Fisheries and management projects

Here you can find ideas for projects within fisheries and management for bachelor and master students. You may also contact a supervisor directly in order to formulate another topic.

Laboratory and field work

Bivalve valve opening behaviour – field and laboratory applications (special course)

Bivalve valve gape aperture movements can provide valuable information regarding the behaviour of the animals: feeding, reproduction etc. Physiological rhythms are linked with environmental factors such as adverse conditions linked to food concentration, salinity, disease. The aim of the project is to build up and test an electronic instrument to monitor valve gape aperture of bivalve both in the laboratory and in the field. Image analysis is often used to measure the valve gape aperture of bivalve. This is time consuming. Examples of sensors+loggers exist and are well described in the literature. Sensors placed on valves can record continuously the movements of the valves over long period of time, both in the laboratory and in the field. This project would require a student interested in both the electronic part of the project: building the instrument and in the analyses and testing of the instrument both in the laboratory and in the field. Environmental factors such as: temperature, salinity, food concentration will be recorded at the same time as the valve gape monitoring. In the laboratory, mother oysters from brooding stocks will be studied to detect preliminary symptoms of mortality and release of gametes (only between March and July) alternatively, during other period of the year, testing will be done on mussels. The experiments will be carried out at the Danish Shellfish Centre, Nykøbing Mors. Duration: 1-2 months (5-10 ECTS).

Contact: Camille Saurel

Jellyfish predation on blue mussel larvae (master)

Big blooms of jellyfish, here referring to both the true jellyfish and the comb jellies, are known to have a pronounced effect on the zooplankton community. Most studies have however focused on predation on fish eggs/larvae and copepods to evaluate the consequences for fish stock. It is however known from gut content analysis that jellyfish can also consume the larvae of several benthic filter feeing animals such as M. edulis but the magnitude and there by consequences are not known. The aim of the project is to study the effect of jellyfish predation on the larvae of benthic filter feeding animals with focus on the blue mussel M. edulis – a combined laboratory and field study. The project will focus on the predatory role of the dominating jellies in Limfjorden, the scyphozoan Aurelia and the invasive ctenophore Mnemiopsis, depending on season. Direct predation of jellyfish (Aurelia or Mnemiopsis) on the early larval stage of blue mussels (M. edulis) will be conducted in controlled laboratory experiments. The jellyfish will be sampled in the fjord or alternatively laboratory cultures for Mnemiopsis - depending on season. Gut content analysis of jellies from the Limfjorden will be analyzed. The data from the current project will, together with available data in the literature on jellyfish in Limfjorden and data from the national monitoring program, evaluate if the jellyfish could have an effect on the benthic filter feeders. This would be a first attempt to do such sort of analysis.

Mussel in situ clearance rate methodology based on biodeposition (master)

Mussel defecation method is a handy methodology, non-intrusive which calculates the clearance rate of mussel prior to their manipulation. The method has been previously used in the field and requires the calculation of a calibration factor each time it is used. Modelling of the calibration factor with key environmental factors has not yet fully been developed and requires more experimentation under controlled environment in the laboratory. The aim of the project is to calibrate in situ methodology with existing ones to model the mussel clearance rate from biodeposition material under different environmental conditions (temperature, salinity, food quality and quantity). Multifactorial experiments will be carried out in controlled temperature environment in order to model the calibration factor at the Danish Shellfish Centre, Nykøbing Mors.

Contact: Camille Saurel

Feeding and growth in the common starfish Asteria rubens (master)

The common starfish (A. rubens) feeds primarily on the blue mussel Mytilus edulis. There are so many starfish in some places in the Limfjorden, that they are a threat to both mussel bottom cultures and wild mussel beds and thereby a big problem for the mussel fishermen. It is of interest to know how much the starfish actually consume and if they select some prey sizes over others. The aim of the project is to study bioenergetic parameters, especially feeding and growth, in the common starfish A. rubens in controlled laboratory experiments. When evaluating if the starfish are realizing their growth and feeding potential in the field it is necessary to know the actual potential. This will be studied in controlled laboratory experiments where starfish are fed blue mussels in different concentrations. First it will be evaluated experimentally which size classes of M. edulis are preferred by starfish of different sizes. Larger growth experiments can then be carried out with the optimal combination of starfish vs. mussels. The growth of the starfish is followed over a month where they are fed blue mussels in different concentrations under controlled conditions. Together wit a literature review, it will be possible to construct carbon budgets for the starfish and calculate their impact potential impact on the mussel beds.

