Papers by Georg Cefas
The Journal of Pacific History
Marine environmental history analyses the changing relationships between human societies and mari... more Marine environmental history analyses the changing relationships between human societies and marine natural resources over time. This is the first book which deals in a systematic way with the theoretical backgrounds of this discipline. Major theories and methods are introduced by leading scholars of the field. The book seeks to encapsulate some of the major novelties of this fascinating new discipline and its contribution to the management, conservation and restoration of marine and coastal ecosystems as well as the cultural heritages of coastal communities in different parts of the world.
ICES Journal of Marine Science: Journal du Conseil, 2015
As a discipline, marine historical ecology (MHE) has contributed significantly to our understandi... more As a discipline, marine historical ecology (MHE) has contributed significantly to our understanding of the past state of the marine environment when levels of human impact were often very different from those today. What is less widely known is that insights from MHE have made headway into being applied within the context of present-day and long-term management and policy. This study draws attention to the applied value of MHE. We demonstrate that a broad knowledge base exists with potential for management application and advice, including the development of baselines and reference levels. Using a number of case studies from around the world, we showcase the value of historical ecology in understanding change and emphasize how it either has already informed management or has the potential to do so soon. We discuss these case studies in a context of the science–policy interface around six themes that are frequently targeted by current marine and maritime policies: climate change, bio...
PloS one, 2015
Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the ... more Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the 1950s. Causes for the population increase last century, and understanding of whether such large numbers will be maintained in the future, are unclear. To explore this, we digitised and interrogated historical cod catch and diet datasets from the Barents Sea. Seventeen years of catch data and 12 years of prey data spanning 1930-1959 cover unexplored spatial and temporal ranges, and importantly capture the end of a previous warm period, when temperatures were similar to those currently being experienced. This study aimed to evaluate cod catch per unit effort and prey frequency in relation to spatial, temporal and environmental variables. There was substantial spatio-temporal heterogeneity in catches through the time series. The highest catches were generally in the 1930s and 1940s, although at some localities more cod were recorded late in the 1950s. Generalized Additive Models showed that...
During breeding, procellariiform seabirds are typical central-place foragers, depending on distan... more During breeding, procellariiform seabirds are typical central-place foragers, depending on distant pelagic resources. Especially in polar environments, where there is only a short time window to complete the breeding season, high chick provisioning rates are needed to allow chicks to fledge successfully. The duration of the chick period and of chick growth are linked to provisioning parameters such as the frequency and quantity of the chick meals, but probably also to the quality of the food delivered. We studied the provisioning and growth of chicks of Southern Fulmars Fulmarus glacialoides and Antarctic Petrels Thalassoica antarctica on Ardery Island (66°S, 110°E) near the Australian Antarctic station Casey. During two seasons (1998, 1999) we deployed artificial nests to collect data on chick provisioning. Southern Fulmars delivered meals more frequently (one per 14 hours) than did Antarctic Petrels (one every 25-26 hours). In 1998, the mass of meals brought to chicks of both species was not significantly different and averaged around 128 g. In 1999, the meal mass of Southern Fulmars remained the same, but that of the Antarctic Petrel was 28 g heavier. Chick provisioning rates calculated from meal frequencies and masses were significantly different between Southern Fulmars (254 g/day) and Antarctic Petrels (151 g/day), even after correction for body size. Because growth rates for the two species were not significantly different we suggest that Antarctic Petrels deliver meals of higher nutritional value, probably related to food reaching a higher density in the parents' stomach during their longer foraging trips.
Journal of Sea Research, 2013
ABSTRACT In the North Sea, turbot (Scophthalmus maximus) and brill (Scophthalmus rhombus) represe... more ABSTRACT In the North Sea, turbot (Scophthalmus maximus) and brill (Scophthalmus rhombus) represent highly valuable species in commercial fisheries. Still, available data for both species are limited, making stock assessment difficult. Long-term fisheries data have the potential to improve the understanding of stock dynamics such as long-term distribution changes or development in species' abundances. Historical British otter trawler lpue (landings-per-unit-effort) data from 1923 to 2009, and at the spatial scale of ICES rectangles, revealed that the distribution patterns of turbot and brill were different for most of the 20th century and only became similar in the recent decade. Further, between the 1920s and 1960s, turbot was commonly caught in the northern North Sea and in particular on Turbot Bank, at that time a turbot hotspot off the east coast of Scotland. Within a short time period turbot nearly disappeared from this region. Brill, in contrast, revealed a stable distribution in the southern and central North Sea with a slow expansion into the central North Sea. We used survey cpue (catch-per-unit-effort) from the International Bottom Trawl Survey (IBTS; 1970-2009) and the Beam Trawl Survey (BTS; 1985-2009), as well as British otter trawler lpue, as proxies for the abundance of adult turbot and brill. Commercial lpue suggested for brill and turbot a long-term decrease in abundance. IBTS cpue suggested an increase in abundance for turbot, but this was not confirmed by the BTS. For brill, both surveys did not show a clear trend.
