Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Fish abundance, fisheries, fish trade and consumption in sixteenth-century Netherlands as described by Adriaen Coenen
    Bennema, F.P. ; Rijnsdorp, A.D. - \ 2015
    Fisheries Research 161 (2015). - ISSN 0165-7836 - p. 384 - 399.
    pleuronectes-platessa l - atlantic bluefin tuna - southern north-sea - cod gadus-morhua - wadden sea - population-dynamics - medieval europe - resource use - lower rhine - history
    Concern about fisheries impact on marine ecosystems has raised the interest in the reconstruction of the state of marine ecosystems and the nature of the human activities in the past. We present late 16th century information on the occurrence and relative abundance of biota in Dutch coastal and inland waters (50 marine fish, 13 diadromous or freshwater and 4 marine mammal species), as well as a description of the sea fisheries (target species, fishing grounds, gear), fish trade, export, and fish consumption in Holland as documented in the handwritten Fish Book by Adriaen Coenen (1577–1581). The species composition and abundances are compared to published trawl survey data from around 1900 and in the 1990s. Fish species that have disappeared almost completely, were already rare around 1900 and are characterised by a large body size (rays and sharks, sturgeon, ling), whereas currently abundant species were already abundant in the 16th century. Intensive fisheries for herring occurred near Orkney, Fairhill and Shetland. Coastal and freshwater fisheries provided fresh fish for local as well as export markets, but also provided bait for the massive offshore hook and line fishery for the production of salted cod, which remained largely unnoticed. Dried flatfish were exported to Germany. Consumption of fish and marine invertebrates differed between social classes. Coenen distinguished eight consumer categories, a refinement of the categories ‘rich’ and ‘poor’ used in archaeological studies.
    Effects of fishing during the spawning period: implications for sustainable management
    Overzee, H.M.J. van; Rijnsdorp, A.D. - \ 2015
    Reviews in Fish Biology and Fisheries 25 (2015)1. - ISSN 0960-3166 - p. 65 - 83.
    cod gadus-morhua - loligo-vulgaris-reynaudii - north-sea plaice - halibut hippoglossus-stenolepis - palinurus-elephas fabricius - pleuronectes-platessa l - life-history evolution - coral-reef fish - atlantic cod - closed areas
    While fishery closures during the spawning season are commonplace, direct evidence for their benefit is mainly restricted to species forming large spawning aggregations. This paper analyses the conditions under which spawning closures could contribute to sustainable fisheries management by reviewing how fishing during spawning may affect the physiology, behaviour and ecology of individuals and how this may influence the dynamics and the genetics of the population. We distinguish between the effects of fishing activities in relation to mortality, disturbance of spawning activity, and impact on spawning habitat. Spawning closures may be of benefit it they: (1) reduce the fishing mortality of the large and older spawners; (2) avoid negative effects on spawning habitats; (3) reduce the risk of over-exploitation in species which form large spawning aggregations; (4) reduce the evolutionary effects on maturation and reproductive investment; and (5) reduce the risk of over-exploitation of specific spawning components. The contribution of spawning closures to sustainable fisheries will differ among species and depends on the complexity of the spawning system, the level of aggregation during spawning and the vulnerability of the spawning habitat. The importance of these closures depends on the degree of population depletion but does not cease when populations are ‘healthy’ (i.e. no sign that recruitment is impaired).
    Assessing the state of pelagic fish communities within an ecosystem approach and the European Marine Strategy Framework Directive
    Shephard, S. ; Rindorf, A. ; Dickey-Collas, M. ; Hintzen, N.T. ; Farnsworth, K. ; Reid, D.G. - \ 2014
    ICES Journal of Marine Science 71 (2014)7. - ISSN 1054-3139 - p. 1572 - 1585.
