Film: Många bäckar små

Posted by Daniel Nyqvist | Dam removal

Sportfiskarna presenterar tillsammans med Freewater Pictures filmen “Många bäckar små”, om det rinnande vattnets naturvärden och dammutrivningsprojekt i Hudiksvalls och Nordanstigs kommuner. Se filmen här:

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Jessica Dolk märker i filmen öring med radiosändare. Det är en del av NRRVs studier på vandrande fisks beteende i Nianån, efter dammutrivning. Läs mer om dessa studier här. Undersökningen av fiskvandring i Nianån är en del av en större studie på ekologiska effekter av dammutrivning i området. 

Short film: The hyporheic zone

Posted by Daniel Nyqvist | Nyheter

The hyporheic zone –  the region beneath the river bottom – is home to a wide range of minute life forms and processes of high importance for the ecology of the river. Learn more in the short film Secret Life of Rivers:

Dokumentären “Tana älv – mellan tre länder” (“Tanaelv – den beste elva” på norska) ligger just nu uppe på SVT-play. FIlmen handlar om laxen i älven och människorna runt den. Forskare, förvaltare, husbehovsfiskare och repressentanter för turistfisket kommer till tals. Älven – och dess biflöden – är hem för en mängd lokalt anpassade laxpopulationer och fisketrycket måste minskas för att skydda hotade laxpopulationer. Detta skapar både lokala och internationella konflikter.


Se filmen på SVT-Play eller på NRK:s hemsida.

Film: Electric fish

Posted by Daniel Nyqvist | Nyheter

The famous electric eel (Electrophorus electricus) generates strong electric discharges for prey capture and defense. Other genera of fish have evolved to use electricity to sense objects as well as to communicate between individuals. Weakly electric fish have evolved independently at least two times in evolutionary history and is now present within two groups of fish – the South American knifefishes and the African freshwater elephantfish. The weakly electric fish generate an electric field around their body using a special electric organ. Electroreceptors are distributed over their skin making it possible for the fish to sense perturbations of the self-generated electric field, which translates in to the detection of objects and other fish. In this way, the fish can “see” in turbid waters and even through visually opaque objects. A documentary (“Amazonas elektriska fiskar”) about electric fish (electric eels and and knifefishes) in the Amazon-basin is currently available at SVT-play:



Dams in rivers not only obstruct fish migration but can also have substantial ecological effects upstream and downstream of the dam. Conservation Magazine writes about a new study on how hydropeaking affects macroinvertebrate communities downstream of the regulating dams:

“A massive new study led by the U.S. Geological Survey lays much of the blame on hydropeaking, the practice of varying river flows below a dam depending on electricity demand. Because of hydropeaking, the amount of water released from a dam can vary by as much as ten-fold throughout the day, creating an artificial intertidal zone that propagates for hundreds of kilometers downstream.

The hour-by-hour variation in water levels is a major problem for aquatic insects, which are a key element of river food webs and important prey for fish, birds, bats, and other wildlife, researchers reported last week in the journal BioScience. But lowering river flows during times of peak egg-laying and low electricity demand could give those insects a boost.

Consulting a database of insect life-history traits, the researchers determined that more than three-quarters of aquatic insects lay their eggs in shallow water at the river’s edge or by cementing eggs to the undersides of partially submerged rocks. These species could be vulnerable to hydropeaking, they reasoned, because eggs laid during high river flows are likely to be exposed to the air once the hydropeaking tide passes.” 

Read the article from Conservation Magazine here: A hydropeak tweak could make dams less damaging. The orginal paper is titled “Flow management for hydropower extirpates aquatic insects, undermining river food webs” and available here.

Part of the study was conducted in the Colorado River by young citizen scientist organized by the Grand Canyon Youth. The groups data collection and broader activities feature in this short film by Freshwater Illustrated:

National Geographics presents the film and credits the filmmakers here: Deeper Grand Canyon, More Communal Colorado River Revealed in New Online Film. 


“Fins in the Fynbos: the hidden struggle of South Africa’s freshwater fish” is a short film about native fresh water fish in South Africa. It’s a story about a unique native fish fauna threatened by invasive species and habitat degradation. But also about ongoing conservation work:

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Additional information is available on the YouTube-page.