Ewan - Hunter

Agri-Food and Biosciences Institute

This pilot study used programmed acoustic tags implanted into S. salar smolts, in conjunction with an extensive offshore marine receiver array, to investigate late-stage migratory behaviour and survival of returning adult salmon. 100 smolts were tagged in 2020 and a number of individuals were successfully detected as returning adults in 2021. After...

Truly sustainable development in a human-altered, fragmented marine environment subject to unprecedented climate change, demands informed planning strategies in order to be successful. Beyond a simple understanding of the distribution of marine species, data describing how variations in spatio-temporal dynamics impact ecosystem functioning and the...

The European COST Action “Unifying Approaches to Marine Connectivity for improved Resource Management for the Seas” (SEA-UNICORN, 2020‐2025) is an international research coordination initiative that unites an interdisciplinary community of scientists and policymakers from over 100 organizations across Europe and beyond. It is establishing a globall...

Truly sustainable development in a human-altered, fragmented marine environment subject to unprecedented climate change, demands informed planning strategies in order to be successful. Beyond a simple understanding of the distribution of marine species, data describing how variations in spatio-temporal dynamics impact ecosystem functioning and the...

The collaboration that forms the basis of the UK edible crab (Cancer pagurus) case study builds on a relationship between scientists and fishermen that was first established in 1996. The emphasis of the case study has been to develop awareness among fishermen of the need to be more involved in the management of the resource on which their livelihoo...

A review of the functional role of jellyfish in Ecopath with Ecosim (EwE) models by Pauly et al. [Pauly, D., Graham, W., Libralato, S., Morissette, L., and Deng Palomares, M. L. 2009. Jellyfish in ecosystems, online databases, and ecosystem models. Hydrobiologia, 616: 67–85.] a decade ago concluded that recreation of jellyfish population dynamics i...

Quantifying connectivity within fish metapopulations is an important component in understanding population dynamics and providing an evidence base for assessment and management. We investigate metapopulation connectivity of the common sole (Solea solea) in the Eastern English Channel (EEC). The EEC common sole stock is currently assessed as a singl...

To establish if fishes’ consumption of jellyfish changes through the year, we conducted a molecular gut‐content assessment on opportunistically sampled species from the Celtic Sea in October and compared these with samples previously collected in February and March from the Irish Sea. Mackerel Scomber scombrus were found to feed on hydrozoan jellyf...

Metabarcoding has been used in a range of ecological applications such as taxonomic assignment, dietary analysis, and the analysis of environmental DNA. However, after a decade of use in these applications there is little consensus on the extent to which proportions of reads generated corresponds to the original proportions of species in a communit...

Artificial structures in the marine environment may have direct and/or indirect impact on the behaviour and space use of mobile foragers. This study explores whether environmental and physical features in the North Sea-including artificial structures (wrecks, wind turbines, cables, and oil and gas structures) were associated with local abundance of...

Otoliths or ear-stones are hard, calcium carbonate structures located within the inner ear of bony fishes. Counts of rings and measurements of seasonal growth increments from otoliths are important metrics for assessment and management of fish stocks, and the preparation and microscopic analysis of otoliths forms an essential part of the routine wo...

In recent years, technical and analytical developments in sclerochronology, based on the analysis of accretionary hard tissues, have improved our ability to assess the life histories of a wide range of marine organisms. This Theme Section on the innovative use of sclerochronology was motivated by the cross-disciplinary session ‘Looking backwards to...

The European Seabass (Dicentrarchus labrax) is a slow-growing late maturing fish. The northern stock has been declining since 2010 and is thought to be caused by a combination of fishing and weak year classes. Large inter-annual variation in settlement has been observed, so a better understanding of the mechanisms driving settlement success will ai...

ABSTRACT: The oxygen isotopic ratio of fish otoliths is increasingly used as a ‘natural tag’ to assess provenance in migratory species, with the assumption that variations in δ18O values closely reflect individual ambient experience of temperature and/or salinity. We employed archival tag data and otoliths collected from a shelf-scale study of the...

