Do you want to work with marine biology, marine ecology, freshwater biology, freshwater ecology, limnology or sustainable development? Make a difference for the Baltic Sea, the Skagerrak or Kattegat, for lakes or running waters!
As a thesis worker at our department, you will get the chance to deal with real problems in ongoing research projects, and have supervisors who are Sweden's leading experts in the field. You get to use theoretical knowledge in practice, and get the chance to participate in exciting fieldwork,
Our current calls concern a variety of topics in our field, such as fish, fisheries, shellfish, seals, waterfowl, ecosystems and sustainability issues.
Master project in Biology (30-60 credits)
This project aims to resolve how warming of water bodies changes the efficiency of energy transfer from primary producers to fish (i.e. food web efficiency, FWE), and how this may be modified by concurrent change in other environmental drivers. The thesis project will be part of a larger project aiming to identify strategies to maintain ecosystem services in face of multiple environmental stressors, with the goal to maintain the ability of aquatic ecosystems to act as carbon sinks and uphold high production of fish biomass in the future.
Along with warming, many freshwater and coastal ecosystems are becoming greener and browner (caused by excess humic substances and nutrients). The key factors (temperature, light, nutrients) that control basal energy production in aquatic ecosystems are thus changing. Even though the link between nutrients, light, temperature and algal growth is more or less established, the flow of energy produced by these primary producers to higher trophic levels such as fish is less predictable. The latter is especially true for the combined impact of these environmental drivers on FWE.
The student (one or several) will set up tank experiment(s) with phytoplankton, zooplankton and fish at our coastal experimental field site in Forsmark to test how warming may change FWE, as well as the potential for browning and/or greening of waters to modify those responses. The detailed set-up and more specific study questions will be decided after discussions between the student and supervisors. You will learn skills such as experimental design, sampling of plankton and fish, identification of aquatic organisms, statistics and scientific writing. Preferred project start would be sometime in the period May-July 2023.
Not only will you gain new knowledge and skills by doing your own project, but you will also become an integrate member of our research group Fish in food-webs, where you will join group meetings and seminars at campus Ultuna in Uppsala. There may also be opportunities for paid part-time work helping out in the field or lab while doing your project and to contribute to a scientific publication.
Magnus Huss, Senior Lecturer, Director of Studies - postgraduate education
Department of Aquatic Resources, Institute of Coastal Research, SLU
magnus.huss@slu.se, +46 10 478 41 27
The suggested topics are suitable for master student projects. The projects can include field work, lab work, literature studies, data analysis and scientific writing.
The contents and scope of the work can be discussed and adapted to prevailing conditions.
Background
The populations of seals and cormorants in Sweden have increased in size and distribution during the last decades.
Consequently, requirements and needs of information about the ecological roles of seals and cormorants have increased, e.g. for inclusion of top predators in ecological models and for development of ecosystem-based management. In addition, conflicts with fish conservation biology and coastal fisheries have intensified.
At present, relevant information on prey choice and abundance of these predators and their impact on fish stocks is insufficient.
Diet analysis of seals and cormorants
Monitoring of seals and cormorants
Predator-prey dynamics
Contact:
Karl Lundström, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
karl.lundstrom@slu.se, +46 10 478 41 38
Research questions: Understanding variation in the number, abundance, identities, and traits of species over space and time is a key topic for ecologists today. In this project, you will investigate the following questions: (i) what environmental variables drive patterns in benthic species abundance and distribution? (ii) how is this related to the traits of species? (iii) how do species interactions shape these spatial distributions?
Tasks: Explore and fit models to benthic community data sampled within national and regional programmes (available at start) using the R package HMSC. You will fit multivariate species distributions models with environmental covariates and explore species-by-species level correlations in distributions.
What you will learn: Key skills for ecologists, including (i) how to apply state-of-the-art joint species distribution models in R (ii) how to work with ecological data following good practices for reproducible analysis (iii)… and also learn about benthic community dynamics in the Baltic Sea!
Prerequisites: Familiarity with R and statistical concepts for applied ecology is a merit. However, we offer a supportive environment with dedicated supervisors and firmly believe that any motivated student can take on this project and succed.
Location: SLU Aqua in Lysekil, or remotely since the project is about analysing and quantifying already available data.
Please do not hesitate to reach out for more information!
