Managing Marine Mammals and Fisheries: A Calibrated Programming Model for the Seal-Fishery Interaction in Sweden

Abstract

This paper develops a model based on the concept of Positive Mathematical Programming (PMP) that is useful for ex-ante analyses of how policy measures affect commercial fisheries. PMP models are frequently used in agriculture, but rarely for analyzing fisheries. Fisheries often face a large set of constraints such as effort regulations and catch quotas of which some might be binding and others not. An econometric approach is developed for calibrating models with both binding and non-binding constraints. The interaction between seals and Swedish fisheries is used as an empirical application. Seal interaction is modeled as seals predating fish from passive gear (nets and hooks), which is primarily an issue for the coastal fishery. The model contains 24 fleet segments involved in 247 different fishing activities in 2012. The results show that if no further management action is taken, fisheries using passive gear will reduce their activities from about 46 000 days at sea per year to about 41 000 and reducing their economic performance from losses of about 2 million Euros to about 3.3 million. The impact from seals can be reduced by reducing the seal population or providing economic compensation.

Joint management of marine mammals and a fish species: The case of cod and grey seals in the Nordic‐Baltic Sea countries

“…Adaptation strategies for salmon fisheries in Finland under various scenarios for the grey seal population by using calculated values of the current and future profits are identified in Holma et al (2014), while Finnoff and Tschirhart (2003) analyze how the harvest of pollock in the northern Pacific depends on the population of stellar sea lions. Finally, Boncoeur et al (2002) investigate how the optimal size of marine protected areas depends on the interaction between grey seals and fish species, while Jansson and Waldo (2022) investigate profits in the Swedish fisheries sector under different assumptions about the grey seal population. However, in this literature, there is no attempt to discuss the management implications of considering the benefits and costs related to marine mammals, and this constitutes an important research topic.…”