Recent Submissions

  • Ertrags- und Einnahmeverluste bei Dorsch, Hering und Sprotte durch Unterfischung von Dorsch in der östlichen Ostsee.

    Bethke, Eckhard (Eckhard BethkeWendel, Germany, 2019)
    Kurzfassung: Aus dem aktuellen WGBFAS-Bericht des ICES geht hervor, dass Nahrungsmangel in der östlichen Ostsee Kümmerwachstum und damit einen Verlust an Produktivität bei Dorsch verursacht. Dieser Zustand, zunächst unbemerkt, verschlimmert sich seit etwa 30 Jahren. Hungernde Bestände müssen unbedingt vermieden werden, denn, nur der über den Grundbedarf hinausgehende Anteil der assimilierten Nahrung, wird für das Wachstum eingesetzt. Eine Reduktion der Bestandsgröße ist erforderlich! Der Internationale Rat für Meeresforschung (ICES) hat jedoch die Schließung der Fischerei auf Dorsch empfohlen. Betrachten wir die Fischerei durch die Brille der Aquakultur, stellen wir fest, dass diese Empfehlung kritisch hinterfragt werden muss. Nutzt man den „gemästeten“ Dorschbestand nicht ausreichend, werden mögliche Erträge ebenfalls nicht realisiert. Zusätzlich zu diesem Verlust verliert man das zur Mast eingesetzte Futter. Denn, als Alternative zur Dorschmast wären Erträge aus der Fischerei auf Hering und Sprotten möglich. Im Gegensatz dazu verursacht die Überfischung des Dorschbestandes zwar Ertragseinbußen, eröffnet aber gleichzeitig erweiterte Fangmöglichkeiten auf die Futterfischbestände. Die Überarbeitung der verwendeten Bestandsmodelle und die Hinwendung vom Einartenansatz über den Ökosystemansatz, hin zu Ansätzen, die Ökonomie und Ökologie vereinen, sind notwendig. Vergleicht man die Futterkosten mit den späteren Erlösen wird klar, dass bei der Mast von Dorsch über einer Körpermasse von etwa 1 kg mehr Geld in der alternativen Futterfisch-Fischerei verloren wird, als bei der Fischerei auf Dorsch gewonnen wird. Ein reflexartig geforderter Bestandsschutz verursachte in den vergangenen Jahrzehnten geringe Wachstumsraten bei Dorsch durch Unterfischung in der östlichen Ostsee und damit einen Rückgang der Produktivität auch bei anderen Arten. Man kann keine ertragreiche Fischerei auf Dorsch, Hering und Sprotten erwarten, wenn man einen hungernden Dorschbestand duldet. Um nun aber größere Dorsche fangen zu können, muss die Zahl der Rekruten ausreichend gering sein. Wir wissen es aus unserem Kleingarten. Wenn wir die Radieschenreihen nicht ausdünnen, können wir nur kleine Radieschen ernten. Das Gleiche gilt für den Kabeljau in der Ostsee. Wenn wir die Zahl der Rekruten nicht frühzeitig reduzieren, werden wir immer kleinen Kabeljau zu unattraktiven Preisen fangen.You can find the English version of the manuscript here: https://ssrn.com/abstract=3419758Abstract: The latest ICES WGBFAS report shows that food shortages in the eastern Baltic Sea are causing poor growth and thus a loss of cod productivity. This situation, initially unnoticed, has been worsening for about 30 years. It is essential to avoid starving stocks, because only the part of assimilated food that exceeds basic needs is used for growth. A reduction of the stock size is necessary! However, the International Council for the Exploration of the Sea (ICES) has recommended the closure of the cod fishery. If we look at fishing through the eyes of aquaculture, we see that this recommendation must be questioned critically. If the "fattened" cod stock is not used sufficiently, potential yields will not be realised either. In addition to this loss, the feed used for fattening is also lost. Because, as an alternative to cod fattening, yields from fishing for herring and sprat would be possible. In contrast, overfishing of the cod stock may result in a loss of yield, but at the same time it opens up greater fishing opportunities for forage fish stocks. A revision of the stock models used and a shift from the one-species approach via the ecosystem approach to approaches that combine economy and ecology are necessary. If one compares the feed costs with the later revenues, it becomes clear that when fattening cod beyond a body mass of about 1 kg more money is lost in the alternative forage-fish fishery than is gained when fishing for cod. A reflex-like demand for stock protection has caused low growth rates for cod in recent decades due to underfishing in the eastern Baltic Sea and thus a decline in productivity for other species as well. You cannot expect high-yield fishing for cod, herring and sprat if you tolerate a starving cod population. In order to catch larger cod, however, the number of recruits must be sufficiently low. We know this from our allotment garden. If we don't thin out the rows of radishes, we can only harvest small radishes. The same applies to cod in the Baltic Sea. If we do not reduce the number of recruits beforehand, we will always catch small cod at unattractive prices.
  • World Ocean Review: Living with the oceans

