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  • 11
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Deepwater sculpin, Myoxocephalus thompsoni (Girard), were sampled from six stations from the 15–100 m depth contours in Lake Michigan between April 1983 and July 1984. In south-eastern Lake Michigan M. thompsoni lay benthic eggs in offshore waters, which hatch between November and August, with peak hatching in March. Abundance of larvae in pelagic samples was higher offshore than inshore, but larval size was greater and development more advanced at inshore stations, indicating an inshore movement after hatching. Larvae reached metamorphosis at 20 mm and settled to the bottom beginning in July. Pelagic larvae 20–40 mm were found in the lower water column at all stations, but newly settled individuals were only captured with bottom trawls at inshore locations (≤60 m depth). Data from ichthyoplankton and bottom trawl samples in 1983 and 1984 indicated that locations for successful settlement of larvae to the bottom extended only as deep as the shallowest fringe of the adult population (〉 50 m in 1983). In 1983, maximum density of larvae reached 0.4 individuals m−3 by June. Survival from the pelagic larval stage to the demersal young-of-year stage in 1983/1984 was c. 0.1–0.4%. The specific mechanism of mortality at the time of transition to a demersal habit has not been determined.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 113 (1992), S. 463-468 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The requirement of plaice (Pleuronectes platessa L.) larvae for the fatty acids 20:5ω 3 and 22:6ω 3 was studied. Larvae were reared from first feeding to beyond metamorphosis on Artemia sp. nauplii (EG brand), whose nutritional content had been manipulated by enrichment. Some larvae were fed Artemia rich in 20:5ω 3 and 22:6ω 3, and others were fed nauplii with no 22:6ω 3 and low levels of 20:5ω 3 (1.9% of the total fatty acids). The differences in diet had no significant difference on growth or survival of the plaice larvae. The results indicate that the plaice larvae in this study did not require 22:6ω 3 in their diet, even when the levels of 20:5ω 3 were low.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between sperm characteristics and reproductive success was examined in male herring, Clupea harengus L. Males were categorised as being first-time or repeat spawners on the basis of their age; they were also grouped according to whether their sperm were immediately active and exhibited forward motion on contact with seawater (FM) or had little or only vibratory motion (VM). Unlike the Pacific herring C. pallasii Valencienes, Atlantic herring sperm is usually motile on contact with seawater. The age, weight and gonadosomatic index (testes mass as a percentage of somatic mass = GSI) were measured and used as characteristics for individual fish. Sperm traits measured were (1) adenosine triphosphate (ATP) concentration, (2) sperm count, (3) duration of sperm motility. Reproductive success for each male was estimated from the fertilisation rate and from the length of larvae at hatching. Fertilisation rates for all fish were generally 〉80%. The ATP concentration of non-activated spermatozoa was negatively correlated with fertilisation rate. Among repeat spawners, fish with higher GSIs produced larvae that were larger at hatching. Although VM sperm fertilised eggs at rates equivalent to fertilisation by FM sperm, the larvae produced by VM sperm were significantly smaller at hatching. Larval length tended to increase in parallel with the duration of sperm motility, but the relationship was not significant in these tests. The results did not indicate any age or size pattern to spawning readiness in male herring. Sperm that are not yet ready to be shed are not fully motile on contact with seawater, but are still capable of fertilising eggs that hatch successfully. There is likely to be a progression of males which come into spawning readiness within a spawning shoal; therefore it is possible that paternal influences would result in a progressive decrease in larval size over the spawning period in winter-spawning Celtic Sea herring.