Archaeological Fish Research Articles

Caviar, soup and other dishes made of Eurasian ruffe, Gymnocephalus cernua (Linnaeus, 1758): forgotten foodstuff in central, north and west Europe and its possible revival

BackgroundMany freshwater fish species that were earlier appreciated by consumers have disappeared in the central, north and west European foodways. Although they were regarded as healthy and tasty, commercially captured marine species and highly processed products have nowadays replaced these fishes. The global transformations of the food system contribute to the erosion of many local foodstuffs. Habitual tastes disappear.MethodsThe article is based on a vast amount of scattered original data found in sources such as in local ethnographical studies, fishing reports, topographic literature, zoological literature, archaeological fish reports, and cookery booksResults and discussionThis article discusses how Eurasian ruffe, Gymnocephalus cernua (L., 1758), once was used, and the reason for its disappearance, as foodstuff in some parts of Europe. Actually, it is a fish with potential for a revival as fine food. The authors discuss the chances of its rediscovery as a foodstuff, which could be used for instance within the concept of the New Nordic Cuisine and beyond. There are also environmental reasons to increase the use of local biodiversity not to mention making tastier food.ConclusionRuffe is a common species in many waters and nowadays a non-used potential food resource.

Indigenous stewardship of marine and estuarine fisheries?: Reconstructing the ancient size of Pacific herring through linear regression models

Linear regression models constructed from modern fish skeletal collections and applied to archaeological fish remains have a long history in archaeological practice. These data are often employed by researchers to understand ancient human impacts on ichthyofaunas, to consider changes in fishing technologies and techniques, and the effects of environmental change. In this study, I build and apply linear regression formulae of Pacific herring (Clupea pallasii), a keystone and umbrella forage fish to faunal materials from Point Reyes National Seashore on the central California coast, which date to the Late Holocene. Through the application of these formulae to archaeological Pacific herring skeletal elements, I reconstruct the standard length of ancient Pacific herring. The findings are compared to Pacific herring standard length data gathered by the California Department of Fish and Wildlife within Point Reyes and Bodega Bay. These data suggest that Coast Miwok fishers may have used standardized net mesh size to capture Pacific herring selectively. These findings are consistent with expectations from the indigenous coastal management and ecological literature.

A millennium of Icelandic archaeological fish data examined against marine climate records

AbstractThis article combines new marine fish faunal data from medieval and early modern Icelandic archaeological sites with previously published data that focused primarily on the Settlement and Commonwealth periods. This synthesis places these new data into the larger scale of Icelandic history and marine conditions (sea-surface temperature and sea ice) to identify patterns and trends across the last 1000 years of the relationship between humans and Icelandic cod populations. We find no direct correlation between zooarchaeological patterns and sea ice or storminess in the medieval period and a possible correlation in the early modern period. We argue that this suggests a nuanced relationship between changing climates and fishing patterns in Icelandic history. While changes in sea temperature and periods of increased storminess might have made fishing productivity more variable and at times more dangerous, it is only in the early modern period that we see change in the marine zooarchaeological record that might indicate a correlation. Instead, we contend that the impacts of the changing climate relative to marine resources were mediated by social, political, economic, and even technological variables.

Fish and fishing communities: Understanding ancient and modern fisheries through archaeological fish remains

Fish and fishing communities: Understanding ancient and modern fisheries through archaeological fish remains

Abrasion in archaeological fish bones from sand dunes. An experimental approach

Fish bones are still an unknown tool in taphonomic studies. We have carried out several experiments which have shown that fish bones may provide key taphonomic traits. Fossil fish bones in archaeological sites (from caves to riverbanks or seashores) are frequently result of predation by humans or any other predator, as well as abiotic agents. The original environment of fish is aquatic restricted to specific water contexts and the presence of fish in fossil sites provides relevant information regarding paleoenvironments, human/animal predatory behaviors, and site formation. In spite of the interest of fossil fish remains, most taphonomic experiments have been focused on mammalian fossil bones. This paper shows results obtained from experiments that help interpreting palaeoenvironmental changes, potential space-time mixtures, and site formation. Our experiments have provided distinct criteria to distinguish the action of sand projected by wind, friction of bones against sand substrates, or sand with or without water abrading the bone surface. Experimental results have been compared to an archaeological case: El Americano II site (middle Holocene, Argentina) to elucidate how the site was formed. Criteria obtained so far from each type of experiment described here greatly increase knowledge for interpreting other sites that yield fossil fish bones.

