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  • Paulsen, H.  (2)
  • 1
    In: Journal of Fish Biology, Wiley, Vol. 62, No. 3 ( 2003-03), p. 706-723
    Abstract: Standard length, dry mass and RNA : DNA ratio measurements of 3876 Atlantic cod Gadus morhua larvae and juveniles from 26 families of recruit (fish during their first year of spawning) and repeat spawners (fish which were in their subsequent spawning season) reared in two mesocosms (2500 and 4400 m 3 ) under semi‐natural conditions were analysed over a period of 10 weeks using microsatellites. Larvae from recruit spawners were significantly longer and heavier at hatch and throughout the 10 weeks. RNA : DNA ratios from recruit spawner offspring were only significantly higher at week 1. The smaller (2500 m 3 ) mesocosm was characterized by low plankton density during the transition from endogenous to exogenous feeding followed by a higher density during the metamorphosis period (weeks 4 and 5), with the reverse pattern evident in the 4400 m 3 mesocosm. Patterns of larval growth followed patterns of zooplankton density. Significant differences in RNA : DNA ratios between the mesocosms at all comparable sampling dates were found and within each mesocosm individual fish exhibited a wide range of growth and condition responses under the same environmental conditions. RNA : DNA ratios as a function of size differed in the amount of variability between mesocosms, indicating that the higher food density led to a higher proportion of well‐conditioned larvae in the first 3 weeks. Food availability probably has a major role in determining offspring growth and condition, with limited effects due to maternal effects in cases where the broodstock females are approximately of similar size and condition.
    Type of Medium: Online Resource
    ISSN: 0022-1112 , 1095-8649
    Language: English
    Publisher: Wiley
    Publication Date: 2003
    detail.hit.zdb_id: 410564-3
    detail.hit.zdb_id: 1471958-7
    SSG: 21,3
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    In: Journal of Fish Biology, Wiley, Vol. 75, No. 3 ( 2009-08), p. 516-537
    Abstract: An experimental study was performed to disentangle parental and environmental effects on the growth of Atlantic cod Gadus morhua larvae and juveniles. Eggs were collected during the spawning season from spawning pairs (families) kept separately in specially designed spawning compartments. Newly hatched larvae were released simultaneously into two mesocosms of 2500 and 4400 m 3 . Larval growth was monitored by sampling over a 10 week period, after which juveniles were transferred to on‐growing tanks, where they were tagged and kept for up to 2 years. Maternal origin was determined by individual microsatellite genotyping of the larvae ( n = 3949, 24 families) and juveniles ( n = 600). The results showed significant positive correlations between egg size and larval size during the whole mesocosm period. Correlations, however, weakened with time and were no longer significant at the first tank‐rearing sampling at an age of 9 months. Significant family‐specific differences in growth were observed. The coefficient of variation ( c.v. ) was calculated in order to examine variation in standard length of larvae during the mesocosm period. Inter‐family c.v. was on average 69% of intra‐family c.v. Differences in zooplankton densities between the two mesocosms were reflected in larval growth, condition factor and c.v. Low food abundance appeared to reduce c.v. and favour growth of larvae that showed relatively slow growth at high food abundance. It is suggested that genetically determined variation in growth potential is maintained by environmental variability.
    Type of Medium: Online Resource
    ISSN: 0022-1112 , 1095-8649
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2009
    detail.hit.zdb_id: 410564-3
    detail.hit.zdb_id: 1471958-7
    SSG: 21,3
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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