Substitution behavior in German recreational anglers in response to the closure of the harvest fishery for western Baltic cod (Gadus morhua)

Understanding how anglers respond to management restrictions is essential for anticipating spillover effects on other species, fishing sites, and recreational activities. This thesis examined substitution preferences and behaviours among German recreational cod anglers following the 2024 harvest ban on Atlantic cod (Gadus morhua), investigating shifts toward alternative recreational activities, fish species, and fishing sites, and exploring how angler characteristics influenced these responses. The relation between perceived perfect substitutes and post-ban stated behaviours was also analysed. Data came from two survey waves: a first survey conducted in 2020–2021 and a follow-up survey in 2024 after the ban was implemented. Descriptive analyses were used to characterise the population and substitution patterns, and regression models were used to identify predictors of substitution. The most commonly identified perfect substitutes were fishing for other marine species in the German Baltic Sea, freshwater fishing within Germany, and outdoor active recreational activities. Stated behaviours only partially reflected these preferences. The strongest stated substitution behaviour occurred within the German Baltic Sea, with sea trout (Salmo trutta) being the most selected substitute target species. Potential increases in freshwater fishing, marine fishing abroad, and non-fishing activities were also reported, while relatively few anglers reported increased their fishing activity in the German North Sea or travelled abroad for cod fishing. Angler characteristics shaped substitution responses in distinct ways. Psychological commitment and age were the most consistent predictors of the selection of perfect non fishing activity substitutes, while place dependence on the Baltic Sea and attachment to cod were consistent predictors of perfect resource substitution. Regarding stated substitution behaviours following the ban, psychological commitment, place identity, and distance to the preferred fishing site were negatively related to stopping fishing or engaging in other activities as a response. In contrast, place dependence, cod attachment, and cod retention orientation predicted a decrease in fishing activity as a reaction. Place identity predicted resource substitution behaviours within the German Baltic Sea, while cod attachment and distance to the preferred fishing site predicted behaviours related to marine fishing in other locations. These findings contribute to substitution theory by exploring how anglers adapt to a complete harvest closure and what drives variation in their responses. Moreover, this thesis suggests that the selection of perfect substitutes predicts corresponding behaviours, although the strength of the relationship depends on the type of substitution. Importantly for management, the results indicate that the cod retention ban is likely to increase targeting pressure on alternative species particularly within the German Baltic Sea and may reduce overall recreational fishing participation in the region, with potential economic consequences for coastal communities.