Starfish population predatory movements at a broad scale (master)

Fierce starfish predation on mussels (commercial long-line, bottom culture and wild mussel beds) severely impacts the mussel (Mytilus edulis) industry in the Limfjord, Denmark. Monthly monitoring of starfish density around a newly relayed mussel bed will be taking place for at least 7 months within two projects: Idé Katalog and STARPRO. Little is known from the starfish feeding front and the way newly relayed bed might be attracting and feeding the starfish population in the Limfjorden. The aim of the project is to describe and explain the predatory movements of starfish towards relayed mussel beds from monitoring data and laboratory experiments. A relayed mussel bed in a starfish free zone was prepared in Autumn 2015. Monthly monitoring of starfish movements from a distance up to 10km to the bed will be carried out. The monitoring will provide information on starfish morphometry, physiology, density, and populations from various distance from the bed. Field results will be compared to laboratory experiments on starfish locomotion speed and prey selection (crashed vs entire mussels). Video recording from the starfish purse seine used by the fishermen will also be analysed to calibrate the density of starfish on the bottom toward the newly relayed mussel bed. The experiments will be carried out at the Danish Shellfish Centre, Nykøbing Mors.

Contact: Camille Saurel

The invasive round goby (bachelor or master)

The invasive round goby Neogobius melanostomus has spread via ballast water from the Caspian Sea into the Great Lakes in US, the Baltic Sea, and several European rivers. It thrives in both freshwater and brackish water and endures salinities as high as 30 PSU. It was first discovered in southern Denmark in 2008 and is currently spreading northward along the coast at a pace of 30 km per year. It has established dense population in several areas where they are considered a threat to the prevailing ecosystem and local fisheries. In January 2016 DTU Aqua launched a 3 year round goby project. The purpose of this project is to gather more information about the invasion dynamics of the round goby and explore the possibility of regulating round goby abundance through a profitable bio-sustainable fishery. The project opens up for a number of practical student project opportunities, including laboratory experiments and field studies.

Contact: Jane W. Behrens or Mikael van Deurs

Aggressive and hungry: Overtaking the Danish coastal waters?

The round goby Neogobius melanostomus (sortmundet kutling) presumably originated in The Caspian Sea where from it was spread via ballast water into the Great Lakes of the States and further into Danish coastal waters where it was first observed in 2008. It has since then increased dramatically in numbers and spread along the south-eastern coastlines of Denmark. To be able to predict the spreading potential of the round goby we need to know how adults and eggs cope with various oxygen, salinity and temperature conditions. In this project you will investigate salinity tolerance of adult round goby and their eggs, and also determine the energetic costs of osmoregulation (that is, the costs associated with keep internal ionic homeostasis when the fish encounter a salinity gradient).

Contact: Jane W. Behrens, or Mikael van Deurs, or Torkel Gissel Nielsen

How can we track individual behavior of schooling fish? (bachelor or master)

Most of us can recall BCC´s Nature productions and the whirly clouds of fish clumping together in dreadful attempts to avoid hungry predators or the huge schools of migrating fish in the Benguela current. However, we can film schools in the wild or observe them in aquariums as much as we like, but it will not bring us any closer to understanding the mechanisms that control the interactions among the individual fish in the school. Although many scientists over times have probed into this topic, the truth is that our present understanding of how fish schools works is extremely limited. The problem is tracking of individuals. Several attempts to make computer-tracking of individuals filmed in aquariums with white backgrounds has been attempted, but all have failed when schools reach more than 10 – 20 individuals. We are looking for a student that is interested in taking up the challenge as he/she explores new ways of tracking individuals. Innovating small acoustic tags may be one way of approaching the problem, but all ideas are welcome.