Taphonomy of Yellow-legged Gull (Larus michahellis) pellets from the Chafarinas islands (Spain)

Fish are consumed by many predators in addition to humans. Identifying the agent responsible for an archaeological fish bone accumulation is a crucial yet far from straightforward task in the absence of diagnostic criteria. It is for this reason that exploring the features of fish bone collections produced by animals constitutes a key issue of archaeozoological research. In this paper, one such study is presented for the Yellow-legged Gull (Larus michahellis J.F. Naumann, 1840). A total of 48 pellets were collected in a colony of the species on two islands of the Chafarinas archipelago (Mediterranean Sea). The analyses demonstrate that fish remains, represented by 13 species and 1 genus, made up 93% of the 2789 identified remains. Most assemblages were dominated by the European pilchard (Sardina pilchardus (Walbaum, 1792)). Our study indicates that digestive processes modify skeletal elements through abrasion and fragmentation. Based on the modifications that were recorded, a set of diagnostic criteria is proposed to serve as proxies for spotting fish bone deposits produced by Yellow-legged Gulls on archaeological assemblages.

Nuevas contribuciones tecnológicas al estudio de la salsa garum a partir del análisis químico de restos ictiológicos de la ‘Tienda del Garum’ de Pompeya (I.12.8)

The garum fish sauce was a popular ingredient in Roman gastronomy; however, its production process is still unknown, and few remains have been found in the whole ancient world. The aim of this study was to implement a technical approach to determine the ancient garum preparation methods, ingredients and additives by comparing the chemical compositions of archaeological fish remains found in six vessels –dolia– at the ‘Garum Shop’ of Pompeii (Italy) and garum obtained from the Gargilio Martial’s classical recipe. Some organic and inorganic parameters and compounds specific for fish sauces with great physicochemical stability were determined either in the dolia but also in the experimental reconstruction. The total n, fat, ash content, fatty acid, and mineral composition were determined. Differences found in the n and fat contents of dolia could indicate that different garum batches were being manufactured at the moment of the Vesuvian eruption in the ‘Garum Shop’. Fatty acid results showed a similar profile for the remnants and reference garum. The mineral profile, Ca/P ratio and Fe contents reported could be explained by the use of lime in the garum preparation or sanitizing stage, and food coloring respectively.

Shape does matter: A geometric morphometric approach to shape variation in Indo-Pacific fish vertebrae for habitat identification

Traditional fish vertebrae identification relies on the availability of comprehensive reference collections that include every element from the neural spine for each taxon. In regions with great taxonomic diversity, such as the Indo-Pacific, the identification of fish vertebrae to species is difficult. This results in taxonomic lists with many skeletal elements identified only to family. However family level identifications often tell us little about the environmental preferences of the fish and thus, by inference, human fishing practices. Here we apply geometric morphometrics (GM) to examine shape variations within vertebrae in modern specimens of a variety of pelagic and reef species to determine if this method can be used to reliably inform on habitat preferences. Digitized vertebral elements of reef (Acanthuridae, Balistidae, Labridae, Lethrinidae, Lutjanidae and Serranidae) and pelagic/open water (Scombridae and Carangidae) families were scored using 2D landmarks. These were subjected to Generalized Procrustes Analysis and discriminatory multivariate analyses (Linear Discriminant Analysis and Discriminant Function Analysis) in order to assess whether shape can be used to differentiate habitats. Our results suggest that geometric morphometrics do allow the differentiation of habitat in vertebrae and provide an alternative method for the classification of archaeological fish assemblages. These analyses were applied to a sample of archaeological fish remains from a site in Alor Island (Nusa Tenggara Timur, Indonesia) and compared with the results of an earlier traditional comparative icthyoarchaeological analysis. We found that the main component of the Pleistocene marine human diet comprised reef species, with the sporadic addition of open water species, supporting the pattern recorded with traditional analyses. This methodology could be widely applied to archaeological fish material from across the Indo-Pacific allowing a greater number of bones in assemblages to contribute to insights into human exploitation of coastal habitats and fishing techniques over time.

