Researchers from the Spanish National Research Council (CSIC) and other institutions analyzed estimated biomass data for 33,990 fish populations (covering 1,566 species) in the Northern Hemisphere between 1993 and 2021.  

Biomass refers to the total mass of biological organisms within a specific time and area. The results show that long-term warming could lead to an annual decline in Northern Hemisphere fish biomass by as much as 19.8%. Even a temperature increase of just 0.1°C per decade correlates with a 7.2% drop in biomass. 

The study also indicates that the impacts of short-term climate fluctuations and long-term climate change on fish biomass differ. On shorter timescales, warmer years and marine heatwaves can cause a sharp decline of up to 43.4% in populations at the "warm edge" of a species' range (the boundary closest to the equator). Conversely, biomass at the "cold edge" (the boundary closest to the poles) can surge by as much as 176%. 

Source: XINHUA