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Herring
Kinds of Herring Terms modified by Herring Selected AbstractsA spatially explicit, individual-based model to assess the role of estuarine nurseries in the early life history of North Sea herring, Clupea harengusFISHERIES OCEANOGRAPHY, Issue 1 2005JOACHIM MAES Abstract Herring (Clupea harengus) enter and remain within North Sea estuaries during well-defined periods of their early life history. The costs and benefits of the migrations between offshore spawning grounds and upper, low-salinity zones of estuarine nurseries are identified using a dynamic state-variable model, in which the fitness of an individual is maximized by selecting the most profitable habitat. Spatio-temporal gradients in temperature, turbidity, food availability and predation risk simulate the environment. We modeled predation as a function of temperature, the optical properties of the ambient water, the time allocation of feeding and the abundance of whiting (Merlangius merlangus). Growth and metabolic costs were assessed using a bioenergetic model. Model runs using real input data for the Scheldt estuary (Belgium, The Netherlands) and the southern North Sea show that estuarine residence results in fitter individuals through a considerable increase in survival probability of age-0 fish. Young herring pay for their migration into safer estuarine water by foregoing growth opportunities at sea. We suggest that temperature and, in particular, the time lag between estuarine and seawater temperatures, acts as a basic cue for herring to navigate in the heterogeneous space between the offshore spawning grounds at sea and the oligohaline nursery zone in estuaries. [source] The influence of oxygen saturation on the distributional overlap of predator (cod, Gadus morhua) and prey (herring, Clupea harengus) in the Bornholm Basin of the Baltic SeaFISHERIES OCEANOGRAPHY, Issue 1 2002Stefan Neuenfeldt Environmental heterogeneity can create boundary conditions for the co-occurrence of marine predators and their prey. If one or both are spatially constrained by their tolerance to environmental variables, then spatial differences in the availability of possible habitats define the volume of distributional overlap. Cod (Gadus morhua L.) and its prey, herring (Clupea harengus L.), in the vertically stratified Bornholm Basin of the Baltic Sea are presented as an example. A non-linear model was used to estimate oxygen avoidance thresholds for both species. Herring avoided oxygen saturation levels below 50%, while cod tolerated oxygen saturation down to 16%. The threshold of 50% oxygen saturation, below which cod could not encounter its prey, herring, was applied to a time series of vertical oxygen profiles from the centre of the Bornholm Basin to estimate the size of the overlap volume during the winter period from 1958 to 1999. Dependent on the oxygenation of the deep-water, the overlap volume varied between 57 km3 and 250 km3. [source] Effects of Brining Conditions on Weight Gain in Herring (Clupea harengus) FilletsJOURNAL OF FOOD SCIENCE, Issue 7 2005Sveinung Birkeland ABSTRACT: Salted herring is an important product category in many European countries. Reduced need for salt as a preserving agent and the increased emphasis on less salt in the human diet has changed the basis for the traditional processing of these products. This has led to significant changes in the processing conditions and in the characteristics of the salted products. In this perspective, the effects of different brine concentrations (10.0%, 16.5%, and 25.5%), brining temperatures (3.5 °C and 17.5 °C), the presence of skin or not on the fillets, and brining time (1, 2, 3, 4, and 7 d) were investigated on the weight gain (%) and final salt content (%) of herring (Clupea harengus). A significant (P < 0.001) higher weight gain of the fillets were observed at the lowest brining temperature (3.5 °C) compared with at the higher temperature (17.5 °C), independently of brine concentration and brining time. Increased brine concentration and skinning of the fillets caused the weight gain to significantly decrease (P < 0.001) and increase (P < 0.001), respectively. After 1 d of brining, the weight gain was in the range of 10% to 12% for both brining temperatures, and at the lowest temperature, the weight gain increased significantly (P < 0.001) as a function of brining time. At the higher temperature, no further significant increase in weight was observed from 1 to 7 d of brining. It is concluded that the weight gain in herring fillets brined according to the present commercial practice is significantly affected by temperature, brine concentration, brining time, and the presence or not of skin on the fillets and that the weight gain may be of high magnitude. [source] Global perspective on Wikipedia researchPROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2008Pnina Shachaf This panel will provide a global perspective on Wikipedia research. The literature on Wikipedia is mostly anecdotal, and most of the research has focused attention primarily on the English Wikipedia examining the accuracy of entries compared to established online encyclopedias (Emigh & Herring, 2005; Giles, 2005; Rosenzweig, 2006) and analyzing the evolution of articles over time (Viégas, Wattenberg, & Dave, 2004; Viégas, Wattenberg, Kriss, & van Ham, 2007). Others have examined the quality of contribution (Stvilia et al., 2005). However, only a few studies have conducted comparative analyses across languages or analyzed Wikipedia in languages other than English (e.g., Pfeil, Zaphiris, & Ang, 2006). There is a need for international, cross-cultural understanding of Wikipedia. In an effort to address this gap, this panel will present a range of international and cross-cultural research of Wikipedia. The presenters will contribute different perspectives of Wikipedia as an international sociocultural institution and will describe similarities and differences across various national/language versions of Wikipedia. Shachaf and Hara will present variation of norms and behaviors on talk pages in various languages of Wikipedia. Herring and Callahan will share results from a cross-language comparison of biographical entries that exhibit variations in content of entries in the English and Polish versions of Wikipedia and will explain how they are