Directorate of Fisheries

The occurrence of hermaphrodite fish in the lagoons of sewage treatment works led us to hypothesize that sewage effluent might contain a substance, or substances, estrogenic to fish. to test this hypothesis, we placed cages containing rainbow trout in the effluent from sewage-treatment works, and one to three weeks later measured the vitellogenin concentration in the plasma of the fish. Vitellogenin is a protein synthesized by the liver of oviparous fish in response to estradiol stimulation; it is then conveyed by the blood to the ovary, where it is sequestered by oocytes to form the yolk. Thus, the presence of vitellogenin in the plasma is indicative of estrogenic stimulation of the liver. an initial study, at a sewage-treatment works, showed that plasma vitellogenin concentrations rose rapidly and very markedly (over 1000-fold in three weeks) when trout were maintained in the effluent. an extensive nationwide survey was then conducted. Results were obtained from fifteen sewage-treatment works distributed throughout England. in all cases, exposure of trout to effluent resulted in a very pronounced increase (500 to 100,000-fold, depending on site) in the plasma vitellogenin concentration. Induction of vitellogenesis was also observed in carp, but to a much lesser extent than in trout. The identity of the estrogenic substance is unknown. It is suggested that the two most likely possibilities are ethynylestradiol, originating from pharmaceutical use, or alkylphenol-ethoxylates (APE), originating from the biodegradation of surfactants and detergents during sewage treatment. Laboratory studies on the potency of ethynylestradiol demonstrated that levels as low as 1 to 10 ng 1−1 could generate the response shown by the caged fish and that positive responses may arise at 0.1 to 0.5 ng 1−1. Further work is in progress on the potency of APE.

The utilisation of dietary carbohydrates and their effects on fish metabolism are reviewed. Details on how dietary carbohydrates affect growth, feed utilisation and deposition of nutrients are discussed. Variations in plasma glucose concentrations emphasizing results from glucose tolerance tests, and the impact of adaptation diets are interpreted in the context of secondary carbohydrate metabolism. Our focus then shifts to selected aspects of hormonal regulation of carbohydrate metabolism and dietary carbohydrates and their variable effects on glycogen and glucose turnover. We analyse the interaction of carbohydrates with other nutrients, especially protein and protein sparing, and de novo synthesis of lipids, and finish by discussing the correlation of dietary carbohydrates with fish health.

Summary 1. Functional traits have been extensively used to describe, group and rank species according to their functions. There is now growing evidence that intraspecific functional variability, as well as interspecific variability, can have significant effects on community dynamics and ecosystem functioning. A core hypothesis for the use of functional traits expressed as species means, that their intraspecific variability is negligible compared with their interspecific variability, has however been too rarely tested empirically. We then addressed four questions: Is intraspecific functional variability across species ranges negligible compared with interspecific variability? Are the major resource economics trade‐off and functional strategies robust to individual trait variability? Are species rankings or ordination robust across species ranges once considering intraspecific variability? Can species be discriminated by their leaf traits? 2. Using an environmentally stratified sampling design within an alpine catchment, we collected five functional traits for 13 common plant species with contrasting life histories and traits. Several populations from a range of environmental conditions were then sampled for each species across their ranges. 3. With an original combination of single‐trait and multi‐trait analyses, we highlighted a non‐negligible contribution of intraspecific variability to overall functional trait variability (∼30%). Although not affecting general and well‐known functional trade‐offs and strategies, intraspecific functional variability had the potential to alter species ordination and produced a functional continuum rather than a clear‐cut species classification. 4. Deciding whether intraspecific functional variability can be considered as negligible – species being represented by mean trait values –, or not – species being represented by multivariate trait distributions –, is an essential question for multiple ecological issues. However, this decision cannot be generic, but will depend on the studied system and selected traits and species, as well as on study objectives.

