Maciej Tomasz Tomczak

Swedish University of Agricultural Sciences | SLU · Department of Aquatic Resources

The project “Cumulative effects assessment tools for the Baltic Sea – BalticCAT” aimed to support the work on cumulative environmental assessments for the Baltic Sea ecosystem in marine and fisheries management and marine spatial planning. The project has studied which stressors interact to explain the poor situation of cod in the eastern Baltic Se...

The Workshop on pathways to climate-aware advice (WKCLIMAD) met in the autumn of 2021 to develop a proposal for an advisory framework that accounts for the influences of climate change on aquaculture, fisheries, and ecosystems. The workshop worked through online ses-sions with over 40 participants. Climate-informed advice should be provided through...

Multispecies models have existed in a fisheries context since at least the 1970s, but despite much exploration, advancement, and consideration of multispecies models, there remain limited examples of their operational use in fishery management. Given that species and fleet interactions are inherently multispecies problems and the push towards ecosy...

The complexities of ecosystem-based management require stepwise approaches, ideally involving stakeholders, to scope key processes, pressures, and impact in relation to sustainability and management objectives. Use of qualitative methods like Fuzzy Cognitive Mapping (FCM) with a lower skill and data threshold than traditional quantitative models af...

Ecosystem-based management requires understanding of food webs. Consequently, assessment of food web status is mandatory according to the European Union’s Marine Strategy Framework Directive (MSFD) for EU Member States. However, how to best monitor and assess food webs in practise has proven a challenging question. Here, we review and assess the cu...

The occurrence of regime shifts in marine ecosystems has important implications for environmental legislation that requires setting reference levels and targets of quantitative restoration outcomes. The Baltic Sea ecosystem has undergone large changes in the 20th century related to anthropogenic pressures and climate variability, which have caused...

Sustainable environmental management needs to consider multiple ecological and societal objectives simultaneously while accounting for the many uncertainties arising from natural variability, insufficient knowledge about the system's behaviour leading to diverging model projections, and changing ecosystem. In this paper we demonstrate how a Bayesia...

Marine Protected Areas (MPAs) are an important tool for management and conservation and play an increasingly recognised role in societal and human well-being. However, the assessment of MPAs often lacks a simultaneous consideration of ecological and socio-economic outcomes, and this can lead to misconceptions on the effectiveness of MPAs. In this p...

The MSP Challenge Simulation Platform helps planners and stakeholders understand and manage the complexity of Maritime Spatial Planning (MSP). In the interactive simulation different data layers covering an entire sea region can be viewed to make an assessment of the current status. Planners can create scenarios for future uses of the marine space,...

Eutrophication is one of the most important anthropogenic pressures impacting coastal seas. In Europe, several legislations and management measures have been implemented to halt nutrient overloading in marine ecosystems. This study evaluates the impact of freshwater nutrient control measures on higher trophic levels (HTL) in European marine ecosyst...

Identifying key indicator species, their life cycle dynamics and the multiple driving forces they are affected by is an important step in ecosystem-based management. Similarly important is understanding how environmental changes and trophic interactions shape future trajectories of key species with potential implications for ecosystem state and ser...

Ecosystem-based marine management can be considered to be most effective through establishing end-to-end representations of marine ecosystems from physical processes to fish using ecosystem models. Yet no single model includes sophisticated delineations of physical, biogeochemical and food web processes altogether to form a realistic picture of mar...

Aquatic ecosystem services are important for human wellbeing, but they are much less studied than terrestrial ecosystem services. The objectives of this study are to broaden, itemize and exemplify the human‐nature interactions in modeling the future provision of aquatic ecosystem services. We include shared socioeconomic and representative concentr...

Two-way coupling between an existing biogeochemical model and a food web (Ecosim) model of the Baltic Sea

The MSP Challenge Simulation Platform helps planners and stake-holders understand and manage the complexity of Maritime Spatial Planning (MSP). In the interactive simulation different data layers covering an entire sea region can be viewed to make an assessment of the current status. Planners can create scenarios for future uses of the marine space...

We developed numerical simulations of potential future ecological states of the Baltic Sea ecosystem at the end of century under five scenarios. We used a spatial food web (Ecospace) model, forced by a physical–biogeochemical model. The scenarios are built on consistent storylines that describe plausible developments of climatic and socioeconomic f...

Long-term scenario analyses can be powerful tools to explore plausible futures of human development under changing environmental, social, and economic conditions and to evaluate implications of different approaches to reduce pollution and resource overuse. Vulnerable ecosystems like the Baltic Sea in North-Eastern Europe tend to be under pressure f...