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 134 (1999), S. 637-643 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sperm characteristics and fertilization success were measured in two groups of Manx autumn-spawning herring, Clupea harengus L., captured 1 wk apart. Samples contained motile sperm for up to 45 min after activation (average 7 min). Individual spermatozoa were motile for up to 5 min. The activation of individual spermatozoa is probably phased, although the mechanism for the delay is not clear. This can account for the overall low levels of active sperm at any one time, the periodic fluctuations observed in the proportion of motile sperm, and for successful fertilization rates achieved using samples of apparently immotile sperm. The proportion of motile sperm was not affected by the presence of eggs, but the duration of motility was longer when sperm was activated in the presence of eggs rather than in seawater alone. Individual males differed significantly in the duration of motility in their sperm samples and in the fertilization rates achieved, but not in the proportion of motile sperm in each sample. There were no consistent changes in the characteristics of the spawners or the sperm between the two sample dates. Sperm motility and duration of motility were significantly correlated, but none of the sperm characteristics measured was significantly related to fertilization success.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 71 (1982), S. 317-326 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Larvae of Clyde spring-spawning Clupea harengus L. and hatchery-produced Scophthalmus maximus (L.) were reared from hatching through metamorphosis in 1980 and 1981 in laboratory tanks and in large enclosures under various light, temperature, and feeding regimes in order to study otolith ring deposition and growth under different conditions. Ring deposition and growth rates were significantly affected by rearing conditions in both species. The ring deposition rates observed under the conditions tested ranged from 0.34 to 0.92 rings d-1 in herring larvae, and from 0.07 to 1.0 rings d-1 in turbot larvae. Growth rates ranged from 0.11 to 0.42 mm d-1 in herring and from 0.05 to 0.27 mm d-1 in turbot. The number of otolith rings was dependent on the growth rate of the individual larva. At the population level, higher ring deposition rates were observed in faster growing populations. In herring larvae, the relationship between average growth rate and average ring deposition rate was logarthmic, reaching an asymptote at 1 ring d-1 for growth rates approaching 0.40 mm d-1. The relationship was linear for turbot larvae for the range of growth rates observed.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Reviews in fish biology and fisheries 5 (1995), S. 461-473 
    ISSN: 1573-5184
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 17
    Publication Date: 2019-07-17
    Description: Ocean acidification (OA), caused by increasing atmospheric concentrations of CO2 is one of the most critical anthropogenic threats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to long-term effects such as reduced growth rates and reproduction4,5. In teleost fishes, early life-history stages are particularly vulnerable as they lack specialized internal pH regulatory mechanisms. So far, impacts of relevant CO2 concentrations on larval fish have been found in behavior and otolith size mainly in tropical, non-commercial species. Here we show detrimental effects of OA on the development of a mass-spawning fish species of high commercial importance. We reared Atlantic cod larvae at three levels of CO2 (1) today, (2) end of next century, and (3) an extreme, coastal upwelling scenario, in a long-term (2½ months) mesocosm experiment. Exposure to CO2 resulted in severe to lethal tissue damage in many internal organs, with the degree of damage increasing with CO2 concentration. As larval survival is the bottleneck to recruitment, OA has the potential to act as an additional source of natural mortality, affecting populations of already exploited fish stocks.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 18
    Publication Date: 2018-06-25
    Description: The growth and development of the aragonitic CaCO3 otoliths of teleost fish could be vulnerable to processes resulting from ocean acidification. The potential effects of an increase in atmospheric CO2 on the calcification of the otoliths were investigated by rearing Atlantic cod Gadus morhua L. larvae in 3 pCO2 concentrations—control (370 µatm), medium (1800 µatm) and high (4200 µatm)—from March to May 2010. Increased otolith growth was observed in 7 to 46 d post hatch (dph) cod larvae at elevated pCO2 concentrations. The sagittae and lapilli were usually largest in the high pCO2 treatment followed by the medium and control treatments. The greatest difference in mean otolith surface area (normalized to fish length) was for sagittae at 11 dph, with medium and high treatments being 46 and 43% larger than the control group, respectively. There was no significant pCO2 effect on the shape of the otoliths nor were there any trends in the fluctuating asymmetry, defined as the difference between the right and left sides, in relation to the increase in otolith growth from elevated pCO2.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 19
    Publication Date: 2016-05-02
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 20
    Publication Date: 2016-05-02
    Type: Conference or Workshop Item , NonPeerReviewed
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