Effects of lipid extraction and different collagen extraction methods on archaeological fish bones and its implications for fish bone diagenesis

Gelatin extracted from archaeological fish bones typically exhibits relatively high C/N ratios, presumed to be caused by contamination with lipids or humic substances. The effects of lipid extraction and different collagen extraction methods applied has been studied on modern fish bones but has never been studied systematically on archaeological specimens because of taphonomic and experimental reasons. In this study, the effects of lipid extraction and order of NaOH treatment in collagen extraction method on carbon and nitrogen stable isotope analysis of archaeological fish bone (n = 30) excavated from the Hamanaka 2 site, Hokkaido, Japan (approximately 8th BC–10th AD) is investigated. Gelatin extracted from the same fish bone subsamples with or without lipid extraction procedure indicates neither significant nor systematic differences in carbon and nitrogen stable isotope ratios, elemental concentrations, C/N ratios, and yield. However, reproducibility of stable isotope ratios and elemental concentrations decrease in gelatin extracted from poorly-preserved cod bones (<3.5% yield). Gelatin extracted from archaeological fish bones may contain humic contaminants, and its effect becomes greater in gelatin with lower extraction yield. Although there is no significant change in the stable isotope and C/N ratios, change in atomic concentration of carbon and nitrogen suggests that the purity of extracted gelatin increases when NaOH treatment is applied after decalcification. Because this is only a study from one archaeological site, further case studies that evaluate lipids and diagenesis in fish bones are required.

Long-term archaeological and historical archives for mulloway, Argyrosomus japonicus, populations in eastern South Australia

Native fish populations have been strongly impacted by fishing, habitat alteration and the introduction of invasive species. Understanding the dynamics of native fish populations prior to commercial fishing can be problematic, but provides critical baseline data for fish conservation, rehabilitation and management. We combined fish size, age and growth data, as well as month of catch data, from archaeological fish otoliths (1670–1308 cal BP to 409–1 cal BP), historical anecdotes (CE 1871–1999), and contemporary data sources (CE 1984–2014) to examine changes to mulloway, Argyrosomus japonicus, populations in the waters of eastern South Australia. We found that the data from the three different sources – archaeological, historical and contemporary – corroborate each other in many aspects. The time of catch for all three datasets was seasonal, with increases evident during the summer months. No significant changes in fish length over time were evident over the time span of the three data sources. Given the impact that fishing in the region is regarded to have had, this may imply that while the maximum recorded sizes of the species have remained stable, the abundance of these large specimens may have declined.

Hydroclimatic conditions and fishing practices at Late Paleolithic Makhadma 4 (Egypt) inferred from stable isotope analysis of otoliths

The late Paleolithic site of Makhadma 4, located along the Nile River in Upper Egypt, yielded an important ichthyofauna characterized by a very high proportion of tilapia (Oreochromis niloticus). We used isotopic analysis (δ18O) of well-preserved otoliths (“ear stones”) of tilapia to reconstruct the former hydrological conditions, as well as the fishing strategies of the site's inhabitants. Otoliths from two modern fish captured in the Nile River near Esna were also examined to test how accurately tilapia otoliths reflect their ambient environment. All otoliths were sequentially micromilled to recover high resolution isotopic profiles along the main growth axis. Comparison of the modern otolith profiles with environmental data shows that tilapia δ18O values record seasonal variations of the modern Nile hydroclimate but that their values are offset. The archaeological otoliths record very large intra-individual cyclical variations in δ18O values, with relatively consistent amplitude, as well as very high seasonal maximum values (up to +8.3‰), compared with the modern otoliths. The hydrological regime of the water body in which the archaeological fish lived was characterized by a reduced Nile water inflow that could not negate the effect of local evaporation during spring. The reconstructed hydrological conditions are in accordance with a new model of Nilotic behavior that assumes the creation of lakes by damming of the Nile as a result of a high eolian activity during hyper-arid periods of the Late Pleistocene. Although large seasonal evaporation may have resulted in a severe seasonal reduction in the lake's volume and extent, the lake was, nevertheless, maintained for several years. Cyclic variations in otolith δ18O values permit reconstruction of the period of the hydrological cycle during which the fish were captured. Fishing of young individuals occurred mostly after the maximum input of inflow water from the Nile, when evaporitic conditions were at their lowest, i.e. during fall.