    cod gadus-morhua - north-sea - celtic sea - southern benguela - condition indexes - energy reserves - horse mackerel - forage fish - indicators - management
    Pelagic fish are key elements in marine foodwebs and thus comprise an important part of overall ecosystem health. We develop a suite of ecological indicators that track pelagic fish community state and evaluate state of specific objectives against Good Environmental Status (GES) criteria. Indicator time-series are calculated for the EU Marine Strategy Framework Directive “Celtic Seas” (CS) and “Greater North Sea” subregions. Precautionary reference points are proposed for each indicator and a simple decision process is then used to aggregate indicators into a GES assessment for each subregion. The pelagic fish communities of both subregions currently appear to be close to GES, but each remains vulnerable. In the CS subregion, fishing mortality is close to the precautionary reference point, although the unknown dynamics of sandeel, sprat, and sardine in the subregion may reduce the robustness of this evaluation. In the North Sea, sandeel stocks have been in poor state until very recently. Pelagic fish community biomass is slightly below the precautionary reference point in both subregions.
    Forage fish, their fisheries and their predators: who drives whom?
    Engelhard, G.H. ; Peck, M.A. ; Rindorf, A. ; Smout, S.C. ; Deurs, M. van; Raab, K.E. ; Andersen, K.H. ; Garthe, S. ; Lauerburg, R.A.M. ; Scott, F. ; Brunel, T.P.A. ; Aarts, G.M. ; Kooten, T. van; Dickey-Collas, M. - \ 2014
    ICES Journal of Marine Science 71 (2014)1. - ISSN 1054-3139 - p. 90 - 104.
    herring clupea-harengus - sprat sprattus-sprattus - sandeel ammodytes-marinus - ecosystem-based management - pout trisopterus-esmarkii - cod gadus-morhua - north-sea fish - population-dynamics - trophic cascades - environmental variability
    The North Sea has a diverse forage fish assemblage, including herring, targeted for human consumption; sandeel, sprat, and Norway pout, exploited by industrial fisheries; and some sardine and anchovy, supporting small-scale fisheries. All show large abundance fluctuations, impacting on fisheries and predators. We review field, laboratory, and modelling studies to investigate the drivers of this complex system of forage fish. Climate clearly influences forage fish productivity; however, any single-species considerations of the influence of climate might fail if strong interactions between forage fish exist, as in the North Sea. Sandeel appears to be the most important prey forage fish. Seabirds are most dependent on forage fish, due to specialized diet and distributional constraints (breeding colonies). Other than fisheries, key predators of forage fish are a few piscivorous fish species including saithe, whiting, mackerel, and horse-mackerel, exploited in turn by fisheries; seabirds and seals have a more modest impact. Size-based foodweb modelling suggests that reducing fishing mortality may not necessarily lead to larger stocks of piscivorous fish, especially if their early life stages compete with forage fish for zooplankton resources. In complex systems, changes in the impact of fisheries on forage fish may have potentially complex (and perhaps unanticipated) consequences on other commercially and/or ecologically important species.
    Fecundity regulation in horse mackerel
    Damme, C.J.G. van; Thorsen, A. ; Fonn, M. ; Alvarez, P. ; Garabana, D. ; O'Hea, B. ; Perez, J.R. ; Dickey-Collas, M. - \ 2014
    ICES Journal of Marine Science 71 (2014)3. - ISSN 1054-3139 - p. 546 - 558.
    daily egg-production - herring clupea-harengus - trachurus-trachurus l. - pleuronectes-platessa l - saronikos gulf greece - scomber-scombrus l. - north-sea plaice - cod gadus-morhua - batch fecundity - spawning frequency
    Egg production methods have been used successfully in the provision of advice for fisheries management. These methods need accurate and unbiased estimates of fecundity. We explore the reproductive strategy of horse mackerel and estimation of fecundity. Fecundity and fecundity regulation in relation to condition was investigated over a number of years. Fulton's K, lipid content, and hepatosomatic index increased after the start of spawning, though decreased again at the end of spawning. The increase in the gonadosomatic index, fecundity, and body condition after the onset of spawning suggests that horse mackerel utilizes food resources during the spawning season and might be an income breeder. However, the decline in K and lipid before the spawning season suggests that the first batch of oocytes is developed on stored energy. Fecundity varied between years and within a spawning season. Over latitude, variations in fecundity were small. K and lipid content are not reliable indices as proxy for fecundity. Batch fecundity appears to be heterogeneous across the spawning season but homogeneous across latitude. The homogeneity of batch fecundity over latitude could indicate that the daily egg production method is an appropriate approach for estimating the abundance of a wide ranging species, as horse mackerel.