Contact: Asbjørn Christensen or Mikael van Deurs

Non-lethal species interactions: Are territorial wrasses harassing juvenile cod? (bachelor or master)

The majority of studies dealing with species interactions have focused on the lethal aspects of interactions between predators and their prey. However, a small number of studies have demonstrated the importance of also considering the non-lethal effects of species interactions. In a new DTU Aqua project starting up in 2014, we will study species interactions on marine reefs in Danish waters. We will in particular be focusing on the non-lethal interactions between territorial wrasses and juvenile cod utilizing reefs as nursery habitats. We ask the question to what extent wrasses and juvenile cod display an overlap in reef habitat preferences, and whether the territorial wrasses harass the less aggressive juvenile cod and thereby force the cod to settle for sub-optimal locations on the reef (or outside the reef) with consequences for growth and survival. The project has both a field component and a laboratory component. The laboratory experiments will be conducted at facilities at the Blue Planet, where interactions between wrasses and juvenile cod will be monitored on designed reefs using tagging equipment and video-technology.

Contact: Mikael van Deurs

Winter migration of fish in lakes: Migration patterns of perch in relation to body shape and size (bachelor or master)
An understanding of fish behavior is essential to manage the waters of freshwater lakes in general and its fish-stocks in particular. In shallow lakes seasonal coarse fish like bream and roach often perform seasonal migrations into adjacent streams and rivers where they overwinter. Predator fish such as perch and pike rarely participate in the winter migration. However, in one lake, we have to our surprise repeatedly observed immense migrations of perch during winter. We have data for several years of migration behavior, but so far these data has not been analysed. This project aims to describe patterns of winter migration and next to clarify if factors such as body shape (based on photographs of migratory and non-migratory perch) and size influence which perch and when perch migrate. Migration patterns of perch in freshwater systems has never been described before so here is a chance to do some true pioneering work. Field work can easily be included in the project, but it is not a necessity.

Contact: Christian Skov

Winter migration of fish in lakes: How does migration patterns of individual fish relate to previous experienced growth patterns? (bachelor or master)
An understanding of fish behavior is essential to manage the waters of lakes in general and fish-stocks in particular. In shallow lakes fish like bream and roach migrate out of the lakes in winter and overwinter in adjacent streams. However, not all bream and roach are involved in migration and the reasons for these individual differences are not clearly established. One theory is that only fish in good body condition participate in migration (because they energetically can afford it), while fish in poorer condition stay put in the lake. This project is about analyzing the differences in growth between individuals that migrate and fish that stay in the lake. Specifically, it should be tested if fish that migrate have had a better growth during the summer (and thus probably also a better condition) than fish staying in the lake during winter. Field work can easily be included in the project, but it is not a necessity.

Contact: Christian Skov

Survival and behavior of stocked trout in lakes (bachelor or master)
In Denmark we stock trout of smolt size (17-22cm) in a number of lakes, as compensation for lack of natural recruitment. However, there is almost no knowledge of the fate of these fish after stocking and there are very few reports on trout catches. This could be investigated by tagging trout before stocking and follow the fish afterwards. Tagging with pittags, will enable us to monitor a large amount of fish to see whether the migrate out of the lake and tagging with radio-transmitters will allow us to follow a smaller amount of fish closely by tracking their position in the lake regularly.

Feeding behavior and swimming activity of larval European eel (master)
Starvation and predation are main causes of extensive mortality rates in fish larvae. In the wild, size selective predation contributes significantly to mortality during early life and ultimately determines the optimal size for a larva at any given age throughout ontogeny. In an aquaculture setting, predation pressure is removed (unless cannibalistic) thus starvation and environmental conditions become important factors for survival. To avoid starvation, feeding rate of a larvae depends on opportunities for the larvae to encounter prey which is dependent on the swimming velocity of the larvae as well as the distance the prey item is detected and reacted upon. Capture success also determines feeding rate and is dependent on the speed of a strike and the accuracy in aiming. In order to better understand fish recruitment processes and to improve culture conditions, foraging and swimming activity will be evaluated for European eel. Studies will be conducted at DTU Aqua’s facility in Vamdrup and data analyses/thesis preparation will be completed at DTU Aqua in Charlottenlund.

