Long-Term Observation of Radioactivity Contamination in Fish around
Chernobyl
Igor N. RYABOV
A.N.Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences
Leninski pr. 33, Moscow, 117071, Russia: platon@genome.eimb.relarn.ru

Abstract
Dynamics of 137Cs accumulation by marketable fishes in different kinds of water bodies (cooling pond,
water reservoir, lake) polluted by radionuclides after the Chernobyl accident has been studied. The
highest concentration of 137Cs, reaching 500 kBq/kg w.w. (wet weight) was registered in fish
inhabiting the cooling pond of ChNPP in 1986. During the last 15 years the level of radionuclides infishes of all water bodies came down, but rates of lowering are different. Peculiarities of 137Cs
accumulation by fishes depending on the trophic level have been revealed. During the first months
after the Chernobyl accident the concentration of 137Cs in peaceable species of fishes in Kiev
Reservoir was by 10 times higher than in pike. After 1987 predatory fishes have the concentration of137
Cs by 2-3 times higher than peaceable fishes. Higher indices have been marked in pike and large
perches. By 2001 the content of 137Cs in fishes in the cooling pond did not exceed 5 kBq/kg w.w., inRiver Teterev – 0.09 kBq/kg w.w., in Kiev Reservoir – 0.5 kBq/kg w.w. High content of 137Cs
remained in the lakes of Bryansk region of Russia and in Mogilev region of Belorussia, which have
low content of +K in water and stagnant water, although these lakes are situated 100 - 200 km fromthe place of the accident. Biological effects of fishes in morphology of body and reproductive systemhave been marked in all studied water bodies. The largest quantity of abnormalities in the
reproductive system has been marked in predatory fishes.

Introduction
The Chernobyl accident of 1986 resulted in contamination of many bodies of water around Europe.
Three branches of radioactive plume dispersed radionuclides over northern, southern and western Europe.
Radioactivity from man-made nuclides increased considerably in freshwater bodies of Scandinavian
countries, England and in mountain lakes in Germany [1]. Forests and water bodies, located in close
proximity of Chernobyl NPP (i.e. within 30-km zone) appeared to be the most heavily contaminated alongwith Gomel’ and Mogilev region of Belarus, and Bryansk region in Russia [2,3].
A Combined Radioecological Expedition of USSR Academy of Sciences attached to the
A.N.Severtsov Institute of Evolutionary Animal Morphology and Ecology (now A.N.Severtsov Instituteof Ecology and Evolution, Russian Academy of Sciences) started its activity in the field of radioecology
of fish directly at the cooling pond of Chernobyl NPP in June, 1986. Later on, some other heavily
contaminated bodies of water, such as Kiev Reservoir, River Teterev, Lake Kozhanovskoe (Russia) and
Lake Svyatoe (Belarus) have been studied (Fig. 1).
The main objectives of our activity were:(a) To study the dynamics of radionuclide accumulation in fish after the Chernobyl accident in different
ecosystems such as cooling pond, river, lake, and reservoir;(b) To reveal peculiar features of 137 Cs and 90Sr accumulation in fish of different trophic level;(c) To evaluate doses of radiation and to find out their biological effects in fish living under the influenceof chronic irradiation.
Studied bodies of water differ by their hydrology, hydrochemistry and by the distance from the site of

112

137

Cs: Ci/km2
1-5
5 - 1515 - 40>40Оз.
Святое
Lake
Svyatoe

Kozhavskoeoe
Оз.LakeКожановское

Пруд-охладитель
ЧАЭС
Cooling Pond
ChNPP
с. Страхолесье
с. Ораное

Киевское
Kievводохранилище
ReserverRiver Teterev

Fig.1. Regions of expedition activity at water bodies contaminated by radionuclides
after the Chernobyl accident.
release (Table 1).
In all, 45 species of fish from 12 families and one species of Cyclostomata have been registeredduring multiple fish surveys (Table 2). The highest number of fish species was registered in River Teterev.
Natural water bodies are populated by a set of species, typical of this part of Europe. Different from thenatural bodies of water, the cooling pond of Chernobyl NPP was used before the accident as a raising
pond for a fish farm and contained several introduced species. These were grass carp, silver carp andspotted silver carp of Chinese origin as well as North American bigmouth buffalo and bullhead. The
isolated individuals of grass carp and silver carp may be found in Kiev Reservoir.
Altogether, more than six thousand individuals belonging to 46 species have been studied
morphologically. More than four thousand samples have been analyzed in a laboratory of radiation
spectrometry. Scintillometer RTF 20026 (made in Germany) has been used to evaluate the concentrationof 137Cs in different samples. Dose assessment has been done using the data on radionuclide concentrationin muscles and the gut content of fish according to the method suggested by S.V.Kazakov [4], taking into
account the main biological parameters, such as size and weight, of every studied individual.
Table 1. Hydrological and hydrochemical characteristics of studied bodies of water.
Max. depth,
Volume,Distance fromArea,
Water bodyK+, mg/lmm3
ChNPP, km
km2
Cooling pond of ChNPP
22
18
1.5
3.4-4.0
150×106