    Ecosystem-based management objectives for the North Sea: riding the forage fish rollercoaster
    Dickey-Collas, M. ; Engelhard, G.H. ; Rindorf, A. ; Raab, K.E. ; Aarts, G.M. ; Brunel, T.P.A. ; Kooten, T. van - \ 2014
    ICES Journal of Marine Science 71 (2014)1. - ISSN 1054-3139 - p. 128 - 142.
    cod gadus-morhua - scottish waters 1992-2003 - climate-change - harbor seals - multispecies fisheries - engraulis-encrasicolus - seasonal-variation - phocoena-phocoena - reference points - food conversion
    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.
    Evolutionary impact assessment: accounting for evolutionary consequences of fishing in an ecosystem approach to fisheries management
    Laugen, A.T. ; Engelhard, G.H. ; Whitlock, R. ; Mollet, F.M. ; Rijnsdorp, A.D. - \ 2014
    Fish and Fisheries 15 (2014)1. - ISSN 1467-2960 - p. 65 - 96.
    cod gadus-morhua - maturation reaction norms - effective population-size - life-history evolution - north-sea plaice - pike esox-lucius - herring clupea-harengus - eco-genetic model - atlantic cod - marine fish
    Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries-induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life-history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries.
    Modeling cooking of chicken meat in industrial tunnel ovens with the Flory-Rehner theory
    Sman, R.G.M. van der - \ 2013
    Meat Science 95 (2013)4. - ISSN 0309-1740 - p. 940 - 957.
    water-holding capacity - protein cross-linking - cod gadus-morhua - mass-transfer - moisture transport - porous-media - heat-transfer - theoretical aspects - capillary-pressure - structural-changes
    In this paper we present a numerical model describing the heat and mass transport during the cooking of chicken meat in industrial tunnels. The mass transport is driven by gradients in the swelling pressure, which is described by the Flory-Rehner theory, which relates to the water holding capacity (WHC). For cooking temperatures up to boiling point and practical relevant cooking times, the model renders good prediction of heat and mass transport and the total loss of moisture. We have shown that for cooking temperatures above boiling point, the model has to be extended with the dynamic growth of capillary water (drip) channels. Furthermore, we discuss that the Flory-Rehner theory provides the proper physical basis for describing the change of the WHC by a wide variety of factors like salt and pH. (C) 2013 Elsevier Ltd. All rights reserved.
    A review on broodstock nutrition of marine pelagic spawners: the curious case of the freshwater eels (Anguilla spp.)
    Heinsbroek, L.T.N. ; Støttrup, J.G. ; Jacobsen, C. ; Corraze, G. ; Kraiem, M.M. ; Holst, L.K. ; Tomkiewicz, J. ; Kaushik, S.J. - \ 2013
    Aquaculture Nutrition 19 (2013)s1. - ISSN 1353-5773 - p. 1 - 24.