Contact: Jonna Tomkiewicz

Effect of density on embryonic and larval performance in the European eel (master)
European eel has long been a valued species targeted for aquaculture production. Recent experimental research in the international PRO-EEL project has led to the successful production of many large egg batches, with high fertilization rates, and viable embryos and larvae from both wild-caught and farmed eels. Further research is still required to evaluate the effect of density on embryonic and larval performance as “suboptimal” culture conditions, especially when intensive culture systems are used, can lead to poor water quality, occurrence of epizootics, decreased foraging efficiency, and an increase in size segregation and cannibalism. Here, two experimental studies will be conducted. The first study will investigate how density influences embryonic development, while the second study will examine how density effects larval foraging behaviour, growth and survival. Studies will be conducted at DTU Aqua’s facility in Vamdrup and data analyses/thesis preparation will be completed at DTU Aqua in Charlottenlund.

Contact: Jonna Tomkiewicz

Phenotypic plasticity in early life history traits of the European eel: assessment using different genotypes across a thermal gradient (master)
Fish populations are dependent on good quality gametes for production of offspring. Maternal contributions to progeny are comprised not only of nuclear genetic material, but also an extra-nuclear contribution in the form of a yolk supply. In many species of fish, yolk accounts for a substantial percentage of mass in developing embryos and acts as the primary energy reserve from fertilization to first feeding. On the contrary, paternal contributions to growth and survivorship during the early life have been largely neglected. However, when paternal effects are tested in properly designed experiments they have been shown to account for a significant amount of variation in phenotypic expression. In these studies the influence of parental effects on offspring performance will be investigated across a thermal gradient to examine phenotypic plasticity. Studies will be conducted at DTU Aqua’s facility in Vamdrup and data analyses/thesis preparation will be completed at DTU Aqua in Charlottenlund.

Contact: Jonna Tomkiewicz

Modeling and data analysis

Projects that combine management, fisheries science and ecology (bachelor or master)
Industrial fisheries are exploiting the highly abundant short-lived forage fishes and selling their catches to the fish meal industry. Fishing for forage-fishes (i.e. sandeel, sprat, capelin, norway pout) is subject to major criticism, and for good reasons. Forage fishes, given their immense biomass and small size, are the primary linkage between lower and higher trophic levels. Removing forage fish biomass could potentially result in shorter food chains and reduced biomass at the highest trophic levels, unless we are capable of fishing at or near maximum sustainable yield where fishing is assumed to release density dependent mechanisms an increase productivity. Consequently, the demand for high quality catch advice is immense. We have identified several student projects spanning from hands-on practical projects to modeling projects and from highly applied studies to purely theoretical studies.

Contact: Henrik Mosegaard or Mikael van Deurs

A fine scale analysis of the relationship between fish-activity and water quality in lakes (bachelor or master)
An understanding of fish behavior is essential to manage the waters of lakes in general and fish-stocks in particular. Many lakes suffer from poor water quality i.e turbid water. EU Water Framework Directive requires that water quality in many lakes must be improved. The turbid water in lakes may be due to algal blooms, but it may also be due to resuspension of sediment material coursed by bottom feeding fish such as bream and carp. In a shallow Danish lake we have for a prolonged period monitored water turbidity as well as bream activity on an hourly basis. These dataset must be combined and can certainly give new and more detailed knowledge of the fish's role in relation to water clarity in shallow lakes and it is up to the student to make sure this happens.