Main supervisor: Max Lindmark (postdoc), max.lindmark@slu.se,
Co-supervisor: Federico Maioli (PhD student), f.maioli@unibo.it
Co-supervisor: Mattias Sköld (researcher), mattias.skold@slu.se
Research questions: The world is getting warmer and ectothermic species such as fish are predicted to spawn earlier1, grow faster, and reach smaller adult body sizes2, 3. Numerous studies have found empirical support for faster growth rates in natural systems4, 5 (inferred from larger size-at-age). However, it remains to be seen whether increases in size-at-age are purely due to faster growth rates, or because earlier spawning times give fish a head start in the race to be larger.
In other words: what are the relative contributions of temperature-dependent growth and earlier spawning times (and longer growing seasons) for explaining patterns in fish growth and size in relation to climate change?
Tasks: In this project, you will work with an exceptionally unique Biotest system (which contains long time series of fish growth taken from lakes with large differences in temperature). You will parameterise an existing R-based Individual Based Growth Model (IBM) for perch (Perca fluviatilis) and use it as a basis to quantify how changes in spawning times and temperature dependent growth describe empirical patterns.
What you will learn: Key skills for ecologists, including R-programming for performing data-analysis, data visualisation, and simulations following good practices for reproducible science.
Prerequisites: Familiarity with R and statistical/quantitative concepts for applied ecology is a merit. However, we offer a supportive environment with dedicated supervisors and firmly believe that any motivated student can take on this project and succeed.
Location: SLU Aqua in Lysekil, or work can be conducted remotely.
Please do not hesitate to reach out for more information!
Main supervisor: Max Lindmark (postdoc), max.lindmark@slu.se,
Co-supervisor: Christopher Griffiths (researcher), christopher.griffiths@slu.se
Are you passionate about working with biodiversity in the sea? If so, this is a project for you. The project is based on two innovation projects run by the city of Helsingborg in Öresund in the recent year. The vision of Helsingborg is to enhance biological diversity in coastal areas.
Unfortunately, many important habitats in shallow coastal areas have disappeared in the study area, as the city of Helsingborg has expanded. The shallow areas are key areas for biodiversity. They function as both feeding areas and nurseries for many different animals and plants. In harbors and ports, organisms now encounter straight quaysides and nowhere to hide or find food. The city of Helsingborg has tried to changes this situation. In one of the largest ports, an artificial reef has been built and structures have been set up on the quayside to increase habitat complexity, thus adding more suitable environments for different animal species and algae.
In this thesis, you will investigate how artificial structures, such as a reef and structures on quaysides, can potentially contribute to biodiversity in coastal areas. More specifically, you will collect and obtain data on species composition and biomass at various structures in the port, and perform analyzes to see what effects they have. You can influence the design of your project in a direction that is relevant to you. No matter of what path you choose, there are many ways in which you can contribute to new knowledge on biodiversity enhancement. The purpose of the work is to address how coastal municipalities and cities can work actively to increase biodiversity in shallow coastal areas, with a focus on ports.
The work is carried out as a collaboration between the city of Helsingborg and SLU, under the supervision of SLU by Lena Bergström, Department of Aquatic Resources. A marine biologist employed at the city of Helsingborg will be linked to the project and will be available to assist with expertise in your field work and on biology in the Öresund. The work can be started from autumn term 2022.
Lena Bergström, Researcher
Department of Aquatic Resources, Institute of Coastal Research, SLU
lena.bergstrom@slu.se, +46 10 478 41 16
Within this project you will have the opportunity to develop a socio-ecological model for the Bothnian Sea that can be used for future management decisions in collaboration with stakeholders, managers and scientists.
Background: A key aim in ecosystem-based management (EBM) is to establish common goals among stakeholders, as this is expected to enable the continued delivery of ecosystem services, while reducing user conflicts. Socio-ecological models are often used to support this aim. The models help increase the understanding between stakeholders and scientists and investigate how management actions could affect the ecosystem and the people who depend upon it. The Swedish Agency for Marine and Water Management has initiated an EBM pilot project in the southern Bothnian Sea to involve stakeholders in developing an ecosystem-based management that integrates environmental goals with societal goals for the region.
Project: As part of the pilot EBM project, you will develop a socio-ecological model for the Bothnian sea in collaboration with stakeholders, managers and scientists. This, so called fuzzy cognitive model can be used in preparing future management decisions and increase the understanding between managers, stakeholders and scientists of the ecological and societal processes that affect environment status.
