Jonas

Hentati-Sundberg

MSc

PhD student, Marine dynamics and fisheries management

+46 739 387 969

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Jonas Hentati-Sundberg's research focuses on the social-ecological dynamics of marine system, with particular focus on fisheries

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His main research areas are: 

- Behavioral adaptions in fishers and their influence on social-ecological system level outcomes. Specific research topics includes how social and ecological system factors shape fishing behavior, factors contributing to compliance/noncompliance to fisheries management and the role of social-ecological diversity in fisheries systems. This work builds on statistical analysis of detailed longitudinal data on Baltic Sea fisheries.    

- Drivers of long term social-ecological change in fisheries. Specifically, social-ecological regime shifts are investigated using statistical time series methods. This work builds on a unique 100-year database of Baltic Sea fisheries on social-ecological variables, aggregated by Swedish counties.  

- Links between complex ecosystem change and long-term seabird demographics and behavior. This work is focussed on Common Murres (Uria aalge) in Stora Karlsö in the Baltic Sea. Here, a large artificial breeding tower situated in the middle of the colony ("The Karlsö Murre Lab") were build in 2008, allowing for highly-detailed field studies. 

The work is performed in association with the Institute of Marine Research, Swedish Agricultural University, Lysekil, Sweden. Jonas holds an MSc degree in ecology from Stockholm University, which included studies in France, UK and Germany.

Before being accepted as a PhD Candidate, Jonas worked as a marine policy officer at the Swedish Society for Nature Conservation. He also lead a construction of a world-unique artificial colony for breeding seabirds, and performed seabird field-work during a number of seasons in the main seabird colony in the Baltic Sea, the island of Stora Karlsö.

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Publications by Hentati-Sundberg, Jonas

Common Guillemot Uria aalge parents adjust provisioning rates to compensate for low food quality

Kadin, M., O. Olsson, J. Hentati-Sundberg, E. Willerström Ehrning, T. Blenckner

2015 - Journal / article

The quantity and quality of food available within the foraging area set important constraints for chick-rearing birds, but responses to low quality are not well understood. This study explored the potential for parent birds to adjust quantity (feeding rate) and quality (energy content) in chick provisioning, by studying Common Guillemots  Uria aalge  on Stora Karlsö, Baltic Sea, predominantly utilizing Sprat Sprattus sprattus , during conditions of high food quantity but reduced food quality. Quality is central to reproductive success in this single-prey loader. From the chick's perspective, provisioning rates should be increased to compensate for low food quality and to fulfil its growing needs with increasing age. However, the high energy cost of flying in Guillemots makes it important for parent birds to minimize commutes to feeding areas. Provisioning parameters were recorded during three dawn-to-dusk watches each breeding season from 2005 to 2013, when clupeids, presumably Sprat ,  constituted 98% of chick diet. Generalized additive mixed models showed that both feeding rate and size of clupeids (a proxy for energy content) varied between years and changed non-linearly with chick age, but that there was no change within breeding seasons. Chick age and year explained 36% of the variation in feeding rate but only 2% of the variation in the size of clupeids in chick diets. We conclude that parent birds tried to adjust both feeding rate and prey size, but were less successful with the latter. A strong negative correlation was found between annual feeding rates and size of clupeids, evaluated as the differences relative to the baseline year, and adjusted for the effects of chick age. Although the differences between years were small, the relationship indicates a compensation mechanism that does not seem to impact adult survival, and by which increased feeding rates can partly counteract reduced chick energy intake when food quality is low.


Masked, diluted and drowned out: How global seafood trade weakens signals from marine ecosystems

Crona, B.I., T.M. Daw, W. Swartz, A.V. Norström, M. Nyström, M. Thyresson, C. Folke, J. Hentati-Sundberg, H. Österblom, L. Deutsch, M. Troell

2015 - Journal / article

Nearly 40% of seafood is traded internationally and an even bigger proportion is affected by international trade, yet scholarship on marine fisheries has focused on global trends in stocks and catches, or on dynamics of individual fisheries, with limited attention to the link between individual fisheries, global trade and distant consumers. This paper examines the usefulness of fish price as a feedback signal to consumers about the state of fisheries and marine ecosystems. We suggest that the current nature of fisheries systems and global markets prevent transmission of such price signals from source fisheries to consumers. We propose several mechanisms that combine to weaken price signals, and present one example – the North Sea cod – to show how these mechanisms can be tested. The lack of a reliable price feedback to consumers represents a challenge for sustainable fisheries governance. We therefore propose three complimentary approaches to address the missing feedback: (i) strengthening information flow through improved traceability and visibility of individual fishers to consumers, (ii) capitalizing on the changing seafood trade structures and (iii) bypassing and complementing market mechanisms by directly targeting citizens and political actors regarding marine environmental issues through publicity and information campaigns. These strategies each have limitations and thus need to be pursued together to address the challenge of sustainability in global marine fisheries.


Management forcing increased specialization in a fishery system

Hentati-Sundberg, J., Hjelm, J., Boonstra, W. J., & Österblom, H.

2015 - Journal / article

Fisheries systems are shaped by dynamic social-ecological interactions that determine their capacity to provide ecosystem services. Human adaptation is often considered a key uncertainty, and there are few quantitative empirical analyses that address long-term social and ecological change in the analyses of fisheries systems. The aim of this study was twofold: (i) to understand how different drivers influenced the adaptations by fishers, and (ii) to evaluate different consequences of such adaptations, especially with regard to diversity of social and ecological links. We used the Baltic Sea as a case study, a system with different fisheries, largely managed with a single-stock advice, in a top-down basis. The study period 1995–2009 was characterized by profound inter-annual fluctuations in fish stock status and prices, and introduction of new types of management measures. We used multivariate statistical methods to define longitudinal changes in fishing tactics and strategies based on logbook data. Our results indicate that changes in fishing strategies have mainly been driven by regulations, and there were only weak linkages between fishing activities, fish stocks, and price fluctuations. We found contrasting trends between large- and small-scale fishers, where large-scale fishers became more specialized and inflexible, whereas small-scale fishers diversified over time. We conclude that management has had a dominating role in shaping fishing patterns, leading to a reduction of important qualities related to the resilience in this social-ecological system.


Hentati-Sundberg, Jonas

Stockholm Resilience Centre is a collaboration between Stockholm University and the Beijer Institute of Ecological Economics at the Royal Swedish Academy of Sciences

Stockholm Resilience Centre
Stockholm University, Kräftriket 2B
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info@stockholmresilience.su.se

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