Michaela Aschan

Michaela Aschan
UiT The Arctic University of Norway · Norwegian College of Fishery Science

PhD

About

53
Publications
16,859
Reads
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2,416
Citations
Citations since 2016
15 Research Items
1555 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
Additional affiliations
May 2005 - present
UiT The Arctic University of Norway
Position
  • Professor in Fisheries biology and Management
May 2005 - present
UiT The Arctic University of Norway
Position
  • Professor
May 2005 - present
UiT The Arctic University of Norway
Position
  • Professor

Publications

Publications (53)
Article
Full-text available
As temperatures rise, motile species start to redistribute to more suitable areas, potentially affecting the persistence of several resident species and altering biodiversity and ecosystem functions. In the Barents Sea, a hotspot for global warming, marine fish from boreal regions have been increasingly found in the more exclusive Arctic region. He...
Article
Marine mammals are important players in the Barents Sea ecosystem but their structural role in the foodweb has been little explored. We compare foodweb-related characteristics within and between phylogenetic groups for 19 marine mammals. As a group, they directly connect to the most central species (i.e cod and haddock) in the Barents Sea (i.e. cod...
Technical Report
Full-text available
This report summarize the outputs from the first multi-stakeholder physical meeting in the FarFish project. The aim of the meeting was to discuss stakeholders’ interests and needs, related to how they can contribute to the development of the Management Recommendations, while improving the sustainability of the fishery of the EU fleet fishing in dis...
Article
The main challenge for the European seafood industry is to ensure sustainable production volume while adapting to climate warming. Marine fisheries mainly target 41 species which account for 80% of the seafood production in Europe. The remaining 20% comes from marine and freshwater aquaculture, which harvest mainly 5 and 11 species, respectively. E...
Article
Full-text available
When facing environmental change and intensified anthropogenic impact on marine ecosystems, extensive knowledge of how these systems are functioning is required in order to manage them properly. However, in high-latitude ecosystems, where climate change is expected to have substantial ecological impact, the ecosystem functions of biological species...
Data
Summary statistics of ANOVA on the species' trophic level (TL) as function of functional group. Significant (alpha = 0.05; Bonferroni corrected alpha = 0.005) relationships in longevity among functional groups are indicated in bold. (DOCX)
Data
Summary statistics of ANOVA on the species' longevity as function of functional group. Significant (alpha = 0.05; Bonferroni corrected alpha = 0.005) relationships in longevity among functional groups are indicated in bold. (DOCX)
Data
Summary statistics of ANOVA on the species' maximum body length (ML) as function of functional group. Significant (alpha = 0.05; Bonferroni corrected alpha = 0.005) relationships in longevity among functional groups are indicated in bold. (DOCX)
Article
Full-text available
In this data article, we present the 2004–2014 average European seafood production volume by production sector, country, and species. The production data originates from the Food and Agriculture Organisation of the United Nations (FAO) and covers three production sectors: Marine fisheries, marine aquaculture, and freshwater production. We present t...
Article
Mixed fisheries and the marine ecosystems that sustain them are complex entities and involve multiple and potentially conflicting management objectives and stakeholder interests. The presence of multiple trade-offs complicates the identification of strategies that satisfy various policy requirements while being acceptable to affected stakeholder gr...
Article
Full-text available
Large‐scale patterns in species diversity and community composition are associated with environmental gradients, but the implications of these patterns for food‐web structure are still unclear. Here, we investigated how spatial patterns in food‐web structure are associated with environmental gradients in the Barents Sea, a highly productive shelf s...
Article
Full-text available
Significance Arctic marine ecosystems are experiencing a rapid biogeographic change following the highest warming rates observed around the globe in recent decades. Currently, there are no studies of how the observed shifts in species composition are affecting Arctic marine ecosystem functioning at a biogeographic scale. We address this issue via f...
Article
We present a framework for results-based management (RBM) of commercial fisheries. The core idea of RBM is to reduce micromanagement by delegating management responsibility to resource users. The RBM framework represents an industrial organization approach to co-management and comprises three defining processes, conducted by three independent “agen...
Article
Full-text available
Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the...
Article
Full-text available
Arctic marine ecosystems are warming twice as fast as the global average. As a consequence of warming, many newcoming species experience increasing abundances and expanding distribution ranges in the Arctic. The Arctic is expected to have the largest species turnover with regard to invading and locally extinct species, with a modelled invasion inte...
Technical Report
Full-text available
The lack of correlation between changes in the shrimp stock and the cod consumption has been the reason why several assessment models including the predator has failed when applied on the Barents Sea shrimp stock. We modify the current Norwegian procedure to calculate cod consumption of shrimp in the Barents Sea, and explore how this affects the co...