Practical work includes conducting interviews with managers and stakeholders and contributing to workshops within the southern Bothnian Sea EBM project. You should be familiar with R, interested in ecosystem-based management and comfortable interacting with people of different backgrounds. No previous modelling experience is necessary.
Contact:
Carolyn Faithfull, researcher
Department of Aquatic Resources, Institute ov Coastal Research , SLU
carolyn.faithfull@slu.se, +46(0)10-478 41 74
Sustainable tourism is committed to making a low impact on the environment and local culture, while helping to generate income and community development. Situated in the Stockholm archipelago, candidate Biosphere, Nämdö archipelago is currently in the process of developing strategies for sustainable tourism. The project involves identifying interactions between conservation and commercialization/tourism and develop strategies for sustainable development (with focus on local fishery and cascade effects, seabirds and top predators and more).
The project will be conducted at Sötvattenslaboratoriet at SLU Aqua, Drottningholm or at the Biosphere office at Nämdö Island.
Photos från Nämdöskärgården by Elin Dahlgren, Per Fjärdhäll, Nilla Söderqvist, Anders Söderberg.
Within this project you will have the chance to evaluate how exposure to algal toxins in fish from the Baltic Sea has changed over time, and in addition link levels of these substances to fish health data from ongoing environmental monitoring.
The eutrophication of the Baltic Sea is driving large blooms of phytoplankton and cyanobacteria as well as contribute to the occurrence of filamentous algae. The increased abundance of these primary producers can lead to an elevated production
of algal toxins with potentially harmful effects on fish. As part of current environmental monitoring is the programme integrated coastal fish health monitoring – a programme where coastal fish (e.g., perch) is examined in relation to different fish health parameters, from different reference stations along the Swedish coastline. At station Kvädöfjärden in the Baltic Proper, an assumed unaffected area but with large algae blooms during the summer, ongoing health examinations show that perch is far from unaffected. Signs of oxidative stress, immunological response and altered metabolism that cannot be coupled to anthropogenic contaminants points to algal toxins, showing similar effects in ecotoxicological studies, as a potential cause for the deteriorating fish health status in the area.
The project will take advantage of material (perch) collected within the integrated coastal fish health monitoring and stored at the Environmental Specimen Bank at the Swedish Museum of Natural History to do a retrospective study of algal toxins in perch from 1995 to 2019, as well as combine the information with already existing data for fish health. By doing so you will be able to answer how these substances change over time, are the exposure stable or is there an upward/downward trend? You will also have the opportunity to evaluate possible effects of algal toxins in the environment by coupling the chemical data to fish health parameters from the same individuals. Combined, these two research questions will advance the field of algal toxins in the Baltic Sea and contribute to the overall understanding of future needs in this area; no problem exists, annual monitoring is necessary, improved measures to reduce nutrients is warranted, other conclusions?
Practical parts of the project involves sample preparations and aiding in the chemical analysis both done at Stockholm University at the Department of Environmental Science (ACES). In addition to that, data handling and statistical analysis as well as scientific writing will be included and conducted at the Freshwater Institute at Drottningholm, Stockholm.
In this research project you will explore the behavioural effects of tagging using the European eel. Fish will be collected, held at the laboratory, tagged with PIT-tags, and behavioural experiments will be conducted. The experiments will be videorecorded and analysed using automated software.
Mark and recapture techniques are traditionally used in ecology to estimate a range of parameters, such as migration patterns, growth, survival, and population size. In fish ecology, both external and internal tags are used to answer such questions. According to the 3R principle for ethical use of animals (replace, reduce, refine), tagging methods should affect the animal to the least possible extent. The test animal might be affected by the tagging procedure and/or by the tag itself, and behave in an unnatural way, or even suffer from injury or mortality due to tag and/or handling. Such cases induce suffering to the animal, but cases of less detrimental effects can still bias the data (without harming the fish). Most tagging procedures are quite well developed and does not harm the fish, but non-lethal effects, such as behavioural effects, are important to evaluate since it can bias the data.
This research project will explore the behavioural effects of tagging using the European eel (Anguilla anguilla). It is assessed as critically endangered on the IUCN red list, wherefore data on the effects of different research techniques, such as tagging, are particularly needed.