Contact: Christian Skov

Species-, size- and seasonal-specific differences in fish behavior in a shallow lake: First mover results (bachelor or master)
An understanding of fish behavior is essential to manage the waters of lakes in general and fish-stocks in particular. DTU Aqua is currently testing a new method to study fish behavior in lakes. We have placed 6 "monitoring stations" (three close to the shore and three in open water) in a shallow lake which all year round and around the clock detects fish activity, previously tagged with a minute electronic tag. Annually we tag about 1000 fish and hence the data set is substantial. In this project the student will, as the first person ever, make a general description of these data. Much of the initiative in order to define the focus of this will be in the hands of the student, but studies of differences in habitat choice and activity (number of fish recorded) in relation to species, fish size, time of day and season seems recommendable. This particular method to explore fish behavior has basically never been described before and its potential is therefore underexplored, so here is a chance to do some true pioneering work.

Contact: Christian Skov

Cost effective biomanipulation: Fish removal in streams during winter-migrations (bachelor or master)
Many lakes suffer from poor water quality i.e turbid algae-filled water. EU Water Framework Directive requires that water quality in many lakes must be improved. A method for this is biomanipulation where zooplanktivorous fish such as bream and roach are removed to "push" the lake towards a clear water state. This can be an economically costly affair, but opportunities exist for cost efficient fish removals. In winter, massive amounts of fish gather in the inlet and outlets to shallow lakes and in theory it should be more cost efficient to catch fish here compared to chasing fish in the open water of the lake. However, a successful fish removal in the streams depends on knowledge on when fish-biomass is at the highest density in the streams. Moreover it needs to be explored if fish removals that exclusively occur on migratory fish affect the evolutionary potential of the fish population.

Contact: Christian Skov

Winter migration of fish in lakes: Why are there differences between year and lakes? (bachelor or master)
An understanding of fish behavior is essential to manage the waters of lakes in general and fish-stocks in particular. In shallow lakes fish like bream and roach migrate out of the lakes in winter and overwinter in adjacent streams. However, not all bream and roach are involved in migration and the reasons for these individual differences are not clearly established. DTU has for several years studied such migrations and published many results about this. However, we still need further understanding of the factors driving the differences we observe in migration patterns between years and lakes. This relates both to the amount of fish that migrate and the way in which migration takes place, for example in some years all fish migrate out of the lake within a few days, while in other years the migration is more gradually. This project should describe and explore patterns of migration in two lakes which DTU has sampled 2005. Next, migration patterns should be correlated with factors such as water temperature, ice cover, Secchi depth and coverage of aquatic plants.

Contact: Christian Skov

Winter migration of fish in lakes: Migration patterns of perch in relation to body condition, growth and feeding patterns (bachelor or master)
An understanding of fish behavior is essential to manage the waters of freshwater lakes in general and its fish-stocks in particular. In shallow lakes coarse fish like bream and roach often perform seasonal migrations into adjacent streams and rivers where they overwinter. Predator fish such as perch and pike rarely participate. However, in one lake, we have to our surprise repeatedly observed immense migrations of perch during winter. We have data for several years of migration behavior, but so far these data has not been analyzed and so far we have no understanding of why perch migrate and how they are doing through the winter in the streams where food is scarce. In this project, stomach contents from migratory and non migratory perch shall be compared throughout a winter season. This will give us an idea if perch has an energetically cost to migration. At the same time growth patterns of migratory and non-migratory perch will be established from scale samples and compared. Finally, analysis of water content in muscle tissue of migrants and residents should be analyzed to examine if the two groups differ in body condition.

Contact: Christian Skov

Fisheries selectivity and balanced harvesting (master)
A key instrument in fisheries management is how the fisheries gear selects for the size of the caught fish. The classic theory states that the Maximum Sustainable Yield from the fishery is achieved when only the largest individuals are caught. This theory has recently been challenged by the concept of “balanced harvesting” suggesting that all components of the ecosystem should be harvested, and that the fishing pressure should be proportional to the productivity of each component of the community. The aim of this project is to compare the “classic” theory with “balanced harvesting” adressing the following questions: Which size-selectivity of the fishing gear gives the highest yield? What is the impact of fishing on resilience to environmental noise and on stock variability? The methodology is structured population models of a single fish stock or two or more interacting species.