Different ecosystem models often provide contrasting predictions (model uncertainty), which is perceived to be a major challenge impeding their use to support ecosystem-based fisheries management (EBFM). The focus of this manuscript is to examine the extent of model disagreements which could impact management advice for EBFM in the central Baltic S...

Description of models and scenarios used in the study. (DOCX)

Ecosystem Overviews (EOs) are central products in the ICES approach to support Ecosystem Based Management, through providing the ecoregion context, identifying main pressures, asso-ciated human activities and impacts on ecosystem state. The WKEO3 explored and discussed both stakeholder/client and expert views on the development of the EOs, and asse...

Seal populations are recovering in many regions around the world and, consequently, they are increasingly interacting with fisheries. We used an Ecopath with Ecosim model for the offshore Central Baltic Sea to investigate the interactions between the changes in fish stocks and grey seal (Halichoerus grypus) population under different fishing and en...

In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribution of functional groups within a marine ecosystem, w...

Ecosystems are known to change in terms of their structure and functioning over time. Modelling this change is a challenge, however, as data are scarce, and models often assume that the relationships between ecosystem components are invariable over time. Dynamic Bayesian Networks (DBN) with hidden variables have been proposed as a method to overcom...

In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribution of functional groups within a marine ecosystem,...

Marine ecosystems evolve under many interconnected and area-specific pressures. To fulfil society's intensifying and diversifying needs while ensuring ecologically sustainable development, more effective marine spatial planning and broader-scope management of marine resources is necessary. Integrated ecological–economic fisheries models (IEEFMs) of...

Biomass reconstructions to pre-assessment periods for commercially important and exploitable fish species are important tools for understanding long-term processes and fluctuation on stock and ecosystem level. For some stocks only fisheries statistics and fishery dependent data are available, for periods before surveys were conducted. The methods f...

Data set underlying the input data and findings in study in the manuscript “Extension of biomass estimates to pre-assessment periods using density dependent surplus production approach” by Jan Horbowy and Maciej T. Tomczak. (XLSX)

Modern approaches to Ecosystem-Based Management and sustainable use of marine resources must account for the myriad of pressures (interspecies, human and environmental) affecting marine ecosystems. The network of feeding interactions between co-existing species and populations (food webs) are an important aspect of all marine ecosystems and biodive...

Fishing is a social and economic activity, and consequently socio-economic considerations are important for resource management. While this is acknowledged in the theory of Ecosystem-Based Management (EBM) and its sector-specific development Ecosystem-Based Fisheries Management (EBFM), currently applied fishery management objectives often ignore ec...

An existing Ecopath with Ecosim model of the Northern Benguela ecosystem for 1956, previously fitted to time series for 50 years, was used to describe the impact that the different pressures (fishing and climate drivers) had on the structure of the ecosystem. Ecological network analysis indices and Integrated Trend Assessment of the input data and...

The previous decade has witnessed a flourishing of studies on how fisheries and marine food webs interact, and how trophicmodels and indicators can be used for assessment and management purposes. Acknowledging the importance of complex interactions among species, fishermen and the environment has led to a shift from single species to an ecosystem-w...

An integrated trend assessment was conducted for the Gulf of Gdańsk (GoG), Baltic Sea for the period 1994– 2010 to describe changes and potentially important drivers of the ecosystem. We found changes in the biota, including an increase in open sea taxa (flatfish, sprat and cod), a decrease in typical coastal species such as eelpout and lumpfish an...

Metadata - time series used for the integrated ecosystem analysis of the GoG.

Data anomalies.

Coastal areas are among the most biologically productive aquatic systems worldwide, but face strong and variable anthropogenic pressures. Few studies have, however, addressed the temporal development of coastal ecosystems in an integrated context. This study represents an assessment of the development over time in 13 coastal ecosystems in the Balti...

The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measures, and the EB cod was considered one of the most succ...

Abundance and biomass of cod, haddock, and whiting in the waters off of the west coast of Scotland (wcoS) have undergone large changes in recent years, most notably a recent decline. These three species contribute a considerable part of Scottish demersal landings from this area and as such it is important to understand why these stocks are behaving...

Several marine ecosystems under anthropogenic pressure have experienced shifts from one ecological state to another. In the central Baltic Sea, the regime shift of the 1980s has been associated with food-web reorganization and redirection of energy flow pathways. These long-term dynamics from 1974 to 2006 have been simulated here using a food-web m...

Human activities have substantial impacts on marine ecosystems, including rapid regime shifts with large consequences for human well-being. We highlight the use of model-based scenarios as a scientific tool for adaptive stewardship in the face of such consequences. The natural sciences have a long history of developing scenarios but rarely with an...

