From the dark muscle of British Columbia herring a highly active enzyme capable of peroxidising unconjugated unsaturated fatty acids was isolated. This ‘lipoxidase’, which was shown to be a nitrogenous complex possessing no heavy metals or sulphydryl group as the active centre, is heat-labile and can act only in presence of activators such as certain iron-containing organic nitrogenous compounds. Two such compounds, namely haemoglobin and cytochrome ‘C’ were isolated. The enzyme exhibits optimum activity at 15°C. and pH 6.9. There is also an optimum concentration of enzyme, substrate, and of the activators for maximum enzyme activity. The presence of the activators appears to change the kinetics of the reactions. The inhibition of the enzymic reaction brought about by cyanide and azide is possibly due to the inactivation of the iron-containing activators rather than of the enzyme itself. / Science, Faculty of / Zoology, Department of / Graduate

Cohorts of larval Pacific herring, Clupea harengus pallasi Valenciennes 1847, were studied from hatch during the spring of 1985, 1986, and 1987 in the Strait of Georgia, British Columbia. The main objectives were to study the patterns in the larval dispersal process, to study a major spawning area for Pacific herring to determine whether this site may act as a nursery area for the resulting year-class, and to evaluate the current hypotheses concerning survival of the larval year-class for their applicability to Pacific herring. Results indicated a significant proportion of larval herring which hatched in Lambert Channel quickly dispersed into Baynes Sound, probably through a combination of tidal movements and wind driven surface currents. Baynes Sound was shown to be much more stable than Lambert Channel due to strong stratification through freshwater input and protection from wind mixing by the surrounding land masses which may also have resulted in an earlier spring plankton bloom. Baynes Sound also had significantly higher densities of microzooplankton important to the early feeding herring larvae than Lambert Channel and outside waters. The suite of potential predators was also different between the two channels with Baynes Sound having more hydromedusae and Lambert Channel having more chaetognaths and polychaetes. Analysis of larval growth rates using an RNA/DNA ratio technique on individuals from the yolk sac stage onwards indicated the larvae initially grew very slowly but, by postflexion were growing over 25 %•d⁻¹ in protein. Starvation did not appear to play an important role in mortality. The RNA/DNA ratio was demonstrated to be directly correlated with a morphometric condition factor Pacific herring larvae indicating it can also be used as a condition factor. There was a significant positive correlation between the mean protein growth rate measured with RNA/DNA ratios and the mean nauplii density. Feeding larvae in Baynes Sound were found to be growing faster than those in Lambert Channel suggesting Baynes Sound was being used as a nursery area. Analysis of otoliths suggested there was a significant increase in survival of larval herring having higher growth rates over as little as a 3-week period. / Science, Faculty of / Zoology, Department of / Graduate

Pelagic forage fishes play critical roles in productive marine food webs by providing a link between zooplankton and piscivores and transferring energy from feeding grounds to other ecosystems. The amount of energy moved to higher trophic levels or new systems is directly linked to the consumption rate of pelagic forage fishes. In the Gulf of Maine, Atlantic herring (Clupea harengus) is the dominant forage fish; the purpose of this study is to determine their specific consumption rate (g prey/g fish/day). Using fish collected in autumn 2012 and spring 2013, we applied a mercury mass-balance model to estimate individual and population consumption of Atlantic herring in the Gulf of Maine. Our results suggest that the specific consumption rate increases from age 1.5 until age 6 (years) and then asymptotes. These estimates were contradictory to much of what exists in the literature; for most fishes, specific consumption estimates decrease with age and overall are much lower than our estimates. We looked further into our results to explore the underlying cause of the increase in specific consumption rate. We combined the mercury mass-balance model with a Wisconsin (WI) bioenergetics model and ran several simulations adjusting the most sensitive factors in each--prey mercury in the former and activity in the latter. The results of our simulations showed that an increase in activity relative to age and mass can best explain the increase in the consumption rate of Adult herring. This suggests that an ontogenetic shift to migration in adult Atlantic herring results in increased energy demand with age, and ultimately increased consumption.

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 12, 2010) Includes bibliographical references (p. 85-95)

Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 104-106).

