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Nephrops norvegicus: Introduction to the Issue
NEPHROPS NORVEGICUS: INTRODUCTION TO THE ISSUE M.L. Johnson*, M.P. Johnson†
*Centre for Environmental and Marine Sciences, University of Hull, Scarborough, United Kingdom † Ryan Institute for Environmental, Marine and Energy Research, School of Natural Sciences, National University of Ireland, Galway, Ireland
The opportunity to produce this collection of papers on Nephrops norvegicus (L.) arose through a gathering of researchers from varied backgrounds within a European Union-funded FP7 project called, appropriately, NEPHROPS. This project will examine the potential for the development of hatcheries, ranching and enhanced survival of animals discarded from fishing. In order to meet these aims, the project will need to explore the development, physiology, ecology and exploitation of Nephrops. There are a few marine invertebrate animals where quite so much of our understanding of them is a product of knowledge gained through their exploitation. The impact of the fishing industry on our understanding of Nephrops is a thread that connects most of the chapters throughout this volume. As with tuna, Nephrops service a range of consumers: from food for mass consumption, ‘pub grub’ in the form of scampi, to haute cuisine as langoustine. It is not clear when Nephrops first became a target for human consumption. Despite the exoskeleton of Nephrops potentially preserving well, the species has not featured in Mesolithic shell middens. In the North Atlantic, such middens are often dominated by intertidal species such as the limpet Patella vulgata; where crustaceans have been identified, these are crabs generally available by shore-gathering (Pickard and Bonsall, 2009). That consideration of Nephrops as a valuable species is a relatively recent phenomenon is reflected in anecdotes about the species previously being used for fertilizer or simply discarded as part of the bycatch for other species. The singularity of Nephrops is reflected in the review of systematics given by Dale Tshudy (Chapter 1). Nephrops is a monospecific genus, but it is not clear yet where the species N. norvegicus came from. Morphologically, N. norvegicus is similar to Metanephrops species found in the Caribbean, South Atlantic and Pacific, which contrasts with genetic evidence for closer affinity to North Atlantic lobsters. The mystery is only made more intriguing by the almost complete absence of a fossil record—with only one recognized fossil, a claw from the Miocene of Denmark. xiii
xiv
M.L. Johnson and M.P. Johnson
While the fishery for Nephrops may be a relatively recent phenomenon (Chapter 7), landings may be in a state of flux, both due to gear and management changes and reflecting processes such as climate change. Nephrops live in a habitat that may be particularly susceptible to deoxygenation events. Eriksson et al. review the typical stresses that occur from living in the sediment (Chapter 5). Oxygen is a key environmental variable, but the level of oxygen is linked to the availability and concentration of other potential stressors, including sulphide and reduced metals mobilized from anoxic sediments. With deoxygenation events potentially being stimulated by eutrophication and climate change (Diaz and Rosenberg 2008), some Nephrops grounds may become less suitable for the continued support of populations. To deal with the challenges posed by global change and the economic and social pressures on Nephrops fisheries, we need to better understand processes at both the individual and the ecosystem level. Johnson et al. emphasize that we do not really know much about the distribution of the species, except where it is fished (Chapter 2). Resource dynamics seem to shape Nephrops populations, in terms of the sediment composition and the potential for competition to reduce growth. However, the data are far from complete. As long as the fishing pressure is not too intense, Nephrops may be facilitated by trawling, and extensive Nephrops grounds, in association with fishing, may influence biodiversity, nutrient and carbon flows at large scales. The details of individual behaviour and growth are central to any efforts to rear or ranch Nephrops and can help understand their interactions with other species in the ecosystem. Reproduction is described by Powell and Eriksson, who review attempts to raise adults from eggs and point out priority areas for research (Chapter 6). The social interactions and the impacts of environment on behaviour are covered in depth by Katoh et al. who reveal some of the secrets behind the enigmatic crepuscular behaviour of this animal (Chapter 3). As they point out, crustaceans are covered in chemical sensory organs that determine and guide much of their behaviour. However, Gaten et al. discuss in detail one of the most obvious features of Nephrops, their large and complex kidney-shaped superposition compound eyes (Chapter 4). These delicate eyes are tuned anatomically and physiologically to the range of depths that Nephrops inhabit. While we enjoy this treatise on a single animal, we should also perhaps reflect that it is possible only because there are funds available to study it, driven by the economic importance of Nephrops. Recent advances and policies in fisheries resource management have emphasized the need to
Nephrops norvegicus: Introduction to the Issue
xv
500 Nephrops norvegicus Homarus gammarus Munida rugosa
Citations per year
400
300
200
100
0 1970
1980
1990 Year
2000
2010
Figure 1 Numbers of papers published each year on three European species of longbodied benthic decapod (numbers generated from searches of species names for 5-year periods using Google Scholar).