influenced by the culture and history of the US and Poland. Stvilia will discuss some of the commonalities and variability of quality models used by different Wikipedias, and the problems of cross-language quality measurement aggregation and reasoning. Matei will describe the social structuration and distribution of roles and efforts in wiki teaching environments. Solomon's comments, as a discussant, will focus on how these comparative insights provide evidence of the ways in which an evolving institution, such as Wikipedia, may be a force for supporting cultural identity (or not). [source] Influence of herring (Clupea harengus) and herring fractions on metabolic status in rats fed a high energy dietACTA PHYSIOLOGICA, Issue 3 2009H. Lindqvist Abstract Aim:, Few dietary studies have looked beyond fish oil to explain the beneficial metabolic effects of a fish-containing diet. Our aim was to study whether addition of herring, or sub-fractions of herring, could counteract negative metabolic effects known to be induced by a high-fat, high-sugar diet. Methods:, Rats were given six different diets: standard pellets; high energy diet with chicken mince (HiE control); high energy diet with herring mince (HiE herring); and high energy diet with chicken mince and either herring oil (HiE herring oil), herring press juice, PJ (HiE PJ) or herring low molecular weight PJ (HiE LMW-PJ). Factors associated with the metabolic syndrome were measured. Results:, There were no differences in energy intake or body weight between the groups, but animals fed high energy diets had a higher body fat content compared with the pellet group, although not statistically significant in all groups. Mesenteric adipocyte size was smaller in the HiE herring oil group compared with the HiE control. Glucose clamp studies showed that, compared with the pellet group, the HiE control and HiE herring diets, but not the HiE herring oil diet, induced insulin resistance. Addition of herring or herring oil to the high energy diet decreased total cholesterol levels, triacylglycerols and the atherogenic index compared with the HiE control group. Conclusions:, The results suggest that addition of herring or herring oil counteracts negative effects on blood lipids induced by a high energy diet. The lipid component of herring thus seems to be responsible for these beneficial effects. [source] Effect of Microcystis aeruginosa and Nodularia spumigena on survival of Eurytemora affinis and the embryonic and larval development of the Baltic herring Clupea harengus membrasENVIRONMENTAL TOXICOLOGY, Issue 4 2003Evald Ojaveer Abstract Laboratory experiments were carried out to investigate the effect of two strains of Microcystis aeruginosa and a strain of Nodularia spumigena on the survival of Eurytemora affinis (Copepoda) and on the embryonic and larval development of the Baltic spring-spawning herring Clupea harengus membras. The trials were made in water taken from Pärnu Bay, at a salinity of 3.7,5.1 psu, a constant temperature (15°C ± 1°C in trials with Eurytemora and herring embryos; 18°C ± 2°C with herring larvae), and an oxygen concentration of 8.8,10.4 ppm. The strains tested had a negative impact on the survival of Eurytemora, as well as on the embryonic development and hatching regime of the Baltic herring. In Eurytemora the response depended on the sex of the animals: the survival was clearly higher in females. In the embryonic stages of herring, the influence resulted in an increase in deviations from the normal pattern of development and a higher mortality. The impact of the strains on the larval development of herring was rather moderate. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 236,242, 2003. [source] Toxicity of dispersed weathered crude oil to early life stages of Atlantic herring (Clupea harengus)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2010Stephen McIntosh Abstract Reports of the chronic toxicity of dispersed crude oil to early life stages of fish perpetuate uncertainty about dispersant use. However, realistic exposures to dispersed oil in the water column are thought to be much briefer than exposures associated with chronic toxicity testing. To address this issue, the toxicity of dispersed weathered oil to early life stages of Atlantic herring (Clupea harengus) was tested for short exposure durations, ranging from 1 to 144,h. Toxicity was a function of concentration and duration of exposure, as well as of the life stage exposed. Medium South American crude oil dispersed with Corexit 9500 caused blue sac disease in embryos, but not in free-swimming embryos. The age of embryos was negatively correlated with their sensitivity to oil; those freshly fertilized were most sensitive. Sensitivity increased after hatch, with free-swimming embryos showing signs of narcosis. Gametes were also tested; dispersed oil dramatically impaired fertilization success. For exposures of less than 24,h, gametes and free-swimming embryos were the most sensitive life stages. For those of more than 24,h, young embryos (<1 d old) were most sensitive. The results are presented as statistical models that could assist decisions about dispersant use in the vicinity of fish spawning habitats. Environ. Toxicol. Chem. 2010;29:1160,1167. © 2010 SETAC [source] Vitamins A1 and A2 in hepatic tissue and subcellular fractions in mink feeding on fish-based diets and exposed to Aroclor 1242ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2002Anne Käkelä Abstract Two-month-old female mink were fed diets based on either Baltic herring (Clupea harengus membras) or freshwater smelt (Osmerus eperlanus) for 21 weeks. A portion of the smelt-fed mink were exposed orally to polychlorinated biphenyls (PCBs), Aroclor 1242 (1 mg/d). Retinol (vitamin A1), 3,4-didehydroretinol (vitamin A2), and their different fatty acyl esters were studied in hepatic tissue, microsomes, and cytosol by argentated reversed-phase high-performance liquid chromatography. As a result of Aroclor exposure, concentrations of the fatty acyl esters of vitamins A1 and A2 were about one-tenth and those of unesterified A2 one-fourth those of the control levels. In the fatty acyl esters, percentages of stearates (A1 -18:0 and A2 -18:0) increased at the expense of the other fatty acyl esters. The Aroclor exposure decreased concentrations of alcoholic and esterified forms of the A2 analog