest years, λ values were significantly higher on the semi-deciduous than on the deciduous host (Δ λ = 0.13 and 0.15, respectively). This was due to higher survival and growth. A. punicea populations appear more vulnerable to dry conditions than O. brachyandrum, likely due to its smaller pseudobulbs, and hence lower water-storing capacity. Our results show that host tree species can both influence the vital rates and the long-term dynamics of orchid populations, and these effects vary across orchids species and over time. Our results highlight the importance of maintaining a diversity of host trees to ensure long-term population persistence.

Opposing effects of spatiotemporal variation in resources and temporal variation in climate on density dependent population growth in seabirds.

Understanding how ecological processes combine to shape population dynamics is crucial in a rapidly changing world. Evidence has been emerging for how fundamental drivers of density dependence in mobile species are related to two differing types of environmental variation-temporal variation in climate, and spatiotemporal variation in food resources. However, to date, tests of these hypotheses have been largely restricted to mid-trophic species in terrestrial environments and thus their general applicability remains unknown. We tested if these same processes can be identified in marine upper trophic level species. We assembled a multi-decadal data set on population abundance of 10 species of colonial seabirds comprising a large component of the UK breeding seabird biomass, and covering diverse phylogenies, life histories and foraging behaviours. We tested for evidence of density dependence in population growth rates using discrete time state-space population models fit to long time-series of observations of abundance at seabird breeding colonies. We then assessed if the strength of density dependence in population growth rates was exacerbated by temporal variation in climate (sea temperature and swell height), and attenuated by spatiotemporal variation in prey resources (productivity and tidal fronts). The majority of species showed patterns consistent with temporal variation in climate acting to strengthen density dependent feedbacks to population growth. However, fewer species showed evidence for a weakening of density dependence with increasing spatiotemporal variation in prey resources. Our findings extend this emerging theory for how different sources of environmental variation may shape the dynamics and regulation of animal populations, demonstrating its role in upper trophic marine species. We show that environmental variation leaves a signal in long-term population dynamics of seabirds with potentially important consequences for their demography and trophic interactions.

Population dynamics of Baltic herring since the Viking Age revealed by ancient DNA and genomics

The world's oceans are currently facing major stressors in the form of overexploitation and anthropogenic climate change. The Baltic Sea was home to the first "industrial" fishery ∼800 y ago targeting the Baltic herring, a species that is still economically and culturally important today. Yet, the early origins of marine industries and the long-term ecological consequences of historical and contemporary fisheries remain debated. Here, we study long-term population dynamics of Baltic herring to evaluate the past impacts of humans on the marine environment. We combine modern whole-genome data with ancient DNA (aDNA) to identify the earliest-known long-distance herring trade in the region, illustrating that extensive fish trade began during the Viking Age. We further resolve population structure within the Baltic and observe demographic independence for four local herring stocks over at least 200 generations. It has been suggested that overfishing at Øresund in the 16th century resulted in a demographic shift from autumn-spawning to spring-spawning herring dominance in the Baltic. We show that while the Øresund fishery had a negative impact on the western Baltic herring stock, the demographic shift to spring-spawning dominance did not occur until the 20th century. Instead, demographic reconstructions reveal population trajectories consistent with expected impacts of environmental change and historical reports on shifting fishing targets over time. This study illustrates the joint impact of climate change and human exploitation on marine species as well as the role historical ecology can play in conservation and management policies.