The possible roles of viruses in phytoplankton dynamics were investigated in seawater mesocosms with natural assemblages of phytoplankton growing under various nutrient regimes. Blooms of the marine coccolithophorid Emiliania huxleyi (Lohmann) Hay & Mohler were in some cases succeeded by an increase in the abundance of a morphologically homogeneous population of viruses. The viruses had an hexagonal outline and were about 180 nm in diameter. Similar viruses were found both intracellularly and associated with apparently lysed cells. Viral lysis could account for 25 to 100 % of the net mortality of E huxleyi when the blooms declined under non-limiting nutrient conditions or when the nitrate concentration was low. Production of viruses was limited when the phosphate concentration was low. Dur~ng a bloom of E. huxleyi in Norwegian coastal waters in 1990 we found that the concentration of free algal viruses was increasing at the end of the bloom, indicating that viruses of E. huxleyi may be important under natural conditions as well. These results suggest that viral mortality of phytoplankton may be an important factor regulating community structure, diversity and biomass production in marine environments.

MOTIVATION: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. MAIN TYPES OF VARIABLES INCLUDED: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. SPATIAL LOCATION AND GRAIN: ). TIME PERIOD AND GRAIN: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. MAJOR TAXA AND LEVEL OF MEASUREMENT: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. SOFTWARE FORMAT: .csv and .SQL.

Fishers have been complaining about the effects of bottom trawl gear on the marine environment since at least the 14th century. Trawl gear affects the environment in both direct and indirect ways. Direct effects include scraping and ploughing of the substrate, sediment resuspension, destruction of benthos, and dumping of processing waste. Indirect effects include post‐fishing mortality and long‐term trawl‐induced changes to the benthos. There are few conclusive studies linking trawling to observed environmental changes since it is difficult to isolate the cause. However, permanent faunal changes brought about by trawling have been recorded. Research has established that the degree of environmental perturbation from bottom trawling activities is related to the weight of the gear on the seabed, the towing speed, the nature of the bottom sediments, and the strength of the tides and currents. The greater the frequency of gear impact on an area, the greater the likelihood of permanent change. In deeper water where the fauna is less adapted to changes in sediment regimes and disturbance from storm events, the effects of gear take longer to disappear. Studies indicate that in deep water (>1000 m), the recovery time is probably measured in decades.

Residents’ overall well-being and quality-of-life require a deeper understanding of their perceived social impacts of tourism to determine appropriate management strategies to promote behaviours in support of tourism development. Aligning with the 2030 Agenda for sustainable development, this paper proposes a new framework for residents’ quality-of-life. Bringing together multi-disciplinary evidence from environmental, social and cognitive psychology, political science and tourism, this study critically examines how residents’ perceived social impacts of tourism and their interpersonal trust can make them become more place attached and protect their tourism resources. The framework proposes that residents’ perceived social impacts of tourism exerts a direct influence on residents’ interpersonal trust. It further posits that residents’ perceived social impacts of tourism and their interpersonal trust exert a direct influence on residents’ place attachment. The proposed model further considers place attachment to exert a direct influence on residents’ pro-social and pro-environmental behavioural intentions. Pro-social behaviour is proposed to influence pro-environmental behaviour. Further pro-social and pro-environmental behaviours are proposed to influence residents’ support for tourism development. The framework then considers residents’ support for tourism development to exert a direct influence on residents’ overall quality-of-life. The theoretical contributions, practical implications for sustainable community tourism and sustainable tourism in general and the limitations of the study are discussed.