Localized outbreaks of jellyfish, known as blooms, cause a variety of adverse ecological and economic effects. However, fundamental aspects of their ecology remain unknown. Notably, there is scant information on the role jellyfish occupy in food webs: in many ecosystems, few or no predators are known. To identify jellyfish consumers in the Irish Se...

Stock-separation of highly mobile Clupeids (sprat – Sprattus sprattus and herring – Clupea harengus) using otolith morphometrics was explored. Analysis focused on three stock discrimination problems with the aim of reassigning individual otoliths to source populations using experiments undertaken using a machine learning environment known as WEKA (...

A three-dimensional computer reconstruction of a plaice Pleuronectes platessa otolith is presented from data acquired by the Diamond Light synchrotron, beamline I12, X-ray source, a high energy (53-150 keV) source particularly well suited to the study of dense objects. The data allowed non-destructive rendering of otolith structure, and for the fir...

The GAP2 project, funded by the European Commission, has been bringing together scientists, fishers and policy makers to jointly develop solutions for sustainable fisheries and fishing communities. The programme was composed of 13 case studies in 11 European countries. One such collaboration is described, which aimed to develop more effective, fish...

Trace element concentrations in fish earstones (‘otoliths’) are widely used to discriminate spatially discrete populations or individuals of marine fish, based on a commonly held assumption that physiological influences on otolith composition are minor, and thus variations in otolith elemental chemistry primarily reflect changes in ambient water ch...

Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory dat...

ABSTRACT: Most studies that infer geographic distributions of fish using otolith microchemistry assume that environmental factors (e.g. temperature, salinity) outweigh intrinsic effects (e.g. size, condition); however, this assumption has not been rigorously tested, particularly in marine fish. Here, we report the results of a long-term experimenta...

Crustaceans are key components of marine ecosystems which, like other exploited marine taxa, show seasonable patterns of distribution and activity, with consequences for their availability to capture by targeted fisheries. Despite concerns over the sustainability of crab fisheries worldwide, difficulties in observing crabs' behaviour over their ann...

Mortality during the egg and larval stages is thought to play a major role in de termining year-class strength of many marine fish. Predation of eggs and larvae is normally considered to be a major factor but the full suite of predators responsible has rarely been identified. Potential predators on a patch of plaice Pleuronectes platessa eggs locat...

Experiments were conducted on the ability of TaqMan molecular probes to detect plaice Pleuronectes platessa DNA from eggs, and cod Gadus morhua DNA from eggs and larvae following ingestion by a teleost predator, whiting Merlangius merlangus. Estimated half-life detection rate (T50) for eggs was 31 h, and 26 h for larvae, with some positive detectio...

Otolith microchemistry can provide valuable information about stock structure and mixing patterns when the magnitude of environmental differences among areas is greater than the cumulative influence of any vital effects. Here, the current understanding of the underlying mechanisms governing element incorporation into the otolith is reviewed. Hard a...

Plirú, A., van der Kooij, J., Engelhard, G. H., Fox, C. J., Milligan, S. P., and Hunter, E. 2012. Sprat feeding behaviour, selective predation, and impact on plaice egg mortality. – ICES Journal of Marine Science, 69: 1019–1029. Although the causes of fish egg and larval mortality are poorly understood, predation is thought to be a major contributi...

Although the causes of fish egg and larval mortality are poorly understood, predation is thought to be a major contributing factor. The feeding behaviour of sprat at a plaice spawning ground in the Irish Sea during February 2009 is described and their contribution to plaice egg mortality investigated. Acoustic observations and analysis of stomach c...

A key challenge of the ecosystem approach to fisheries management is to sustain viable populations of large-bodied less-productive vulnerable elasmobranchs that are the bycatch of fisheries that target more productive species. The North Sea population of thornback ray Raja clavata is now mainly confined to the Thames Estuary and surrounding SW Nort...

