Elonkirjo ehtyy : suosituksia luonnon monimuotoisuuden turvaamiseksi

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

Depending on their reproductive strategy, different fish species aim to aggregate or disperse eggs and larvae in their reproductive habitat. Many pelagic species disperse their eggs widely around the potential nursery areas. Larval dispersion or aggregation affects population sub‐structuring, which has important implications in fisheries management and conservation of the natural spatial diversity in populations. The dispersion of larval vendace (Coregonus albula) was quantified in two oligotrophic Finnish lakes, and effects of density and environmental variables on the inter‐annual variation in the larval distribution were examined by analysing spatial abundance data from the lakes from 19…

Harjuskannan tila ja luonnonvaraisen lisääntymisen mahdollisuudet Kokemäenjoessa

Life in the ice lane: the winter ecology of stream salmonids

Despite the common view that conditions in winter strongly influence survival and population size of fish, the ecology of salmonids has not been as extensively studied in winter as in other seasons. In this paper, we review the latest studies on salmonid winter survival, habitat use, movement and biotic interactions as they relate to the prevailing physical and habitat conditions in rivers and streams. The majority of research conducted on the winter ecology of salmonids has been carried out in small rivers and streams, where temperatures are above zero and where there is no ice. Investigations in large rivers, regulated and dredged rivers, and under conditions of different ice formations a…

Recovering and restoring deleted salmonid populations

Salmon and trout have been considered as an umbrella species indicating a good status of the ecosystem. They have a notable existence value producing variety of ecosystem services but moreover, indicating healthy rivers, they can be seen as the key species for stream restoration and adapting human induced changes (e.g. climate change). In less than hundred years we have lost the genetic diversity of salmon by hydropower production all over the country and the Baltic Sea region. Besides hydropower salmonid populations have encountered challenges by habitat loss due timber floating, overall human impact on catchment scale deteriorating water quality and effective fisheries which have all been…