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  • Blackwell Publishing Ltd  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 49 (1996), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A review of energy use and the life histories of deep-water demersal fishes suggests that there are two primary groups or guilds; those that live dispersed over the sea floor and those that aggregate in association with topographic features like seamounts. Dispersed deep-sea fishes typically have a body plan designed for slow cruising or ‘sit and wait’ predation, and are characterized by very low energy stores and metabolic rates. Scaled for body size, the metabolism of these fishes was comparable to that of bathypelagic fishes. On the other hand, aggregatory deep-water species are characterized by robust morphology and strong locomotory ability to maintain themselves in environments characterized by strong, variable currents. Their flesh has high protein and lipid but low water content. The metabolic rate of orange roughy, an aggregating deep-water species, was substantially higher than that of dispersed deep-water fishes and was comparable to that of haddock, a shelf demersal species. However, although the estimated ration of orange roughy was higher than that of dispersed demersal deep-water species, its growth rate was comparable and its growth efficiency was far lower due to its high metabolic costs. Large deep-water dispersed fish species are characterized by late maturity and an extended reproductive period, but these characteristics are less pronounced than in deep seamount-associated species, which may live in excess of 100 years.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 46 (1995), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Morphometric variation was used to examine the stock structure, in southern Australian waters, of the deepwater marine teleost Hoplostethus atlanticus, orange roughy. Seven samples were collected from non-spawning aggregations in 1989–1990. Three samples were also collected in the winter of 1992, two from the main spawning site off the eastern coast of Tasmania (St Helens), and the third from the other main fishing ground south of Tasmania. The 38 morphometric measurements taken from each of over 1300 fish were size-standardized by an allometric formula and analysed by univariate and multivariate statistics. The results indicate significant variation in the morphology of orange roughy caught from geographically distinct aggregations. They further suggest that the main spawning aggregation may consist of fish from different groups at different times of the spawning period. There appear to be at least seven morphologically distinguishable stocks of orange roughy in southern Australian waters, despite genetic data indicating appreciable levels of gene flow between them.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Fecundity of orange roughy in 1987–1989 adjusted for standard length (S.L.) varied significantly between New South Wales (42 787 eggs female−1) South Australia (35 339 eggs female−1) and east Tasmania (31 085 eggs female−1). Only 10-17% of the variability in fecundity of eastern Tasmania orange roughy was explained by s.l. in any year from 1987–1992. However, liver condition and age of the fish, in combination with s.l., explained 27% of the variation in fecundity. Fecundity declined in fish over 60 years old. It was also significantly correlated with lipid levels in the ovary, in particular, with triacylglycerol as a proportion of the total lipid fraction. Significant interannual changes in fecundity appeared to be related to the impact of fishing. From 1987–1992, the orange roughy stock off east Tasmania was reduced by 50% by the fishery, and mean fecundity increased 20% over that period. This compensatory increase in individual fecundity, combined with an apparent increase in the proportion of females spawning annually from 54 to 71%, limited the decline in the population's egg production over this period to approximately 15%.
    Type of Medium: Electronic Resource
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