    Bollmann, Moritz; et, al (Maribus GmbHHamburg, Germany, 2010)
  • Traditional and geometric morphometrics detect morphological variation of lower pharyngeal jaw inCoris julis(Teleostei, Labridae)

    Fruciano, C.; Tigano, C.; Ferrito, V. (2011)
    In the present study, variation in the morphology of the lower pharyngeal element between two Sicilian populations of the rainbow wrasse Coris julis has been explored by the means of traditional morphometrics for size and geometric morphometrics for shape. Despite close geographical distance and probable high genetic flow between the populations, statistically significant differences have been found both for size and shape. In fact, one population shows a larger lower pharyngeal element that has a larger central tooth. Compared to the other population, this population also has medially enlarged lower pharyngeal jaws with a more pronounced convexity of the medial-posterior margin. The results are discussed in the light of a possible more pronounced durophagy of this population.
  • Geographical and morphological variation within and between colour phases inCoris julis(L. 1758), a protogynous marine fish

    Fruciano, Carmelo; Tigano, Concetta; Ferrito, Venera (2011)
    The possible differences between sexes in patterns of morphological variation in geographical space have been explored only in gonochorist freshwater species. We explored patterns of body shape variation in geographical space in a marine sequential hermaphrodite species, Coris julis (L. 1758), analyzing variation both within and between colour phases, through the use of geometric morphometrics and spatially-explicit statistical analyses. We also tested for the association of body shape with two environmental variables: temperature and chlorophyll a concentration, as obtained from time-series of satellite-derived data. Both colour phases showed a significant morphological variation in geographical space and patterns of variation divergent between phases. Although the morphological variation was qualitatively similar, individuals in the initial colour phase showed a more marked variation than individuals in the terminal phase. Body shape showed a weak but significant correlation with environmental variables, which was more pronounced in primary specimens.
  • Body shape variation and colour change during growth in a protogynous fish

    Fruciano, Carmelo; Tigano, Concetta; Ferrito, Venera (2012)
    Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.
  • A report on the strategic fisheries stock assessment survey of the minor catchments in South West Cumbria 1996 with particular reference to salmonids

    Watson, E.P.K.; McCubbing , D.J.F. (Environment Agency North WestUK, 1996)
    This is the report on the strategic fisheries stock assessment survey of the minor catchments in South West Cumbria 1996 with particular reference to salmonids, produced by North West Water in 1994. The 1996 Minor Catchment survey indicates variations in salmonid production within these catchments. Survey results indicate that production may be reaching its limit in certain areas whilst others are underachieving and others are unsuitable for salmonid production. Trout production within the catchments is higher and more widespread than that of salmon. Water quality levels vary considerably between catchments and intra-annually within individual catchments. The need for selective habitat surveys, with a view to habitat improvement schemes (H.I.S) is discussed. This report formed a basis for subsequent reports, thus, allowing data comparisons and analysis of production level fluctuations. It was the most extensive assessment of these catchments to date, taking into account comparisons with the new National Database on salmonid production in England and Wales.
  • River Gowy rapid corridor survey July 1995. Ecology South Mersey