    fatty-acid-composition - bass dicentrarchus-labrax - european sea bass - cod gadus-morhua - free amino-acids - yolk-sac larvae - seabream sparus-aurata - halibut hippoglossus-hippoglossus - turbot scophthalmus-maximus - dentex dentex-dentex
    To sustain eel aquaculture, development of reproduction in captivity is vital. The aim of this review is to assess our current knowledge on the nutrition of broodstock eels in order to improve the quality of broodstock under farming conditions, drawing information from wild adult eels and other marine pelagic spawners. Freshwater eels spawn marine pelagic eggs with an oil droplet (type II), and with a large perivitelline space. Compared with other marine fish eggs, eel eggs are at the extreme end of the spectrum in terms of egg composition, even within this type II group. Eel eggs contain a large amount of total lipids, and a shortage of neutral lipids has been implied a cause for reduced survival of larvae. Eel eggs have higher ARA but lower EPA and DHA levels than in other fish. Too high levels of ARA negatively affected reproduction in the Japanese eel, although high levels of 18:2n-6 in the eggs of farmed eels were not detrimental. The total free amino acid amount and profile of eel eggs appears much different from other marine pelagic spawners. Nutritional intervention to influence egg composition seems feasible, but responsiveness of farmed eels to induced maturation might also require environmental manipulation. The challenge remains to succeed in raising European eel broodstock with formulated feeds and to enable the procurement of viable eggs and larvae, once adequate protocols for induced maturation have been developed.
    Boarfish (Capros aper) target strength modelled from magnetis resonance imaging (MRI) scans of tis swimbladder
    Fassler, S.M.M. ; O'Donnell, C. ; Jech, J.M. - \ 2013
    ICES Journal of Marine Science 70 (2013)7. - ISSN 1054-3139 - p. 1451 - 1459.
    relative frequency-response - pout trisopterus-esmarkii - herring clupea-harengus - cod gadus-morhua - species identification - atlantic mackerel - in-situ - kirchhoff-approximation - fisheries acoustics - walleye pollock
    Boarfish (Capros aper) abundance has increased dramatically in the Northeast Atlantic from the early 1970s after successive years of good recruitment attributed to an increase in sea surface temperature. Due to increased commercial fishing over recent years, an acoustic boarfish survey funded by the Killybegs Fishermen's Organisation was initiated by the Marine Institute to establish a baseline for the future management of this stock. In the absence of any species-specific boarfish target strength (TS), acoustic backscatter was estimated by a Kirchhoff-ray mode model using reconstructed three-dimensional swimbladder shapes which were computed from magnetic resonance imaging scans of whole fish. The model predicted TS as a function of size, fish tilt angle, and operating frequency. Standardized directivity patterns revealed the increasing importance of changes in the inclination of the dorsal swimbladder surface at higher frequencies (120 and 200 kHz) and a less directive response at lower frequencies (18 and 38 kHz). The model predicted a TS-to-total fish length relationship of TS = 20 log10(L) - 66.2. The intercept is ~1 dB higher than in the general physoclist relationship, potentially reflecting the bulky nature of the boarfish swimbladder with its relatively large circumference.
    Is age structure a relevant criterion for the health of fish stocks?
    Brunel, T.P.A. ; Piet, G.J. - \ 2013
    ICES Journal of Marine Science 70 (2013)2. - ISSN 1054-3139 - p. 270 - 283.
    cod gadus-morhua - northern north-sea - atlantic cod - spawning stock - fisheries sustainability - reference points - climate-change - baltic cod - egg size - recruitment
    The age and size structure of exploited fish stocks is one of the criteria for Good Environmental Status of commercial fish. However, two underlying assumptions to this criterion remain to be tested: first, that a well-balanced age structure is indeed indicative of a “healthier” stock, and second, that managers can exert a control on the age structure, independently from the regulation of stock abundance. This study investigates these questions using simulations from a population model in which recruitment is based on egg production, which is more sensitive to age structure variations than the traditionally used spawning stock biomass (SSB) and that was parameterized to represent the population dynamics of North Sea cod, plaice, and herring. Our results show that (i) the age structure is highly dependent on the selection pattern, as well as on the level of fishing mortality; (ii) the selection pattern determines the ability of fish stocks to withstand, and recover from, external perturbation; and (iii) the selection pattern determines the output of the fishery providing the management option to balance stable but relatively low yields vs strongly fluctuating high yields. Therefore, we propose to make the selection pattern, for which clear management targets can be set, a policy goal instead of the age structure that is currently in place
    Can fisheries-induced evolution shift reference points for fisheries management?
