Audrey J. Geffen

University of Bergen | UiB · Department of Biological Science

Adult plaice in the Irish Sea have distinct traits that reflect the spawning locations that could suggest a number of different populations. However, do connectivity pathways support this concept? Different tools are directed at measuring exchange or connectivity between different life‐history stages, and the challenge is to integrate the signals t...

Fish species of the genus Amphiprion (Perciformes: Pomacentridae) seek protection from predators among the tentacles of sea anemones as their natural habitat, where they live essentially unharmed from stinging by the host's nematocysts. The skin mucus of these anemonefish has been suggested as a protective mechanism that prevents the discharge of t...

Investigating marine species population structure in a multidisciplinary framework can reveal signatures of potential local adaptation and the consequences for management and conservation. In this study we delineate the population structure of common sole (Solea solea) in the Mediterranean Sea using genomic and otolith data, based on single nucleot...

Specific changes in the macrostructure of fish otoliths have long been suspected to represent individual maturity and spawning events. In Norway these zones are routinely read for some gadoids, particularly Atlantic cod, but they remain underutilized and poorly understood. Recent experimental work has also suggested a more complex origin than the a...

Water temperature is key to the study of aquatic ectotherm ecology, but precise measurements of individual‐based thermal experience remain difficult to validate. The stable isotope composition of oxygen in biominerals acts as a natural thermometer due to the temperature dependence of isotopic fractionation between water and mineral phases. Coeffici...

Large‐scale, climate‐induced synchrony in the productivity of fish populations is becoming more pronounced in the world's oceans. As synchrony increases, a population's “portfolio” of responses can be diminished, in turn reducing its resilience to strong perturbation. Here we argue that the costs and benefits of trait synchronization, such as the e...

Population connectivity is an increasingly important focal area for the understanding of how marine fish populations respond to anthropogenic pressures like climate change and fisheries. Our model species, the saithe Pollachius virens (Linnaeus, 1758), was chosen because genetic analyses have documented a mismatch between the assessed stocks and th...

Specific changes identified in the otolith macrostructure of Northeast Arctic cod as “spawning zones” are presumed to represent spawning events, but recent experimental studies have challenged this relationship. Because these zones are not routinely recorded outside of Norway, otoliths from multiple Atlantic cod populations with different life hist...

Seasonal variation in the incorporation of trace elements into the calcified structures of fish can produce intra annual variation in the microchemistry of those structures. Interpretation of these seasonal signals can provide information about fish age. This approach offers great promise for objectively estimating age and corroborating other metho...

Lemon sole Microstomus kitt is a commercially valuable flatfish species that occurs in shelf waters around the northeast Atlantic. Only the most basic life‐history information is available for the North Sea. Spawning is generally assumed to occur between early May and October, with a peak between May and August. Lemon sole larvae have been found in...

The isotopic composition of inorganic carbon in otoliths (δ¹³Coto) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ¹³Coto variation in Icelandic and Northeast Arctic (NEA) cod (Gadus morhua) over the years 1914–2013. Individual annual growth increme...

Otolith biochronologies combine growth records from individual fish to produce long-term growth sequences, which can help to disentangle individual from population-level responses to environmental variability. This study assessed individual thermal plasticity of Atlantic cod (Gadus morhua) growth in Icelandic waters based on measurements of otolith...

Marine ecosystems, particularly in high‐latitude regions such as the Arctic, have been significantly affected by human activities and contributions to climate change. Evaluating how fish populations responded to past changes in their environment is helpful for evaluating their future patterns, but is often hindered by the lack of long‐term biologic...

The distribution of Atlantic cod (Gadus morhua) in northern Norwegian waters is expanding eastward and northward in the Barents Sea and along western Svalbard. In the Arctic fjords of Svalbard, cod has become abundant, but little is known about the biology, origin, or residence patterns of these populations. To address this issue, we used laser abl...

Otolith shape analysis provides a robust tool for the discrimination of many fish stocks in the context of fisheries management. However, there has been little research to examine within-stock temporal stability of otolith morphology in relation to changes in the environment and stock conditions. This study investigated the variability of Northeast...

The association between anemonefish and anemone is a classical example of mutualism in coral reefs. Although mutualism is probably the key innovation that triggered the adaptive radiation of anemonefish into a wide range of habitats, the coevolutionary history between the groups has not been thoroughly tested in a phylogenetic framework. We examine...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Connectivity between spawning and nursery grounds influences the colonization, replenishment and resilience of populations of marine organisms. Connectivity rate, measured as the exchange of individuals between spawning and nursery grounds, is therefore a crucial determinant of stock size. However, connectivity of early-life stages is hard to explo...

