Proportion of river- and sea-spawning whitefish in catches at the Åland Islands (Baltic Sea), estimated from gill raker counts

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)

Interna författare/redaktörer

Publikationens författare: Andreas Lindén, Mikael Himberg, Mikael von Numers, Tom Wiklund, Christine Engblom, Piotr Hägerstrand, Jan-Olof Lill, Henry Hägerstrand
Publiceringsår: 2019
Tidskrift: Boreal Environment Research
Volym: 24
Artikelns första sida, sidnummer: 101
Artikelns sista sida, sidnummer: 113


The Åland Islands are feeding grounds for river- and sea-spawning whitefish (Coregonus
lavaretus), including also hatchery-reared released whitefish. Management of fisheries
requires knowledge of whitefish origin from their catches, but such information is deficient
at the Åland Islands. The numbers of gill rakers had unique (discretized) Gaussian
frequency distributions in all three forms studied. This justified the usage of Gaussian
finite mixture models on gill raker data for estimating the proportions of the forms in
mixed catches during the non-spawning season. From 14 catches at the Åland Islands
from 2012–2013, on average 54.8% were river-spawning whitefish, while the presence
of hatchery-reared, sea-spawning whitefish was low but uncertain. Using a hierarchical
variant of the model, we showed that the proportion of river-spawning whitefish decreased
from 69.6% in June to 38.3% in August. Our study provides feasible methods for monitoring
spatio-temporal variation in the proportions of river- and sea-spawning whitefish.

Senast uppdaterad 2020-04-04 vid 08:31