Triplicate groups of Atlantic salmon (Salmo salar L.) were fed four diets containing different oils as the sole lipid source, i.e., capelin oil, oleic acid-enriched sunflower oil, a 1:1 (w/w) mixture of capelin oil and oleic acid-enriched sunflower oil, and palm oil (PO). The beta-oxidation capacity, protein utilization, digestibility of dietary fatty acids and fatty acid composition of lipoproteins, plasma, liver, belly flap, red and white muscle were measured. Further, the lipid class and protein levels in the lipoproteins were analyzed. The different dietary fatty acid compositions did not significantly affect protein utilization or beta-oxidation capacity in red muscle. The levels of total cholesterol, triacylglycerols, and protein in very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and plasma were not significantly affected by the dietary fatty acids. VLDL, LDL, and HDL fatty acid compositions were decreasingly affected by dietary fatty acid composition. Dietary fatty acid composition significantly affected both the relative fatty acid composition and the amount of fatty acids (mg fatty acid per g tissue, wet weight) in belly flap, liver, red and white muscle. Apparent digestibility of the fatty acids, measured by adding yttrium oxide as inert marker, was significantly lower in fish fed the PO diet compared to the other three diets.

The spawning periods of four temperate or high-latitude fish species - Pacific sockeye salmon, herring, plaice and cod - have been examined. The mean date of peak spawning was established and it was found that the standard deviation of this mean date was low, often less than a week. For three species no trend of date of peak spawning was found; a trend towards later spawning was detected in the Arcto-Norwegian cod stock, about eight ays in seventy years. In contrast the Californian sardine was shown to spawn at very variable periods and it is likely that tuna in the North Pacific anticyclone spawned during most of the year. It is likely that production is continuous in the anticyclonic regions and discontinuous in the high-latitude cyclones; this would be sufficient to account for the differences found between the two groups of fish.

Summary 1. Winged morph production in aphids is a phenotypic trait that has traditionally been seen as a response to unfavourable environmental conditions. The evidence to support this theory is reviewed and the ecological and evolutionary significance of the findings is discussed. 2. The common assertion of poor host‐plant nutritional quality leading to increased production of winged morphs does not always apply, particularly when the host‐plant quality is exceptionally poor. The available data are skewed heavily towards Myzus persicae , and for this species the dynamical change in plant quality appears to be important with respect to wing induction. 3. Crowding may be a less influential stimulus for wing induction as study methods approach natural conditions experienced by aphids on their host plant. 4. The growing evidence that interactions with other organisms can induce the production of winged morphs by aphid colonies is reviewed. In the case of natural enemies, such a response by an aphid colony may be regarded as induced defence. Wing induction may also act as a means of transmission for a virus or fungal pathogen.

Aspects of the reproduction of reared cod, Gadus morhua L., with special emphasis on the females, were studied under laboratory conditions. The fecundity and condition factor were 2–5 and 1–5 times, respectively, that of wild cod. A total of 18 spawning females were kept in separate tanks/ chambers, each with one or two males. Seven of the 18 females were classified as stressed, based upon behaviour, irregular spawning intervals and low fertilization rates of the eggs. The reared cod were found to spawn 17–19 batches. The number of eggs liberated in each batch normally followed a smooth, dome‐shaped curve with time. The fertilization rate was normally 100%. Egg size decreased from first to last batch and the egg dry weight decreased by about 20–30%. The reared cod showed the same egg diameter to dry weight relation as wild cod. Egg diameter of first batch and maternal fish length were significantly positively correlated. The mean spawning interval for the female and the mean water temperature during its spawning were negatively correlated. The reared cod spawned in both the night and the day for about 50–60 days.

Weight-at-age of cod varies greatly for different stocks throughout the North Atlantic. For example, the average weight of a 4-year-old cod ranges from about 0.6 kg at Labrador to 7.3 kg in the Celtic Sea. A simple exponential model in which mean catch weight-at-age is a function of the product of age × temperature (mean annual ambient temperature) accounts for 92% of the variance for 2–4-year-old cod from 17 stocks throughout the North Atlantic. In(weight-at-age in kg)=0.06821 × (temperature × age)– 1.042. A logistic model accounts for 91% of the variance over the age range 2–9 for 12 of the 17 stocks Weight-at-age=10.28/(1 + exp(0.085(41.27 – temperature × age))). Parameters were estimated by fitting both models to data from many stocks (i.e a between-stock comparison, using average temperature), but the same models and parameters also explain observed time trends in weight-at-age within stocks at Faroe and West Greenland and differences between areas around Iceland. Within these stocks weight-at-age can vary by a factor of two or more, with very important consequences for stock assessment (including forecasting) and for the evaluation of possible effects of climate change on cod stocks. The conclusion that most of the observed variability in growth is due to temperature needs to be tested thoroughly, and this will require detailed information on the ambient temperature experienced by different ages of cod in different years.