Oral presentation of the early results of our analysis of long term temporal stability of Northeast arctic cod otolith shape.

In this study, we investigated the host choice of naïve Amphiprion ocellaris, a specialist, at two different stages of development (newly settling juveniles and post‐settlement juveniles). The fish were exposed to their natural and unnatural host species in the laboratory and their fitness was assessed in terms of activity and growth rate. Newly se...

Catches of European hake (Merluccius merluccius) in the North Sea have increased substantially during the last decade, even though there is no directed commercial fishery of hake in this area. We analysed the spatial distributions of hake in the northern the parts of its range, (where it is less well-studied), using ICES international bottom trawl...

Spatial and temporal variations in size for fish at different reproductive states were investigated in the Barents Sea between 1997 and 2016. The study focused on fish caught in August/September, separated into four reproductive states based on gonad and otolith reading. Variations in size were interpolated using ordinary spatial kriging and contou...

Recently, there have been reports of increased abundance and landings of European hake in the northern part of the species range. Biological studies are however scarce and information about finer scale population structure important for stock assessments and fishery management is largely lacking. Here, we report on a population genetic study using...

Recently, there have been reports of increased abundance and landings of European hake in the northern part of the species range. Biological studies are however scarce and information about finer scale population structure important for stock assessments and fishery management is largely lacking. Here, we report on a population genetic study using...

Acartia tonsa is a calanoid copepod with high potential as live feed for marine aquaculture. However, its usage remains limited at an industrial scale, with cost effective production being conditional on successful culture at high density. The present study took an integrated approach to provide further insight on the effects of A. tonsa stocking d...

Spatial and temporal patterns of reproductive maturity were examined for European hake (Merluccius merluccius) in the northern North Sea, the Skagerrak and the Norwegian mid-west coast. Maturity stages based on macroscopic examination of gonads and Gonadosomatic Index data were collected from annual scientific surveys conducted in winter, summer, a...

Age and growth studies of flatfish form some of the oldest contributions to the scientific literature. Age estimation methods are based mostly on reading otolith annuli and scales in some species. A variety of age validation studies have been pursued, using direct methods and radiometric techniques. The growth of flatfish larvae is better understoo...

The implementation of ecosystem-based approaches to marine management points to several shared objectives between conservation and fisheries management that require: better knowledge of the life history of the exploited resources; to elucidate the information encoded into the calcified tissues (otoliths, scales, bones, shells and corals) of marine...

Fish otoliths have provided biologists with a treasure-house of valuable life history information across levels of biological organization from individuals to ecosystems. Otoliths have long been used to provide the age and growth estimates which are basic data that underpin scientific fisheries and fisheries ecology. The traditional use of calcifie...

Flatfishes have been the subject of research in support of their management in fisheries, use in restocking of natural populations, and domestication in aquaculture. Their life history and habitat also make flatfishes valuable models for ecotoxicology research. Their unique ontogeny, from bilateral to asymmetric, also makes them a compelling target...

Fascinating and instantly recognizable, flatfishes are unique in their asymmetric postlarval body form. With over 800 extant species recognized and a distribution stretching around the globe, these fishes are of considerable research interest and provide a major contribution to commercial and recreational fisheries worldwide. This second edition of...

The growth and development of the aragonitic CaCO3 otoliths of teleost fish could be vulnerable to processes resulting from ocean acidification. The potential effects of an increase in atmospheric CO2 on the calcification of the otoliths were investigated by rearing Atlantic cod Gadus morhua L. larvae in 3 pCO2 concentrations-control (370 µatm), me...

The dissolution of anthropogenically emitted excess carbon dioxide lowers the pH of the world's ocean water. The larvae of mass spawning marine fishes may be particularly vulnerable to such ocean acidification (OA), yet the generality of earlier results is unclear. Here we show the detrimental effects of OA on the development of a commercially impo...

Shallow population structure is generally reported for most marine fish and explained as a consequence of high dispersal, connectivity and large population size. Targeted gene analyses and more recently genome-wide studies have challenged such view, suggesting that adaptive divergence might occur even when neutral markers provide genetic homogeneit...