Changes in climate, in combination with intensive exploitation of marine resources, have caused large-scale reorganizations in many of the world's marine ecosystems during the past decades. The Baltic Sea in Northern Europe is one of the systems most affected. In addition to being exposed to persistent eutrophication, intensive fishing, and one of...

Theory behind ecosystem-based management (EBM) and ecosystem-based fisheries management (EBFM) is now well developed. However, the implementation of EBFM exemplified by fisheries management in Europe is still largely based on single-species assessments and ignores the wider ecosystem context and impact. The reason for the lack or slow implementatio...

Natural resource management requires approaches to understand and handle sources of uncertainty in future responses of complex systems to human activities. Here we present one such approach, the 'biological ensemble modelling approach', using the Eastern Baltic cod (Gadus morhua callarias) as an example. The core of the approach is to expose an ens...

Natural resource management requires approaches to understand and handle sources of uncertainty in future responses of complex systems to human activities. Here we present one such approach, the "biological ensemble modeling approach," using the Eastern Baltic cod (Gadus morhua callarias) as an example. The core of the approach is to expose an ense...

An integrated ecosystem assessment was carried out for the Limfjord over the period from 1984 to 2008 to describe changes in ecosystem structure and potentially important drivers. The Limfjord is a eutrophic transitional Danish fjord system with the main inflow from the North Sea in the west and main outflow to the Kattegat in the east. We showed t...

Carbon flows in five south-eastern Baltic coastal ecosystems (Puck Bay, Curonian Lagoon, Lithuanian coast, Gulf of Riga coast and Pärnu Bay) were compared on the basis of ECOPATH models using 12 common functional groups. The studied systems ranged from the hypertrophic Curonian Lagoon to the mesotrophic Gulf of Riga coast. Interestingly, we found t...

Recent recruitment failure of lesser sandeel Ammodytes marinus, a key prey fish in the North Sea, followed by several years of low spawning stock biomass, prompted us to investigate factors influencing the recruitment of this species. We tested 2 hypotheses that relate to ecological mechanisms of recruitment regulation in lesser sandeel: (1) a posi...

Lassalle, G., Lobry, J., Le Loc'h, F., Mackinson, S., Sanchez, F., Tomczak, M. T., and Niquil, N. 2013. Ecosystem status and functioning: searching for rules of thumb using an intersite comparison of food-web models of Northeast Atlantic continental shelves. – ICES Journal of Marine Science, 70:135–149. This work aimed to provide a better understan...

Models that can project ecosystem dynamics under changing environmental conditions are in high demand. The application of such models, however, requires model validation together with analyses of model uncertainties, which are both often overlooked. We carried out a simplified model uncertainty and sensitivity analysis on an Ecopath with Ecosim foo...

Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics to past and future environmental forcings provided by t...

The Baltic Proper is a semi-enclosed, highly productive basin of the Baltic Sea with a low biodiversity, where only a few key species drive the system's dynamics. Recently, an ecosystem regime shift was described having pronounced changes at all trophic levels, driven by changes in fishery and climate and leading to a food–web reorganisation. An Ec...

A wide range of possible recruitment drivers were tested for key exploited fish species in the Baltic Sea Regional Advisory Council (RAC) area: Eastern Baltic Cod, Central Baltic Herring, Gulf of Riga Herring, and sprat. For each of the stocks, two hypotheses were tested: (i) recruitment is significantly related to spawning stock biomass, climatic...

Status of exploited Baltic flounder stocks in the southern Baltic area (ICES SD 26) Flounder is the target of directed fisheries in coastal waters and is a bycatch of cod fishing. Flounder were fished in the Baltic region ICES Subdivision 26 (SD 26) by Polish and Soviet fleets until 1991. Since that time political and economic changes have altered...

The fecundity and gonad development cycle of the round goby (Neogobius melanostomus Pallas 1811) from the Gulf of Gdańsk Abstract The round goby (Neogobius melanostomus Pallas 1811) is a non-native species in the Gulf of Gdańsk. The aim of this article is to assess the absolute fecundity and attempt to describe the gonad development cycle of round...

Carbon flows in five South Eastern Baltic coastal ecosystems (Puck Bay, Curonian Lagoon, Open Baltic Coast, exposed Gulf of Riga coast and Pärnu Bay) were compared based on a common 12 compartment ECOPATH model structure. Primary producers were represented by phytoplankton and perennial and annual macrophytes. Zooplankton was divided into meso- and...

In the Baltic proper, a number of local herring stocks (e.g. south-coast or north- eastern) can be distinguish on the basis of the spawning areas, otolith shape (Kompowski 1969), maturation or growth rate, but here they have been grouped for assessment and management purposes into different stock-units. Since 1990, ICES has been assessing and recom...