Lake Pavin History, geology, biogeochemistry, and sedimentology of a deep meromictic maar lake

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misunderstanding with the people responsible for carrying
out the work, individuals got tagged several consecutive
years with the same type of tag (adipose ablation). The fi rst
years of tagging are not exploitable from a statistical point
of view, and we can draw no information from this type of
tag.
In the second type of tagging realized, either the adipose
fi n is clipped or color marking is used, thus making it possi-
ble to differentiate separate cohorts. While this tagging
methodology makes it possible to specify the year of release,
the people in charge of emptying the nets forgot to record the
type of tag as well as the size of the fi sh caught, thus render-
ing any attempt to follow the stock by tag futile.

21.4.2.5 Tracking According to WFD Protocol

NF EN 14757

This standardized protocol was implemented when the Water

Framework Directive was adopted in order to qualify the sta-

tus of European bodies of water both above and below

ground. Monitoring on the fi sh populations in water bodies is

performed according to standard WFD protocol NF EN

14757 (AFNOR 2005 ). The engineering consulting fi rm

ASCONIT (ASCONIT 2006 ) and the ONEMA (Olivier

2012 ) performed two samplings on Lake Pavin in 2005 and

2012.

This method provides a fairly comprehensive picture of

the fi sh population and its spatial distribution.

0

0.2

0.4

0.6

0.8

1

1.2

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

1996 1997 1998 1999 2000 2001 2002 2003 2004

Fig. 21.11 Ratio of 1 + juveniles number
( blue ) to CPUE (×100) 2 years later (red)

0

1000

2000

3000

4000

5000

6000

7000

0

0.2

0.4

0.6

0.8

1

1.2

1998 1999 2000 2001 2002 2003 2004 2005

Fig. 21.12 Comparison of changes in
CPUE (*100, blue ) and estimated
number of catchable fi sh from
stocking ( red )

21 History of the Fish Fauna of Lake Pavin: A Population Heavily Infl uenced by Man?