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  • 1
    Keywords: Konferenzschrift 2006 ; Großbritannien ; Fische ; Ökosystem ; Biotopschutz
    Type of Medium: Book
    Pages: 270 S , Ill., graph. Darst., Kt
    Series Statement: Journal of fish biology 69.2006, Suppl. C
    Language: English
    Note: Literaturangaben
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  • 2
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: When access to food is restricted, faster growing fish may be those whose behaviour is relatively unaffected by the presence of nearby conspecifics. Behavioural experiments were carried out to determine the relation between growth and motor activity levels in crowded and uncrowded conditions, and measures of aversion/attraction to groups of conspecifics. Two experimental groups of Or)-ius laripes (Temminck and Schlegel) were grown for several weeks in two environments manipulated so as to maximize differences in social interactions. In the high interaction environment (HI), food was provided inside a floating cork ring. In the low interaction environment (LI), food was spread over the container's surface. Fish were measured at the end of the growth period and tested for their activity levels in the presence of conspecifics and for their preference for, or tolerance of crowded conditions. The correlation between motor activity and growth was significantly more positive in the HI environment than in the LI environment. The relationship between preference for crowded conditions and growth was negative for both groups of fish, although less so for HI than for LI. We conclude that artificial selection for faster growth may produce more aggressive fish only under very high levels of forced social interaction (competition), if at all. Under conditions of reduced social interaction, the social-aversive or socially indifferent fish grow faster.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 56 (2000), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Polymorphisms at five microsatellite DNA loci provide evidence that Atlantic cod Gadus morhua inhabiting Gilbert Bay, Labrador are genetically distinguishable from offshore cod on the north-east Newfoundland shelf and from inshore cod in Trinity Bay, Newfoundland. Antifreeze activity in the blood suggests that Gilbert Bay cod overwinter within the Bay. Gilbert Bay cod are also smaller (weight and length) for their age and consequently less fecund for their age, than cod elsewhere within the northern cod complex. The productivity and recruitment potential of coastal cod off Labrador may thus be much lower than that of offshore northern cod or of inshore cod farther south, implying that a more conservative management strategy may be required for cod from coastal Labrador than traditionally practised for northern cod inhabiting less harsh environments. Relatively high FST and RST measures of population structure suggest that important barriers to gene flow exist among five components that include two inshore (Gilbert and Trinity Bay) and three offshore cod aggregations on the north-east Newfoundland Shelf and the Grand Bank. DA and DSW estimates of genetic distance that involve Gilbert Bay cod are approximately three- and 10–fold larger, respectively, than estimates not involving Gilbert Bay cod. The differences between inshore cod from Gilbert Bay and Trinity Bay raise the possibility that other genetically distinguishable coastal populations may exist, or may have existed prior to the northern cod fishery collapse. Harvesting strategies for northern cod should recognize the existence of genetic diversity between inshore and offshore components as well as among coastal components.
    Type of Medium: Electronic Resource
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