Eelgrass and sea trout project 2024 field season
During the field season of 2024 we PIT-tagged migrating smolts in four streams along the Swedish west coast and followed up by conducting a beach seine net survey in the coastal area adjacent to the streams. The survey provided information about prey choice of sea trout and species community in each area. Additionally, we collected epifaunal samples in each coastal area to estimate prey abundance and benthic community composition in eelgrass meadows and unvegetated sites.
In the autumn, we visited cormorant colonies around our sites to investigate potential cormorant predation of our PIT-tagged sea trout. By using portable antennas, we scanned for PIT-tags around the colonies used by the cormorant during the spring and summer.
Field work during 2024. Photos: Magnus Lovén Wallerius and Karl Karlsson
Various prey found in sea trout stomachs. Photo: Karl Karlsson
Scanning of cormorant colonies. Photo: Magnus Lovén Wallerius
In 2025, we are planning to conduct an acoustic telemetry study to assess habitat use of sea trout smolt in an area with both eelgrass meadows and unvegetated sites. This study will increase the knowledge of how these habitats influence residence time and diel activity patterns of sea trout in coastal areas.
We will also conduct a mark-recapture study, using passive fyke nets, in an area that contains both eelgrass meadows and unvegetated sites. Not only will we potentially recapture tagged sea trout and measure growth at sea, but also collect stomach content data of untagged sea trout to quantify prey choice in different habitats. In collaboration with 8-fjordar and SLU we will also PIT-tag and measure other fish species to quantify the fish community and different tropic levels that would impact the trophic chain in the eelgrass meadows. By targeting and tagging more fish species in this area, we could also get a better understanding of how cormorant predation could limit the recovery of important fish species and their impact on eelgrass meadows.