Article
Full-text available
In results based management (RBM), responsibility for achieving defined objectives is delegated to resource users.•RBM integrates rationales of state centred, participatory and market based governance.•RBM requires that authorities accept and motivate delegation of defined responsibilities for management and documentation, and that resource users d...
Data
Supplementary tables, including life history trait matrix, citations for the life history trait matrix, sampling locations of trait data, correlation table, explanatory variables and a nested taxonomic matrix for Barents Sea fish.
Data
Appendix S2. Reference list for the life history trait matrix. Appendix S3. Supplementary figures.
Article
Full-text available
Under exploitation and environmental change, it is essential to assess the sensitivity and vulnerability of marine ecosystems to such stress. A species' response to stress depends on its life history. Sensitivity to harvesting is related to the life history “fast–slow” continuum, where “slow” species (i.e., large, long lived, and late maturing) are...
Data
Full-text available
A food web is an ecological network and its topological description consists of the list of nodes, i.e., trophospecies, the list of links, i.e., trophic interactions, and the direction of interactions (who is the prey and who is the predator). Food web topologies are widely used in ecology to describe structural properties of communities or ecosyst...
Article
Full-text available
In a warmer Arctic, living conditions will change at all trophic levels of the marine ecosystem. Increased air and water temperatures will likely substantially reduce ice coverage. Trophic interactions might change and increased competition between resident Arctic species and invasive species seems likely. A theme session on “Marine harvesting in t...
Article
Full-text available
This paper provides the first assessment of the functional diversity (FD) of the Barents Sea fish community. FD is recognized as an important driver of ecosystem functions and, thus, governs the adaptability of ecosystems in the face of disturbance. We integrate ecosystem survey data with an extensive trait matrix and show that fish FD displayed la...
Article
Full-text available
A food web is an ecological network and its topological description consists of the list of nodes, i.e., trophospecies, the list of links, i.e., trophic interactions, and the direction of interactions (who is the prey and who is the predator). Food web topologies are widely used in ecology to describe structural properties of communities or ecosyst...
Article
Full-text available
Change in oceanographic conditions causes structural alterations in marine fish communities, but this effect may go undetected as most monitoring programs until recently mainly have focused on oceanography and commercial species rather than on whole ecosystems. In this paper, the objective is to describe the spatial and temporal changes in the Bare...
Article
Full-text available
Our studies of larval growth of Pandalus borealis revealed that the available literature for identification of the larval stages was inconsistent and thereby difficult to use. We present a robust key for identification of larval stages of P. borealis, that separates the five zoea stages (ZI-ZV), one megalopa stage (M) and the post-larva (P) in the...
Article
This paper describes a well-proven process mapping method designed for structured investigation of material flow and information flow in a food producing company or a whole supply chain. The material flow is viewed as an alternating sequence of durations and transformations, and a pre-determined set of questions is associated with each phase. These...
Article
The Jan Mayen area has an extreme environment with low temperatures and infrequent, but abrupt temperature changes. The shrimp population here is considered to be on its edge of distribution. The life-history parameters are in the same range as in other high-latitude shrimp populations and are characterized by slow growth, large size at maturation...
Article
The shrimp spawn in autumn, and the females carry their eggs as out roe until spring when the larvae hatch. Within a period of 2 months the shrimp larvae settle to the bottom. It has been claimed that the year-class strength probably is determined during the larval phase. Today's assessment and forecast of the shrimp stock productivity and potentia...
Article
Full-text available
The Arctogadus glacialis is endemic to the Arctic Ocean and its apparently disjunct circumpolar distribution range from the Siberian coast through the Chukchi Sea and the Canadian Arctic to the shelf off NE Greenland. Records of A. glacialis are scarce in the European Arctic and here we present all available and reliable records of the species in t...
Article
Full-text available
Climate change could lead to mismatches between the reproductive cycles of marine organisms and their planktonic food. We tested this hypothesis by comparing shrimp (Pandalus borealis) egg hatching times and satellite-derived phytoplankton bloom dynamics throughout the North Atlantic. At large spatial and long temporal (10 years or longer) scales,...
Article
Williams, T., Helle, K., and Aschan, M. 2008. The distribution of chondrichthyans along the northern coast of Norway. – ICES Journal of Marine Science, 65: 1161–1174. The relationship between temperature, latitude, and depth and the distribution and relative abundance of chondrichthyans along the northern coast of Norway was examined based on catch...
Article
Full-text available
Fish species inhabiting the Barents Sea display great seasonal and inter-annual variation in abundance and distribution. This study describes the assemblages and distributions of fish species in the southwestern and central part of the Barents Sea, which includes the polar front. The area has an unpredictable environment due to variable inflow of A...