    National Rivers Authority (National Rivers AuthorityUK, 1995)
    This is the River Gowy rapid corridor survey July 1995: Ecology South Mersey report produced by the National Rivers Authority North West Region in 1995. This report looks at the survey carried out by the South Mersey Ecology Team prior to routine deweeding operations on the main River Gowy at the end of July, 1995. The survey covered Flood Defence Stretch References RGOW03 to RGOW16. These stretches were further divided into a series of 43 stretches, each one being approximately 500m in length for ease o f mapping by Ecology. Recommendations for each length have been cross-referenced with the Bill of Quantities where possible, e.g. retention o f margins. In Flood Defence stretch RGOW03, the South West Winter Wetland forms an important habitat for birds. In stretches RGOW04 to RGOW05, the Gowy Meadows and Ditches have been designated a Grade A, Site of Biological Importance, by Cheshire County Council due to the nature of the acidic grassland and diverse ditches. In stretches RGOWIO to RGOW11 the left bank forms Hockenhull Platts, Grade A Site of Biological Importance and County Trust Reserve. In stretches RGOW15 to RGOW16, the area from Mill Farm to the Shropshire Union Canal is a Grade A Site of Biological Importance. These sites are very sensitive and detailed recommendations for working practices can be found in the relevant sections o f the survey.
  • Water quality monitoring in the Mersey

    Environment Agency (Environment Agency North WestUK, 2001)
    This is the Water Quality Monitoring in the Mersey Estuary report produced by the Environment Agency in 2001. This report focuses on the Water Quality Monitoring Programme held in the Mersey Estuary. Since the mid-1960s water samples have been collected at approximately monthly intervals along the length of the estuary between Warrington and New Brighton and in later years further off-shore. This data-set provides an invaluable resource to determine how the very large capital spending of recent years has resulted in the dramatic improvements in water quality that we are now able to record. Initially, the interest was focused on parameters such as dissolved oxygen, BOD, nutrients and suspended solids. Over the last decades, as analytical methods have improved, toxic metals and persistent organic compounds have been included in the routine monitoring programme at a limited number of sites. Moreover, with the introduction of the European Water Framework Directive monitoring programmes it was an opportune time to review the Mersey monitoring strategy. This revised monitoring programme required data from several other components (water, sediments, flora, fauna, fish and birds. This report also contains information about Routine monthly surveys, Special surveys, Chloralkali Directive, UKNMP, British Geological Survey, EDMAR and NERC Environmental Diagnostics Thematic Programme.
  • Egg survival [River Wyre].

    Anonymous (1990)
    The report looks at egg survival in the River Wyre with use of three different techniques, (burying eggs in Harris boxes, eggs recovered in freeze cores and excavating redds). The report provides a detailed method and the results for each of the three different techniques, and gives an overall discussion of the findings.
  • The calibration of a semi-quantitative approach to fish stock assessment in the North West Region of the NRA

    Farooqui, M.A.; Aprahamian , M.W. (National Rivers Authority North WestWarrington, UK, 1993)
    (1) A total of 45 sites was sampled, each being fished usingthe semi-quantitative and quantitative techniques.(2) A significant relationship existed between thesemi-quantitative and Quantitative results for all agegroups of salmonids (R2 83.4% to 96.1%, p < 0.0001).(3) The results from each site were categorised according toan existing classification system for quantitative andsemi-quantitative data. The semi-quantitative component ofthis system was modified using the results of thisinvestigation. The degree of error associated with sitesclassified semi-quantitatively was found to be slightlyless when using the modified system for 0+ salmon, > 0+salmon and 0+ trout, ranging from 10.5% to 30%.(4) Insufficient data points were available for the analysisof coarse fish data.
  • La Pesca nel Golfo di Napoli

    Costa, Achille (G. NobileNapoli, 1871)
  • The brine and gas content of sea ice with attention to low salinities and high temperatures

    Leppäranta, Matti; Manninen, Terhikki (Finnish Institute of Marine ResearchHelsinki, Finland, 1988)
    Based on the well known sea ice phase diagram, equations are derived for determining the brine and gas content of sea Ice for high temperatures (range 0 to -2 °C) and low salinities. The presently widely used equations of Cox andWeeks (1982) are valid only for temperatures below -2°C. Fresh-water ice is used as a boundary condition for the equations. The relative salt concentrations in brine are_assumed to be the same as in normal (or standard)seawater. Two sets of equations are presented: 1) accurate formulae based on UNESCO standard sea water equations, and 2) approximate formulae based on general properties of weak solutions. The approximate formulae are not essentially different from the classical system which basically assumes the freezing point to be a linear function of fractional salt content. The agreement between the two approaches is excellent and the approximate system is good enough for most applications.
  • Social Organisation of the Short-finned Pilot Whale, Globicephala macrorhynchus, with Special Reference to the Comparative Social Ecology of Delphinids