Blood samples from healthy adult Atlantic salmon fed an optimal diet in net sea pens were collected at intervals from October to May. Haematological determinations and biochemical serum analyses were carried out on 20 fish in each of seven samples. The ranges of haemato‐logical values for sample means were: haematocrit 44–49%, haemoglobin 8.9–10.4 g 100ml −1 , red blood cell count 0.85–1.10 × 10 12 l −1 , MCV 441–553 × 10 −15 1, MCH 94–106 × 10 −6 g, MCHC 19.4–21.7 g 100ml −1 and leucocrit 0.43–0.96%. The ranges of enzyme activities in serum, for sample means, were: alkaline phosphatase 647–988Ul −1 , aspartate aminotrans‐ferase 202–351 Ul −1 and alanine aminotransferase 4–8 Ul −1 . The ranges of the other parameters analyzed in serum were: total protein 41.6–56.6 gl −1 , albumin 18.3–24.3 gl −1 , albumin/total protein ratio 39.3–44.0%, creatinine 26–46 μmol, triglycerides 2.53–4.98 μmol and cholesterol 9.3–12.8 μmol. These values are considered to be the normal ranges in healthy fish. Variations due to seasonal changes, and the clinical significance of the selected parameters, are discussed. Data showing the reproducibility of the biochemical analyses in serum are presented.

Flesh proteins, in the context of this article, are taken to be the component proteins of the contractile muscle of animals used for food (i.e., meat, poultry, and fish). Attention is given to the similarities and differences between the proteins from these different sources and in particular to the effects on them of freezing and frozen storage. It is believed that myosin and action, the main contractile proteins, are largely responsible for the functional properties of flesh foods, and that on frozen storage, myosin, in particular, undergoes aggregation reactions which lead to toughening of the muscle and a loss in water‐holding capacity. Variation in stability of flesh of different species on frozen storage can be attributed to some extent to the intrinsic characteristics of the respective myosins. Myosin from fish is generally less stable than its mammalian or avian counterparts and this is reflected in the stability of the flesh on frozen storage. Cryoprotectants, usually in the form of low molecular weight polyhydroxy compounds, are added to some processed products such as surimi to counter the denaturation process. Theories on the mechanism of protein denaturation and of the action of cryopro‐tectants are reviewed. The potential of using the freezing process to form textures from comminuted flesh or protein dispersions is also discussed.

Michael Graham; Modern Theory of Exploiting a Fishery, and Application to North Sea Trawling, ICES Journal of Marine Science, Volume 10, Issue 3, 1 December 193

Three groups of eight volunteers were administered stable isotope-labelled phthalate diesters in a single dose and the amount of the corresponding phthalate monoesters excreted in the urine was measured. Amongst the phthalates administered were the symmetrical dibutyl-, di-2-ethyl- and diisooctyl- phthalates along with the unsymmetrical benzylbutylphthalate. The control group received no dose, the low dose group received 168-255 microg of each phthalate and the high dose group received 336 to 510 microg of each phthalate. The excreted phthalate monoesters were measured by LC-MS following hydrolysis of conjugates. The bulk of phthalate monoester was excreted in the first 24 hour period following the dose. For dibutylphthalate, 64% and 73% on a mole basis of the low, and high dose respectively was excreted as monobutylphthalate. For dioctylphthalate (sum of the 2-ethylhexyl and the isooctyl species) the yield was 14 and 12% of the low and high dose excreted as monooctylphthalate. For benzylbutylphthalate, 67% and 78% was eliminated as monobenzylphthalate and only 6% (measured for the high dose only) was eliminated as monobutylphthalate. These conversion factors can be used in future studies to assess exposure to phthalate esters via measuring urinary levels of the monoester metabolites.