Article
The genetic structure of shrimp (Pandalus borealis) in the Northeast Atlantic was examined by RAPD analysis on specimens caught at eight stations in the Barents Sea, three off Svalbard, two off Jan Mayen, and in two northern Norwegian fjords (19 < n > 31 per station). A total of 34 polymorphic markers generated by seven 10-mer arbitrary primers was...
Article
Full-text available
A bioeconomic model on the management ofby-catch of juvenile fish in the shrimp fisheryin the Barents Sea and the Svalbard Zone,presented by the Norwegian Directorate ofFisheries to the Joint Norwegian RussianFisheries Commission in 1993, is evaluated. The model is based on management of by-catchthrough closure of areas when the by-catch ofjuvenile...
Article
Larval dispersal and spatial distribution of reproducing females of Pandalus borealis in the Barents Sea were investigated. The approach was based on particle tracking using flow fields and a biological model incorporating ontogenetic migration and temperature dependent development of the zoea stages. By the use of individual-based particle-trackin...
Article
In this paper, we outline a geostatistic method to simulate the relative precision (coefficient of variation, CV) of total abundance estimates of one species in a predetermined, stratified area when it is appropriate to treat the observations within each stratum as realizations of a second-order homogenous and ergodic random process. To model the s...
Article
Full-text available
Modal analyses of carapace length frequency distributions reveal differences in growth and age at first female maturity of shrimp, Pandalus borealis, at Svalbard. The shelf slope west and north of Svalbard within a depth range of 200-600 m was divided into seven Areas. Between seven and ten age groups of shrimp were identified in each Area. The slo...
Article
Full-text available
Shrimp (Pandalus borealis) length frequencies from Barents Sea shrimp surveys were analysed to evaluate their usefulness in determining stock structure and optimising station groupings for assessment purposes. Four groups of stations were identified using cluster analysis on the Spearman coefficients correlating individual station length frequency...
Article
Full-text available
In order to elucidate the population structure of the deep-sea shrimp (Pandalus borealis) in the NE Atlantic, 32 subsamples and 3865 individuals were analysed for allozymic variation. They were caught at various locations in the Barents Sea, in waters off Svalbard, Jan Mayen and Iceland, and in fjords along the Norwegian coast. Only three enzymes (...
Article
Full-text available
In 1993 an important shrimp (Pandalus borealis) fishery developed on Flemish Cap, (NAFO Div. 3M) and has continued with many nations still involved. There are important difficulties connected with the regulation placed on the fishery of limiting fishing effort, because of insufficiency of reliable long-term time series data and the lack of basic kn...
Article
A method for optimal effort allocation in stratified trawl surveys with uncorrelated grid sampling is developed. Two related optimisation criteria are considered: (1) to minimise the coefficient of variation (CV) of the biomass index for a given available vessel time (t) and (2) to minimise the vessel time needed in order to obtain a required CV va...
Article
As part of a programme to re-assess the existence of latitudinal gradients in the diversity of the macrobenthic infauna of soft sediments, samples were taken from Sassenfjord, Spitzbergen. Abundancebiomass curves showed the shallowest sites to be moderately disturbed, possibly as a result of glacial run-off from the Gipselva. These clearly differed...
Article
Sublittoral macrofauna was sampled along a putative pollution gradient at 6 sites in Frierfjord/Langesundfjord. Norway, during the GEEP Mlorkshop. Data were subjected to a variety of multivariate statistical analyses which discriminate between sites on their faunistic attributes, and univariate measures of community stress were determined. Multivar...
Article
Full-text available
Annales Zoologici Fennici, ISSN 0003-455X, nr. 27, 329-336 A comparison is made between three study areas on the Finnish and Norwegian coasts with differing environmental gradients in order to determine the macrozoobenthic community structure. Regression analysis is used to find the environmental parameters that correlate with the two most importan...
Article
Full-text available
Sublittoral macrofauna was sampled along a putative pollution gradient at 6 sites in Frierfjord/Langesundfjord. Norway, during the GEEP Workshop. Data were subjected to a variety of multivariate statistical analyses which discriminate between sites on their faunistic attributes, and univariate measures of community stress were determined. Multivari...
Article
Full-text available
Macrozoobenthos was surveyed in August 1982 close to Tvarminne Zoological Station, SW Finland. Abundance was high (mean 9200 ind/m2), biomass low (mean 69.1 g/m2). The high abundance may indicate a community change in the Baltic Sea during the last 50 yr or it may be related to the maximum abundances in the 6-7 yr population fluctuation pattern. Th...
Article
Full-text available
The shrimp spawn in autumn and the eggs are carried as out roe by the females until spring when the larvae hatch. Within a period of 2-3 months the shrimp larvae settle to the bottom. Today's assessment and forecast of the shrimp stock productivity and potential fishing yields is weak. This is partly due to poor knowledge on population dynamics fro...

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Projects

Project (1)
Project
SimFish - Innovative interdisciplinary learning in fisheries and aquaculture