The student’s task will consist of collecting eels (or use eels that are already available at the laboratory), tag them with PIT-tags and perform behavioural experiments. All experiments will be video recorded. Since the eel is primarily night active, behavioural trials can also be run after sunset, using IR lights and IR sensitive cameras. The specific experiments to perform depends on the student’s interest and whether it’s a 30 or 60 hp thesis. Relevant behaviours to measure include swimming activity, feeding, boldness, sheltering and similar. Swimming activity will be tracked using automated tracking software. Other behaviours will be analysed using behavioural scoring software. Data collected within the project can also be combined with existing long-term data on tagged eels.
The work will take place at the Institute of Freshwater Research, Stockholm - Drottningholm, under supervision of Dr Josefin Sundin. The student should have an interest in fish ecology, fish handling, data analysis, statistics, and scientific writing. The work can commence at any time, depending on whether fish will be collected/bought for the experiment, or if using eel that are already available at the laboratory.
Josefin Sundin, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
josefin.sundin@slu.se, +46 10 478 42 24
In this research project you will explore migration behaviour and survival of the European eel in a natural river. When the eels start their migration back to the Sargasso Sea, they are hindered by hydropower plants. You will track tagged eels and investigate their migration behaviour and quantify hydropower induced mortality.
River ecosystems serve an important role for biodiversity, but they also provide renewable energy via hydropower electricity production. Hydropower plants, however, hinder natural river connectivity and often involve the construction of dams, causing severe ecological damage to numerous organisms. The critically endangered European eel (Anguilla anguilla) is one of many diadromous species that suffers greatly from hydropower plants. It is affected both by up- and downstream migration barriers, hydropower induced mortality, and habitat destruction and alteration. Our knowledge on the effects of hydropower on the European eel is currently insufficient to provide policymakers and stakeholders with tools to improve the conditions.
Recently, the Government Offices of Sweden decided o
n a national plan to retrial the environmental legal conditions for all hydropower plants. This enormous project aims to ensure that all hydropower plants in Sweden follow national and international (EU) environmental legislation, which is currently not the case for most hydropower plants. In general, detailed knowledge about the negative effects of hydropower on river connectivity and diadromous species is lacking from natural systems. This means that we are currently lacking the knowledge that will very soon be needed within the national retrial plan. This project will fill some of those knowledge gaps.
The student’s task will consist of tracking tagged eel in a river system. Depending on start date, the student can also be involved in the tagging procedure. In that case, collecting and caring for the fish will be part of the work. The migration data will be used to estimate survival (including hydropower induced mortality) and movement. Data collected within the project can also be combined with existing data on migration and survival.
The work will take place at the Institute of Freshwater Research, Stockholm - Drottningholm, and at river Kävlingeån in Skåne (southern Sweden). The work will be supervised by Dr Josefin Sundin. The student should have an interest in fish ecology, fish handling, data analysis, statistics, and scientific writing. Since some eels have already been tagged within this system, the work can commence at any time by analysing existing data. Additional tagging will be conducted in ~May and September 2022.
Josefin Sundin, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
josefin.sundin@slu.se, +46 10 478 42 24
The health situation for our native salmon is worrying, both in the Atlantic and in the Baltic Sea. Disease outbreaks (bleedings, erythemas and fungal infections) along with well-studied reproductive disorder (M74), are reported by most Nordic countries. The reason(s) behind the failing salmon health are unclear and it is not known how the various symptoms are related. To mitigate stock collapses, research and monitoring efforts to shed light on the magnitude and cause of the deteriorating salmon health, are of the essence.
The project aims to increase our understanding of wild salmon health using new techniques (non-invasive sampling using scales, genetics and more). The projects contains fieldwork along with data management and analysis.
The round goby is native in the Black sea and Capian Sea but has probably come by ballast water to the Baltic Sea. It was first reported 1990 in the bay of Gdansk where ot is now the most common coastal fish species. In 2008 it was reported in Sweden for the first time, in the archipelago of Karlskrona. It now occurs from Kalmar Sound up to Gävle and also around Gotland and in Gothenburg.
The round goby is an invasive species with high reproduction speed and highly tolerant for environmental stressors. There is a risk that it will compete with other bottom dwelling species and also consume eggs & fry of native species but it can also be a resource for predatory fish and humans. One concern is that it may invade freshwater systems and knowledge about its migrating capability and potential barriers to stop it from entering rivers is needed. In order to utilize the species and develop efficient fishing gear knowledge is needed about the behavior of the fish around different fishing gears. The suggested projects below are experimental studies contributing with knowledge in both these important areas and they are part of the Research project Round goby – turning risk to resource.