more than those of the corresponding A1 analog. In microsomes, Aroclor decreased the alcoholic and esterified vitamin analogs to the same extent (to 9,17%). In the cytosol compared to the control, the concentrations of the vitamin esters fell below 10%, but the alcoholic analogs remained at 30 to 40%. Despite equal dietary supply, in mink fed on Baltic herring, the hepatic levels of vitamin A1 were only about one-third of the values found in the smelt-fed mink. The organochlorines also altered hepatic lipid composition and impaired breeding and kit growth. In the kits of the females fed on Baltic herring, blood hemoglobin was decreased. [source] Exposure of pacific herring to weathered crude oil: Assessing effects on ova,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Mark G. Carls Abstract In order to determine if exposure to Exxon Valdez oil would adversely affect progeny, reproductively mature Pacific herring were confined in water contaminated with weathered crude oil. Progeny were generally not affected by a 16-d parental exposure to initial aqueous concentrations of ,58 ,g/L total polynuclear aromatic hydrocarbons (PAHs), yielding concentrations of up to 9.7 ,g/g in ova. In contrast, previous research indicated that a 16-d direct exposure of herring eggs to similarly weathered oil was detrimental to developing embryos at total initial PAH concentrations of 9 ,g/L. Progeny of exposed fish could have been insulated from toxic effects for two reasons. First, as an apparent result of partitioning and metabolism in parental tissues, lower concentrations and less toxic PAHs were preferentially accumulated by ova (primarily naphthalenes; 84,92%). Second, peak exposure concentrations occurred before cell differentiation. The opposite was true for directly exposed eggs; the more toxic multi-ring PAHs (e.g., phenanthrenes and chrysenes) and alkyl-substituted homologues were accumulated, and internal concentrations increased during cell division, differentiation, and organ development. Thus, Pacific herring embryos are more critically sensitive to oil pollution than are gametes. [source] Variation in abundance of Norwegian spring-spawning herring (Clupea harengus, Clupeidae) throughout the 20th century and the influence of climatic fluctuationsFISH AND FISHERIES, Issue 3 2000R. Toresen A long-term (1907,98) virtual population analysis (VPA) was made for Norwegian spring-spawning herring (NSSH), which is a huge pelagic fish stock in the north-east Atlantic. It shows that this herring stock has had large fluctuations during the last century; these fluctuations have mainly been determined by variations in the temperature of the inflowing water masses to the region. The spawning stock biomass (SSB) increased from a rather low level in the early years of this century and reached a high level of around 14 million tons by 1930. The spawning stock biomass then decreased to a level of around 10 million tons by 1940, but increased again to a record high level of 16 million tons by 1945. The stock then started to decrease and during the next 20-year period fell to a level of less than 50 000 tons by the late 1960s. Through the 1970s and 1980s, the stock slowly recovered and after the recruitment of strong year classes in 1983 and 1990,1992 the stock recovered to a spawning stock biomass of about 10 million tons. The long-term fluctuation in spawning stock biomass is caused by variations in the survival of recruits. It is found that the long-term changes in spawning stock abundance are highly correlated with the long-term variations in the mean annual temperature of the inflowing Atlantic water masses (through the Kola section) into the north-east Atlantic region. The recruitment is positively correlated with the average temperature in the Kola section in the winter months, January,April, which indicates that environmental factors govern the large-scale fluctuations in production for this herring stock. [source] Population estimation methods to quantify temporal variation in fish accumulations downstream of a weirFISHERIES MANAGEMENT & ECOLOGY, Issue 6 2006L. J. BAUMGARTNER Abstract, Temporal changes in the population sizes of seven migratory species were assessed over a 2-year period prior to the construction of a fishway on the Murrumbidgee River, Australia. Mark-recapture (Chapman,Petersen) and Jackknife removal methods were used at 3-month intervals to determine the composition and sizes of migratory fish populations. No difference in population size estimate was detected between the two methods. However, the Jackknife removal estimator generally provided less variable estimates for a greater number of species. Population sizes were greatest during summer and autumn when bony herring, Nematalosa erebi Günther, and common carp, Cyprinus carpio L., dominated the migratory community. Both estimators provided data essential to further the development of an appropriate fish passage facility and could be applied to other sites where the size of migratory fish populations is of interest. [source] The influence of life history dynamics and environment on the determination of year class strength in North Sea herring (Clupea harengus L.)FISHERIES OCEANOGRAPHY, Issue 4 2005R. D. M. NASH Abstract The inter-annual variability in year class strength (1976,2000) of North Sea herring (Clupea harengus) was investigated using Paulik diagrams based on survey data and Virtual Population Analysis. The herring life cycle was split into five stages: spawning stock biomass (SSB), egg production, larvae, fish with 0 winter rings on the otolith (0-wr), 1-wr and 2-wr. Surveys were used as indices and Paulik analysis revealed relationships between stages. In 80% of the years, year class strength reflected SSB. Poorer than expected year classes were determined during the larva to 0-wr phase, whilst stronger than expected year classes were apparently determined during the 0-wr to 1-wr stage. There was no clear relationship between survival of young stages of herring and the abundance of Calanus finmarchicus but the year class strength of 0-wr and 1-wr had a negative relationship to bottom water temperature. Lower sea water temperatures in the North Sea are associated with higher Calanus abundance. The analysis shows that the strength of aberrant year classes of North Sea herring is determined between the pelagic larval and