A key challenge of the ecosystem approach to fisheries management is to sustain viable populations of large-bodied less-productive vulnerable elasmobranchs that are the by-catch of fisheries that target more productive species. The North Sea population of the thornback ray (Raja clavata) is now mainly confined to the Thames Estuary and surrounding...

A key challenge of the ecosystem approach to fisheries management is to sustain viable populations of large-bodied less-productive vulnerable elasmobranchs that are the by-catch of fisheries that target more productive species. The North Sea population of the thornback ray (Raja clavata) is now mainly confined to the Thames Estuary and surrounding...

Otoliths are calcium carbonate 'earstones’ common to all bony fish. By sampling discrete growth rings on the otolith, it is possible to reconstruct environmental histories of individual fish and link them to lifetime movements. However, the effect of physiology on otolith chemistry is poorly understood, with gonad development and growth rate sugges...

We describe a protocol for the preservation, extraction, and detection of plaice (Pleuronectes platessa) DNA from the stomach contents of the brown shrimp, Crangon crangon and the shore crab, Carcinus maenas. These two predatory species are thought to be important sources of mortality of small juvenile plaice on inshore nursery grounds. Previous st...

We examined the mid-water swimming activity of 139 mature female plaice Pleuro- nectes platessa L. These were tagged with electronic data storage tags (DST1s and DST3s) to test whether swimming at different times of the year differed among areas of the North Sea with average tidal current velocities ranging from fast (West), to intermediate (East),...

Recent field studies of commercially exploited marine fish stocks have demonstrated compelling evidence of complex population structure and varying rates of exchange between different management areas. In spite of this, the stock assessment methods currently applied by ICES to advise on total allowable catches (TACs) and technical conservation meas...

IntroductionAcoustics in Fisheries ScienceTelemetryFish GeneticsTissue MicrochemistryComputationally Intensive ModellingTracking Environmental Processes: Advances in Remote Sensing of the EnvironmentConclusions References

Although most of us, whether lay person or scientist, do have an idea of what is meant by ‘migration’, it is difficult to find a generally accepted definition of the term. This is largely because those who work on different animal groups tend to use the word in rather different contexts. For instance, ornithologists usually regard migration as some...

Summary • Sharks and rays are vulnerable to fisheries exploitation because of late maturation and low fecundity, highlighting the need for effective conservation strategies. Area closures have been proposed as an appropriate management option for thornback rays in the southern North Sea, where they appear to form local subpopulations between which...

Water currents are a dominant feature of the open sea and often play an important part in the life cycle of the fish that live there. For over three decades, a focus of research at Lowestoft has been the role of tidal water currents as a part of wider understanding of the population dynamics of plaice (Pleuronectes platessa) in the North Sea. Incre...

Tagged with an electronic data storage tag on 6 October 1999 in the Thames Estuary (UK), a thornback ray, Raja clavata, was recaptured after 504 days at liberty, 276 km north-west of release. The tag recorded 423 days of data. The migration was reconstructed using the tidal location method, and illustrates seasonal migration out of the Thames Estua...

Although depleted throughout the European continental shelf, the relatively high density of thornback rays Raja clavata, in the Thames Estuary (UK) makes it an important stock centre and potential focus for species management. To describe spatial and temporal distribution, 197 thornback rays were tagged with electronic data storage tags (DSTs) and...

For more than a century, scientists have used mark-recapture techniques to describe the spatial dynamics of marine demersal fish species in the North Sea. Although such experiments have provided extensive data sets, the information is limited to the date and position at release and at recapture. Furthermore, these data may be biased due to the dist...

Analysis of continuous behaviour records of adult female plaice Pleuronectes platessa tagged with electronic data storage tags, and released in the southern North Sea, has yielded new insights into spatial and temporal variation in vertical activity (swimming). Here we describe migra- tion-linked changes in vertical activity patterns observed from...

Twentieth century mark-recapture studies of conventionally tagged plaice suggested that the maximum exchange rate of fish between the North Sea and the eastern English Channel did not exceed 10%. However, recent studies with electronic data storage tags have suggested that this figure may be significantly greater. In spite of this, current stock as...