A study was conducted to determine the effects of incubation salinity and temperature . and post-hatching temperature on salinity tolerance of Pacific herring (Clupea pallasi Valenciennes) larvae. Calorimetry experiments were also conducted on herring larvae that were incubated and reared in various combinations of salinity and temperature. In the salinity tolerance test, herring eggs were artificially fertilized in three salinities (13, 21 and 29°/ooS) at 6°C. Newly fertilized eggs were incubated in the same salinities as those in which they were fertilized at two levels of incubation temperature (6 and 12°C), making six incubation groups. During the peak of the hatching period, groups of larvae from each incubation group were exposed to a series of test salinities, ranging from 20 to 55°/ooS at three levels of post-hatching temperatures (6, 9 and 12°C). Salinity tolerance was measured by determining the mortality of larvae occurring in each test salinity over a period of 72 hours. Two approaches were employed: 1) time-mortality, and 2) dosage-mortality. The former provided estimates of the effective time to 50% mortality (ET₅₀), the latter, the effective dosage (salinity) to 50% mortality (ED₅₀). The ET₅₀ or ED₅₀ values were used as bases for comparison of the responses of larvae to incubation temperature and salinity, and post-hatching temperature. The results indicate that both incubation salinity and temperature exert a significant influence on the salinity tolerance of larvae. Eggs incubated in the highest salinity (29°/ooS) and lower temperature (6°C) produced larvae most tolerant to higher post-hatching salinities. Post-hatching temperature also showed a possible influence, although the trends seen were not statistically significant. Salinity tolerance of larvae hatching from the 6°C incubation temperature appeared to be maximized at post-hatching temperatures between 6 and 9°C; whereas, those larvae from the 12°C incubation temperature showed maximum salinity tolerance at 9 to 12°C post-hatching temperatures. The response. of. larvae to salinity may be a result of an irreversible non-genetic adaptation of the embryo to salinity and temperature during incubation. In the calorimetry experiments, samples of herring larvae were combusted in a microbomb calorimeter to determine caloric values. These larvae were hatched and reared in the same six combinations of incubation salinities and temperatures as those used in the main experiment. Larvae were sampled at day 0 (peak of hatching), 3, 6 and 9. Standard lengths, dry weights, ash-free dry weights and ash content of the larval samples were also taken. There was a considerable variability in the data for calorimetry of the herring larva. In general, larvae from all treatments, at hatching, averaged 6,586 cal/g ash-free dry weight and had a mean ash value of 8.25%, obtained by direct ashing. Mean standard length of larvae at the peak of hatching (day 0) ranged from 7.67 mm (12°C, 29°/ooS) to 9.93 mm (6°C, 13°/ooS). There was a trend towards larger larvae (greater standard length) at lower temperatures in lower salinities in all ages tested. Data on dry weights show a linear decrease in larval (body and yolk) weight from day 0 to day 9. Mean dry weight of larva at the peak of hatching ranged from 0.142 mg (6°C, 13°/OOS) to 0.162 mg (12°C, 21°/ooS; 12°C, 29°/ooS). At day 0, the largest larvae (in terms of dry weight) were found at higher temperatures in higher salinities, while at day 9 (past yolk-sac stage), the largest larvae were found at lower temperatures in lower salinities. The same trend was observed in terms of ash-free dry weight. / Science, Faculty of / Zoology, Department of / Graduate

Univ., Diss.--Göteborg, 2005. / Literaturverz. S. 210 - 221.

