Impact of Fisheries on Marine Ecosystems

GONZÁLEZ, RAÚL; NARVARTE, MAITE; ARIAS, MAGDALENA; AVACA, MARIA SOLEDAD; CRESPO, ENRIQUE

An Ecosystem View of Anthropogenic Impacts in the Ocean

SCIENCE PUBLISHERS (An Imprint of CRC Press/ Taylor & Francis Group)

Lugar: Londres; Año: 2024;

On a global level, fisheries produce around 179 million tons and marine fishing constitutes 88% of global fish catches. Fishing industry provides approximately 17% of the world population’s intake of animal proteins, whereas the global consumption of seafood increased at an average annual rate of 3.1% in the last six decades. Around 60 million people are directly engaged in the primary sector of capture fishing (40 million people) plus aquaculture (20 million people), while women accounted for 14% of the total. Without a doubt, the great impact that fishing has on the well-being of humanity at a global level explains to a large extent the reason why fishing is a sector of growing importance on the world economy. Global fishing, however, currently faces a variety of threats that put at risk the continuity and sustainability: for example, human stressors, including overfishing, habitat destruction, biodiversity loss, excessive nutrient loads, marine pollution, and other adverse factors, such as irresponsible tourism, are affecting the entire ocean and fishery productivity. In addition, climate change increases the intensity and frequency of natural hazards and causes shifts in the distribution and abundance of fish populations, thus adversely affecting fishing-dependent developing countries. The impact of fishing on marine ecosystems, and particularly the effects of bottom trawling, has generated so much concern in the last two decades. Fishing affects marine habitats and ecosystems in many ways, depending on the spatial extent, the level of the effort, and the type of gear used. Beyond the type of fishing gear used, the effects of fishing on the marine ecosystems may be direct through the removal of biomass or the bycatch, or when mobile fishing gear (e. g., bottom-trawling nets and dredges) disturbs the structure of the seafloor so as to affect the physical environment and the composition and biodiversity of benthic communities. Indirect effects result when fishing causes a disruption of the food web, an alteration in the rate of decomposition of organic matter, and/or a recycling of nutrients through resuspension of bottom sediments. In this chapter, we present a review of the present knowledge dealing with the impact of fishing on marine ecosystems, focusing on the main aspects that have been at the center of the debate in recent decades. We explore first the available information referring to the direct effects (i.e.: the magnitude of the catches in relation to the biologic productivity of the stocks, the problem of bycatch and discards, and the mechanical effect and disturbance of bottom trawling on the seafloor structure and dynamics) and also we review the knowledge on the indirect impacts of fishing, such as the alteration of trophic webs and the effects on top predators.