Between December 1993 and February 1997, 302 electronic data storage tags (DSTs), programmed to record depth at 10-min intervals and temperature daily, were attached to mature female plaice, Pleuronectes platessa, and released in the southern North Sea. Fifty tags were returned, 38 of which functioned fully and recorded 2,955 days of data. Twenty-s...

Summary 1. Migration is widespread among marine fishes, yet little is known about variation in the migration of individuals within localities, and the consequences for spatial popu- lation structure. We tested the hypothesis that variation in the migratory behaviour among plaice ( Pleuronectes platessa L.) in the North Sea could be explained by lar...

To improve survival and reproductive success, many fish species have evolved migratory life-histories, showing ontogenetic and/or seasonal changes in habitat use. Individuals move between different areas, each of which is ‘best’ for a particular activity, such as feeding, growing or spawning. The benefits of moving to a different habitat, however,...

Migration is widespread among marine fishes, yet little is known about variation in the migration of individuals within localities. We tested the hypothesis that variation in the migratory behaviour among plaice (Pleuronectes platessa) in the North Sea could be explained by large-scale differences in the speed and directions of the tidal streams, w...

Data from plaice, Pleuronectes platessa L., tagged with electronic data storage tags, were used to test whether these fishes exhibited migration route and spawning area fidelity in successive spawning seasons. Depth and temperature data were recorded for each fish over 365-512 days in the central North Sea and this information was used to reconstru...

Demersal fish cannot readily be tracked using satellite-based or light-based geolocation techniques. As an alternative, we describe the tidal location method, which uses tidal data recorded by electronic data storage tags (DSTs), to determine geoposition. Times of high water (H) and tidal ranges (R) recorded by DSTs moored at known locations, and f...

Increased miniaturisation and recording capacity of electronic data storage tags (DST), and advances in methods applied to the interpretation of DST data now allow accurate and fisheries-independent description of the seasonal changes in spatial distribution of commercially exploited demersal fish species. Here we present the results from experimen...

Distributions of serotonin and catecholamines in larvae of the marine bryozoan Bugula neritina (Bryozoa: Cheilostomatida) were investigated using immunohistochemistry with anti-serotonin antiserum and glyoxylic acid induced fluorescence histochemistry. Anti-serotonin immunoreactive substances and glyoxylic acid-induced fluorescent substances had si...

Distributions of serotonin and catecholamines in larvae of the marine bryozoan Bugula neritina (Bryozoa: Cheilostomatida) were investigated using immunohistochemistry with anti-serotonin antiserum and glyoxylic acid–induced fluorescence histochemistry. Anti-serotonin immunoreactive substances and glyoxylic acid–induced fluorescent substances had si...

The European spiny lobster, Palinurus elephas, occurs in the Mediterranean Sea, and from the northwest African coast to Norway in the Atlantic. In the Mediterranean, peak moulting occurs in December-January and May to June. U.K. females moult from July to September and males moult mainly in winter. Moult frequency declines with size, pronouncedly i...

Larvae of the marine cheilostomatid bryozoan Bugula neritina (L.) were prevented from settling for 1, 4 and 8 h by mechanical agitation, following which settlement and metamorphosis success were examined. Settlement rates were significantly affected by swimming time, which decreased from 100% after 2 h to 93.7 ± 4.3% after 8 h. Similarly, metamorph...

The effects of extended swimming on short-lived lecithotrophic larvae of the marine bryozoan Bugula neritina (L.) were examined. Larvae were forced to swim for 2 or 24 h by bath application of serotonin. Settlement and metamorphosis success were significantly reduced, larval dimensions were unaffected and ancestrulae were smaller after 24 h of swim...

From May 1993 until January 1994, 788 male and 1604 female crawfish, Palinurus elephas in total, were examined from the South Wales and Cornish fisheries. Mean carapace length (CL) of Cornish crawfish was 125.6 mm for males, 132.4 mm for females and 135.0 mm for berried females, while mean CL for Welsh crawfish was 155.8 mm for males, 138.7 mm for...