Building better salmon, eel and sturgeon

John Crump

By GRID-Arendal

June 18^th, 2018

Three of Europe’s most important fish species are in trouble and new ideas are needed to “build a better fish.”

That is one of the main messages delivered by participants at an important conference held in Arendal this week where 70 students and researchers from around the world have gathered to discuss the state and future of salmon, eel and sturgeon in Europe.

This is the final conference in the four-year, four-million Euro IMPRESS programme. IMPRESS is a multi-disciplinary initiative involving 15 PhD students from 10 countries funded by the European Union’s H2020 ITN Programme. Many of the students will present their research results at the conference.

Building better salmon, eel and sturgeon

The conference focus is on the “potential and pitfalls of cultivation” of these three species which migrate between freshwater and marine or saltwater environments. This kind of adaptation is known as “diadromy” and it poses challenges for the fish, their protection and cultivation.

“Diadromy is not free. There is no free lunch,” said Alan Walker with the Centre for Environment, Fisheries and Aquaculture in the United Kingdom. Walker specializes in eel but his comments were directed at all three species.

The fish are challenged by climate change altering water temperatures as well as physical barriers like dams which have been built on Europe’s major rivers, Walker said. There are also nonphysical barriers, such as chemical pollution in the water and light pollution. The latter comes from the fact that waterways run through urban areas where lights have “banished the night.”This can affect the timing of migration. Another major threat is overfishing.

There is much research still to be done. Besides the obstacles created by human societies, for example, eels are challenged by their own evolution.

The eel found in the Arendal harbour were born in the Sargasso Sea in the mid-Atlantic, said Eva Thorstad from the Norwegian Institute for Nature Research in Trondheim. From here they will head to Scotland before turning south again to reproduce in the Sargasso.

Diadromous fish move to evolutionary rhythms we don’t completely understand. For example, sturgeon can live up to 100 years, Thorstad said. “That means there are sturgeon alive today that were around at the end of World War I.” The age, complexity and vulnerability of these species, combined with the fact that all three are declining, makes the question of breeding “fitter fish” to restock populations even more of a challenge.

Migration between salt and fresh water is one of the biggest challenges these fish face, said Thorstad. “They change habitats at different stages of their lives but it’s a large bottleneck with high mortality.”

IMPRESS is a collaboration between more than a dozen institutions in seven European countries.It focussed on “building better fish” through understanding the complex genetic codes that control reproduction or guide the fish as they migrate from fresh to salt water environments.

GRID-Arendal has been working with IMPRESS to introduce students to different ways to increase public awareness of the importance of these key fish species to freshwater biodiversity, and on the major societal benefits of healthy fish populations. As part of this, they have made movies, written press releases and some have published a book on the lifecycle of eel targeted at younger audiences.