    Heino, M. ; Baulier, L. ; Boukal, D.S. ; Mollet, F.M. ; Rijnsdorp, A.D. - \ 2013
    ICES Journal of Marine Science 70 (2013)4. - ISSN 1054-3139 - p. 707 - 721.
    cod gadus-morhua - north-sea plaice - life-history evolution - exploited fish stocks - pleuronectes-platessa l - eco-genetic model - atlantic cod - population-dynamics - reproductive investment - natural mortality
    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 changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and “precautionary” reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics.
    The effect of tryptophan supplemented diets on brain serotonergic activity and plasma cortisol under undisturbed and stressed conditions in grouped-housed Nile tilapia Oreochromis niloticus
    Martins, C.I. ; Silva, P.I.M. ; Costas, B. ; Larsen, B.K. ; Santos, G.A. ; Conceicao, L.E.C. ; Dias, J. ; Overli, O. ; Höglund, E. ; Schrama, J.W. - \ 2013
    Aquaculture 400-401 (2013). - ISSN 0044-8486 - p. 129 - 134.
    trout oncorhynchus-mykiss - sole solea-senegalensis - neutral amino-acids - cod gadus-morhua - rainbow-trout - flesh quality - atlantic salmon - meat quality - preslaughter stress - interrenal activity
    Tryptophan (TRP) supplemented diets have been shown to have therapeutic effects in farmed animals including fish by modulating the activity of the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT). The effects reported in fish have been obtained using individually-housed fish and include a reduction in stress response, aggression and stress-induced anorexia. In land farmed animals, TRP supplemented diets have also been shown to improve meat quality as a result of reduced stress during slaughter while in fish no data is currently available. This study aims at investigating whether short-term supplementation with TRP supplemented diets changes brain serotonergic activity and the stress response associated with slaughter handling in grouped-housed Nile tilapia Oreochromis niloticus. Adult fish (n = 108, 490.6 ± 4.0 g, 12 individuals per tank) were exposed to one of the three treatments (triplicates per treatment were used): control (0.48 g/100 g), TRP 4 × (1.87 g/100 g) and TRP 10 × (4.45 g/100 g) diets during 7 days. Afterwards, half of the fish in each tank were subjected to an acute stressor consisting of a combination of crowding and chasing, just prior to slaughter. The other half of the fish represented undisturbed conditions. Blood and brain samples were collected for cortisol and serotonergic activity analyses, respectively. Flesh quality was also assessed in both undisturbed and stressed fish for all treatments by measuring muscle pH and rigor mortis over a 72 h period. Results showed that the highest TRP supplemented diet (TRP 10 ×) induced a significant reduction in undisturbed plasma cortisol (10.57 ± 2.71 ng/ml) as compared to TRP 4 × (24.93 ± 3.19 ng/ml) and control diets (18.69 ± 2.94 ng/ml) and no effect on post-stress cortisol levels. After stress, the major 5-HT metabolite (5-hydroxyindoleacetic acid, 5-HIAA) was higher in the TRP 10 × (471.31 ± 60.95 ng/g) as compared to the other diets (TRP 4 ×: 313.52 ± 30.12 ng/g; control: 260.36 ± 19.65 ng/g). Stress before slaughter induced a significant increase in plasma cortisol (from 18.40 ± 1.76 ng/ml under undisturbed conditions to 80.34 ± 7.16 ng/ml), however, it was not sufficient to cause a faster deterioration of flesh quality. TRP supplement diets had also no effect on muscle pH and rigor mortis during the 72 h observation period. In conclusion, this study showed that only the highest levels of supplementation (10 × the control diet) affect serotonergic activity. However, these levels did not result in reduced stress responsiveness or improved flesh quality when an acute stressor is applied before slaughter. Therefore, these results underline the fact that effects of TRP on cortisol production are dose- and context-dependent, and further experiments are needed to determine under which conditions the optimal effect is obtained.