Ca++, mg/l
37.0-64.0

Kiev Reservoir

922

14.5

3.7×10960

2.9-3.4

32.4-60.0

River Teterev

-

20

-

Lake Kozhanovskoe
Lake Svyatoe

6
0.25

80

3.1-3.4

35.5-40.5

2.5

6

9×10

210

2.6-2.7

24.6-44.3

5.1

4

225

0.9-1.0

17.4-19.8

7×10

113

Table 2. List of species Cyclostomata and fishes registered during work of the Complex
Radioecological expedition of A.N. Severtsov Institute of Ecology and Evolution RAS.
Cooling
pond

SpeciesI. Petromyzontidae
II. Clupeidae

1. Ukrainian lamprey - Eudontomyzon mariae (Berg) х
2. Common kilka – Clupeonella cultriventris cultriventris(Nord.)
III. Esocidae
3. Pike − Esox lucius L.
IV. Cyprinidae
4. Roach − Rutilus rutilus (L.)
5. Dace − Leuciscus leuciscus (L.)
6. Chub - Leuciscus cephalus (L.)
7. Orfe Leuciscus idus (L.)
8. Rudd – Scardinius erythrophthalmus (L.)
9. Grass carp – Ctenopharyngodon idella (Val.) •10. Asp - Aspius aspius (L.)
11. Verkhovka – Leucaspius delineatus (Heck.)
12. Tench Tinca tinca (L.)
13. Undermouth – Chondrostoma nasus (L.)
14. Stone moroco – Pseudorasbora parva (Temm. andSchl.) •15. Gudgeon - Gobio gobio (L.)
16. White – finned gudgeon Pomanogobio albipinnatus(Lukasch)
17. Bleak – Alburnus alburnus (L.)
18. Bystranka – Alburnoides bipunctatus (Bloch) х
19. Silver bream -Blicca bjoerkna (L.)
20. Bream − Abramis brama (L.)
21. White eye – Abramis sapa (Pall.)
22. Blue bream − Abramis ballerus (L.)
23. Vimba − Vimba vimba vimba (L.) х
24. Sabrefish - Pelecus cultratus (L.)
25. Bitterlings - Rhodeus sericeus amarus (Bloch)
26. Crucian carp – Carassius carassius (L.)
27. Golden carp - Carassius auratus gibelio (Bloch) •28. European carp − Сyprinus carpio L.
29. Silver carp − Hypophthalmichthys molitrix (Val.) •30. Spotted silver carp − Aristichthys nobilis (Rich.) •V. Catostomidae
31. Bigmouth buffalo − Ictiobus cyprinellus (Val.)
VI.Cobitidae
32. Spiny loach − Cobitis taenia L.
33. Loach − Misgurnus fossilis (L.)
VII. Siluridae
34. Wels - Silurus glanis L.
VIII. Ictaluridae
35. Bullhead – Ictalurus punctatus (Raf.) •IX. Gadidae
36. Burbot - Lota lota (L.)
X. Gasterosteidae
37. Nine spined stickleback − Pungitius pungitius (L.)
38. Three spined stickleback − Gasterosteus aculeatus L.
ХI. Percidae
39. Sander – Stizostedion lucioperca (L.)
40. Perch - Perca fluviatilis L.
41. Ruffe − Gymnocephalus cernuus (L.)
42. Don ruffe – Gymnocephalus acerinus (Guld.)
XII. Gobiidae
43. Monkey goby − Neоgobius fluviatilis (Pall.)
44. Tube nosed goby – Proterorhinus marmoratus (Pall.)
45. Round goby – Neogobius melanostomus (Pall.)XIII. Syngnathidae 46. Black striped pipefhish − Syngnathus nigrolineatus(Eichw.)