Millennia-Long Co-Existence of Two Major European Whitefish (Coregonus spp.) Lineages in Switzerland Inferred from Ancient Mitochondrial DNA

Archaeological fish remains are an important source for reconstructing past aquatic ecosystems and ancient fishing strategies using aDNA techniques. Here, we focus on archaeological samples of European whitefish (Coregonus spp.) from Switzerland covering different time periods. Coregonus bones and scales are commonly found in archaeological assemblages, but these elements lack species specific features and thus inhibit morphological species identification. Even today, fish taxonomy is confusing and numerous species and ecotypes are recognized, and even more probably existed in the past. By targeting short fragments of the mitochondrial d-loop in 48 morphologically identified Coregonus scales and vertebrae from 10 archaeological sites in Switzerland, endogenous d-loop sequences were found in 24 samples from one Neolithic, two Roman, and four Medieval sites. Two major mtDNA clades, C and N, known from contemporary European whitefish populations were detected, suggesting co-occurrence for at least 5000 years. In the future, NGS technologies may be used to explore Coregonus or other fish species and ecotype diversity in the past to elucidate the human impact on lacustrine/limnic environments.

Carbon and nitrogen isotopic ratios in archaeological and modern Swiss fish as possible markers for diachronic anthropogenic activity in freshwater ecosystems

The aim of this study is to investigate isotopic variability in archaeological (n=85) and modern (n=29) freshwater fish specimens from Switzerland. Here, carbon (δ13C) and nitrogen (δ15N) stable isotope ratio analysis was performed on bone collagen samples of pike (Esox lucius), perch (Perca fluviatilis), barbel (Barbus barbus), roach (Rutilus rutilus) and carp (Cyprinus carpio) from eleven archaeological (11th to 18/19th centuries CE) and modern sites. The archaeological vs. modern fish data revealed significant isotopic differences for pike, perch and barbel (δ13C p≤0.03; δ15N p≤0.008), and provides possible evidence for a temporal change in Swiss aquatic ecosystems from Medieval to modern times. In comparison to archaeological fish (δ13C mean±SD; −23.3±1.6‰; δ15N mean±SD; 8.3±1.8‰), the modern fish samples show decreased δ13C and increased δ15N values (δ13C mean±SD; −27.4±2.3‰; δ15N mean±SD; 12.5±4.1‰) that can be associated with anthropogenic effects: fossil fuel combustion, deforestation and organic waste in the form of sewage and fertilizers. The isotopic signatures of archaeological fish remains indicate a local fishery practice, but also the exploitation of distant fishing grounds and freshwater fish transportation. Furthermore, a diachronic isotopic trend is observed in young perch from sites in Basel, dating between the 12th and 15/16th centuries CE, and the isotopic data from the Rhine freshwater fish (18/19th century CE) suggests that a significant shift in the river's trophic state was possibly caused by organic pollution from urban and industrial wastewater. This retrospective research illustrates possible natural processes and human activities which can cause differences in fish stable isotope data and highlights the ability to elucidate changes in past bodies of water. Furthermore, this study provides an interpretative framework for additional palaeoenvironmental studies and modern restoration projects focused on freshwater ecosystems.

Tropical ancient DNA from bulk archaeological fish bone reveals the subsistence practices of a historic coastal community in southwest Madagascar

Taxonomic identification of archaeological fish bones provides important insights into the subsistence practices of ancient coastal peoples. However, it can be difficult to execute robust morphological identification of fish bones from species-rich fossil assemblages, especially from post-cranial material with few distinguishing features. Fragmentation, weathering and burning further impede taxonomic identification, resulting in large numbers of unidentifiable bones from archaeological sites. This limitation can be somewhat mitigated by taking an ancient DNA (aDNA) bulk-bone metabarcoding (BBM) approach to faunal identification, where DNA from non-diagnostic bone fragments is extracted and sequenced in parallel. However, a large proportion of fishing communities (both past and present) live in tropical regions that have sub-optimal conditions for long-term aDNA preservation. To date, the BBM method has never been applied to fish bones before, or to fossils excavated from an exposed context within a tropical climate. Here, we demonstrate that morphologically indistinct bulk fish bone from the tropics can be identified by sequencing aDNA extracted from 100 to 300 ya archaeological midden material in southwest Madagascar. Despite the biases of the approach, we rapidly obtained family, genus, and species-level assemblage information, and used this to describe a subset of the ichthyofauna exploited by an 18th century fishing community. We identified 23 families of fish, including benthic, pelagic, and coral-dwelling fishes, suggesting a reliance on a variety of marine and brackish habitats. When possible, BBM should be used alongside osteological approaches to address the limitations of both; however, this study highlights how genetic methods can nevertheless be a valuable tool for helping resolve faunal assemblages when morphological identification is hindered by taphonomic processes, lack of adequate comparative collections, and time constraints, and can provide a temporal perspective on fish biodiversity in the context of accelerated exploitation of the marine environment.

