According to the FAO, anchovy and sardine made up 13% of global catch in 2012. These small fish are consumed by humans, marine mammals, seabirds, squid, and other fish. They are also used for aquaculture feed, industrial oil, and health supplements. “Climate, Anchovy, and Sardine” a new study in the Annual Review of Marine Science, co-authored by Nereus Alumni Rebecca Asch (Princeton University) and Ryan Rykaczewski (University of South Carolina), reviews the past, present, and future of anchovy and sardine.
Despite their remoteness, the high seas and deep ocean in areas beyond national jurisdiction (ABNJ) are at the forefront of CO2-induced climate stress, both in their mitigation capacity, and their vulnerabilities. Carbon dioxide (CO2) emission alters ocean conditions, leading to ocean warming, deoxygenation and acidification. These ocean changes affect marine life throughout the ABNJ, from the surface to the deep sea, by changing species’ distributions, migration routes, ecosystem structure and functions.
The ocean has provided incredible services for us — taking up 28% of carbon emissions since preindustrial levels and absorbing 93% of the Earth’s excess heat since the 1970s — but because of this, it is undergoing changes. In order to manage ocean ecosystems and resources in the future, we must begin to understand what those changes may look like using climate change impact projections.
Climate change is expected to have major impacts on the ocean, the species that live there, and the people who rely it for their food and livelihood. Since the beginning of the 20th century, CO2 emissions from human activities have altered physical and chemical properties of the ocean. The ocean has become warmer and, in some areas, less oxygenated, which has caused changes in the productivity and distribution of marine species.
A range of human pressures is threatening the sustainability of marine fisheries. Amongst those, overfishing, partly driven by Illegal, Unreported and Unregulated (IUU) fishing, is a major stressor. Thirty percent of global fish catch goes unreported, found a recent study by Nereus Program collaborator Sea Around Us.
But the relationship between IUU fishing and climate change is a new topic. I speculate that climate change impacts on fisheries may indirectly increase IUU fishing.
Based on the current trajectory of human-induced impacts on the environment, it is clear that we are pushing the oceans and marine ecosystems to unprecedented limits. Environmental changes in ocean properties have led to an array of ecological responses, from shifts in the composition of the ocean’s phytoplankton to changing distributions of fish species.
Climate change could affect temperatures all over the world, but what may not be immediately apparent is that climate change will affect ocean temperatures. If CO2 emission rates do not change, the average sea surface temperature is expected to increase by 2 to 3.5 degrees Celsius by the end of the century. This may not seem like much, but it would impact oceans in many ways, making them quite different from how they are today.
From November 20 to December 11, leaders from more than 195 countries will meet in Paris to discuss the future of the planet. But will oceans be on the agenda?
COP21, the “Conference of Parties”, is the 21st United Nations Conference on Climate Change. It is being hyped as the most important climate event since COP15 in Copenhagen, which produced the Copenhagen Accord — a political agreement that was deemed by many to be unsuccessful. Here Yoshitaka Ota, Nereus Director (Policy), and William Cheung, Nereus Director (Science), discuss whether these negotiations will be successful, what’s at stake for the future of the world’s oceans, and what else can be done to mitigate the effects of climate change.
Thomas Froelicher, Nereus Program Alumni and 2012-2013 Senior Research Fellow (Princeton), has published a paper with co-authors in Biogeosciences entitled Emergence of multiple ocean ecosystem drivers in a large ensemble…
A report entitled “Predicting Future Oceans: Climate Change, Oceans & Fisheries” newly released by the Nereus program, an international interdisciplinary research program aimed at predicting future oceans, suggests that future seafood supply in the world will be substantially altered by climate change, overfishing and habitat destruction if we do not take actions.