the juvenile stages. [source] A spatially explicit, individual-based model to assess the role of estuarine nurseries in the early life history of North Sea herring, Clupea harengusFISHERIES OCEANOGRAPHY, Issue 1 2005JOACHIM MAES Abstract Herring (Clupea harengus) enter and remain within North Sea estuaries during well-defined periods of their early life history. The costs and benefits of the migrations between offshore spawning grounds and upper, low-salinity zones of estuarine nurseries are identified using a dynamic state-variable model, in which the fitness of an individual is maximized by selecting the most profitable habitat. Spatio-temporal gradients in temperature, turbidity, food availability and predation risk simulate the environment. We modeled predation as a function of temperature, the optical properties of the ambient water, the time allocation of feeding and the abundance of whiting (Merlangius merlangus). Growth and metabolic costs were assessed using a bioenergetic model. Model runs using real input data for the Scheldt estuary (Belgium, The Netherlands) and the southern North Sea show that estuarine residence results in fitter individuals through a considerable increase in survival probability of age-0 fish. Young herring pay for their migration into safer estuarine water by foregoing growth opportunities at sea. We suggest that temperature and, in particular, the time lag between estuarine and seawater temperatures, acts as a basic cue for herring to navigate in the heterogeneous space between the offshore spawning grounds at sea and the oligohaline nursery zone in estuaries. [source] The marine copepod, Pseudocalanus elongatus, as a mediator between climate variability and fisheries in the Central Baltic SeaFISHERIES OCEANOGRAPHY, Issue 4-5 2003C. Möllmann Abstract Pseudocalanus elongatus is a key species in the pelagic zone of the deep basins of the Central Baltic Sea. The copepod serves as a major food organism for larval as well as for adult, pelagic planktivorous fish. Large interannual fluctuations in the standing stock of P. elongatus have been attributed to significant changes in the hydrographic environment over the last two decades. In particular, the decreasing salinity in the Baltic deep basins, a result of a change in atmospheric forcing leading to an increase in rainfall since the 1980s and of a lack of pulses of saline water intrusions from the North Sea, was found to affect reproduction and maturation of the copepod. In parallel, dramatic changes in the weight-at-age of herring, one of the most important commercial fishes of the Baltic Sea, have been observed since the late 1980s. Using time-series on herring stomach contents, as well as length and weight, we provide evidence for a chain of events relating variability in climate, salinity and P. elongatus abundance to changes in diet and condition of herring in the Central Baltic Sea. [source] The influence of oxygen saturation on the distributional overlap of predator (cod, Gadus morhua) and prey (herring, Clupea harengus) in the Bornholm Basin of the Baltic SeaFISHERIES OCEANOGRAPHY, Issue 1 2002Stefan Neuenfeldt Environmental heterogeneity can create boundary conditions for the co-occurrence of marine predators and their prey. If one or both are spatially constrained by their tolerance to environmental variables, then spatial differences in the availability of possible habitats define the volume of distributional overlap. Cod (Gadus morhua L.) and its prey, herring (Clupea harengus L.), in the vertically stratified Bornholm Basin of the Baltic Sea are presented as an example. A non-linear model was used to estimate oxygen avoidance thresholds for both species. Herring avoided oxygen saturation levels below 50%, while cod tolerated oxygen saturation down to 16%. The threshold of 50% oxygen saturation, below which cod could not encounter its prey, herring, was applied to a time series of vertical oxygen profiles from the centre of the Bornholm Basin to estimate the size of the overlap volume during the winter period from 1958 to 1999. Dependent on the oxygenation of the deep-water, the overlap volume varied between 57 km3 and 250 km3. [source] Implications of interannual variability in euphausiid population biology for fish production along the south-west coast of Vancouver Island: a synthesisFISHERIES OCEANOGRAPHY, Issue 1 2002R. W. Tanasichuk This is a synthesis of published and unpublished research on euphausiid and fish populations using the south-west coast of Vancouver Island. Overall, the studies covered 1985,98, when there were two ENSO events and considerable variation in upwelling. The population biology of the dominant euphausiids (Thysanoessa spinifera, Euphausiapacifica) was monitored during 1991,98. The species abundance trends differed. Results of simple correlation analyses suggested that variations in temperature, salinity and upwelling do not explain variations in the abundance of larval or adult euphausiids, or in the abundance of portions of euphausiid populations on which fish feed. I found significant interannual variations in daily ration of the dominant planktivorous fish species, but euphausiids remained the most important prey. Pacific hake (Merluccius productus), the dominant planktivore, fed on larger (>17 mm) T. spinifera, even though the biomass of this part of the euphausiid biomass decreased by 75% between 1991 and 1997, but Pacific herring (Clupea pallasi) may have begun feeding on smaller E. pacifica. Therefore, any study of the relationship between fish production and krill biology must consider that part of the euphausiid biomass exploited by fish. In addition, some fish species and/or life history stages appeared to adapt to changes in euphausiid availability, while others did not. Such variation in adaptations also has to be described and considered to understand how changes in euphausiid biology affect fish productivity. [source] Ecosystem controls of juvenile pink salmon (Onchorynchus gorbuscha) and Pacific herring (Clupea pallasi) populations in Prince William Sound, AlaskaFISHERIES OCEANOGRAPHY, Issue 2001Robert T. Cooney Abstract Five years of field, laboratory, and numerical modelling studies demonstrated ecosystem-level mechanisms influencing the mortality of juvenile pink salmon and Pacific herring. Both species are prey for other fishes, seabirds, and