Fishing gear from the Roman period in the Netherlands: An overview

This paper presents an overview of fishing gear recovered from Roman period sites in the Netherlands. Fish hooks, line sinkers, net sinkers, floaters, wickerwork fish traps, canoes with live wells and fish tanks have been identified. These artefacts provide additional insight into the widespread practice of fishing and thus of fish consumption during this time period and is a valuable addition to research on archaeological fish bone remains.

Effects of lipid extraction and ultrafiltration on stable carbon and nitrogen isotopic compositions of fish bone collagen.

Fish bone collagen isotopic measurements are increasingly important in palaeodietary and paleoenvironmental studies yet differences in the chemical and physical properties of fish relative to other vertebrate bones are rarely considered. Lipid content in fish bone, which can exceed 50%, may underlie the poor collagen integrity criteria typically observed in archaeological studies. We compare stable carbon and nitrogen isotopic and elemental compositions of bone collagen prepared using four different methods from a wide range of modern fish species to: (1) assess the extent to which lipid content influences bone collagen δ(13) C and δ(15) N values, and (2) evaluate the relative efficacy of chemical (2:1 chloroform/methanol) and physical (30 kDa ultrafilters) methods for removing lipids from bones. Lower δ(13) C values were observed when the lipid content exceeded 5% of the initial bone mass. The lipid content did not influence the δ(15) N values. 30 kDa ultrafiltration, a common pretreatment for purifying archaeological collagen, removed fewer lipids and was associated with reduced collagen yields (37% loss) as well as altered amino acid compositions. In contrast, collagen prepared using a 2:1 chloroform/methanol lipid extraction step resulted in significantly improved collagen yields, elemental compositions, and isotopic measurements relative to a control treatment. The chemical lipid extraction method (2:1 chloroform/methanol) performed significantly better than the physical lipid extraction method (30 kDa ultrafilters). Given the high quantities of lipids in fish bones we recommend the inclusion of a chemical lipid extraction step when isolating collagen from modern and archaeological fish bones. Copyright © 2016 John Wiley & Sons, Ltd.

Indicator groups and effective seasons on the coast: Zooarchaeology of fish in the lower Suwannee region of Florida

Recent assessments of subsistence procurement in coastal areas of the southeastern United States accentuate the continuity of fish resources through time. Seasonality and habitat inferences based on archaeological fish assemblages, however, are deemed ineffective measures due to the absence of fishes with marked seasonal or habitat characteristics. I argue that archaeological fish assemblages provide useful indications of procurement conditions when 1) present-day fish data provide a framework for analysis and 2) alternatives to conventional seasonal categories are considered.Fish species are arranged into indicator groups based on common characteristics, which allows for seasonal pattern recognition that may not be evident in analyses of individual taxa. Broad-scale astronomically based seasons do not encompass the variations of local environmental processes or human practices on archaeological fish assemblages. Further, localized seasons cannot be explored in absence of local habitats. The effective seasons, habitats, and indicator groups presented herein provide a localized framework by which to consider coastal fishing practices, sedentism, and mobility.Effective seasons and habitats are described that may have been relevant to coastal fishers of the lower Suwannee region of Florida. Indicator groups, derived from these categories, are used to examine fish assemblages with AMS assays between 2630 and 2290 BCE. Results suggest that past peoples incorporated both sedentary and mobile practices; people collected fish from multiple habitats throughout the year, which included traveling several kilometers to the coast to procure specific fish resources.