    Heimlich-Boran, James Robert (University of Cambridge, Department of Zoology, 1993)
    As a contribution to the understanding of comparative social trends within the cetacean family Delphinidae, a 22-month study was conducted on the shortfinned pilot whale, Globicephala macrorhynchus, which has been suggested to have a unique social system in which males and females in the same group are related and mating occurs outside of the group. The individual identification of 495 pilot whales, analysed in daily group association patterns, allowed identification of 46 pods. They were classified as productive or non-productive based on the presence or absence of immature animals. Productive pods were a significantly larger, although 12% of them lacked adult males. Two classes of whales (residents and visitors) were defined by patterns of occurrence,suggesting differential patterns of habitat use. Resident pods occasionallytravelled together (41% of all groups) and associations between age and sex classes showed that in mixed-pod groups, the highest ranked associations of thereproductive females were with males from other pods, while within pods, adult males and females associated less. During summer, the proposed peak conception period, pilot whale groups were significantly larger and containedindividuals from a significantly greater number of pods. These findings support the hypothesis that males and females mate when associating with individuals from other pods. A comparative analysis of sexual dimorphism, brain size, and testes size, habitat, prey and group size within the 17 delphinid genera identified a correlation between sexual dimorphism and body size, but relative measures ofbrain size and testes size did not correlate with broad ecological or social classifications. However, a comparison of three delphinid societies identified two distinct male mating systems: males of the small, mono-morphic Tursiopstruncatus live in age/sex segregated groups and mate with a number of discrete female communities. Males in the large sexually dimorphic Glob icephala spp. and Orcinus orca mate with associated female pods and yet remain with theirfemale kin. This corresponds to the avunculate social system described in some human societies. It could evolve from a promiscuous mating system where there is little guarantee of paternity and where males that live with their kin increase their inclusive fitness.
  • Recherches sur l'embryologie des gastropodes

    Pelseneer, Paul (Académie royale de BelgiqueBruxelles, Hayez, 1911)
    (PDF contains 167 pages and 22 plates)
  • Histogénèse et structure de la glande hermaphrodite d'Helix pomatia (Linn.)

    Ancel, Paul (Université de Nancy, 1903)
    (PDF contains 267 pages)
  • Traité général des pesches : et histoire des poissons qu'elles fournissent tant pour la subsistance des hommes que pour plusieurs autres usages qui ont rapport aux arts et au commerce. [3 volumes bound in 2 parts in folio]

    Duhamel du Monceau, M.; La Marre, L.H. (Chez Saillant & NyonParis, 1769)
    Early illustrated book about fish, fishing and fisheries by one of the preeminent scientific investigators of the French enlightenment. This work deals extensively with the species of fish found in Europe and beyond, their habits and habitats, techniques and equipment used in fishing and fish processing, and many other aspects of these endeavours. Roughly 185 engraved plates illustrate the text. The scans for this version come from 3 volumes bound in two parts in folio.
  • Functional morphology of cephalopod gills

    Eno, Nancy Clare (University of Cambridge, Darwin College, 1987)
    There is a wealth of literature dealing with fish gills(Review, see Hoar & Randall, 1984), yet hardly anything is known about the gills of cephalopods. This is rathersurprising considering the commercial importance of thecephalopods.In view of the paucity of information available it wasnecessary to start by establishing the morphology of thegills. This is covered in the first section of this thesis.Of all the cephalopods, Octopus vulgaris was singled outfor more detailed investigation (see chapters 2 & 3) as itsphysiology is comparatively well understood (Wells, 1978).The gills of cephalopods are the major sites for respiratorygaseous exchange. It follows that their dimensions might beexpected to govern their potential for absorbing oxygen.Section two deals with the morphometries of cephalopod gills, and predicted values are compared with physiologicalmeasurements of oxygen uptake for four representativeThe final section describes the physiological experiments Iperformed on octopuses. These experiments were designed tofind out whether the animals could regulate the gills'potential to take up oxygen through changes to the gillsthemselves.

View more