    Spatial variation in growth, maturation schedules and reproductive investment of female sole solea solea in the Northeast AtlanTic
    Mollet, F.M. ; Engelhard, G.H. ; Vainikka, A. ; Laugen, A.T. ; Rijnsdorp, A.D. ; Ernande, B. - \ 2013
    Journal of Sea Research 84 (2013). - ISSN 1385-1101 - p. 109 - 121.
    cod gadus-morhua - plaice pleuronectes-platessa - herring clupea-harengus - long-term changes - countergradient variation - reaction norms - bergmanns rule - rana-temporaria - sea plaice - evolutionary significance
    Latitudinal variation in life-history traits is often explained by phenotypically plastic responses or local adaptations to different thermal regimes. We compared growth, maturation schedules and reproductive investment of female sole Solea solea between 8 populations, covering much of the species' distribution in northern Europe, with respect to thermal gradients. An energy allocation model was fitted to size–age data, and probabilistic maturation reaction norms were estimated from size–age–maturity data. We found that northern populations from colder environments had higher rates of energy acquisition and reproductive investment, an intrinsic tendency to mature earlier, and had smaller asymptotic sizes than southern populations from warmer environments. Consequently, growth rate was higher before maturation but lower after maturation in the north compared to the south. This is opposite to Bergmann's rule according to which slower growth, delayed maturation and larger asymptotic sizes are usually observed at lower temperatures. The observed patterns could indicate strong countergradient thermal adaptation for rapid growth and development as well as sustained fecundity in the north, or indicate a response to other selection pressures correlated with the thermal gradient. Potentially higher mortality in northern populations during cold winters might be one of the key drivers of the observed geographical variation in growth and maturation of sole.
    Impacts of climate change on the complex life cycles of fish
    Petitgas, P. ; Rijnsdorp, A.D. ; Dickey-Collas, M. ; Engelhard, G.H. ; Peck, M.A. ; Pinnegar, J.K. ; Drinkwater, K. ; Huret, M. ; Nash, R.D.M. - \ 2013
    Fisheries Oceanography 22 (2013)2. - ISSN 1054-6006 - p. 121 - 139.
    cod gadus-morhua - plaice pleuronectes-platessa - anchovy engraulis-encrasicolus - herring clupea-harengus - north-sea plaice - juvenile atlantic cod - arcto-norwegian cod - flounder platichthys-flesus - dependent development rates - western wadden sea
    To anticipate the response of fish populations to climate change, we developed a framework that integrates requirements in all life stages to assess impacts across the entire life cycle. The framework was applied on plaice (Pleuronectes platessa) and Atlantic herring (Clupea harengus) in the North Sea, Atlantic cod (Gadus morhua) in the Norwegian/Barents Seas and European anchovy (Engraulis encrasicolus) in the Bay of Biscay. In each case study, we reviewed habitats required by each life stage, habitat availability, and connectivity between habitats. We then explored how these could be altered by climate change. We documented environmental processes impacting habitat availability and connectivity, providing an integrated view at the population level and in a spatial context of potential climate impacts. A key result was that climate-driven changes in larval dispersion seem to be the major unknown. Our summary suggested that species with specific habitat requirements for spawning (herring) or nursery grounds (plaice) display bottlenecks in their life cycle. Among the species examined, anchovy could cope best with environmental variability. Plaice was considered to be least resilient to climate-driven changes due to its strict connectivity between spawning and nursery grounds. For plaice in the North Sea, habitat availability was expected to reduce with climate change. For North Sea herring, Norwegian cod and Biscay anchovy, climate-driven changes were expected to have contrasting impacts depending on the life stage. Our review highlights the need to integrate physiological and behavioural processes across the life cycle to project the response of specific populations to climate change.