Growth and variation in size of turbot and sole larvae originating from different genetic sources were compared at different stocking densities, including genetically based information that might lead to a better knowledge of heterogeneity in cultivated populations. There was no effect of density on growth rate in either species. However, between t...

Kinematics of swimming behavior of larval Atlantic cod, aged 12 and 27 days post-hatch (dph) and cultured under three pCO 2 conditions (control-370, med-ium-1800, and high-4200 latm) from March to May 2010, were extracted from swim path recordings obtained using silhouette video photography. The swim paths were ana-lyzed for swim duration, distance...

Otolith microchemistry is a powerful tool for fisheries biology, but many applications stretch the limits of analytical techniques. Sources of measurement error were evaluated with a methodological comparison of solution and laser ablation inductively coupled plasma mass spectrometry at two laboratories, using otoliths and certified reference mater...

Teleost fish are more diverse than any other vertebrate group, and yet only a limited number of species are fished and farmed globally. Efforts to expand the quantity and diversity of fish produced are hampered by the extreme diversity of ontogenetic responses of fish, especially during larval development. This review looks at advances in molecular...

The genomic architecture underlying ecological divergence and ecological speciation with gene flow is still largely unknown for most organisms. One central question is whether divergence is genome-wide or localized in ‘genomic mosaics’ during early stages when gene flow is still pronounced. Empirical work has so far been limited, and the relative i...

Otolith elemental composition is a commonly used tool in the classification of fish stocks. Lower detection limits associated with trace element analysis techniques are the source of much debate among fisheries biologists. Using empirical data from Atlantic herring (Clupea harengus) from two separate origins in the British Isles, we addressed metho...

The aragonitic calcium carbonate composition of the otoliths of teleost fishes could bring the organism in direct risk to ocean acidification. The potential effects of increase in atmospheric CO2 on the calcification of the otoliths were investigated by rearing Atlantic cod larvae (Gadus morhua L.) in three pCO2 concentrations, control-370, medium-...

Transport models for planktonic fish eggs and larvae often use temperature to drive growth because temperature data are readily available. This pragmatic approach can be criticised as too simplistic as it ignores additional factors, such as food availability and growth-rate-dependent mortality. We examined the extent to which temperature could expl...

Kinematics of swimming behavior of larval Atlantic cod, aged 12 and 27 days post-hatch (dph) and cultured under three pCO2 conditions (control-370, medium-1800, and high-4200 µatm) from March to May 2010, were extracted from swim path recordings obtained using silhouette video photography. The swim paths were analyzed for swim duration, distance an...

The relationship between water temperature, growth rate, and otolith isotopic ratios was measured for juvenile plaice ( Pleuronectes platessa ) reared at two temperatures (11 and 17°C) and two feeding regimes (1 and 3 prey items·ml −1 ). The otolith isotope ratios in individual fish ranged from −2 to −4 for carbon isotope ratios (δ 13 C) and from 0...

Laser ablation ICPMS (inductively coupled plasma mass spectrometry) analysis is a powerful tool for studies of fish ecology, based on measurement of the chemical composition of otoliths (ear stones). A key trade-off for this analysis is selecting the size of the ablation area to maximize the resolution for discrete temporal intervals during the lif...

Chia-Hui Wang, Audrey J. Geffen, and Richard D.M. Nash (2012) Geographical variations in the chemical compositions of veined squid Loligo forbesi statoliths. Zoological Studies 51(6): 755-761. The chemical composition of statoliths of the veined squid Loligo forbesi Steenstrup (Cephalopoda: Loliginidae) was analyzed by inductively coupled plasma-ma...

A female cod Gadus morhua L. 87.1 cm total length was captured off Mallorca (Balearic Islands, NW Mediterranean) in June 2009 by a bottom trawler between 63 and 110 m depth. This is the first documented occurrence of the species in the Mediterranean. The fish was mature, with a very low hepatosomatic index and atretric gonads. Age assigned from the...

Argyrosomus regius uses different water masses during its life history, being associated with estuaries for reproduction. In order to study the life history and migration patterns, variations in otolith Na, Sr and Ba were measured by laser ablation-ICPMS along transects running from the first year of life to the otolith edge, comprising up to 12 ye...

Fish otoliths are comprised primarily of CaCO3 and grow throughout an individual's lifetime. The chemical composition of otoliths is often a distinctive characteristic of the populations that live in discrete areas, and as a result, it has been used for population classification studies, supporting ecological and fisheries research. However, the de...