marine mammals in Prince William Sound. We identified critical time-space linkages between the juvenile stages of pink salmon and herring rearing in shallow-water nursery areas and seasonally varying ocean state, the availability of appropriate zooplankton forage, and the kinds and numbers of predators. These relationships defined unique habitat dependencies for juveniles whose survivals were strongly linked to growth rates, energy reserves, and seasonal trophic sheltering from predators. We found that juvenile herring were subject to substantial starvation losses during a winter period of plankton diminishment, and that predation on juvenile pink salmon was closely linked to the availability of alternative prey for fish and bird predators. Our collaborative study further revealed that juvenile pink salmon and age-0 herring exploit very different portions of the annual production cycle. Juvenile pink salmon targeted the cool-water, early spring plankton bloom dominated by diatoms and large calanoid copepods, whereas young-of-the-year juvenile herring were dependent on warmer conditions occurring later in the postbloom summer and fall when zooplankton was composed of smaller calanoids and a diversity of other taxa. The synopsis of our studies presented in this volume speaks to contemporary issues facing investigators of fish ecosystems, including juvenile fishes, and offers new insight into problems of bottom-up and top-down control. In aggregate, our results point to the importance of seeking mechanistic rather than correlative understandings of complex natural systems. [source] Ecological processes influencing mortality of juvenile pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, AlaskaFISHERIES OCEANOGRAPHY, Issue 2001T. M. Willette Abstract Our collaborative work focused on understanding the system of mechanisms influencing the mortality of juvenile pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Coordinated field studies, data analysis and numerical modelling projects were used to identify and explain the mechanisms and their roles in juvenile mortality. In particular, project studies addressed the identification of major fish and bird predators consuming juvenile salmon and the evaluation of three hypotheses linking these losses to (i) alternative prey for predators (prey-switching hypothesis); (ii) salmon foraging behaviour (refuge-dispersion hypothesis); and (iii) salmon size and growth (size-refuge hypothesis). Two facultative planktivorous fishes, Pacific herring (Clupea pallasi) and walleye pollock (Theragra chalcogramma), probably consumed the most juvenile pink salmon each year, although other gadids were also important. Our prey-switching hypothesis was supported by data indicating that herring and pollock switched to alternative nekton prey, including juvenile salmon, when the biomass of large copepods declined below about 0.2 g m,3. Model simulations were consistent with these findings, but simulations suggested that a June pteropod bloom also sheltered juvenile salmon from predation. Our refuge-dispersion hypothesis was supported by data indicating a five-fold increase in predation losses of juvenile salmon when salmon dispersed from nearshore habitats as the biomass of large copepods declined. Our size-refuge hypothesis was supported by data indicating that size- and growth-dependent vulnerabilities of salmon to predators were a function of predator and prey sizes and the timing of predation events. Our model simulations offered support for the efficacy of representing ecological processes affecting juvenile fishes as systems of coupled evolution equations representing both spatial distribution and physiological status. Simulations wherein model dimensionality was limited through construction of composite trophic groups reproduced the dominant patterns in salmon survival data. In our study, these composite trophic groups were six key zooplankton taxonomic groups, two categories of adult pelagic fishes, and from six to 12 groups for tagged hatchery-reared juvenile salmon. Model simulations also suggested the importance of salmon density and predator size as important factors modifying the predation process. [source] Habitat associations of Atlantic herring in the Shetland area: influence of spatial scale and geographic segmentationFISHERIES OCEANOGRAPHY, Issue 3 2001CHRISTOS D. Maravelias This study considers the habitat associations of a pelagic species with a range of biotic and abiotic factors at three different spatial scales. Generalized additive models (GAM) are used to analyse trends in the distributional abundance of Atlantic herring (Clupea harengus) in relation to thermocline and water depth, seabed roughness and hardness, sea surface salinity and temperature, zooplankton abundance and spatial location. Two geographical segments of the population, those east and west of the Shetland Islands (northern North Sea, ICES Div IVa), are examined. The differences in the ecological preferences of the species in these two distinct geographical areas are elucidated and the degree that these environmental relationships might be modulated by the change of support of the data is also considered. Part of the observed variability of the pre-spawning distribution of herring was explained by different parameters in these two regions. Notwithstanding this, key determinants of the species' spatial aggregation in both areas were zooplankton abundance and the nature of the seabed substrate. The relative importance of the variables examined did not change significantly at different spatial scales of the observation window. The diverse significance of various environmental factors on herring distribution was attributed mainly to the interaction of species' dynamics with the different characteristics of the ecosystem, east and west of the Shetland Islands. Results suggest that the current 2.5 nautical miles as elementary sampling distance unit (ESDU) is a reasonable sampling scheme that combines the need to reduce the data volume while maintaining spatial resolution to distinguish the species/environment relationships. [source] Pacific herring, Clupea pallasi, recruitment in the Bering Sea and north-east Pacific Ocean, II: relationships to environmental variables and implications for forecastingFISHERIES OCEANOGRAPHY, Issue 4 2000Erik H. Williams Previous studies have