Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Modern Fish Communities Live Fast & Die Young

27.06.2011
Archeological study by Wildlife Conservation Society finds that sustained overfishing results in fewer long-lived species and top predators

Fish communities in the 21st Century live fast and die young. That’s the main finding of a recent study by researchers from the Wildlife Conservation Society who compared fish recently caught in coastal Kenya with the bones of fish contained in ancient Swahili refuse heaps in order to understand how to rebuild the current fisheries.

Of course, modern fish communities are not victims of reckless living, but of overfishing which has caused an ecosystem-level transition that may not be easily reversible, according to the study. Over the centuries, human fishing has greatly reduced or eliminated larger and longer-lived species that were more commonly caught in the Middle Ages. The remaining fish communities today contain more species with shorter life spans, faster growth rates, smaller average sizes, and fewer top predators.

The study—which utilized more than 5,475 samples of ancient fish remains dating between 1250 and 600 years before the present (approximately AD 750—1400)—appears in the current online edition of the journal Conservation Biology. The authors are Tim R. McClanahan and Johnstone O. Omukoto of the Wildlife Conservation Society.

“The ancient Swahili middens represent a time capsule of data, containing information on the composition of the region’s fish assemblages and how human communities influenced the marine environment,” said McClanahan, WCS Senior Conservationist and head of the WCS’s coral reef research and conservation program. “The historical data suggest that fishing removes the slower-growing, longer-lived species over time and that marine protected areas are only partially successful in recovering the fish communities of the past.”

Seeking to examine how fish populations are impacted by increasing fishing pressure over time, McClanahan and Omukoto compared data on the life histories of modern fish communities (gathered from fish caught in both heavily fished sites and protected closures on the Kenyan coast) with data gathered from fish remains excavated from an ancient Swahili settlement located in Shanga, Kenya. Spanning some 650 years, the refuse heaps provided the researchers with valuable insights into how fish assemblages and fishing pressures changed during that time span.

The researchers discovered that the life histories of fish caught by modern fisheries and the remains of ancient fish assemblages were significantly different. Whereas ancient fish communities had a high percentage of top predators—species that prey on fish and large invertebrates such as snails, sea urchins, and clams—modern fish communities contain more species that feed on plants, small invertebrates like sea lice, generally smaller species that feed lower on the food chain.

Modern fish assemblages also contain more species that are smaller in size with higher growth and mortality rates.

The researchers also found that the number of fish bones in the middens peaked between AD 1000-1100 (approximately 1000-900 BP) before declining, while the bones of sheep and goats become more prevalent in the higher levels of substrate, suggesting a shift in human diet to domesticated animals.

“The archeological evidence demonstrates the incredible longevity of humanity’s utilization of coastal fisheries, while emphasizing the critical need to actively manage slower growing, longer-lived species within an ecosystem approach,” said Dr. Caleb McClennen, Director of WCS’s Marine Program. “The evidence from Kenya aligns with findings from around the world that for millennia humanity has relied on the world’s oceans for our basic needs—but has more recently failed to do so in a manner that also will sufficiently sustain that resource.”

From Fiji to Kenya to Glover’s Reef, Dr. McClanahan’s research has been examining the ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world. This work has been supported by the John D. and Catherine T. MacArthur Foundation and The Tiffany & Co. Foundation.

The Wildlife Conservation Society saves wildlife and wild places worldwide. We do so through science, global conservation, education and the management of the world's largest system of urban wildlife parks, led by the flagship Bronx Zoo. Together these activities change attitudes towards nature and help people imagine wildlife and humans living in harmony. WCS is committed to this mission because it is essential to the integrity of life on Earth. Visit www.wcs.org.

The MacArthur Foundation supports creative people and effective institutions committed to building a more just, verdant, and peaceful world. In addition to selecting the MacArthur Fellows, the Foundation works to defend human rights, advance global conservation and security, make cities better places, and understand how technology is affecting children and society. More information is at www.macfound.org.

Established in 2000, The Tiffany & Co. Foundation provides grants to nonprofit organizations working in two main program areas: the environment and the arts. The Foundation’s environmental conservation program promotes responsible mining, healthy marine ecosystems, the enhancement of urban environments and the preservation of culturally significant landmarks. In addition, the Foundation fosters design excellence by supporting organizations dedicated to the decorative arts. For more information on The Tiffany & Co. Foundation, please visit www.tiffanyandcofoundation.org.

Stephen Sautner | Newswise Science News
Further information:
http://www.tiffanyandcofoundation.org
http://www.wcs.org

More articles from Studies and Analyses:

nachricht Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University

nachricht New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>