The aim of the present study was to investigate the effects of different dietary sustained-release microencapsulated sodium butyrate (MSB) products (0 (non-supplement), 1·5 and 3·0 h) for a control or oxidised soyabean oil (SBO) diet on fish production, intestinal mucosal condition, immunity and intestinal bacteria in juvenile common carp (Cyprinus carpio). Dietary MSB increased weight gain and reduced the feed conversion ratio within the control and oxidised SBO groups. Gut mucosa was damaged in the oxidised SBO group fed without MSB, in contrast to a normal appearance found in fish fed the MSB1·5 and MSB3·0 diets in the oxidised SBO group. Microvillus density increased in fish fed the MSB1·5 and MSB3·0 diets in the oxidised SBO group (P< 0·001); however, microvillus density was affected by the different pre-fed diets in the midgut (P< 0·001) and by the different sustained-release times of MSB in the distal gut (DG) (P= 0·003). The interaction between the pre-fed diets and the sustained-release times of dietary MSB was significant for the relative gene expression levels of gut heat shock protein-70 (HSP70), pro-inflammatory cytokines (IL-1β and TNF-α) and anti-inflammatory cytokines (transforming growth factor-β) within each gut segment, except for HSP70 in the DG and IL-1β in the foregut. Modulation of adherent bacterial communities within each gut segment investigated was not obvious when the common carp were fed the diets with MSB, as similarity coefficients of >0·79 were observed. These results indicated that MSB can be used as a dietary supplement to repair or prevent intestinal damage in carp fed oxidised SBO.

The author discusses the way in which bacterial and fungal diseases of crustaceans can be and have been transmitted via commercial movements of stocks. Two classic examples of such diseases are presented, namely gaffkaemia (a bacterial disease of marine lobsters) and crayfish plague (a fungal disease of freshwater crayfish). In both cases, there is ample evidence that much of the disease spread can be linked to the commercial movement of infected animals caught from infected wild stocks and transported over large distances for wholesale and retail. In the case of crayfish plague, much of the relentless spread of this disease through Europe for nearly 140 years can also be liked to the movement of contaminated fishing equipment without disinfection.

Abstract This study addressed the issue of the dietary supplements; probiotic, prebiotic and synbiotics considered as functional food ingredients in sturgeon aquaculture. Developments of this strategy have been suggested and practiced as an alternative to antibiotic administration in aquaculture. Sturgeons are commercially valuable species due to their meet and roe, which is made into caviar. Aquaculture of sturgeons up to marketable size has increased during the last decade while disquieting decreases have been noticed of the natural populations. In line with the expand evaluations of microbial dietary supplements and prebiotics in finfish and shellfish aquaculture, the scientific community has also increased their interest in approaches to these issues in sturgeon aquaculture. The present review summarizes and discusses the results on intestinal microbiota of sturgeon species and the effects of probiotic, prebiotic or synbiotic administration on growth performance, gut physiology, intestinal microbiota, immune response and health. Furthermore, this study tries to cover the gaps of existing knowledge and suggest issues that merits further investigations.

Maturity ogives for the Northeast Arctic cod for year classes 1923 to 1976 were computed from the age and number of spawning zones in otoliths of cod caught on the spawning grounds at Lofoten. A reduction in the median age at maturity of approximately 2.5 years over the period was found. The change has primarily affected year classes 1950 and later. A reduction in the mean age of the spawning stock by approximately 2.5 years was also found. Males generally matured at a lower age than females, but the difference has become smaller over the period studied. It is suggested that the reduction in median age at maturity is primarily a compensatory response to the reduced stock size. Higher fishing pressure on the late maturing individuals than on the early maturing individuals may also have contributed to the changes, with or without the mediation of genetic changes.