ICES Journal of Marine Science, 2011
Engelhard, G. H., Pinnegar, J. K., Kell, L. T., and Rijnsdorp, A. D. 2011. Nine decades of North ... more Engelhard, G. H., Pinnegar, J. K., Kell, L. T., and Rijnsdorp, A. D. 2011. Nine decades of North Sea sole and plaice distribution. – ICES Journal of Marine Science, 68: 1090–1104. Recent studies based mainly on research survey data suggest that within the North Sea, sole Solea solea and plaice Pleuronectes platessa have exhibited distribution shifts in recent decades—on average southward for sole and northward to deeper waters for plaice. Various hypotheses may account for such shifts, including climate change effects and more intensive fishing in southern and shallower waters; but the relatively short time-span of datasets analysed so far (∼3 decades) has complicated the separation of these two effects. We have made use of a unique dataset of catch and effort data for British North Sea trawlers; these cover nine decades (spanning the period 1913–2007) and are spatially detailed by ICES rectangle (0.5° latitude by 1° longitude). We quantify, for the first time, long-term distributio...
ICES Journal of Marine Science, 2013
Heino, M., Baulier, L., Boukal, D. S., Ernande, B., Johnston, F. D., Mollet, F. M., Pardoe, H., T... more Heino, M., Baulier, L., Boukal, D. S., Ernande, B., Johnston, F. D., Mollet, F. M., Pardoe, H., Therkildsen, N. O., Uusi-Heikkilä, S., Vainikka, A., Arlinghaus, R., Dankel, D. J., Dunlop, E. S., Eikeset, A. M., Enberg, K., Engelhard G. H., Jørgensen, C., Laugen, A. T., Matsumura, S., Nusslé, S., Urbach, D., Whitlock, R., Rijnsdorp, A. D., and Dieckmann, U. 2013. Can fisheries-induced evolution shift reference points for fisheries management? – ICES Journal of Marine Science, 70: 707–721. Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in “true” reference points, whereas the latter is caused by...
ICES Journal of Marine Science, 2014
Dickey-Collas, M., Engelhard, G. H., Rindorf, A., Raab, K., Smout, S., Aarts, G., van Deurs, M., ... more Dickey-Collas, M., Engelhard, G. H., Rindorf, A., Raab, K., Smout, S., Aarts, G., van Deurs, M., Brunel, T., Hoff, A., Lauerburg R. A. M., Garthe, S., Haste Andersen, K., Scott, F., van Kooten, T., Beare, D., and Peck, M. A. Ecosystem-based management objectives for the North Sea: riding the forage fish rollercoaster. – ICES Journal of Marine Science, 71: . The North Sea provides a useful model for considering forage fish (FF) within ecosystem-based management as it has a complex assemblage of FF species. This paper is designed to encourage further debate and dialogue between stakeholders about management objectives. Changing the management of fisheries on FF will have economic consequences for all fleets in the North Sea. The predators that are vulnerable to the depletion of FF are Sandwich terns, great skua and common guillemots, and to a lesser extent, marine mammals. Comparative evaluations of management strategies are required to consider whether maintaining the reserves of pre...
Report of the Workshop on historical data on ... International Council for the Exploration of the... more Report of the Workshop on historical data on ... International Council for the Exploration of the Sea ... Conseil International pour l'Exploration de la Mer ... HC Andersens Boulevard 4446 DK1553 Copenhagen V Denmark Telephone (+45) 33 38 67 00 Telefax (+45) 33 93 42 ...
Canadian Journal of Zoology, 2002
We studied lactation behaviour in relation to pup growth in southern elephant seals (Mirounga leo... more We studied lactation behaviour in relation to pup growth in southern elephant seals (Mirounga leonina) at Macquarie Island, and compared harems in areas of high and low human presence to determine if there is an effect attributable to human activities, including scientific research. Pup weaning mass, a known correlate of firstyear survival, was positively influenced by suckle bout durations during early and middle lactation and by maternal aggression during late lactation; no other behavioural variables were associated with weaning mass. In the area of high human presence, we observed from a distance the behaviour of motherpup pairs directly before, during, and after visits to harems by other researchers. Alertness was raised threefold in the presence of people but quickly returned to predisturbance levels after their departure; there were no significant short-term effects on other behavioural variables. In the areas of high and low human presence, we observed the undisturbed beha...
