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  • 1
    Electronic Resource
    Electronic Resource
    Maturity, oocyte dynamics and fecundity of the roundnose grenadier from the Rockall Trough (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 49 (1996), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The reproductive biology of roundnose grenadier Coryphaenoides rupestris was investigated against a background of increasing commercial exploitation. Samples were taken from surveys carried out in Rockall Trough between 1993 and 1995. An eight-point maturity scale was developed based on both visual inspection of the ovaries and histological screening. The various stages of development of roundnose grenadier oocytes were described and the relative proportion of oocyte types and their respective size range in each maturity stage were investigated. The dynamic organization of the ovary indicated a determinate maturation cycle in this species. Population spawning appears to be prolonged, extending from July to at least November. However, data were insufficient to clarify individual spawning duration. The potential fecundity of 29 mature fish ranged from 11 083-55 175 (63-95 cm total length). The results were very similar to previous values from the North Atlantic. The reproductive strategy of the roundnose grenadier is discussed in the light of the current commercial exploitation of the Species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1996.tb06064.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Catch and discards from experimental trawl and longline fishing in the deep water of the Rockall Trough (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 49 (1996), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Comparative bottom trawl and longline surveys were carried out on two chartered commercial fishing vessels in the deep waters (350-1300 m) of the Rockall Trough, an area subjected to heavy commercial exploitation. The species composition, catch rates and length distributions from each survey were very different and reflected the fundamental difference in the two types of fishing operations. Bottom-trawled catches produced greater species diversity and higher discard rates. Longline catches produced larger specimens of teleost fish and were dominated by squalid shark. Trawl discards, expressed as kgs of discards per tonne of roundnose grenadier Coryphaenoides rupestris landed, were calculated for a broad range of the most abundant species taken in the catch. First estimates of total international discarding from deep-water trawling operations in the Rockall Trough area (7530 tonnes; 26.5 million individuals) were made by raising the discard rates using international grenadier landings for 1995. The outlook for the continued exploitation of the deep-water fish resource in the Rockall Trough and possible management options are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1996.tb06071.x
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The selection of suitable indices for the measurement and analysis of fish condition (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 34 (1989), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A survey of the studies published in two leading fisheries journals revealed that the analysis and measurement of condition, based on length-weight data, has been performed using a wide variety of indices and statistical procedures. Eight forms of index were identified which can be categorized into those which measure the condition of individual fish, i.e. condition factors‘, and those which measure the condition of subpopulations as a whole, i.e. regressions of log, 10 weight on log, 10 length and the parameters of such regressions. Analysis of a test data set indicated that both the form of index and properties of the data set size can dictate the patterns of condition observed. The various indices were reviewed in terms of appropriateness, simplicity and statistical correctness. It was concluded that an index should be selected only after a detailed examination of both the underlying assumptions of the index and the properties of the data set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1989.tb03300.x
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Age estimation of the exploited deepwater shark Centrophorus squamosus from the continental slopes of the Rockall Trough and Porcupine Bank (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 60 (2002), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Dorsal spine sections of the deepwater squalid shark Centrophorus squamosus provided age estimates of 21–70 years. Small specimens were not recorded in the study area. It was not possible to obtain estimates from vertebral centra. The estimates are discussed in the context of other studies using dorsal spines of squalid sharks. Sexual maturity was achieved at large size, 〉75% of maximum length. Total length at 50% maturity was calculated as 101 cm (males) and 128 cm (females).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2002.tb01679.x
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Age estimation, growth, maturity and distribution of the roundnose grenadier from the Rockall trough (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 50 (1997), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This paper summarizes the history of commercial exploitation of roundnose grenadier Coryphaenoides rupestris in the North Atlantic. Length frequencies of C. rupestris in 1993, from 400 to 1200 m on the slopes of the Rockall trough indicate a reduction since the 1970s in the modal length of fish found at 700–1000 m. Ages ranged from 2 to 50 years for males and 2 to 60 years for females, with most between 10–38 years. Females attained a greater asymptotic pre-anus length (L∞=19.5 cm) than males (L∞=15.5 cm) and had a greater weight for a given age (male W∞=761g, female W∞=1132g). This species may have a protracted spawning period. Using pre-anus lengths, 50% of male fish were mature at 10 cm (ages 8–10) while 50% of female fish were mature at 12 cm (ages 9–11). At the greatest depths sampled the length frequency of fish was bimodal with a hiatus between 9 and 11 cm (ages 8–12). Highest catch rates occurred on the Donegal slope in September at a depth of 800–1000 m.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1997.tb01336.x
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    Paper (German National Licenses)
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