Acoustic survey techniques are widely used to quantify abundance and distribution of a variety of pelagic fish such as herring (Clupea harengus). The information provided is becoming increasingly important for stock assessment and ecosystem studies, however, the data collected are used as relative indices rather than absolute measures, due to the uncertainty of target strength (TS) estimates. A fish’s TS is a measure of its capacity to reflect sound and, therefore, the TS value will directly influence the estimate of abundance from an acoustic survey. The TS is a stochastic variable, dependent on a range of factors such as fish size, orientation, shape, physiology, and acoustic frequency. However, estimates of mean TS, used to convert echo energy data from acoustic surveys into numbers of fish, are conveniently derived from a single metric - the fish length (L). The TS used for herring is based on TS-L relationships derived from a variety of experiments on dead and caged fish, conducted 25-30 years ago. Recently, theoretical models for fish backscatter have been proposed to provide an alternative basis for exploring fish TS. Another problem encountered during acoustic surveys is the identification of insonified organisms. Trawl samples are commonly collected for identification purposes, however, there are several selectivity issues associated with this method that may translate directly into biased acoustic abundance estimates. The use of different acoustic frequencies has been recognised as a useful tool to distinguish between different species, based on their sound reflection properties at low and high frequencies. In this study I developed theoretical models to describe the backscatter of herring at multiple frequencies. Data collected at four frequencies (18, 38, 120 and 200 kHz) during standard acoustic surveys for herring in the North Sea were examined and compared to model results. Multifrequency backscattering characteristics of herring were described and compared to those of Norway pout, a species also present in the survey area. Species discrimination was attempted based on differences in backscatter at the different frequencies. I examined swimbladder morphology data of Baltic and Atlantic herring and sprat from the Baltic Sea. Based on these data, I modelled the acoustic backscatter of both herring stocks and attempted to explain differences previously observed in empirical data. I investigated the change in swimbladder shape of herring, when exposed to increased water pressures at deeper depths, by producing true shapes of swimbladders from MRI scans of herring under pressure. The swimbladder morphology representations in 3-D were used to model the acoustic backscatter at a range of frequencies and water pressures. I developed a probabilistic TS model of herring in a Bayesian framework to account for uncertainty associated with TS. Most likely distributions of model parameters were determined by fitting the model to in situ data. The resulting probabilistic TS was used to produce distributions of absolute abundance and biomass estimates, which were compared to official results from ICES North Sea herring stock assessment. Modelled backscatter levels of herring from the Baltic Sea were on average 2.3 dB higher than those from herring living in northeast Atlantic waters. This was attributed to differences in swimbladder sizes between the two herring stocks due to the lower salinity Baltic Sea compared to Atlantic waters. Swimbladders of Baltic herring need to be bigger to achieve a certain degree of buoyancy. Morphological swimbladder dimensions of Baltic herring and sprat were found to be different. Herring had a significantly larger swimbladder height at a given length compared to sprat, resulting in a modelled TS that was on average 1.2 dB stronger. Water depth, and therefore the increase in ambient pressure, was found to have a considerable effect on the size and shape of the herring swimbladder. Modelled TS values were found to be around 3 dB weaker at a depth of 50 m compared to surface waters. At 200 m, this difference was estimated to be about 5 dB. The Bayesian model predicted mean abundances and biomass were 23 and 55% higher, respectively, than the ICES estimates. The discrepancy was linked to the depth-dependency of the TS model and the particular size-dependent bathymetric distribution of herring in the survey area.