    Shifts in the timing of spawning in sole linked to warming sea temperatures
    Fincham, J.I. ; Rijnsdorp, A.D. ; Engelhard, G.H. - \ 2013
    Journal of Sea Research 75 (2013). - ISSN 1385-1101 - p. 69 - 76.
    cod gadus-morhua - plaice pleuronectes-platessa - maturation reaction norms - north-sea - climate-change - fish populations - maturity ogives - marine - growth - fisheries
    Phenotypic traits such as peak spawning time may vary within and differ between populations in relation to environmental factors, such as temperature. Sole (Solea solea) is a valuable, commercially exploited species that spawns in late winter or spring. The date of peak spawning was estimated for each year for seven stocks from monthly fish samples collected from commercial fisheries since 1970. Four out of seven stocks showed a significant long-term trend towards earlier spawning (Irish Sea, east-central North Sea, southern North Sea, eastern English Channel) at a rate of 1.5 weeks per decade. The other three stocks (Bristol Channel, western English Channel and western-central North Sea) failed to show a relationship, but the available time series were limited for these stocks (<10 years). Sea surface temperature during winter significantly affected the date of peak spawning, although the effect differed between stocks. The implications of the effect of winter temperature on the timing of spawning for the population dynamics are discussed.
    The effect of temperature and pH on the growth and physiological response of juvenile yellowtail kingfish Seriola lalandi in recirculating aquaculture systems
    Abbink, W. ; Blanco Garcia, A. ; Roques, J.A.C. ; Partridge, G. ; Kloet, K. ; Schneider, O. - \ 2012
    Aquaculture 330-333 (2012). - ISSN 0044-8486 - p. 130 - 135.
    acid-base-balance - cod gadus-morhua - stress-response - atlantic cod - fish size - environmental hypercapnia - dicentrarchus-labrax - feed conversion - cold-water - sea bass
    A search for a viable new fish species for culture in recirculating aquaculture systems (RAS) in the Netherlands identified yellowtail kingfish Seriola lalandi as having excellent potential. To assist in determining the most appropriate water quality conditions for this species in RAS, the effect of water temperature (21, 23.5, 25, 26.5 and 29 °C) and pH (6.58, 7.16 and 7.85) was tested in two separate experiments. Growth performance, feed conversion, stress-physiological and metabolic parameters were assessed in juvenile yellowtail kingfish grown in pilot-scale RAS. Growth was optimised at a water temperature of 26.5 °C, in combination with maximum food intake and optimum food conversion ratio (FCR). Increasing temperature from 21 °C to 26.5 °C resulted in a 54% increase in the fish's final weight after 30 days. A water pH of 6.58 resulted in mortality and inhibited both growth and FCR due to physiological disruptions to which the fish could not adapt
    Egg production methdos in marine fisheries: An introduction
    Bernal, M. ; Somarakis, S. ; Witthames, P.R. ; Damme, C.J.G. van; Uriarte, A.R. ; Lo, N.C.H. ; Dickey-Collas, M. - \ 2012
    Fisheries Research 117-118 (2012). - ISSN 0165-7836 - p. 1 - 5.
    anchovy engraulis-encrasicolus - mackerel trachurus-trachurus - sardine sardinops-sagax - spawning-stock biomass - cod gadus-morhua - ichthyoplankton mortality-rates - generalized additive-models - pleuronectes-platessa l. - herring clupea-harengus - north-sea pla
    This paper is an introduction of the Fisheries Research special issue on egg production methods (EPM) that emerged from a dedicated workshop held in Athens, Greece, in 2010. The workshop considered if EPMs are still valid today, it reviewed recent developments in the methods and discussed the utility of EPMs in the future. Importantly, experts from both the daily and the annual egg production methods took part in the workshop. This introduction provides the main concepts underlying EPMs. It also gives a brief history of EPM development over the last two decades with examples of their use worldwide. It provides a review on whether EPMs have fulfilled their objectives. Given their increased utilisation on new fish stocks, and their contribution to scientific advances, EPMs continue to be useful. However, concerns about the bias and precision of the methods remain, and a continuous effort to improve those issues together with the cost-efficiency of the methods is still required.