Kiev
Reservoir

+

Lake
Lake
River
KozhaSvyatoe
Teterev
novskoe
+

+

++

+
+
+
+
+
+
+
+
+
+
+

+++
+++
+
+
+
+++
+
+
+
+++
+

+++
+++
++
++
++
+++

+

+

+

+

+

+++

+
+++

+++
++
+
+

+++
+++
+
+
+
++
+
+
+++
+
+

++
+++
+
+
+
+

+++
+++
+

++
+++

+++

+
+
+
+

+

+

+++

+++

+++
+
+
++
++
+++
+
+

+++
+++

+++
+
+++
+++
+
+
+
+++
+
+++
+

+

+++
+++
+

+
+
+
+++
+++
+
+
+
+
+

+
+
+
+++
+++
+
+
+++
+++
+

+
+
+

+
+++

++
+
+++

+
+

+++
+++

+++
+++

+

Note: + occurrence of different species +; low, ++; medium, +++; high,•; species populated in reservoirs because of fishing measures; х; species carried in the list of rare fishes.

Cooling pond of Chernobyl NPP
Chernobyl NPP is situated in the eastern part of the natural region called Poles’e, which means“marshy woodlands”, at the bank of River Pripyat, emptying into Kiev Reservoir. The source of watersupply for plant operation was the cooling pond that was made artificially along River Pripyat and located114

at 1.5 km southeast from the power site.
The highest concentration of radionuclides, reaching 500 kBq/kg wet weight (w.w.) was registered infish inhabiting the cooling pond in 1986. During the first months after the accident non-predatious fishes,
feeding on zoo- and phyto-plankton, were the most contaminated, but later predatious fishes accumulated
more radionuclides [5,6]. During the after-accident period the average concentration of radionuclides insilver carp decreased from 400 kBq/kg w.w. to 5 kBq/kg.
Aggregate dose for silver carp during the whole after-accident period reaches 10-12 Gy. Fish has
absorbed the main part of irradiation dose, 7-8 Gy, during the first two years after the accident. In recent
years internal dose was mainly obtained through intestine irradiation and amounted about 0.4 Gy per year,
while internal dose for muscles averaged only 0.02 Gy per year (Fig. 2).
During special studies of reproductive organs of fish, different abnormalities in anatomy of gonads
and morphology of reproductive cells have been found in silver carp. Gonad pathology included
hermaphroditism, gonad asymmetry and other anatomical defect [7]. A number of fish, surviving theaccident, had sterile gonads. Destruction of some amount of generative cells and contraction of generative
tissue volume were registered in 48% of males. 35% of females had disturbances in oocyte morphology
during vitellogenesis. In spite of various disturbances observed in generative organs, it was possible toobtain viable offspring from some fish in 1989-1990.
Silver carp, surviving the accident, could be easily bred, showing a high percentage of egg
insemination and high survival rates for embryos, larvae and fry [8]. Anatomical abnormalities became
apparent in the second and, especially, in the third year of life. There were curvature and length shortageof the dorsal or one of the pelvic fins, deformations of oral and gill structures, deformations of swimbladder and epidermal neoplasia (i.e. tissue overgrowth) in anal region of females, forming a kind ofgenital papillae.
Ten individuals of silver carp, belonging to generation F1-91, were analyzed in 1996 and only two
mature carp have been found; a male and female. Unusual was the fact of their maturation at amazingly
small size for this species; female was only 24 cm long, weighing 250 g, and a male was 31 cm long witha total weight of 461 g [9].
In 1991 during ichthyological survey of the cooling pond an abnormal young individual of tube-

1000

generation P 84 - 85
generation F1 - 89
generation F1 - 90

100

rad/yeargeneration F1 - 91

1011986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

Fig.2. Internal committed dose for muscles of grass carp ofdifferent generations
115

Fig.3. Abnormal fry of tube-nosed goby caught in the cooling pond of ChNPP (11.05.92).
nosed goby was found, having an eyeball developed inside the mouth cavity (Fig. 3). But the rest of thecollected young fish of this species had no morphologic defects. During young fish collection in thecooling pond in 1992, a larval silver bream was found with spinal pathology and with primordial
malformed pectoral fins. The larva was found among pondweeds and evidently could feed without
swimming but keeping itself at the surface of weeds. It is obvious that individuals having such severe
pathology cannot survive in the natural environment.
In spite of high dose rates during several years after the accident, no significant changes in fish
community at population level have been observed. Comparison of the degree of abnormality indeveloping reproductive cells in both sexes reveals that structural damages are more pronounced in males
than in females.
2500
2000

