Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

From sardines to anchovies and back in 50 years

10.01.2003


Local fisheries part of bigger cycle affecting entire Pacific Ocean



In the late 1930’s, California’s sardines supported the biggest fishery in the western hemisphere, with more than half a million tons of fish caught each year. By the mid-1950s, the sardines had virtually disappeared. Although fishing pressure may have played a part in this process, new research published in the current issue of Science indicates that the sardines’ demise was part of a 50-year cycle that affects not just California, but the entire Pacific Ocean.

Francisco Chavez, a biological oceanographer at the Monterey Bay Aquarium Research Institute (MBARI) and lead author of the study, combined a hundred years of data on physical oceanography, marine biology, and meteorology to examine long-term cycles in different parts of the Pacific Ocean. He points out that sardine catches in California, Japan and Peru followed parallel trends, despite being on opposite sides of the ocean and facing different amounts of fishing pressure. More importantly, when sardine catches in both areas went bust, anchovy catches boomed. Chavez’s research indicates that this alternation between a "sardine regime" and an "anchovy regime" involves much more than just fisheries. As he puts it, "Fish in many parts of the Pacific are marching to the same drummer. This same drummer is causing changes in ocean circulation and in the global carbon cycle. What we’ve been trying to find out is, what is the drummer, and is the beat going to change?"


To this end, Chavez gathered data from fellow scientists, not just on fisheries biology, but on sea-surface temperature, elevation, and currents, atmospheric carbon dioxide concentrations and circulation, global air temperature, and more. Despite considerable year-to-year variability, Chavez found parallel trends across the entire Pacific when he looked at three-year averages and subtracted out gradual long-term increases (such as that of carbon dioxide). These trends show that sardine and anchovy regimes alternate about every twenty five years, and that the most recent shift (from sardines to anchovies) occurred in the late 1990’s.

These cycles are similar to the familiar El Niño and La Niña events, but take place over longer time periods and have greater effects at mid- and high latitudes. For example, average conditions during a sardine regime are analogous to those during an El Niño event, when coastal waters off of Peru and California become warmer than usual. Less nutrient-rich deep water is brought the surface, so phytoplankton populations remain relatively low. This affects the entire marine food web, resulting in fewer zooplankton, anchovies, seabirds, and even salmon and rockfish. In contrast, the waters off Japan and the north-central Pacific respond oppositely, with increased productivity. Surprisingly, sardines tend to be more common on both sides of the north Pacific during these periods. During an anchovy regime, all of these trends are reversed.

Chavez hopes that by studying these long-term cycles, scientists will be able to better understand the effects of human activities. A prime example is the demise of the sardines. Chavez comments, "At least for these fast-growing fish, commercial fisheries are not always the sole cause of the collapse." Similarly, he points out that studies of global warming based on data collected over several decades could be strongly influenced by these natural, multi-decadal oscillations.

Chavez admits that his article may be controversial and hopes that it will stimulate scientific discussion about these long-term cycles, and especially about their possible causes. He remarks, "During the peer review process for this paper, one reviewer called it imaginative. And it is. If we had the ocean wired with a network of instruments and ocean observatories, then we would need less imagination and could understand this a lot better."

Debbie Meyer | EurekAlert!
Further information:
http://www.mbari.org/

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>