Short answers, pulled from the story.
Climate change is projected to decrease the modelled global fish community biomass by as much as 30 percent by 2100. Tropical zones face steeper losses, with fish catch in those regions projected to fall by around 11 percent.
The South Pacific regions are projected to experience the biggest decreases in maximum catch potential. Tropical zones overall are expected to see fish catch decline by around 11 percent by 2100, compared to a global average decline of 6 percent.
Skipjack tuna and bigeye tuna populations are expected to shift further east due to changes in ocean temperatures and currents. This moves fishing grounds toward the Pacific islands and away from Melanesia, disrupting western Pacific canneries and creating uncertainty around regional food security.
Fish provides essential nutrition for 3 billion people and supplies at least 50 percent of animal protein and minerals to 400 million people in the poorest countries. Over 500 million people in developing countries depend directly or indirectly on fisheries and aquaculture for their livelihoods.
About 0.5 percent of total global greenhouse gas emissions in 2012 came from fishing vessels, representing 172.3 million tonnes. Aquaculture contributed an estimated 385 million tonnes of equivalent in 2010, equal to roughly 7 percent of all agricultural emissions.
Over-fished populations have less size, genetic diversity, and age structure than healthy populations, reducing their ability to absorb environmental stress. This makes them more susceptible to climate-related pressures such as rising temperatures and oxygen depletion, increasing the risk of population collapse.