Stock diversity: Major differences between salmon in north and south
There are still distinct differences between stocks of wild salmon in Norwegian waters - even after 30 years of aquaculture activities. Nevertheless, researchers are not relaxing their concerns about diversity.
There have long been worries that production salmon could diminish biological diversity among wild salmon.
"I wish in no way to trivialise the problems caused by escapes, but it is encouraging to find that such large differences between the salmon stocks still exist," says Professor Ole Kristian Berg of the Norwegian University of Science and Technology (NTNU). Together with doctoral research fellow Øivind Solem, he is conducting a project to map and describe the characteristics of various stocks of both wild salmon and production salmon in Norway.
The project is profiled in the most recent newsletter from the HAVBRUK programme ("Nytt fra HAVBRUK" no. 2/2009, available in Norwegian only). This issue of the newsletter is focused on sustainability.
"A natural selection appears to occur that mitigates the impact of escapes," explains Professor Berg. "Compared to their wild counterparts, production salmon appear to be less hardy and less able to adapt - so they do not survive as well."
Ole Kristian Berg observes differences between stocks of wild salmon. (Photo: Per Harald Olsen)
Differences from north to south
In the year since the project started, Professor Berg and Mr Solem have spent their time conducting morphological studies (studies of expressed physical characteristics) of salmon in various Norwegian waters. They have investigated salmon from three rivers in Southern Norway, two in Central Norway and two in Northern Norway.
"Salmon's outward appearance varies from waterway to waterway, but the differences are especially great between salmon from rivers farthest south and farthest north," reports Mr Solem, who believes the differences are likely attributable to divergent conditions in terms of light, temperature and nutrition.
"Summers in the north are short and intense, with continuous daylight, while winters are long and hard. This imposes different survival demands on the individual compared to conditions in the southern waterways, where summers are relatively long, water temperatures are higher, and winters are considerably milder," points out Mr Solem. "These differences are highly significant for natural selection and survival."
Welcome news
The wide variety in appearance between salmon of different waters is good news for the biological diversity of Norwegian salmon stocks, but that is not to say that farmed salmon escapes are not a problem.
"In a later phase of the project," concludes Professor Berg, "we will examine the genetic variations between the various salmon stocks, as well as if and how escaped production salmon impact the wild stocks. This will generate knowledge about the extent of interbreeding between wild and production salmon, and what it means for their survivability in local waters."
- Published:
- 01.09.2009
- Last updated:
- 01.09.2009
Other articles from "Nytt fra HAVBRUK" no. 2/2009
The newsletter (in Norwegian)
- Nytt fra HAVBRUK nr 2/2009 (PDF-336.2 KB)
Contact
- Rolf Giskeødegård +47 22 03 70 97 rg@forskningsradet.no
