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Genetic research shows steelhead, trout links

healthy steelhead runs in Northwest depend on rainbow trout productivity

New research shows that a steelhead, such as the large fish in this image, is just one of the options for steelhead reproduction, along with other fish such as rainbow trout. (Photo by John McMillan)

By David Stauth

SUMMIT COUNTY — Genetic research is showing that healthy steelhead runs in Pacific Northwest streams can depend heavily on the productivity of their stay-at-home counterparts, rainbow trout.

Steelhead and rainbow trout look different, grow differently, and one heads off to sea while the other never leaves home. But the life histories and reproductive health of wild trout and steelhead are tightly linked and interdependent, more so than has been appreciated, a new Oregon State University study concludes.

The research could raise new challenges for fishery managers to pay equally close attention to the health, stability and habitat of wild rainbow trout, the researchers say, because healthy steelhead populations may require healthy trout populations. Continue reading

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More bad news on ‘gender-bending’ water pollutants

UK study shows significant impact to fish reproduction from endocrine disrupting chemicals.

New study shows estrogen from various sources is impacting fish in UK rivers

By Summit Voice

SUMMIT COUNTY — More research from the UK is showing that remnant chemicals from birth control pills, hormone therapy drugs, plastics manufacturing and other sources — collectively known to contain endocrine disrupting chemicals — are bending the gender of fish.

The new study, led by the universities of Exeter and Brunel, shows those chemicals can have a significant impact on the ability of fish to breed in UK Rivers.

“This is the first time we’ve seen firm evidence that the intersex fish, males that have been feminised by EDCs, have a reduced ability to breed,” said Charles Tyler, from the University of Exeter‘s Biosciences department. “Clearly this raises concerns about the implications on the future for wild fish populations living in UK rivers, but there’s also much wider issues raised by these findings. Some of the effects seen in fish could occur in other animals too as hormone systems are quite similar across all vertebrates.

“EDCs have been tentatively linked with human health impacts too, including, falling sperm counts and cardio-vascular disease. These findings remain more controversial,” Prof Tyler added. “In contrast, we have shown, unequivocally that environmental estrogens alter sexual development in fish and now, through this study, that this can impact on their ability to breed.” Continue reading

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