understand whole ecosystems, and in this volume, Ungfors et al. allude to changes that are occurring because of indirect effects from more successful management of whitefish in the North Sea. If the ecosystem approach implies a closer working relationship between academia, state executive agencies and fisher’s organizations, then the chapter involving such a collaboration is a step forward in this respect (Chapter 7). Economical importance, however, does not always equate to ecological importance. From a cursory examination of the numbers of papers published on three well-known long-bodied decapods species found in northern Europe (Fig. 1), it is clear that there are huge discrepancies in the attention we pay to them. In order to understand ecosystems, we must develop an understanding of all of the constituents of the system, not just the attractive or economically important ones. Hopefully some future volumes of this wonderful series will also consist of thorough examinations of the roles of unfished and lesser-known species.
ACKNOWLEDGEMENTS The authors thank all reviewers, both formal and informal, who helped produce this volume. The NEPHROPS project which stimulated this volume received funding from the European Union’s Seventh Framework Programme managed by REA Research
xvi
M.L. Johnson and M.P. Johnson
Executive Agency http://ec.europa.eu/research/rea (FP7/2007–2013) under grant agreement number 286903.
REFERENCES Diaz, R.J., Rosenberg, R., 2008. Spreading dead zones and consequences for marine ecosystems. Science 321, 926–929. Pickard, C., Bonsall, C., 2009. Some observations on the Mesolithic crustacean assemblage from Ulva Cave, Inner Hebrides, Scotland. In: Burdukiewicz, J.M., Cyrek, K., Dyczek, P., Szymczak, K. (Eds.), Understanding the Past: Papers Offered to Stefan K. Kozłowski. Center for Research on the Antiquity of Southeastern Europe, University of Warsaw, Warsaw, pp. 305–313.
*Centre for Environmental and Marine Sciences, University of Hull, Scarborough, United Kingdom † Ryan Institute for Environmental, Marine and Energy Research, School of Natural Sciences, National University of Ireland, Galway, Ireland
The opportunity to produce this collection of papers on Nephrops norvegicus (L.) arose through a gathering of researchers from varied backgrounds within a European Union-funded FP7 project called, appropriately, NEPHROPS. This project will examine the potential for the development of hatcheries, ranching and enhanced survival of animals discarded from fishing. In order to meet these aims, the project will need to explore the development, physiology, ecology and exploitation of Nephrops. There are a few marine invertebrate animals where quite so much of our understanding of them is a product of knowledge gained through their exploitation. The impact of the fishing industry on our understanding of Nephrops is a thread that connects most of the chapters throughout this volume. As with tuna, Nephrops service a range of consumers: from food for mass consumption, ‘pub grub’ in the form of scampi, to haute cuisine as langoustine. It is not clear when Nephrops first became a target for human consumption. Despite the exoskeleton of Nephrops potentially preserving well, the species has not featured in Mesolithic shell middens. In the North Atlantic, such middens are often dominated by intertidal species such as the limpet Patella vulgata; where crustaceans have been identified, these are crabs generally available by shore-gathering (Pickard and Bonsall, 2009). That consideration of Nephrops as a valuable species is a relatively recent phenomenon is reflected in anecdotes about the species previously being used for fertilizer or simply discarded as part of the bycatch for other species. The singularity of Nephrops is reflected in the review of systematics given by Dale Tshudy (Chapter 1). Nephrops is a monospecific genus, but it is not clear yet where the species N. norvegicus came from. Morphologically, N. norvegicus is similar to Metanephrops species found in the Caribbean, South Atlantic and Pacific, which contrasts with genetic evidence for closer affinity to North Atlantic lobsters. The mystery is only made more intriguing by the almost complete absence of a fossil record—with only one recognized fossil, a claw from the Miocene of Denmark. xiii
xiv
M.L. Johnson and M.P. Johnson