Ton

1500
1000
500

1996

1993

1990

1987

1984

1981

1978

1975

1972

1969

1966

0

Fig.4. Dynamics of commercial catches in Kiev reservoir from 1966 to 1996.
planktophagous fish (3%)
predatory fish (6%)

benthophagous fish
(91%)

Fig. 5. Distribution of commercial fishes of Kiev Reservoir according to their food.
116

Kiev Reservoir
Kiev Reservoir is the first one in the Dnieper cascade into which run rivers Pripyat, Teterev and Uzh,flowing across the contaminated areas. During the after-accident period of 1986-1996, 10,245 ton of fish
were harvested in Kiev Reservoir. Such benthophagous species as bream, roach, silver bream andEuropean carp formed more than 90% of the total catch (Fig. 4, 5).
Radioecological monitoring of Kiev Reservoir revealed a decrease of 137Cs concentration in musclesof predatory fish from 1500-2000 to 200-400 Bq/kg w.w. during 1987-2000 (Fig. 6, 7). But in the autumn
of 2001, perches were met having 550 Bq/kg w.w. In muscles of non-predatory fish, constituting the bulk

1800
1600

Bq/kg w.w.

1400
1200
1000
800
600
400
200
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Fig. 6. Dynamics of Cs-137 accumulation in muscles of perch from Kiev
reservoir
1800
1600
1400

1000
800
600
400
200
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Fig. 7. Dynamics of Cs-137 accumulation in muscles of pike from Kiev reservoir

1000
900
800
700
Bq/kg w.w.

Bq/kg w.w.

1200

600
500
400
300
200
100
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Fig. 8. Dynamics of Cs-137 accumulation in muscles of bream from Kiev
reservoir

117

100
90
80

Bq/kg w.w.

70
60
50
40
30
20

perch

bream

tench

1991

pike

1990

0

1992
1993

10

Fig. 9. Dynamics of Sr-90 accumulation in muscles of fish from Kiev reservoir

Table 3. The incidence of gonad malformations in pike females of different generations, (%).
Year of generation
Type of gonad malformations
originGonad asymmetry
Grain of roe resorption Gonad hydration
1986
20.0
20.0
20.0
1987
33.3
0
16.6
1988
45.0
0
9.0
1989
0
0
0
1990
29.0
0
0
1991
46.0
23.0
0
1992
40.0
40.0
0
1993
65.0
10.0
0
1994
13.0
13.0
0
1995
33.0
22.0
0
1996
17.0
17.0
0
Note: the data on the before-accident generations are not cited because of their scarcity.
of commercial catch, bream for example, the concentration of 137Cs was two-three times lower than in
predators; pike and perch (Fig. 8). In the autumn of 2001, the highest figures for 137Cs in bream muscles
ranged between 40 and 70 Bq/kg w.w., averaging 55 Bq/kg.
Fishes of different trophic levels also accumulate in their muscles different amounts of 90Sr,
sometimes equivalent to 100 Bq/kg w.w. In 1991-1993 radionuclide concentration in muscles of bream,
the main commercial fish species, ranged between 15 and 50 Bq/kg w.w. (Fig. 9).
In order to evaluate the biological effect of deposited radionuclides on fish from Kiev Reservoir, 209
pikes, belonging to 17 generations, have been analyzed during 1987-2000. Three types of abnormality inmorphology of the reproductive system were registered: gonad asymmetry (34.1%), total resorption of
eggs (12.5%) and gonad hydration (2.5%). Gonad asymmetry, the most common imperfection, wasfrequently accompanied by constrictions. There were instances that the weight difference between rightand left gonad lobes was very high. Most frequently, this difference ranged from 1.5 to 3.0 times [10].
The first maximum in the number of malformations was observed in pikes born in 1986-1988.
Another rise in malformation number was noted for the second after-accidental pike generation born in
1991-1993 (Table 3). In pike females, born before the accident in years 1982-1985, no gonad
abnormalities was found, but one individual with asymmetric gonads, belonging to the generation of 1981,
has been registered.
118

