11 March 2010

Extinct and quickly forgotten

Many species became extinct because of us, but our impact on Planet Earth continues to be forgotten as we lose track of environment changes.

This is the conclusion of a recent study led by Dr. Samuel Turvey.

In 2006, Turvey participated in a Yangtze River expedition to asses the baiji (Lipotes vexillifer) population. The species was later declared ‘extinct’. Turvey returned in 2008 to interview locals about their knowledge of the baiji. The result was quite depressing: memories of this tremendous loss are quickly fading away.

Younger informants were less likely to know what a baiji was. While older people were aware of the historical decline of the baiji, younger fishermen from the same communities not only had never seen this animal, but had never even heard of it.

Soon, people will forget about the former existence of this cetacean species - once common in their environment. Progressively degraded environmental conditions and low biodiversity will come to be seen as normal.

"These shifts in community perception typically mean that the true level of human impact on the environment is underestimated, or even not appreciated at all, since the original environmental baseline has been forgotten” - Turvey commented.

Silvia Bonizzoni

Drawing by Giovanni Bearzi

The article:
S.T. Turvey, L.A. Barrett, H. Yujiang, Z. Lei, Z. Xinqiao, W. Xianyan, H. Yadong, Z. Kaiya, T. Hart, W. Ding. 2010. Rapidly shifting baselines in Yangtze fishing communities and local memory of extinct species. Conservation Biology. doi: 10.1111/j.1523-1739.2009.01395.x

Abstract - Local ecological knowledge can provide a unique source of data for conservation, especially in efforts to investigate the status of rare or possibly extinct species, but it is unlikely to remain constant over time. Loss of perspective about past ecological conditions caused by lack of communication between generations may create "shifting baseline syndrome," in which younger generations are less aware of local species diversity or abundance in the recent past. This phenomenon has been widely discussed, but has rarely been examined quantitatively. We present new evidence of shifting baselines in local perception of regional species declines and on the duration of "community memory" of extinct species on the basis of extensive interviews with fishers in communities across the middle-lower Yangtze basin. Many Yangtze species have experienced major declines in recent decades, and the Yangtze River dolphin or baiji (Lipotes vexillifer) and Yangtze paddlefish (Psephurus gladius) may have become extinct during the 21st century. Although informants across all age classes were strongly aware of the Yangtze ecosystem's escalating resource depletion and environmental degradation, older informants were more likely to recognize declines in two commercially important fish species, Reeves' shad (Tenualosa reevesii) and Yangtze pufferfish (Takifugu fasciatus), and to have encountered baiji and paddlefish in the past. Age was also a strong predictor of whether informants had even heard of baiji or paddlefish, with younger informants being substantially less likely to recognize either species. A marked decrease in local knowledge about the Yangtze freshwater megafauna matched the time of major population declines of these species from the 1970s onwards, and paddlefish were already unknown to over 70% of all informants below the age of 40 and to those who first started fishing after 1995. This rapid rate of cultural baseline shift suggests that once even megafaunal species cease to be encountered on a fairly regular basis, they are rapidly forgotten by local communities

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