Stable isotope evidence supports pelagic fishing by hunter-gatherers in southern South America during the Late Holocene

Fishing intensification development during the Late Holocene in the Beagle Channel is recognized in zooarchaeological studies, especially in a diversification to pelagic fish, implying an expansion of fishing practices to pelagic zones. In this paper, we undertake a paleoecological framework based on stable isotope analysis (δ13C and δ15N) of modern and archaeological fish collagen bones. In this analysis we intend to provide an independent record to investigate possible variations in the patch use in marine fishing activities by hunter-gatherer societies in southern South America.Archaeological bones of Macruronus magellanicus, Merluccius sp. and Thyrsites atun were recovered from three stratified shellmiddens located in the coast of the Beagle Channel. In addition, modern samples of Macruronus magellanicus, Merluccius hubbsi and Merluccius australis were obtained at three different locations of the Patagonian continental shelf.Macruronus magellanicus results highlight the relative nearshore character of the archaeological specimens. No differences were found between archaeological and modern values for Merluccius sp., which indicate the offshore character of the archaeological specimens of this species. Results also show that the archaeological samples of Thyrsites atun are related to offshore ecosystems. In sum, stable isotope values of archaeological specimens agree with previous interpretations from zooarchaeological analyses of deep-water fishing during the Late Holocene in the Beagle Channel.

Carbon and nitrogen stable isotope values in freshwater, brackish and marine fish bone collagen from Mesolithic and Neolithic sites in central and northern Europe

The aim of this research is to examine the isotopic characterisation of archaeological fish species as it relates to freshwater, brackish and marine environments, trophic level and migration patterns, and to determine intraspecies variation within and between fish populations in different locations within central and northern Europe. Carbon and nitrogen stable isotope analysis was undertaken on collagen extracted from 72 fish bone samples from eight Mesolithic and Neolithic archaeological sites in this region. Thirty-six (50%) of the specimens analysed produced results with acceptable carbon to nitrogen atomic ratios (2·9–3·6). The fish remains encompassed a wide spectrum of freshwater, brackish and marine taxa (n = 12), which were reflected in the δ13C values (−24·5 to −7·8‰). The freshwater/brackish fish (pike, Esox lucius; perch, Perca fluviatilis; zander, Sander lucioperca) had δ13C values that ranged from −24·2 to −19·3‰, whereas the brackish/marine fish (spurdog, Squalus acanthias; flatfish, Pleuronectidae; codfish, Gadidae; garfish, Belone belone; mackerel, Scomber scombrus) ranged from −14·9 to −9·4‰. Salmonidae, an anadromous taxon, and eel (Anguilla anguilla), a catadromous species, had carbon isotope values consistent with marine origin, and no evidence of freshwater residency (−12·7 to −11·7‰). The δ15N values had a range of 6·2‰ (6·5–12·7‰) indicating that these fish were on average feeding at 1·7 trophic levels higher than their producers in these diverse aquatic environments. These results serve as an important ecological baseline for the future isotopic reconstruction of the diet of human populations dating to the late Mesolithic and early Neolithic of the region.

Using Gaussian Mixture Model clustering for multi‐isotope analysis of archaeological fish bones for palaeobiodiversity studies

Modern methods in mass spectrometry permit fast accumulation of a huge amount of data. The analysis of multi-isotope data sets of archaeological remains is of increasing importance for the study of palaeobiodiversity. However, common bivariate isotopic data analysis fails to detect certain patterns in a multi-dimensional data set. This problem can be solved by cluster analysis. Gaussian Mixture Model (GMM) clustering was applied to a multi-isotope data set including 184 individual mass spectrometric measurements (δ(13) Ccollagen , δ(15) Ncollagen , δ(13) Ccarbonate , and δ(18) Ocarbonate values) of archaeological fish bones (n=46) from the Viking Haithabu and medieval Schleswig sites in northern Germany. The number of components was first restricted to the expected number of three (freshwater, brackish, and marine environment). Subsequently, classification was conducted with respect to an optimal Bayesian Information Criterion (BIC). Restriction of the number of components to three clusters leads to the expected clustering results according to the gross ecological niches (freshwater, brackish, marine). The isotopic data of fish bone were, however, optimally clustered into four clearly separated, reasonable groups, namely a freshwater, a brackish, and two marine groups. The two marine clusters differ in their oxygen isotope ratios, indicating different water temperature and therefore probably imported fish. Restriction of the number of clusters resulted in better training and test results. The GMM clustering method is applicable to complex multi-dimensional stable isotope data sets established by isotope ratio mass spectrometry (IRMS). This exemplary application resulted in an identification of habitat preferences and non-local individuals. Depending on the scientific question to be solved, restriction of the cluster size could lead to a better reproducibility; however, with loss of dissolution. Copyright © 2016 John Wiley & Sons, Ltd.