In 1986 internal dose from 137Cs and 134Cs for pikes in Kiev Reservoir was about 0.1 – 0.2 Gy, in
1993-1997 it decreased to 0.001 – 0.002 Gy per year.
Lake Kozhanovskoe
During water bodies monitoring in Bryansk region, scientists from Combined Radioecological
Expedition of USSR Academy of Sciences in 1993 discovered abnormally high content of 137Cs in fishes
from Lake Kozhanovskoe. This lake, located at a distance of 210 km from Chernobyl NPP, has a square
about 6 km2, average depth of 1.5 m, maximum depth of 2.5 m. Lake sides are swampy and overgrownwith coastal vegetation. Its bottom is covered with thick sapropel deposits. According to limnologicalclassification, this lake may be attributed to eutrophic type. The concentration of K+ in water varies from
2.6 to 2.7 mg/l during a year, and the concentration of Ca++ is from 24.6 to 44.3 mg/l. One liter of lakewater during different seasons of 1993 contained 137Cs activity from 6.1 to 8.5 Bq. The lowest index was
registered in autumn. Seasonal measurements of pH showed the lowest figure for March (5.8) and thehighest (7.7) – for autumn [11].
Eleven species of fish were registered in the lake. They were: pike, roach, bleak, silver bream, bream,
crucian carp, golden carp, spiny loach, loach, perch and ruffe. Golden carp is dominating species. The
concentration of 137Cs in different fish species changed depending on their trophic level and size. The
highest figure, equivalent to 70 kBq/kg w.w., was registered in 1993 for big pike, and the lowest, from 5
to 8 kBq/kg w.w., for ruffe and roach. The concentration of 137Cs in muscles of golden carp, the maincommercial fish species in the lake, ranged from 6.5 to 15.6 kBq/kg w.w., being 10.4 kBq/kg in average.
The concentration of 90Sr in this species varied between 160 and 530 Bq/kg w.w. with the average figureof 260 Bq/kg w.w. At the same time, in River Iput’, very close to Lake Kozhanovskoe, the concentrationof 137Cs was almost 100 times lower.
According to the data of 2000, the content of 137Cs in fish flesh was retained at the level of 1993, andfor golden carp averaged at 8.14 kBq/kg w.w. Main factors, determining such high level of fishcontamination with radionuclides in Lake Kozhanovskoe, are the high content of radiocesium in lakewater and, accordingly, in feeding objects of fish, as well as low water exchange in the lake and the lowcontent of K+ in lake water.
Taking into account that the permitted level of 137Cs content in fish products in Russia is 120 Bq/kg
w.w. [12], it can be suggested with certainty that for such lakes as Kozhanovskoe with internal drainage,
fish purification up to the permitted level will take 60-90 years, i.e. two-three half lives of 137 Cs and 90Sr.
Analyses of gonad condition revealed that serious disturbances in gonad morphology were foundonly in predatory fish; pike and perch. In other species, like roach and golden carp, only small amount ofgerminal cells was damaged [13].
River Teterev
River Teterev flows across Kiev region of Ukraine at a distance about 80 km from ChNPP.
Contamination of the river with radionuclides happened primarily by radioactive fallouts from theatmosphere just after the accident, and later, as a result of wash out of radionuclides from thecontaminated river watershed. Ichthyofauna of lower reaches of the river, around settlement Oranoe, isvery similar to that of Kiev Reservoir and includes 38 species. The river supports active but mainly illegal
fishing by local peasants.
The highest indices of 137Cs content during study period (1990-2001) were registered for predatory
species; pike and perch. Monitoring of the contamination dynamics in pike revealed maximal levels of137
Cs concentration in the first year of investigation in this region (1990) with the average value in musclesof 728 Bq/kg w.w. In the summer of 2001 this index became 7-8 times lower with the average figure of 90
Bq/kg w.w. (Fig.10).
119

800

Bq/kg w.w.

700
600
500
400
300
200
100

1998

1997

1996

1995

1990

pike

1999

perch

2000

tench

2001

bream

0

Fig.10. Average concentration of Cs-137 in different species of fish from river
Teterev

