The dramatic decline of coastal fish populations, including Atlantic cod (Gadus morhua), has significantly impacted marine ecosystems along the Swedish west coast. Effective conservation and fisheries management require improved understanding of population structure, connectivity, recruitment dynamics, and local adaptation. This project builds on ongoing work within the Ecosystem-Based Fish Management in the 8-Fjord Area (EBHF) initiative, which aims to support the recovery and sustainable management of coastal fish populations through improved ecological and genetic knowledge. The project focuses on the application of whole-genome sequencing (WGS) and population genomics to investigate these processes in Atlantic cod and other marine fish species. Ongoing analyses are based on a dataset of 280 juvenile cod sampled across fjord and reference areas along the Swedish west coast. These analyses aim to investigate population structure, local adaptation, and the contribution of local versus external recruitment to coastal cod populations. Particular focus is placed on identifying genomic regions associated with adaptation and developing genetic markers that can support future monitoring and management efforts. In addition, the project includes analysis of a newly generated dataset comprising 123 whole-genome sequenced Baltic cod, including samples from the Åland Sea. These genomic data will be integrated with otolith microchemistry analyses to investigate connectivity, population structure, natal origin, and the potential existence of locally reproducing cod populations within the Baltic Sea The project will also expand to include whole-genome sequencing of Atlantic mackerel (Scomber scombrus), with approximately 150-200 samples expected during the project period. These data will be used to investigate population genomic patterns and connectivity in another ecologically and commercially important marine species. Furthermore, the project provides a computational framework for exploratory genomic analyses of additional coastal fish species as new datasets become available. The research integrates population genomics, bioinformatics, and statistical modelling to generate knowledge relevant to conservation, fisheries management, and ecosystem-based management of marine resources. The resulting genomic resources and analytical frameworks will contribute to improved understanding of genetic connectivity and adaptation in marine fish populations and support evidence-based management decisions.