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Title: The Identification of Oestrogenic Effects in Wild Fish - Phase II
Author: Institute for Environment and Health
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1202, Representation ID: 380, Object ID: 2420; Environment Agency Project ID:EAPRJOUT_1640, Representation ID: 566, Object ID:2747
Investigations in wild fish populations have confirmed the continued presence of intersex associated with treated sewage effluent exposure in roach populations within Great Britain, and established that the condition also exists in a second cyprinid species, the gudgeon. The geographical distribution of intersex severity appeared similar for these two species, although the proportion of a population showing intersex and the degree of effect were generally lower in the gudgeon than in the roach for any given sampling site (though the sampling regime for gudgeon was less extensive than for the roach). It was also noted that, as had previously been shown for roach, abnormal induction of vitellogenin occurred in some male and intersex gudgeon. Further studies of roach showed that the intersex condition was associated with changes in the fish’s expression of vitellogenin and also, with altered sex steroid hormone profiles. In addition, it was established that males and females showed heightened sensitivity to xenoestrogens at particular stages of their life cycle. This was shown to have consequences not only for the sexual development and differentiation of fish during their early life stages, but also in mature fish of this species with respect to the seasonal processes of sexual maturation and acquisition of secondary sexual characteristics during recrudescence. In particular, there was evidence of a delay in sexual maturation in male, but not female, roach taken from sites at which effluent exposure was known to occur. It is possible that the various effects on reproductive development and performance in individual fish, as demonstrated by this research, may impact on population recruitment, particularly where the population age structure is skewed towards older fish or when dominated by relatively few year classes. This suggests that wild fish populations in the UK may be under stress as a result of exposure to oestrogenic treated sewage effluents, and other sources of such substances to the aquatic environment. Further research is required to clarify specific aspects and to determine the actual consequences for the sustainability of fish stocks in rivers receiving sewage effluents and recommendations for this and related work are made.
Publisher: Environment Agency
Subject Keywords: SewageFishesEndocrinological functionsEnvironmental monitoringSewage treatmentEffluentsSteroidsOestrogensReproduction
Taxonomic Keywords: Pimephales promelasGobio gobio
Extent: 102
Total file downloads: 44

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