shown that Pacific herring populations in the Bering Sea and north-east Pacific Ocean can be grouped based on similar recruitment time series. The scale of these groups suggests large-scale influence on recruitment fluctuations from the environment. Recruitment time series from 14 populations were analysed to determine links to various environmental variables and to develop recruitment forecasting models using a Ricker-type environmentally dependent spawner,recruit model. The environmental variables used for this investigation included monthly time series of the following: southern oscillation index, North Pacific pressure index, sea surface temperatures, air temperatures, coastal upwelling indices, Bering Sea wind, Bering Sea ice cover, and Bering Sea bottom temperatures. Exploratory correlation analysis was used for focusing the time period examined for each environmental variable. Candidate models for forecasting herring recruitment were selected by the ordinary and recent cross-validation prediction errors. Results indicated that forecasting models using air and sea surface temperature data lagged to the year of spawning generally produced the best forecasting models. Multiple environmental variables showed marked improvements in prediction over single-environmental-variable models. [source] Long-term storage influence on volatile amines (TVB-N and TMA-N) in sardines and herring utilized as food for tuna fatteningJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2009imat Summary The study investigated the influence of volatile amines, total volatile bases nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) quantities in sardines (Sardina pilchardus) and herring (Clupea harengus) after 1 year of frozen storage. TVB-N quantities for both species were within the tolerance limit (25,35 mg/100 g). TVB-N and TMA-N increase factors over the initial values for sardines were 1.6 and 4.9, and 1.4 and 3.6 for herring. Results showed that TMA-N quantities were twice those registered as acceptable for these species, rendering the analysed fish unsuitable for tuna fattening. Previously registered increases in tuna mortalities were caused by secondary bacterial infection (pasteurellosis) from these baitfish. Tissue samples from diseased animals and the control group differed widely in their histological architecture, suggesting that rearing conditions, e.g. quality of administered baitfish, indirectly influenced tuna health. [source] Description of growth by simple versus complex models for Baltic Sea spring spawning herringJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2001J. Gröger The objective was to find a length,growth model to help differentiate between herring stocks (Clupea harengus l.) when their length,growth shows systematically different patterns. The most essential model restriction was that it should react robustly against variations in the underlying age range which varies not only over time but also between the different herring stocks. Because of the limited age range, significance tests as well as confidence intervals of the model parameters should allow a small sample restriction. Thus, parameter estimation should be of an analytical rather than asymptotic nature and the model should contain a minimum set of parameters. The article studies the comparative characteristics of a simple non-asymptotic two-parameter growth model (allometric length,growth function, abbreviated as ALG model) in contrast to higher parametric and more complex growth models (logistic and von-Bertalanffy growth functions, abbreviated as LGF and VBG models). An advantage of the ALG model is that it can be easily linearized and the growth coefficients can be directly derived as regression parameters. The intrinsic ALG model linearity makes it easy to test restrictions (normality, homoscedasticity and serial uncorrelation of the error term) and to formulate analytic confidence intervals. The ALG model features were exemplified and validated by a 1995 Baltic spring spawning herring (BSSH) data set that included a 12-year age range. The model performance was compared with that of the logistic and the von-Bertalanffy length,growth curves for different age ranges and by means of various parameter estimation techniques. In all cases the ALG model performed better and all ALG model restrictions (no autocorrelation, homoscedasticity, and normality of the error term) were fulfilled. Furthermore, all findings seemed to indicate a pseudo-asymptotic growth for BSSH. The proposed model was explicitly derived for of herring length-growth; the results thus should not be generalized interspecifically without additional proof. [source] A phenomenological study of ripening of salted herring.JOURNAL OF CHEMOMETRICS, Issue 2 2002Assessing homogeneity of data from different countries, laboratories Abstract Data from ripening experiments of herring carried out at three Nordic fishery research institutions in the period 1992,1995 were collected and analyzed by multivariate analysis. The experiments were carried out at different times, with different stocks as raw material, using different types of treatments and analyzed in different laboratories. The question considered here is whether these data can be assumed to be one homogeneous set of data pertaining to ripening of salted herring or whether data from different labs, stocks, etc. must be considered independently. This is of importance for further research into ripening processes with these and similar data. It is shown in this paper that all data can be considered as one homogeneous data set. This is verified using resampling where latent structures are compared between different sample sets. This is done indirectly by testing regression models, that have been developed on one sample set, on other sample sets. It is also done directly by monitoring the deviation in latent structure observed between different sample sets. No formal statistical test is developed for whether samples can be assumed to stem from the same population. Although this can easily be envisioned, it was exactly the need for a more intuitive and visual test that prompted this work, developing different exploration tools that visually make it clear how well the data can be assumed to derive from the same population. Subsequently analyzing the data as one homogeneous group provides new