Contact: Ken H. Andersen and Nis S. Jacobsen

Life-history optimization theory (master)
“Nothing in biology makes sense except in the light of evolution” is a famous bon-mot by the evolutionary biologist Theodosius Dobzhansky. This is a way of saying that the design and behavior of any living organism can be understood as an optimization to its environment, an optimization which is brought about by evolution through natural and sexual selection. Such optimization arguments can be formulated through life-history-optimization theory, which can answer questions like: under which conditions should an organism feed and thereby expose itself to predation? How shall ingested food be allocated between growth, reproduction and activity at a given time of the year? Why do large marine organisms (baleen whales and basking sharks) choose to eat very small prey? Etc. The arguments can be formulated using basic mathematics or they can involve sophisticated dynamic optimization theory. This project will be about developing optimization arguments for a behavioral or adaptive trait of a specific marine organism or group of organisms.

Contact: Ken Haste Andersen

Traits of fish (master)
Instead of describing organisms as belonging to a certain species, they can be described as having a certain number of traits. This is the central idea in the Center for Ocean Life at DTU Aqua (see oceanlifecentre.dk). This project will analyse the fish community (or perhaps another marine community) to determine which are the most relevant traits to describe the diversity of fishes. The project will involve collecting data from databases and the literature and making simple statistical analyses.

Contact: Ken Haste Andersen

Response of fish community to fishing (master)
When a fish stock is fished, the result is fewer fish. But what happens to the other species in the fish community? Some species will be prey for the fished stock, and can therefore be expected to benefit from fishing of their predation, while other species may rely on the fished population for food. This project will try to answer how fishing on a specific stock influences the rest of the fish community using size-spectrum models

Contact: Ken Haste Andersen

Balanced fishing (master)
A recent suggestion for fisheries management has been to fish small individuals harder than large individuals through what has been termed “balanced” exploitation. This suggestion runs counter to common management which tries to avoid fishing small individuals through minimum-size catch regulations. This project will evaluate the idea of balanced exploitation for a specific fish stock using size-spectrum models for a single stock.

Contact: Ken Haste Andersen

Fisheries induced evolution (master)
Fishermen, and in particular recreational fishers, tend to prefer catching the largest fish in a population. This is an example of selection, and selection leads to an evolutionary response. This project will try to evaluate the consequences of fisheries-induced evolution on traits like growth rate, size at maturation and investment in reproduction for different fishing patterns. The project could be either a calculation of how different types of fishing leads to evolution, or it could be a statistical evaluation of the amount of evolution observed in a fished stock.

Contact: Ken Haste Andersen

Has climate change impacted the phenology of fish stocks? (master)
The impact of climate change upon the phenology (timing) of key biological events is thoroughly documented in terrestrial systems, yet such evidence is almost absent in marine systems. One reason for this situation is the disparity in the ease of making observations between the two systems: data sets with sufficiently high temporal coverage and resolution are generally lacking in marine science. One such dataset, however, is to be found close by: the North Sea herring fish stock has been the subject of a high quality monitoring program for over 40 years now. In this project, you will analyze this data set with the aim of testing for changes in the timing of spawning over time, and attempt to relate these changes to potential environmental influences, including climate variability.

Have climate-induced changes in the circulation of the North Sea impacted the survival of juvenile fish? (master)
The physical and biological environments of the North Sea are strongly influenced by its open boundary to the Atlantic ocean to the north. The inflow of Atlantic water and the associated circulation within the North Sea proper have long been hypothesised to be important for the fish populations that live there, and particularly for North Sea herring: however, direct quantitative evidence for changes in these processes are lacking. In this project you will analyze the outputs of oceanographic circulation models with the aim of quantifying these changes for the first time. You will then attempt to relate these processes to North Sea herring, and thereby assess the importance of circulation in the early-life history of this fish population.