All experiments are conducted in Älvkarleby, by the river Dalälven south of Gävle, either at SLU Fisheries Resaerch Station (FFS) or at the Vattenfalls experimental facility Laxeratorn. Depending on your skills and interest the thesis can either be within biology or environmental science with room for personal research questions. The work is flexibel and can be either on candidate or master level.
Ann-Britt Florin, Head of Division
Department of Aquatic Resources, Institute of Coastal Research, SLU
ann-britt.florin@slu.se, +46 10 478 41 22
This research project aims to explore how brown trout respond to different anaesthetics. When set in a container with water and an anaesthetic agent fishes initially respond with increased activity. By use of video-recording and analyzing software the duration and intensity of the response will be investigated.
There is a wide array of different teleost species used in scientific research world-wide. These fish are frequently anaesthetised for various procedures and previous studies suggest that there is a divergence in the response to different anaesthetics among species. The use and efficiency, from a practical point of view, of anaesthetics in different species have been studied and reviewed. However, the fish welfare aspect and the in depth understanding of the pharmacological mechanism of action and effect in different species are largely unknown. In view of our increased awareness of animal welfare, also regarding fish, along with an increased use of fish as experimental animals, standardised anaesthetic protocols that are species specific is a necessity to assure best practises with focus on fish welfare.
This project consists of two different steps. First, to anaesthetize juvenile brown trout with four different substances (metomidate, eugenol, tricaine methanesulfonate and benzocaine) and video record their behaviour. Depending on the number of credits the student wish to achieve one or several concentrations can be used as well. Second, to analyse the behaviour with a software (Ethovision). By use of this programme swimming speed, activity, swum distance can be estimated. The data collected will then be statistically analysed. The practical part will done I Älvkarleby, the computer work can be done anywhere.
Erik Petersson, Professor
Department of Aquatic Resources, Institute of Freshwater Research, SLU
erik.h.petersson@slu.se, +46 10-478 42 39
Svante Winberg
Uppsala university
This research project aims to explore the dynamics of two alternative spawning migratory strategies of pike that share a sympatric spawning habitat in the lake Långsjön, Nyköping, Sweden. This area was recently restored by the Swedish Anglers association to aid the declining stock of pike in the coastal Baltic Sea.
Removal of migratory barriers and restoration of exploited spawning habitats are key management actions to conserve and aid the recovery of migratory fish species. Such efforts generally aim at favoring the recruitment success by allowing populations to reach historic spawning habitats. In addition, these efforts will also result in regained connectivity among populations that have be physically separated for many generations opening the opportunity for admixture and source-sink dynamics.
Pike is an ecological and socioeconomical key species in the coastal Baltic Sea that have declined substantially during the last decades - likely due to recruitment failure. To mitigate this wetlands with suitable spawning habitat for pike, which have been inaccessible to pike, are restored.
The core of this project relies on field sampling and tagging of adults migrating to, and recruits emigrating from, Långsjön during the period of late March to early July. This includes quantifying the number, size distribution and morphology of adults and recruits and their phenology using fyke-nets, traps and insertion of Passive Integrated Transponders (PI-tags). The project can be combined with genetic studies that will be conducted at the SLU, Drottningholm.
Erik Petersson, Professor
Department of Aquatic Resources, Institute of Freshwater Research, SLU
erik.h.petersson@slu.se, +46 10-478 42 39
Petter Tibblin, Linnaeus University.
Rickard Gustafsson, Swedish Anglers Association.
In this research project you will explore the possibility to use eye-recognition software as a non-invasive tool for individual identification of fish. Fish will be collected, held at the laboratory, and photographed over time. The photographs will be analysed with iris-recognition software to evaluate the method.
Mark and recapture techniques have traditionally been used in ecology to estimate a range of parameters, such as population size, migration patterns, growth and survival. In fish ecology, both external and internal tags are used to answer such questions. According to the 3R principle for ethical use of animals (replace, reduce, refine), non-invasive methods should be used whenever possible, and the need to develop new techniques is evident.
This research project will explore the possibility to use eye-recognition software as a non-invasive tool for individual identification of fish. The specific species to work with can be decided together with the student, but we suggest working with the Northern pike (Esox lucius). Pike is a highly targeted species for recreational fishing. Currently, it is common practice to catch, photograph and release the fish alive (catch and release fishing). Within a citizen science context, a photograph-based identification technique
could greatly advance our understanding of pike ecology and simultaneously benefit fish welfare. Another suggestion for study species is the European eel (Anguilla anguilla). It is assessed as critically endangered on the IUCN red list, wherefore non-invasive research techniques are particularly needed.