information about factors that govern the ripening of salted herring and can be used in new strategic research as well as in industrial practice. Copyright © 2002 John Wiley & Sons, Ltd. [source] Temporal variability in marine feeding of sympatric Arctic charr and sea troutJOURNAL OF FISH BIOLOGY, Issue 3 2007A. H. Rikardsen The marine feeding pattern of anadromous brown trout (sea trout) Salmo trutta and Arctic charr Salvelinus alpinus was studied during June to August in 1992,1993 and 2000,2004 in a fjord in northern Norway. In general sea trout fed proportionally more on fishes than on crustaceans and insects (81, 1 and 18% by mass, respectively) by comparison with Arctic charr (52, 25 and 22% by mass, respectively). Herring Clupea harengus dominated the total fish diet of both species, but the Arctic charr also fed significantly on gadoids and sandlance Ammodytes spp. While sea trout became virtually all piscivorous at fork lengths (LF) ,250 mm, the Arctic charr was ,400 mm LF before shifting totally to a fish diet. Despite annual variation in diet and forage ratios, there was a clear shift in diet from 1992,1993 to 2000,2004. Sandlance and different crustaceans constituted most of the diet during the initial period with a shift towards gadoids and especially herring during the latter period. This shift seemed to be associated with a high abundance of herring larvae during the latter sampling period, indicating a preferential selection on herring when present, particularly by sea trout. Furthermore, an index indicated dietary overlap in years with intensive feeding on herring of both species, and usually differences in the trophic ecology during years feeding mostly on other prey species. In combination, it was hypothesized that the two species reflect the type of marine prey present within a fjord system over time, and therefore provide an index of variation in the production and biological diversity of their potential prey within fjords. [source] The effect of temperature and somatic growth on otolith growth: the discrepancy between two clupeid species from a similar environmentJOURNAL OF FISH BIOLOGY, Issue 3 2006D. P. Fey Otolith growth rates of the early life stages of herring Clupea harengus (n= 472) and smelt Osmerus eperlanus (n= 348) collected in the Vistula Lagoon (Baltic Sea) during 1997,1999 were analysed. The larvae and early juveniles were not only collected in the same geographical area they were also of the same size (range 15,43 mm standard length, LS), similar ages and were collected during the same seasons (May to July). Although the two clupeid species experienced very similar environmental conditions, there were significant discrepancies in the analysed relationships. The otolith growth of larval and juvenile smelt was very strongly related to somatic growth while temperature had a minor effect. In herring, the effect of somatic growth, although clearly visible and statistically highly significant, was of less importance than temperature. Furthermore, variation in the otolith size and LS relationship was affected by temperature and somatic growth in both species, but the variance of otolith size at LS was higher for herring than for smelt. Although growth backcalculation from otoliths can presently be recommended as an appropriate method for use with both smelt and herring (despite possibly lower precision and accuracy with the latter), other methods referring directly to short-term increment width changes (e.g. marginal increment analysis) are recommended for smelt but not for herring. [source] Morphometry and composition of aragonite and vaterite otoliths of deformed laboratory reared juvenile herring from two populationsJOURNAL OF FISH BIOLOGY, Issue 6 2003J. Tomįs Vaterite otoliths were sampled from two reared populations (Celtic and Clyde Seas) of juvenile herring Clupea harengus. The crystallography, elemental composition and morphometry were analysed and compared with those of normal aragonite otoliths. The incidence of vaterite otoliths in the juveniles sampled (n = 601) ranged from 7·8% in the Clyde population to 13·9% in the Celtic Sea population, and was 5·5% in the small sample (n = 36) of wild adults examined. In all but one case fish had only one vaterite otolith; the corresponding otolith of the pair was completely aragonite. Although the majority of the juveniles sampled showed craniofacial deformities, there was no link between the skull or jaw malformation and the incidence of vaterite otoliths. All vaterite otoliths had an aragonite inner area, and vaterite deposition began sometime after the age of 90 days. The vaterite otoliths were larger and lighter than their corresponding aragonite partners, and were less dense as a consequence of the vaterite crystal structure. The vaterite areas of the otoliths were depleted in Sr, Na and K. Concentrations of Mn were higher in the vaterite areas. The transition between the aragonite inner areas and the vaterite areas was sharply delineated. Within a small spatial scale (20 ,m3) in the vaterite areas, however, there was co-precipitation of both vaterite and aragonite. The composition of the aragonite cores in the vaterite otoliths was the same as in the cores of the normal aragonite otoliths indicating that the composition of the aragonite cores did not seed the shift to vaterite. Vaterite is less dense than aragonite, yet the concentrations of Ca analysed with wavelength-dispersive spectrometry (WDS) were the same between the two polymorphs, indicating that Ca concentrations measured with WDS are not a good indicator of hypermineralized zones with high mineral density. The asymmetry in density and size of the otoliths may cause disruptions of hearing and pressure sensitivity for individual fish with one vaterite otolith, however, the presence of vaterite otoliths did not seem to affect the growth of these laboratory reared juvenile herring. [source] Diel variation in feeding rate and prey composition of herring and mackerel in the southern Gulf of St LawrenceJOURNAL OF FISH BIOLOGY, Issue 5 2003E. Darbyson Diel feeding patterns of herring Clupea harengus and mackerel Scomber scombrus in the southern Gulf of St Lawrence were examined based on samples obtained by midwater trawling between 19 and 26 June 2001. Within 3 h time periods, stomach contents tended to be more similar between fish from the same