ICES Journal of Marine Science, 2014
The North Sea provides a useful model for considering forage fish (FF) within ecosystem-based man... more The North Sea provides a useful model for considering forage fish (FF) within ecosystem-based management as it has a complex assemblage of FF species. This paper is designed to encourage further debate and dialogue between stakeholders about management objectives. Changing the management of fisheries on FF will have economic consequences for all fleets in the North Sea. The predators that are vulnerable to the depletion of FF are Sandwich terns, great skua and common guillemots, and to a lesser extent, marine mammals. Comparative evaluations of management strategies are required to consider whether maintaining the reserves of prey biomass or a more integral approach of monitoring mortality rates across the trophic system is more robust under the ecosystem approach. In terms of trophic energy transfer, stability, and resilience of the ecosystem, FF should be considered as both a sized-based pool of biomass and as species components of the system by managers and modellers. Policy developers should not consider the knowledge base robust enough to embark on major projects of ecosystem engineering. Management plans appear able to maintain sustainable exploitation in the short term. Changes in the productivity of FF populations are inevitable so management should remain responsive and adaptive.
As a discipline, marine historical ecology (MHE) has contributed significantly to our understandi... more As a discipline, marine historical ecology (MHE) has contributed significantly to our understanding of the past state of the marine environment when levels of human impact were often very different from those today. What is less widely known is that insights from MHE have made headway into being applied within the context of present-day and long-term management and policy. This study draws attention to the applied value of MHE. We demonstrate that a broad knowledge base exists with potential for management application and advice, including the development of baselines and reference levels. Using a number of case studies from around the world, we showcase the value of historical ecology in understanding change and emphasize how it either has already informed management or has the potential to do so soon. We discuss these case studies in a context of the science–policy interface around six themes that are frequently targeted by current marine and maritime policies: climate change, biodiversity conservation, ecosystem structure, habitat integrity, food security, and human governance. We encourage science–policy bodies to actively engage with contributions from MHE, as well-informed policy decisions need to be framed within the context of historical reference points and past resource or ecosystem changes.
During breeding, procellariiform seabirds are typical central-place foragers, depending on distan... more During breeding, procellariiform seabirds are typical central-place foragers, depending on distant pelagic resources. Especially in polar environments, where there is only a short time window to complete the breeding season, high chick provisioning rates are needed to allow chicks to fledge successfully. The duration of the chick period and of chick growth are linked to provisioning parameters such as the frequency and quantity of the chick meals, but probably also to the quality of the food delivered. We studied the provisioning and growth of chicks of Southern Fulmars Fulmarus glacialoides and Antarctic Petrels Thalassoica antarctica on Ardery Island (66°S, 110°E) near the Australian Antarctic station Casey. During two seasons (1998, 1999) we deployed artificial nests to collect data on chick provisioning. Southern Fulmars delivered meals more frequently (one per 14 hours) than did Antarctic Petrels (one every 25-26 hours). In 1998, the mass of meals brought to chicks of both species was not significantly different and averaged around 128 g. In 1999, the meal mass of Southern Fulmars remained the same, but that of the Antarctic Petrel was 28 g heavier. Chick provisioning rates calculated from meal frequencies and masses were significantly different between Southern Fulmars (254 g/day) and Antarctic Petrels (151 g/day), even after correction for body size. Because growth rates for the two species were not significantly different we suggest that Antarctic Petrels deliver meals of higher nutritional value, probably related to food reaching a higher density in the parents' stomach during their longer foraging trips.
Oceans past by Georg Cefas
As a discipline, marine historical ecology (MHE) has contributed significantly to our understandi... more As a discipline, marine historical ecology (MHE) has contributed significantly to our understanding of the past state of the marine environment when levels of human impact were often very different from those today. What is less widely known is that insights from MHE have made headway into being applied within the context of present-day and long-term management and policy. This study draws attention to the applied value of MHE. We demonstrate that a broad knowledge base exists with potential for management application and advice, including the development of baselines and reference levels. Using a number of case studies from around the world, we showcase the value of historical ecology in understanding change and emphasize how it either has already informed management or has the potential to do so soon. We discuss these case studies in a context of the science-policy interface around six themes that are frequently targeted by current marine and maritime policies: climate change, biodiversity conservation, ecosystem structure, habitat integrity, food security, and human governance. We encourage science-policy bodies to actively engage with contributions from MHE, as wellinformed policy decisions need to be framed within the context of historical reference points and past resource or ecosystem changes.
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Papers by Georg Cefas
Oceans past by Georg Cefas