Fish genetics

Biodiversity is not only about having a variety of species; genetic variation within species is equally crucial. Most species consist of genetically distinct populations, and managing them sustainably requires a deep understanding of their biology. For instance, when a population is overexploited, such as through overfishing, the number of individuals declines, and recovery becomes more difficult. The loss of genetic diversity can also jeopardize the long-term survival of the species. At SLU Aqua, we use genetic tools in several ways, not only to understand these processes but also to help create conditions that preserve biodiversity.

Genetics Helps Us Differentiate Flounder Species in the Baltic Sea

One of the ways we apply genetics is in mapping the distribution of two flounder species — Platichthys flesus and Platichthys solemdali — in the Baltic Sea. These species share foraging grounds but have distinct spawning patterns. Since they are nearly indistinguishable to the naked eye, managing them becomes a challenge. By using genetic markers, we can pinpoint where each species occurs in the Baltic.

Learn About the Record-Breaking Speciation of Flounders in the Baltic Sea

New DNA Technology Identifies Herring Stocks

In collaboration with Stockholm University, we are working to map the spawning populations of herring (Clupea harengus) along the Swedish coast. By utilizing newly developed genetic markers, we can now distinguish between stocks that were previously indistinguishable. This is critical for accurate stock assessments of herring and other species.

Genetics Reveals Unique Pike Stocks Along the East Coast

As part of the ReFisk project, previously managed by the Stockholm County Administrative Board, we’ve used genetics to study the degree of isolation among pike spawning populations. The genetic differences between pike populations along the coast are significant, with diversity increasing as the geographical distance between populations grows. Some populations, such as those in the outer archipelago and those that migrate into freshwater to spawn, show distinct genetic traits. This new genetic insight led the Swedish Agency for Marine and Water Management to implement stronger protection for pike along the east coast.

How Does Fishing Affect Genes?

We are also investigating how different fishing pressures impact genetic traits. For example, perch in protected areas tend to grow faster than those in areas open to fishing. We are exploring whether these growth differences reflect genetic adaptations to varying fishing pressures.

eDNA – Testing Methodology and Usability

Can a water sample reveal which species live in a lake? We are currently testing and developing the eDNA method as a supplement to traditional environmental monitoring. Learn more about eDNA and how it complements our environmental monitoring efforts.