Life-history theory suggests that animals may skip reproductive events after initial maturation to maximize lifetime fitness. In iteroparous teleosts, verifying past spawning history is particularly difficult; the degree of skipped spawning at the population level therefore remains unknown. We unequivocally show frequent skipped spawning in Northea...

Illegal, Unreported and Unregulated fishing has had a major role in the overexploitation of global fish populations. In response, international regulations have been imposed and many fisheries have been 'eco-certified' by consumer organizations, but methods for independent control of catch certificates and eco-labels are urgently needed. Here we sh...

It is difficult to estimate natural mortality for many marine fish populations, especially during the transition period from larvae to juveniles, because the appropriate data are scarce. Plaice (Pleuronectes platessa) is an exception since it has been studied extensively. The study of mortality rates in juveniles is made easier because the nursery...

The elemental composition of fish otoliths can record the environmental information because once a trace element is deposited in the otolith; it presents a permanent record of the environmental conditions experienced by the fish at a particular time. The elemental signature of the otolith nucleus, the area lying within the first annual growth ring,...

Egg incubation experiments are the primary source of data for temperature-dependent development models used in the egg production method (EPM) for stock assessments. What at first appears as a relatively simple experiment, to incubate fertilized eggs at a variety of temperatures while recording the time they spend in each stage, proves to be a more...

Ocean acidification, caused by increasing atmospheric concentrations of CO2 (refs , , ), is one of the most critical anthropogenicthreats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, lea...

Kinematics of swimming behavior of larval Atlantic cod, aged 12 and 27 days post-hatch (dph) and cultured under three pCO 2 conditions (control-370, medium -1800, and high-4200 latm) from March to May 2010, were extracted from swim path recordings obtained using silhouette video photography. The swim paths were analyzed for swim duration, distance...

Kinematics of swimming behavior of larval Atlantic cod, aged 12 and 27 days post-hatch (dph) and cultured under three pCO 2 conditions (control-370, medium -1800, and high-4200 latm) from March to May 2010, were extracted from swim path recordings obtained using silhouette video photography. The swim paths were analyzed for swim duration, distance...

Ocean acidification, caused by increasing atmospheric concentrations of CO2, is one of the most critical anthropogenic threats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid–base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to lon...

Ocean acidification, caused by increasing atmospheric concentrations of CO2, is one of the most critical anthropogenicthreats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to long...

The ability to determine authenticity and provenance of fish and fish products throughout the international fish trade distribution chain is of paramount importance, and in many countries traceability in the fisheries sector is based on labelling rules. As shown by numerous fraud cases worldwide, however, and the relentless global problem of illega...

Marine fish are a common natural resource and the scenario described in Garrett Hardin's famous essay on`Theon`The tragedy of the commons' (Hardin, 1968), which depicts how individuals driven by self-interest tend to destroy the very resource 15 Tracing fish and fish products from ocean to fork using advanced molecular technologies Abstract: The ab...

Otolith growth is regulated by the condition of an individual fish, and subject to energetic and physiological variation. At the same time, external factors have a direct influence on otolith formation – both on the rate of growth and on the structure and chemical composition. The combination of micro-milling techniques for stable isotope analysis...

Fish otoliths are unique recording structures, since they form before hatching and grow continuously throughout life. During otolith formation and organic matrix is secreted which controls the precipitation of CaCO3 together with other elements as impurities. The elemental concentration of the otolith is influenced by both physiological and environ...

Geffen, A. J., Nash, R. D. M., and Dickey-Collas, M. 2011. Characterization of herring populations west of the British Isles: an investigation of mixing based on otolith microchemistry. – ICES Journal of Marine Science, 68: 1447–1458. Herring along the west coast of the British Isles are managed and assessed as a series of discrete stocks. The rela...

Geffen, A. J., Høie, H., Folkvord, A., Hufthammer, A. K., Andersson, C., Ninnemann, U., Pedersen, R. B., and Nedreaas, K. 2011. High-latitude climate variability and its effect on fisheries resources as revealed by fossil cod otoliths. – ICES Journal of Marine Science, 68: 1081–1089. Cod (Gadus morhua) otoliths from archaeological sites in northern...

Produced water (PW), a by-product of the oil-production process, contains large amount of alkylphenols (APs) and other harmful oil compounds. In the last 20 years, there have been increasing concerns regarding the environmental impact of large increases in the amounts of PW released into the North Sea. We have previously shown that low levels of AP...