34921.3.1 State-of-Knowledge Review
of the Current Population
For many years, the only people sampling the fi sh fauna of
Lake Pavin were lake farmers and recreational fi shermen.
These samplings were quite selective, being done in order to
capture specifi cally targeted species, whether by net or on a
line. The species targeted were fi rst Arctic char, then trout
(brown trout and rainbow trout from releases), followed by
perch. No studies following a scientifi c protocol were con-
ducted on the fi sh fauna of Lake Pavin before 1995.
Between 1988 and 1991, we were able to follow numer-
ous fi sh nettings performed by the lake farmer as well as by
the salmon farmers of the Besse federal fi sh farm in order to
capture spawning adults of the Arctic char species. Artifi cial
spawning, fertilization and hatching was carried out on the
premises below where the restaurant standards today; the
pools are fed by the waters of the lake through an intake
located at approximately 10 m. In all that time, we only ever
caught Arctic char, European perch, brown trout, rainbow
trout, or crayfi sh. Minnows, loach, and white-clawed cray-
fi sh were visually abundant in littoral areas. Fish were netted
using a 27 mm mesh size, which produced strong selectivity
for the species caught and does not allow an objective picture
of the species present.
One of the fi rst scientifi c studies of the lake’s fi sh fauna
was conducted by Jamet ( 1995 ), who set gill nets (20-24-30
mm) from April to October 1992 to study the condition coef-
fi cients, reproduction, and diet of the Arctic char.
Unfortunately, Jamet did not report what other species were
captured during this time.
The years 1996 and 1997 also witnessed the near disap-
pearance of the white-clawed crayfi sh ( Austropotamobius
pallipes ) population. At the time, there was no attempt to
identify the cause of this decline, but the rapidity of mortality
and the sheer size of the event (dead crayfi sh clotted the out-
let grilles) pointed to Aphanomyces. With hindsight from
current studies on trophic change in the lake and the coinci-
dence between this change and the mass mortality of cray-
fi sh, we can now entertain other hypotheses, but unfortunately
the species has all but disappeared. In 2006, divers observed
a crayfi sh in the benthic zone; after examining a photo, it
seems likely that this individual belongs to Austropotamobius
pallipes.
Grandjean’s thesis on the mitochondrial DNA typing of
crayfi sh varieties ( 1997 ) indicates two subspecies of
Austropotamobius pallipes , the subspecies pallipes and itali-
cus. The Italian (Alpine) origin of this subspecies could be
explained by the importation of fi sh from the Thonon-station
salmon farm or by the successive introduction of individuals
from the Alps, but local strains had also been present in
many rivers in the Besse region decades ago.
21.3.2 Piscicultural Tracking from 1995
to 201221.3.2.1 Tracking Performed
by the FDPPMA 63
The FDPPMA (Departmental Federation of Fisheries and
Protection of the Aquatic Environment) of the Puy-de-Dôme
carried out these catches between 1995 and 2005 in order to
count number of fi sh taken by species and implement a
methodological protocol for tracking. However, the protocol
was not a scientifi c protocol:- catches were taken from March to December (depending
on ice cover), which is not year-long monitoring - sampling was dependent on the demand for char in the
restaurant - sampling sites corresponded to those known to be the
most productive - and, in contrast to scientifi c sampling in which several
mesh sizes are used to capture all age groups of a species
that may be present, the manager used meshes allowing
him to capture fi sh large enough to serve to customers
(approximately 30 cm). The mesh sizes used were 26 mm,
27 mm, and 32 mm, which led to strong catch selectivity.
The idea was to track the catches and age groups con-
cerned and compare their evolution. We decided to track
abundance indexed by Catch Per Unit Effort ( CPUE ; Ricker
1980 ; Rivier 1996 , Gerdeaux 2001b ), where the surface of
the nets used is multiplied by how long they are set in the
water, which determines a certain number of Units of Fishing
Effort ( UFE ), a fi shing effort corresponding to 1 m^2 of net set
for 1 h (Fig. 21.2 ). Catches are counted and reported in
CPUE , which serves to track evolution of catches at constant
effort (Rivier 1996 ).
Despite giving fi shing managers entry sheets and method-
ological instructions, fi shing times were often variable from
catch to catch, mesh sizes were inappropriate, and so on.21.3.2.2 Tracking According to Directive NF EN
14757 WFD
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. Tracking of fi sh in water bodies is performed accord-
ing to the standard WFD protocol NF EN 14757. Two
samplings were performed following this protocol—one in
2003 (Asconit 2006 ) and one in 2012 by the ONEMA (the
French National Agency for Water and Aquatic
Environments) (Olivier 2012 ). This method provides a fairly
comprehensive view of the fi sh population and its spatial dis-
tribution using horizontal multi-mesh nets at different depths.21 History of the Fish Fauna of Lake Pavin: A Population Heavily Infl uenced by Man?