While the fishery for Nephrops may be a relatively recent phenomenon (Chapter 7), landings may be in a state of flux, both due to gear and management changes and reflecting processes such as climate change. Nephrops live in a habitat that may be particularly susceptible to deoxygenation events. Eriksson et al. review the typical stresses that occur from living in the sediment (Chapter 5). Oxygen is a key environmental variable, but the level of oxygen is linked to the availability and concentration of other potential stressors, including sulphide and reduced metals mobilized from anoxic sediments. With deoxygenation events potentially being stimulated by eutrophication and climate change (Diaz and Rosenberg 2008), some Nephrops grounds may become less suitable for the continued support of populations. To deal with the challenges posed by global change and the economic and social pressures on Nephrops fisheries, we need to better understand processes at both the individual and the ecosystem level. Johnson et al. emphasize that we do not really know much about the distribution of the species, except where it is fished (Chapter 2). Resource dynamics seem to shape Nephrops populations, in terms of the sediment composition and the potential for competition to reduce growth. However, the data are far from complete. As long as the fishing pressure is not too intense, Nephrops may be facilitated by trawling, and extensive Nephrops grounds, in association with fishing, may influence biodiversity, nutrient and carbon flows at large scales. The details of individual behaviour and growth are central to any efforts to rear or ranch Nephrops and can help understand their interactions with other species in the ecosystem. Reproduction is described by Powell and Eriksson, who review attempts to raise adults from eggs and point out priority areas for research (Chapter 6). The social interactions and the impacts of environment on behaviour are covered in depth by Katoh et al. who reveal some of the secrets behind the enigmatic crepuscular behaviour of this animal (Chapter 3). As they point out, crustaceans are covered in chemical sensory organs that determine and guide much of their behaviour. However, Gaten et al. discuss in detail one of the most obvious features of Nephrops, their large and complex kidney-shaped superposition compound eyes (Chapter 4). These delicate eyes are tuned anatomically and physiologically to the range of depths that Nephrops inhabit. While we enjoy this treatise on a single animal, we should also perhaps reflect that it is possible only because there are funds available to study it, driven by the economic importance of Nephrops. Recent advances and policies in fisheries resource management have emphasized the need to
Nephrops norvegicus: Introduction to the Issue
xv
500 Nephrops norvegicus Homarus gammarus Munida rugosa
Citations per year
400
300
200
100
0 1970
1980
1990 Year
2000
2010
Figure 1 Numbers of papers published each year on three European species of longbodied benthic decapod (numbers generated from searches of species names for 5-year periods using Google Scholar).
understand whole ecosystems, and in this volume, Ungfors et al. allude to changes that are occurring because of indirect effects from more successful management of whitefish in the North Sea. If the ecosystem approach implies a closer working relationship between academia, state executive agencies and fisher’s organizations, then the chapter involving such a collaboration is a step forward in this respect (Chapter 7). Economical importance, however, does not always equate to ecological importance. From a cursory examination of the numbers of papers published on three well-known long-bodied decapods species found in northern Europe (Fig. 1), it is clear that there are huge discrepancies in the attention we pay to them. In order to understand ecosystems, we must develop an understanding of all of the constituents of the system, not just the attractive or economically important ones. Hopefully some future volumes of this wonderful series will also consist of thorough examinations of the roles of unfished and lesser-known species.
ACKNOWLEDGEMENTS The authors thank all reviewers, both formal and informal, who helped produce this volume. The NEPHROPS project which stimulated this volume received funding from the European Union’s Seventh Framework Programme managed by REA Research
xvi
M.L. Johnson and M.P. Johnson
Executive Agency http://ec.europa.eu/research/rea (FP7/2007–2013) under grant agreement number 286903.
REFERENCES Diaz, R.J., Rosenberg, R., 2008. Spreading dead zones and consequences for marine ecosystems. Science 321, 926–929. Pickard, C., Bonsall, C., 2009. Some observations on the Mesolithic crustacean assemblage from Ulva Cave, Inner Hebrides, Scotland. In: Burdukiewicz, J.M., Cyrek, K., Dyczek, P., Szymczak, K. (Eds.), Understanding the Past: Papers Offered to Stefan K. Kozłowski. Center for Research on the Antiquity of Southeastern Europe, University of Warsaw, Warsaw, pp. 305–313.