1 cm

Fig.11. Abnormal roach from river Teterev, SL – 183 mm, age – 6+, caught in February 1998.
Several morphologically abnormal fish have been found during regular surveys of River Teterev.
Four abnormal roaches were caught in 1998. One of them had unusual body proportions – caudal peduncle
was very short, and relative body depth was almost twice higher than in normal fish (45% of standard
length). The age of the fish was 6+ years and it represented, most likely, the second after-accident
generation (Fig. 11). One more abnormal individual, aged 10+ had deformed scales. The rest two fish had
anomalies in body proportion combined with damages of scales. One of these fish in its right pelvic fin
had two more soft rays as compared with the left pelvic fin.
During next three years, 1999-2001 no more fish bearing morphological deformities were found inRiver Teterev.
Lake Svyatoe
Studies of this lake, situated in Mogilev region of Belarus, have been launched in 1997 [14]. It turned
out that in this lake, located at the distance of 225 km from Chernobyl Power Plant, the concentration of137
Cs in muscles of perch was equivalent to activity of 120 kBq/kg w.w. It was twice bigger than inmuscles of predatory fish from lake Kozhanovskoe and 24 times higher than in muscles of fish from thecooling pond of ChNPP. Activity of 137Cs in muscles of non-predatory fish such as roach and rudd
achieved 15 – 20 kBq/kg w.w.; their average values are 15.3 and 14.8 kBq/kg w.w., respectively (Fig. 12).
Maximum accumulated dose was found in perch to be 0.4 Gy per year.
120Bq/kg w.w

45000
40000
35000
30000
25000
20000
15000
10000
5000
0

perch

pike

goldencarp

roachverchovka

rudd

ruffe

Fig.12. Average concentration of Cs-137 in different species of fish from
Lake Svyatoe in May,1998

Fig. 13. Head of pike with deformed upper jaw and pectoral fin rays SL – 453 mm age – 4+.
Lake Svyatoe, Mogilev region, Belarus, 16.05.98.
During fish survey of Lake Svyatoe in May 1998 only one pike was caught. It was four years old andhad several anatomical defects: shortened upper jaw (Fig. 13) and four deformed rays in the left pelvic fin.
Gonad imperfections included gonad asymmetry and constrictions in the right gonad. Calculated internal
dose for this pike was 2.5 Gy for all its life. One of the reasons of morphologic deformities in the afterChernobyl fish generations may be the phenomenon called “extended mutagenesis”. It means that
mutations are manifested in the offspring of parents, subjected to some negative influence. In our instance,
the initial impacts were given during the first days after the Chernobyl accident in 1986.
Conclusion
A considerable reduction of radionuclide content in fishes, inhabiting the most part of contaminatedbodies of water, took place during 15 years, passing from the time of the Chernobyl accident. After 1993,
the concentration of 137Cs in flesh of fish, living in rivers and reservoirs, does not exceed 600 Bq/kg w.w.
Only the cooling pond of ChNPP and some lakes in Russia and Belarus are the exception [15].
The rate of fish decontamination from radionuclides is connected with the initial amount of depositedradionuclides, and also with hydrology and hydrochemistry of the water body. Main reasons for the highconcentration of 137Cs in water, sediments and fish of Lake Kozhanovskoe are low content of K+ in waterand very slow water exchange. High level of contamination of this and some other lakes can last tens ofyears, decreasing only as a result of natural decay of 137Cs with half-life about 30 years. Since the rate ofnatural decontamination of Lakes Kozhanovskoe and Svyatoe is very low, the process of fish
decontamination or “purification” may also take several tens of years.
Predatory fish concentrate 2-3 times more 137Cs than non-predatory ones; in the process of 90Sr
accumulation this effect of trophic level is not expressed so evidently.
Biological diversity of fish in water bodies contaminated as a result of the Chernobyl accident does121not show significant changes, but the abundance of some species, representing the highest trophic level,
may decrease during the next 10-20 years because of disturbances in their reproductive system.
Considering the lack of proven practice and even any experience in rehabilitation of large fisherybodies of water such as rivers, lakes and reservoirs, there is a need in urgent development of scientificrecommendations for safe and rational fishing and fish processing in contaminated bodies of water, withthe help of international scientific community.
Acknowledgments
We would like to thank our colleagues from the ichthyological group of Combined Radioecological
Expedition: N. V. Belova, L. I. Pel’gunova, N. I. Polyakova, N. V. Gemba, S. S. Gonchar, S. A. Smirnov,
M. I. Molyukov, A. O. Kulikov, for their lasting many years help in collection and processing of thematerial.
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2. Ryabov, I.N. (1992) Analysis of Countermeasures to Prevent Intake of Radionuclides via Consumption of Fishfrom the Region Affected by the Chernobyl Accident. Proc. Int. Seminar Intervention Levels andCountermeasures for Nuclear Accident, Commission of the European Communities Press, pp. 379-395.
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