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 Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>