Depending on whether the student wishes to do a 30 or 60 hp thesis, the project can be combined with testing whether the body patterns along the side of the pike can be used for identification.
The student’s task will consist of photographing fish at fixed intervals during a determined time period. Collecting and caring for the fish will be part of this work. The photos will then be analysed using the VeriEye software (Neurotechnology). Body patterns can be analysed using ImageJ software, or AI identification (depending on the development stage of the latter software). If photos are available from elsewhere, this project can be adapted to online teaching, where all supervision will take place via zoom meetings. The student will in that case receive digital photos and analyse them from wherever the student is resident.
The work will take place at the Institute of Freshwater Research, Stockholm - Drottningholm, or online, under supervision of Dr Josefin Sundin and Dr Göran Sundblad. The student should have an interest in data analysis,
statistics and scientific writing. The work can commence at any time, depending on availability of fish photographs (if the project is done online) or when the study species can be collected and photographed.
Josefin Sundin, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
josefin.sundin@slu.se, +46 10 478 42 24
Göran Sundblad, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
goran.sundblad@slu.se, +46 10 478 42 92
Recreational fishing is a popular activity with several human benefits. Excessive fishing can however have negative effects on fish stocks. In many areas in Sweden, fishing with handheld gears is open access, meaning that anyone can fish. The lack of registration poses challenges for estimating recreational fishing pressure, a key variable for a sustainable fisheries management. To increase our knowledge on recreational fishing in Sweden, the Department of Aquatic Resources conducts yearly surveys of recreational fishing.
This research project will use data collected during the summer of 2020 in Lake Mälaren. The field study focused on the pikeperch (Sander lucioperca) trolling fisheries, and consisted of two parts. The first part was an intercept
creel survey, where local fishers were counted and intercepted during fishing for interviews regarding gear, effort and catch. The creel survey covered three larger areas sampled on a subset of days. To complement the creel survey, continuous counting of effort was conducted at selected sites using time-lapse cameras. The two surveys thus covered i) large areas – few occasions and ii) small areas – many occasions. By combining the two survey techniques, the aim is to estimate total recreational fishing effort and provide advice for optimisation of future surveys.
Depending on whether the student wishes to do a 30 or 60 hp thesis, the project can focus on either or both of the two data collection methods.
This project requires an interest in survey design and estimation statistics. Practical work will consist of digitizing the data, including counting effort from the cameras and statistical analysis. The work can be performed online or at the Institute of Freshwater Research, Drottningholm, under the supervision of Dr Göran Sundblad and Dr Nuno Prista (stationed at the Institute of Marine Research, Lysekil).
The student should have an interest in data analysis and statistics. Some knowledge of recreational fishing is advantageous but not necessary. The work can commence at any time.
Göran Sundblad, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
goran.sundblad@slu.se, +46 10 478 42 92
The population of the European eel Anguilla anguilla (L.) is distributed from the North Cape to the Nile Delta, and in all waters in-between – in a panmictic population. That whole stock is derived from a single spawning location, in the far Sargasso Sea (Bermuda) – youngsters drift to our continent and migrate into inland waters; maturing eels leave our rivers and swim back to the Sargasso. Throughout the whole distribution area, small-scaled fisheries occur, targeting different life stages and using a wide variety of techniques. During the 20th century, the population has gradually declined to ~10% of its former abundance; since 1980, recruitment of youngsters from the ocean rapidly declined too. In 2007, the EU adopted the Eel Regulation for the protection and recovery of the stock. In this context, knowledge on the history of the stock and fishery may contribute to the effective protection, and the recovery of this remarkable fish.
