Evolusjonær økologi


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Bachelor research project

Martine completes her BIO299 project

Martine Røysted Solås participated in BIO299, Research Project in Biology. Her task was to study whether salmon fry from enriched hatchery environment have higher survival in the wild than those from the normal hatchery environment. The final touch to the work was given while she was taking the Arctic Biology course at UNIS (University Centre in Svalbard).

A lady in winter gear against arctic landscape
Martine is enjoying her time at Svalbard!


BIO299 – Research Project in Biology is a good course for any student who wishes to get experience from doing a practical research project. The student learns the research process; from having a scientific question, using methods to do the study, then analysing the data and write up a term paper (scientific paper).

Since there is no obligatory bachelor thesis following the bachelor degree in biology at UiB, Martine Røysted Solås wished to attend this course to get as much experience and knowledge about field study and writing as possible. Anne Gro Vea Salvanes was her supervisor and Helge Skoglund at UNI taught her skills needed for examining otoliths. Martine’s BIO299 project was a part of a project aiming to study if enriched hatchery environments can improve survival after release for Atlantic salmon (Salmo salar) fry.

Fry of Atlantic salmon were reared in two different environments; one group in a standard hatchery environment (hatchery fry) without any added enrichment, while the other group was reared in a tank with various structures (enriched fry). The fry were group marked with alizarin at the egg-stage; giving them a different number of fluorescent rings in their otoliths that are visible under UV-light (lowermost figure on the right, top panels). 

Martine’s research was to examine if the rearing environment affected the anti-predator behaviour of fry after release into the river. Two days after the release of the fry we caught trout, the predators of salmon fry. These were first anaesthetized before we flushed out the stomach contents and let them back into the river.  The stomach contents were afterwards examined for the number of enriched- and hatchery fry, which we could identify by checking their otoliths for red fluorescent rings. The standard length and weight was also measured and a categorical variable was made to see whether the fry were fresh (category 1), very digested (category 4), or something in between (lowermost figure on the right, bottom panel).

She examined eight trout predators which together had consumed 72 salmon fry. When she looked at the numbers of enriched and hatchery fry in the stomachs, there were no differences in numbers. However, when taking into account how digested the fry were, some interesting results were found; the most digested fry were the hatchery fry, which then must have been eaten at an earlier time than enriched fry. This could indicate an initial difference in the ability to escape predators, but more research is needed since the findings are based on a small sample size of predators. Still, the results are promising and inspire us to plan more research.

One–two master’s students and new BIO299 bachelor students are welcome to the EvoFish group to continue the predator-prey research on trout-juvenile salmon.