Has climate-change impacted the growth rates of fish in European waters? (2 projects; master)
A warming climate impacts the growth of fish species in many complex ways. For example, warming increases metabolism and thereby food requirements, but it can also change the quantity and quality of food available. Growth rates are therefore a sensitive indicator to climate-induced changes in both the physical and biological environment. This work, which can be expanded to two separate projects if there is interest, will analyze data from around European waters with the aim of identifying such changes. The first project will focus on the various populations of a single species (herring), looking for common patterns in growth. The second project will focus on the fish populations in a given region (the North Sea), looking to derive a region-wide assessment of the impacts of climate change.

Has climate-change impacted the ecosystem of relevance to North Sea herring? (master)
Several regime shifts (a stepwise change in the structure of the ecosystem) have been identified in the North Sea during the last thirty years, possibly in response to a warming climate. These changes are often used to explain variability in the survival and productivity of North Sea herring. However, these analyses are generic and may, or may not, reflect the actual ecosystem (both predators and prey) of relevance to herring. In this work you will develop a list of key species that are potentially of relevance to herring. You will then analyze observational (CPR) data based on this list, with the specific aim of generating an assessment of changes in the “herring-relevant” ecosystem, and thereby attempt to understand the consequences for this fish population.

Data-archaeology: North Sea herring (master)
North Sea herring is one of the most well-studied fish populations in the world: data on this stock can be found back into the late-1800s in some cases. However, although there exists a wealth of such data, only a small fraction of this information is used in both modern science and stock-assessment. This project aims to improve this situation. As a starting point, herring larval surveys performed in the 1960s and 1970s will be recovered and statistically merged with the modern data sets to gain a comprehensive overview of the dynamics of these fish populations through time. It is expected that the process of unearthing these larval data sets will also lead to the identification other, hereto unknown, data sources that can also potentially be used to shed fresh new light on this population.

Individual quota allocation scheme for the Danish fishing vessels: A linear programming example (master)
A recent shift in fisheries management advocated for developing individual quotas in place of Total Allowable Catches (TACs) which are usually recognized as perverse incentives for fishermen to “race for fish” and create excess vessel capacity. Hence, individual quotas now start to be implemented worldwide and should also be soon included in the next EU common fishery policy reform scheduled for 2013, while the problem of quota allocations remains a highly challenging issue for managers and scientists. To prepare to this, the main goal of the training period is to develop and parameterize a generic model for allocating stock quotas to individual vessels, exemplified to the Danish fisheries (approximately 20 assessed stocks for 300 vessels). This model should build upon the so-called linear programming framework, widely used in environmental economics. The developed system should serve as a benchmark tool for quickly evaluating alternative solutions in quota allocation, allowing for sensitive experimentation with the problem parameters and the various constraints. The parameterization of this model would benefit from recent in-house advances in analyzing fishery data at a fine spatial and temporal scale. Among other uses, the output of this work is planned to inform the spatially explicit individual vessel-based model we recently developed at DTU-Aqua to model the economic activity of every single Danish vessels.

This study will be conducted in association to external EU and national research projects. The development of such an approach will be an important tool in near future development in ICES and EU advice and future broader marine spatial planning context being a strong representative for spatial explicit bio-economic models that covers both many stocks and fisheries. With the purpose of empowering the student with practical skills, the student should develop some advanced skills during this period in various fields that make fisheries science attractive as a multi-disciplinary issue, from ecology to fleet dynamics to environmental economics, including advanced statistics and scientific reporting. Prior knowledge in optimization procedures e.g. the GAMS software and/or R programming and/or econometrics would be an advantage.