Circumstantial evidence indicates that the eel stock might have been in decline since the early-1800s, mostly due to habitat loss (draining of swamps) and migration barriers (dams). In the early 1900s, technical innovation and better marketing enabled the development of commercial fisheries, primarily in mainland Europe, mostly for export to Germany (steam trains!), for smoking (Dekker 2019ai). These commercial fisheries (500 to 5000 kg per fisher per year, thousands of fishers) replaced the former subsistence/artisanal fisheries (5 to 500 kg per fisher per year, millions of fishers). Historical sources documenting the subsistence/artisanal fisheries are almost absent, while the documentation of the commercial fisheries is incomplete until ~1950 (Dekker 2019bii). The research question now is: did the replacement of subsistence/artisanal, by commercial fisheries intensify the exploitation pressure, or not? And did this exploitation contribute to the decline of the stock? This requires the comparison of undocumented decades, to little documented decades. In the absence of the regular type of information (catches, efforts, prices, …), it was noted that newspapers regularly publish short articles about the catch of a giant eel. These stories usually indicate date, location, and size of the eel (quantified information!) If exploitation pressure increased, one would expect the size of these giants to diminish, or the number of reports to go down. In Dutch, the conger (sea-eel) and the river-eel share common names, so species identity is a problem. Splitting up results by habitat-type, however, solved that. Note that not many giant river-eels were reported before 1900, and that their size diminished almost consistently over time, since 1900. This intriguing result needs confirmation from other countries; and other countries might improve our insight in the how and why. Any other country (in Western Europe) will be of value, especially since you as a native speaker will be much more able to understand historical stories than I am.
Newspaper archives are often available on-lineiii, and most archives offer a search engine. The student will explore these archives, master the data retrieval procedures, extract the data and compile a database. Though the Dutch results set a clear example, unknown problems might occur, for which creative solutions must be found. Aiming at a consistent data set, a large amount of time will go into the rigorous extraction procedures. However, in my experience, more time was lost on intriguing stories about eel distracting my attention, than on the extraction itself (e.g. a butcher’s wife, calling her eight eels to assemble for their feeding hour). Creativity and ingenuity will be required, to deal with historical complexities and unforeseen problems. Analysis of the compiled data, and reporting. Joint publication in a popular article (national), and potentially a contribution to the final scientific article (international).
Since all data are in on-line archives, this project is not time-bound, nor location specific (visits to the physical archives?). Estimated time: three - six months? Time load will depend strongly on the complexity of the archives, the national tradition and culture around eels, and your own focus. This job might fit students in history or socio-ecology as well.
Willem Dekker, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU
willem.dekker@slu.se, +46 10 478 42 48
SLU:s Fisheries research station in Älvkarleby produce c.a. 140 000 salmon and trout per year for river Dalälven. A prerequisite for environmental friendly and ethical aquaculture is that reserach is conducted on breeding and rearing of fish. Here we have ongoing reserach and environmental analsysis, and we have aquarieas, creeks and streams for experiments and in addition skilled personel.
Depending on previous education and interest the thesis can either be in ecology or environmental analysis and there is room for reserach questions of your own making. The extent is flexibel and the thesis can be done either on candidate or masterlevel.
Ann-Britt Florin, Head of Division
Department of Aquatic Resources, Institute of Coastal Research, SLU
ann-britt.florin@slu.se, +46 10 478 41 22
The paradigm shift from single species to ecosystem based fisheries management (EBFM) requires a broader, mechanistic and more in-depth understanding of marine ecosystems. Multispecies models able to account for trophic interactions and the effect of environmental variability on populations are an essential tool to move towards an EBFM. To account for predator-prey interactions in age-size structured population dynamic models high quality information on predator consumption, prey preference and trophodynamics are essential. Stomach data provide fundamental information on predators’ diet, but their collection has been generally limited which is considered one of the limiting factors for the implementation of multispecies models for the purposes of fisheries advice within the context of EBFM.
The Baltic Sea has been one of the fortunate exceptions. Here, stomachs of cod, the main predatory fish in the system, have been collected for decades. This dataset is important not only for the implementation of advanced multispecies models for EBFM in the Baltic, but also because it can serve as a benchmark to design future stomach sampling programs for the Baltic and other ecosystems.
This master project aims to explore the spatial and temporal correlation among the cod stomachs and the implications of sampling design and sample size for the estimation of the main processes linked to the implementation of multispecies models. The analyses are expected to yield alternative strategies of stomach sampling in Baltic cod and highlight costeffective sampling
schemes which sampling intensity appropriately quantifies cod predation on clupeids in the Baltic and beyond.
Requirements: good skills in spoken and written English, basic statistical skills and familiarity with R programming (ability to write simple own functions).
Work location: Lysekil
Valerio Bartolino, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
valerio.bartolino@slu.se, +46 10 478 40 58
Stock assessment of herring in the southern Baltic is currently based on a rigid geographical definition of stock boundaries which allocate herring western of Bornholm Island to the so called Western Baltic Spring spawning herring stock and herring on the eastern side of Bornholm to the large central Baltic herring stock. In reality, in this region herring reproduce in coastal habitats along the southern Swedish coasts and along the entire southern Baltic coast from the western to the eastern limits of the basin giving origin to a number of subcomponents within these two stocks.