    Extracting a century of preserved molecular and population demographic data from archived otoliths in the endangered European eel (Anguilla anguilla L.)
    Schaerlaekens, D.G. ; Dekker, W. ; Wickstrom, H. ; Volckaert, F.A.M. ; Maes, G.E. - \ 2011
    Journal of Experimental Marine Biology and Ecology 398 (2011)1-2. - ISSN 0022-0981 - p. 56 - 62.
    cod gadus-morhua - old scale samples - age-determination - dna extraction - ancient dna - microsatellite loci - genetic analyses - north-sea - amplification - conservation
    Archived otolith collections represent an invaluable source of information to study demographic and genetic changes in commercially important fish populations. Studies combining both approaches are however rare and reliable extraction of molecular and population demographic data from the same collection of otoliths has never been assessed in the endangered European eel (Anguilla anguilla L). Here we evaluate various DNA extraction protocols to compare DNA yield, microsatellite amplification success, genotype integrity and precision of age determination for eel otoliths that have been archived for 4 weeks, and for 28 and 48 years. Our results show a high amplification success and an equal genotype integrity for DNA fragments extracted from both recently sampled otoliths and high quality reference DNA tissue. Although historical samples yielded low amounts of DNA. PCR amplification was successful and genotyping reliable for short fragments, but decreased significantly with PCR fragment size. None of the extraction protocols caused physical damage to the otoliths and precision of age determination was high for both treated and untreated otoliths. Hence, the methodology can be applied as a standard for the further joint analysis of past demographic and genetic changes during the last century in the highly exploited European eel and in other fish requiring urgent conservation measures.
    Detecting population structure in a high gene-flow species, Atlantic herring (Clupea harengus): direct, simultaneous evaluation of neutral vs putatively selected loci
    Andre, C. ; Larsson, L.C. ; Laikre, L. ; Bekkevold, D. ; Brigham, J. ; Carvalho, G.R. ; Dahlgren, T.G. ; Hutchinson, W.F. ; Mariani, S. ; Mudde, C.M. ; Ruzzante, D.E. ; Ryman, N. - \ 2011
    Heredity 106 (2011)2. - ISSN 0018-067X - p. 270 - 280.
    cod gadus-morhua - salmon salmo-salar - histocompatibility class-i - mitochondrial-dna - north-sea - molecular markers - balancing selection - statistical power - natural-selection - computer-program
    In many marine fish species, genetic population structure is typically weak because populations are large, evolutionarily young and have a high potential for gene flow. We tested whether genetic markers influenced by natural selection are more efficient than the presumed neutral genetic markers to detect population structure in Atlantic herring (Clupea harengus), a migratory pelagic species with large effective population sizes. We compared the spatial and temporal patterns of divergence and statistical power of three traditional genetic marker types, microsatellites, allozymes and mitochondrial DNA, with one microsatellite locus, Cpa112, previously shown to be influenced by divergent selection associated with salinity, and one locus located in the major histocompatibility complex class IIA (MHC-IIA) gene, using the same individuals across analyses. Samples were collected in 2002 and 2003 at two locations in the North Sea, one location in the Skagerrak and one location in the low-saline Baltic Sea. Levels of divergence for putatively neutral markers were generally low, with the exception of single outlier locus/sample combinations; microsatellites were the most statistically powerful markers under neutral expectations. We found no evidence of selection acting on the MHC locus. Cpa112, however, was highly divergent in the Baltic samples. Simulations addressing the statistical power for detecting population divergence showed that when using Cpa112 alone, compared with using eight presumed neutral microsatellite loci, sample sizes could be reduced by up to a tenth while still retaining high statistical power. Our results show that the loci influenced by selection can serve as powerful markers for detecting population structure in high gene-flow marine fish species. Heredity (2011) 106, 270-280; doi:10.1038/hdy.2010.71; published online 16 June 2010
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