tow than between fish from different tows. Thus, in contrast to previous diet studies, which have used individual fish stomachs as independent observations, tow was used as the experimental unit in statistical analyses in this study. Diel patterns in stomach fullness were identified using generalized additive models. Two peaks in stomach fullness occurred for herring, one in the morning and the other in the evening. Mackerel showed an increase in feeding intensity throughout the day with a peak in mid-afternoon. The diel changes in stomach contents suggested rapid gastric evacuation rates for both species, especially for herring. The estimate of the instantaneous evacuation rate for herring was twice that for mackerel. Calanus copepods (mainly C. hyperboreus), fishes (mainly capelin Mallotus villosus) and euphausiids were the main prey found in the stomachs of both species. Calanus copepods dominated the diet of herring regardless of time period. They also dominated the diet of mackerel during the late afternoon, evening and night while fishes and euphausiids were dominant during the morning and early afternoon. These diel patterns emphasize the need for sampling throughout the day and night in order to estimate ration and diet composition for bioenergetic and ecosystem models. [source] The detection of elements in larval otoliths from Atlantic herring using laser ablation ICP-MSJOURNAL OF FISH BIOLOGY, Issue 4 2003D. Brophy Trace element concentrations of otoliths from larval herring Clupea harengus collected from known spawning beds in the Celtic and Irish Seas, were investigated using laser ablation ICP-MS and compared with concentrations in the larval cores of juvenile otoliths from the same populations and year class. A range of elements (Mg, Zn, Sr, Ba and Pb) was detectable in early larval otoliths (20,40 µm diameter). Larval otolith concentrations exceeded the larval core concentrations of juvenile otoliths and also the concentrations reported in the literature, for Mg, Zn, Ba and Pb, indicating that the measurement of elements in larval otoliths was severely affected by post-mortem contamination, most likely due to adherence of tissue and endolymph residue on the otolith surface. Comparison of otolith composition between larvae from two freezing treatments showed that contamination from Mg and Zn was more serious in otoliths that had remained in frozen larvae for prolonged periods. Larval populations from the two seas showed significant differences in otolith Sr concentrations, which were consistent over two sampling years. Similar differences were seen in the corresponding juvenile populations. The results show that while early larval otoliths are extremely susceptible post-mortem contamination, Sr concentrations can be reliably measured using laser ablation ICP-MS and for this element, the detection of region specific differences is possible. [source] Effects of temperature on larval fish swimming performance: the importance of physics to physiologyJOURNAL OF FISH BIOLOGY, Issue 4 2002I. Hunt von Herbing Temperature influences both the physiology offish larvae and the physics of the flow conditions under which they swim. For small larvae in low Reynolds number (Re) hydrodynamic environments dominated by frictional drag, temperature-induced changes in the physics of water flow have the greatest effect on swimming performance. For larger larvae, in higher Re environments, temperature-induced changes in physiology become more important as larvae swim faster and changes in swimming patterns and mechanics occur. Physiological rates at different temperatures have been quantified using Q10s with the assumption that temperature only affected physiological variables. Consequently, Q10s that did not consider temperature-induced changes in viscosity overestimated the effect of temperature on physiology by 58% and 56% in cold-water herring and cod larvae respectively. In contrast, in warm-water Danube bleak larvae, Q10s overestimated temperature-induced effects on physiology by only 5,7%. This may be because in warm water, temperature-induced changes affect viscosity to a smaller degree than in cold water. Temperature also affects muscle contractility and efficiency and at high swimming velocities, efficiency decreases more rapidly in cold-exposed than in warm-exposed muscle fibres. Further experiments are needed to determine whether temperature acts differently on swimming metabolism in different thermal environments. While hydrodynamic factors appear to be very important to larval fish swimming performance in cold water, they appear to lose importance in warm water where temperature effects on physiology dominate. This may suggest that major differences exist among locomotory capacities of larval fish that inhabit cold, temperate waters compared to those that live in warm tropical waters. It is possible that fish larvae may have developed strategies that affect dispersal and recruitment in different aquatic habitats in order to cope not only with temperature-induced physiological challenges, but physical challenges as well. [source] Ribosomal DNA sequences indicate isolated populations of Ichthyophonus hoferi in geographic sympatry in the north-eastern Pacific OceanJOURNAL OF FISH DISEASES, Issue 10 2002C D Criscione Abstract Infections of Ichthyophonus hoferi, a cosmopolitan parasite of marine fish, have recently been reported in rockfish, Sebastes spp., from the north-eastern Pacific. Because I. hoferi also infects Pacific herring, Clupea pallasi Valenciennes, and salmonids in this region, we wanted to determine if Ichthyophonus parasites from rockfishes, Pacific herring and chinook salmon, Oncorhynchus tshawytscha (Walbaum), were the same. Small subunit ribosomal deoxyribonucleic acid sequence data revealed two haplotypes that were fixed among host species in geographic sympatry, one from rockfish and the other from both Pacific herring and salmon. These isolated populations of Ichthyophonus could be part of the same species that are ecologically separated because of host behaviours, or they could be distinct species that are host specific. Dietary patterns of the hosts indicate that ecological separation among hosts is possible, but the presence of distinct species may better explain the observed Ichthyophonus haplotype association with host species. [source] | |||||||||||||||||||