The relationships among the different sub-components within and between the two stocks are poorly understood, as well as the level of mixing and geographical extents of overlap between the different components belonging to the two stocks remain unknown. This lack of knowledge on population structure has profound implications for the management of herring in the Baltic, both in terms of diversity and productivity.
This master project aims to evaluate the relationships between some of the main herring spawning components in the southern Baltic Sea to contribute to the harmonization of stock assessment units definitions and population structure. Moreover, the analyses are expected to identify solid baselines for future discrimination of the main herring components occurring in mixed
catches of commercial fisheries and scientific survey across this broad geographical region.
Requirements: good skills in spoken and written English, basic statistical skills (familiarity with multivariate analyses is an advantage).
Work location: Lysekil.
Valerio Bartolino, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
valerio.bartolino@slu.se, +46 10 478 40 58
Carina Jernberg, Head of Unit
Department of Aquatic Resources, Institute of Marine Research, SLU
carina.jernberg@slu.se, +46 10 478 4025, +46 761-26 80 16
Common guillemots Uria aalge L. (Am. Eng.: Common Murre) are marine piscivorous top predators with a circumpolar Arctic distribution. Long-term studies have shown that they can be important indicators of changes in marine food webs and ecosystems. The largest Common guillemot colony in the Baltic Sea (~ 15 000 pairs) is at the island of Stora Karlsö. Since 1997, a long-term research program is following this colony and collects annual data on survival, reproduction and diet, among other things.
Obtaining high energy food is a prerequisite for successful breeding and survival in Common guillemots. Several studies have shown that the main food in the Baltic Sea is sprat Sprattus sprattus. New data however show that herring Clupea harengus can also be a significant part of the diet. The energy content of herring of different sizes, and the possible energy content differences between sprat and herring is today unknown. The knowledge is important for evaluating the conservation status of Common guillemots in the Baltic Sea and how much fish that must be left in the sea to ensure survival of seabirds.
The degree thesis focusses on analyzing the energy content of the prey fish of Common guillemots. The fish has already been collected by the Institute of Marine Research in Lysekil. The fish will be analyzed using a bomb calorimeter by the student. This work will take place in Ultuna, Uppsala. The data obtained will be analyzed statistically. The project is planned for Bachelors level (15 ECTS) but can be expanded into a Masters project as well (30 – 60 ECTS).
Links:
www.balticseabird.com
www.storakarlso.se
Jonas Hentati Sundberg, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
jonas.sundberg@slu.se, +46 10 478 40 70, +46 739-38 79 69
Common guillemots Uria aalge L. (Am. Eng.: Common Murre) are marine piscivorous top predators with a circumpolar Arctic distribution. Long-term studies have shown that they can be important indicators of changes in marine food webs and ecosystems.
The largest Common guillemot colony in the Baltic Sea (~ 15 000 pairs) is at the island of Stora Karlsö. Since 1997, a long-term research program is following this colony and collects annual data on survival, reproduction and diet, among other things. In 2008, a world unique research facility, the Karlsö Auk Lab, was built in the middle of the colony. Scientists can study breeding birds from the inside of the Auk lab at a very close distance (20 – 30 cm). This opens up for extremely detailed studies to a low disturbance.
This degree thesis is about evaluating a new technology for monitoring breeding success in Common guillemots – through automatic cameras. Today breeding is monitored through daily observations to check which eggs and chicks that are present. The new technology builds on images taken at regular intervals, and at a later stage analysis of the images. If this technology is working, there is a big potential of increasing data collection and reduce time spent close to the birds (which also leads to lower disturbance levels). The field work includes both traditional observations studies and collection and analysis of images.
At least four weeks will be spent at Stora Karlsö for field work. The island has a simple field station in the period May – early July. The student will work with experienced field personnel and a field work coordinator. The project is planned for Bachelors level (15 ECTS) but can be expanded into a Masters project as well (30 – 60 ECTS).
Links
www.balticseabird.com
www.storakarlso.se
Jonas Hentati Sundberg, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
jonas.sundberg@slu.se, +46 10 478 40 70, +46 739-38 79 69
Andreas Bryhn, Researcher, Director of Studies
Department of Aquatic Resources, SLU
andreas.bryhn@slu.se, +46 10 478 41 52