Detta examensarbete syftade till att ta fram ett underlag för en regional åtgärdsplan avseende dibenso-p-dioxiner och dibensofuraner, gemensamt benämnda som PCDD/F eller dioxiner, i Gävleborgs län. Länet har historiskt varit ett av de mest utsatta områdena i Sverige beträffande dessa föroreningar och höga koncentrationer i bland annat strömming har medfört att denna inte får saluföras i övriga EU.   I arbetet har resultaten från den rådande forskningen på området studerats för att få kunskap om nuvarande källor och möjliga förklaringar till de fortsatt förhöjda koncentrationerna av dioxiner. Därefter har data från tidigare undersökningar av dioxinkoncentrationer i Gävleborgs län samlats in, sammanställts och använts för att studera hur koncentrationerna varierar geografiskt inom länet. Principalkomponentanalys (PCA) av specifika dioxinkongeners koncentrationer har sedan använts för att försöka identifiera verksamhetstyper som potentiellt kan ha bidragit till föroreningarna på olika platser - en analys som dock är behäftad med stora osäkerheter. De insamlade provresultaten har även använts för att genom massbalansmodellering undersöka återhämtningen i två känt förorenade fjärdar i länet; Norrsundet och Gårdsfjärden. Utifrån resultaten av ovanstående analyser diskuterades även nyttan av att genomföra eventuella åtgärder för att reducera halterna i kraftigt förorenade områden.   Proverna som sammanställts visade klara geografiska skillnader i sedimentkoncentration, och till viss del även i koncentration i muskel från abborre, vilket visar på en stark betydelse av lokala källor i vissa områden. Bland strömmingsproverna kunde inget liknande samband ses. Detta kan förklaras av att det migrerande beteendet hos strömming gör att fisken under sin livstid exponeras för varierande föroreningsnivåer i olika områden, medan abborren är mer stationär även som vuxen. Principalkomponentanalysen gav, för vissa prover, indikationer kring vilken typ av verksamhet som bidragit till de uppmätta koncentrationerna. Dessa resultat är dock mycket osäkra och bör inte på egen hand användas som underlag för att fastställa föroreningskällor. Massbalansmodelleringen visade att PCDD/F-koncentrationen i sediment inte har någon betydelse för koncentrationen i vattenmassan utan att inflödet från omgivande hav dominerar även i avgränsade fjärdar. De modellerade jämviktskoncentrationerna mellan sediment och vattenmassa indikerade även att koncentrationerna i sediment kommer fortsätta överskrida somliga gränsvärden tills koncentrationen i vattenmassan reducerats, vilket även stöds av att dessa gränsvärden överskreds i majoriteten av de sammanställda proverna.   Baserat på samtliga ovannämnda resultat drogs slutsatsen att lokala saneringsåtgärder sannolikt inte ger någon effekt på PCDD/F-koncentrationerna i strömming, samt att de inte är tillräckliga för att erhålla sedimentkoncentrationer under samtliga gränsvärden. De kan däremot effektivt minska den exponering som mer stationära organismer som abborre utsätts för i områden med kraftigt förorenade sediment, och kan även ha positiva effekter på förekomsten av andra miljöfarliga ämnen i området. För- och nackdelar måste således övervägas i varje enskilt fall. / The aim of this Master’s Thesis was to provide a basis for a regional plan of action regarding dibenzo-p-dioxins and dibenzofurans, commonly referred to as PCDD/F or dioxins, in Gävle-borg County. This region has historically been one of the Swedish areas most affected by these pollutants, and high concentrations in for example Atlantic herring (Clupea harengus) have resulted in restrictions where some fish species cannot be sold in other EU countries.   In this work, results of current research on the subject were studied in order to gain knowledge about current sources and possible explanations to the continued high concentrations of dioxins. Thereafter, data from earlier investigations of dioxin levels in Gävleborg County have been gathered, compiled and used to study the regional geographic variation of the concentrations. Principal component analysis (PCA) was then used on the concentrations of specific congeners in an attempt to identify source types that might have contributed to the contamination in various sites; this analysis is however marred by uncertainties. The gathered data have also been used to investigate the recovery in two bays with known contaminations, Norrsundet and Gårdsfjärden, using mass balance modelling. The benefits of implementing measures to reduce the PCDD/F-concentrations in highly polluted areas were then discussed based on the results of the above-mentioned analyses.   The measured sediment concentrations, and partly also the concentrations in European perch (Perca fluviatilis), of the compiled samples showed distinct geographic differences, which indicates a strong influence from local sources in some areas. Among the herring samples, no such connection could be seen. This could be explained by the migrating behaviour of adult herring, resulting in an exposure to various levels of contamination in different areas as they migrate, while adult perch has a more stationary behaviour. For some samples, the principal component analysis gave indications on source types that might have contributed to the local contamination levels. These results are however very uncertain and they should not be used as the sole basis when determining emission sources. The mass balance modelling showed that the PCDD/F-concentrations in sediments have no influence on the concentrations in the water body; the inflow from the surrounding sea is predominant also in enclosed bays. The modelled equilibrium concentrations between sediments and water body also indicated that the sediment concentrations will continue to exceed the guideline values until the water concentrations have decreased. This is also supported by the fact that the majority of the samples showed concentrations exceeding these guideline values.   Based on all of the abovementioned results it was concluded that local remediation measures would most likely not affect the PCDD/F-concentrations in herring. It was also concluded that such measures would not suffice to obtain sediment concentrations that fall below all guideline values. They can however be used to lessen the exposure that stationary organisms are subjected to in areas with highly contaminated sediments, and can also have positive effects on the levels of other hazardous substances in the area. Thus, the benefits and disadvantages need to be considered in each specific case.

Many previous studies in evolutionary genetics have been based on few model organisms that can be reared at ease in the laboratory. In contrast, genetic studies of non-model, natural populations are desirable as they provide a wider range of adaptive phenotypes throughout evolutionary timescales and allow a more realistic understanding of how natural selection drives adaptive evolution. This thesis represents an example of how modern genomic tools can be effectively used to study adaptation in natural populations. Atlantic herring is one of the world’s most numerous fish having multiple populations with phenotypic differences adapted to strikingly different environments. Our study demonstrated insignificant level of genetic drift in herring that resulted in minute genetic differences in the majority of the genome among these populations. In contrast, a small percentage of the loci showed striking genetic differentiation that were potentially under natural selection. We identified loci associated with adaptation to the Baltic Sea and with seasonal reproduction (spring- and autumn-spawning) and demonstrated that ecological adaptation in Atlantic herring is highly polygenic but controlled by a finite number of loci. The study of Darwin’s finches constitutes a breakthrough in characterizing their evolution. We identified two loci, ALX1 and HMGA2, which most likely are the two most prominent loci that contributed to beak diversification and thereby to expanded food utilization. These loci have played a key role in adaptive evolution of Darwin’s finches. Our study also demonstrated that interspecies gene flow played a significant role in the radiation of Darwin’s finches and some species have a mixed ancestry. This thesis also explored the genetic basis for the remarkable phenotypic differences between three male morphs in the ruff. Identification of two different versions of a 4.5 MB inversion in Satellites and Faeders that occurred about 4 million years ago revealed clues about the genetic foundation of male mating strategies in ruff. We highlighted two genes in the inverted region; HSD17B2 that affects metabolism of testosterone and MC1R that has a key role in regulating pigmentation, as the major loci associated with this adaptation.