Contact: Francois Bastardie and J. Rasmus Nielsen

Improving management of the Norway pout (mixed) fishery by integrating analyses of highly disaggregated spatial and temporal distribution patterns and gear selectivity developments (master)
The aim of this project is to evaluate optimization of the Norway pout fishery by reducing by-catch of other gadoids (cod, whiting, saithe) and herring by integrating detailed quantitative information on specific distribution patterns according to age and size, geographical bank area, day and night as well as new data on gear technological selectivity devices. From this, details on Norway pout specific distribution and fishery selectivity in time and space and details on spawning will emerge to be used in a more optimized management of the fishery. The student will during the training period make an integrated analysis of fisheries catch and effort data, data from various Danish and Norwegian commercial trial fisheries in different areas at different times (seasons, diurnal – scientific controlled and designed), data from Danish and Norwegian trial fisheries testing different selective devices, which all will be associated with integrated with analysis of data from fisheries research surveys, i.e. the ICES North Sea BITS survey data. This integration and combination of different types of data will enable analysis and management advice on more optimal Norway pout fishery in time and space with optimal fishing gear selective devices to be elaborated on in the the¬sis report. There will for sure be basis for a publication of this in a scientific peer reviewed journal. The aim will be to make a thesis report which can be submitted as a scientific research paper.

Contact: Ole R. Eigaard and J. Rasmus Nielsen

Design and physical optimization of fishing gear (master)
In collaboration with DHI Group, computational fluid dynamical (CFD) simulations of fishing gear is performed in relation to design parameters. Depending on your background and interests, the design parameters can be energy efficiency, catch selectivity and minimizing bottom habitat impact. Also within this area it is possible to simulate fish response to fishing gear using agent-based methods to optimize species selectivity and efficiency. These projects typically involves many disciplines.

Contact: Asbjørn Christensen and Niels Madsen

Design of Marine Protected Areas (bachelor or master)
Marine ecosystems are under pressure from human activities (e.g. fishing, offshore constructions, pollution/eutrophication) and to conserve marine, life marine protected areas (MPAs) are established many coastal regions in these years. However what is the optimal location, size and shape of such protected areas? And what is the impact on e.g. fisheries from protected areas? Today nobody can really tell this and marine protected areas are designed based on empirical and weakly supported principles. In this project you will develop mathematical models of MPAs to describe the efficiency and impact of MPAs in relation to their location, size and shape, which includes relevant oceanographic processes. Depending on your background and interests, you can consider specific case studies (e.g. sandeel in the North Sea, where spatial models are available) or more generic mathematical models based on core oceanographic scales.

Contact: Asbjørn Christensen

Fish school size/shape dynamics (bachelor or master)
Flocking is very common in the animal kingdom. For fish a major reason to form schools is to avoid predation. However fish in schools also have to share food resources and oxygen in the surrounding water. So being in fish schools is a trade-off. I this project you will develop mathematical models of the trade-offs (pros and cons) of a fish school, predicting size/shape distributions of fish schools under various environmental and ecosystem conditions and analyze the formation and stability of fish schools.

Contact: Asbjørn Christensen

Smart swimming (master)
Small fish have limited swimming capability and they need behave cleverly in order not to spend unnecessary energy on swimming against currents or even get carried away by currents. In this project you will consider a case study and develop mathematical models to describe the energy budgets in relation to fish swimming. One case study is North Sea sandeels: they bury in sandy habitats, but each day have to swim to feeding ground in quite strong tidal currents with a period of 12.42 hours. How should the sandeels behave to minimize their swimming costs. In this case study you will setup an agent based model of fish energy budgets, its risk trade-offs and describe simulate fish swimming behavior close to its habitat, in collaboration with DHI Group which provides realistic small scale model of variable water currents and food (zooplankton) distribution. Other case studies addressing optimal swimming behavior for migrating species are also possible, depending on your background and interests.

Contact: Asbjørn Christensen

Modelling of migration dynamics of harbour porpoise (master)
Aarhus University has recently published a report where harbour porpoise migration dynamics is simulated using an agent-based approach in Kattegat and inner Danish waters. The model describes individual motion a correlated random walk, including food availability (and depletion), bioenergetics and presumed recollection of previous high-value feeding areas. The model was compared with data from electronic tracking devices. In the project you will, in collaboration with DHI Group and Århus University, implement/test parts of this model in DHIs agent-based model framework ECO Lab, using input from existing validated 3D hydrodynamical and biogeochemical data sets provided by DHI Group. This project targets environmental impact assessment, including acoustic noise from off shore wind farms, ships and marine seismic explorations.

Contact: Asbjørn Christensen and Finn Larsen