|
Lake Shkoder is generally characterized by a high biodiversity and especially a high variety of fish fauna, making this an important lake for the Balkan. The high biodiversity that characterizes the lake is the result of the existence of a good communication with the sea, and of an extensive network of rivers and streams, communicating with the lake. Its ichthyofauna includes highland coldwater fish species, warm freshwater fish species and several marine species. From ichthyologic studies carried out by both states it appears that the lake has 60 fish species belonging to 17 families (see Annex XIII. The relatively high number of endemic species (15 species according to Maric, 1995) makes the lake significant on regional level (i.e. North Mediterranean). For a relatively warm lake, the number of fish species is considered great. About 10 species are commercially exploited (e.g. carp, bleak and eel). Two fish families are especially important: cyprinids (most abundant in species) and salmonid fish (which are much rarer in the lake due to their specific requirements).
|
|
Fishery constitutes one of the most vital activities in the whole coastal area of Lake Shkoder and fish productivity has been always high. From the collected data we can see a steady production, but if we analyses the fishing data in more detail we observe some Concerning phenomena:
1. Significant decline of migratory fish in the overall production;
2. Decline of autochthonous fish in the 1980s, but a recovery since then;
3. Increase in exotic species, especially after 1980.
|
|
Regarding the catches of migratory fish, the catches of Twaide shad (Alosa alosa) show a sharp eline from 1980 onwards. Among the migratory species also the Mugilidae are of economic importance. They also suffered a decrease in the catches although not as drastic as twaide shad. The Mugilidae catches fluctuate mainly as a result of hydrological changes, especially during the period September-November. Their catch figures for Albania are:
- Year 1973 caught: 85 MT
- Year 1988 caught: 25 MT
- Year 2004 caught: 40 MT
Eel catches seem to be related to hydro-meteorological conditions, but in general the production is stable. Among the autochthonous fish, catches of carp intensified, but bleak catches were less; low value species like Rutilus, Pachychilon etc. are not exploited, which has caused a sensible modification of the catch structure after 1990.
Among the exotic fish, the catches of Carassius show a significant increase (100 MT in Albania) and lately also the catches of Perca and Stisostedion increased. During the last years, also large fishes, belonging to the herbivore and planktivorous exotic fish group, like grass carp and big head carp showed an increase. Above description is primarily based on information from Albanian fishermen. The following should be kept in mind:
- Fishermen in general do not make a distinction between migratory and autochthonous species, so when they state that the production of autochthonous species is in decline, they probably include also fish like mullets and twaite shad (which have really declined).
- Fishermen only take into account the fish of high economic value (from 31 autochthonous
species only 5 have economical importance for the fishermen). Species of low value like Rutilus and Pachychilon, which in the 1980s represented 34-50% of total catch, now only represent 8%. So as long as these species are analysed en group, even when species like salmonids are declining, the group as a whole is not.
- Some of the 2004 statistics may be overestimative.
- Bleak and carp (native carp production was not separated from cultivated carp in the report statistics) has production fluctuations due both to overexploitation (they are the two main target species for fishermen) and to hydrological conditions.
- The recovery of Chondrostoma is interesting as this species is an important indicator for water quality.
Causes for changes in catches
|
|
In general, both primary and secondary productivity in Lake Shkoder is good as it is a shallow lake with sufficient food supply. The decline in the catches of the migratory species (especially twaide shad catch) is probably caused by abusive and uncontrolled fishing which occurred mainly during the 1992-2002 period. Uncontrolled fishing took place during the reproductive period of the species; nets were built over the entire length of Buna-Bojana River and, also until 1990, stationary nets were placed when the twaide shad was going to enter the lake in order to catch the big specimens. Considerable damage was done also by light fishing for young twaide shad together with bleak.This fishing technique has brought considerable damage to the stock which needs time to recover.
With respect to the sturgeon not only uncontrolled fishing, but also damage to their spawning grounds has caused its decline. The only migratory species that did not suffer from this situation was eel because:
a) During the period of entrance to the lake the eel is in the glass eel stage and cannot be caught by uncontrolled fishing practices.
b) The high discharge of Buna-Bojana and Drin waters and their good quality during winter and spring attracts eel to enter in the Drin and Buna-Bojana area.
|
|
Fish Reproduction
|
|
In order to protect the fishery resources in an effective way and to promote sustainable development of fisheries in Lake Shkoder, management measures are necessary to support migration of fish in Lake Shkoder and its surrounding water network; for feeding, spawning and wintering purposes.
The reproductive period for the main species is represented in Annex XIII. It is obvious that the most important period for the protection of spawning grounds and of migration for reproduction purposes is the period from 1 April to 30 June.
For the most important species maps of their spawning grounds are given in Annex XIII:
Carp (Carassius), map 1; bleak, map 2; Chondrostoma, map 3; twaide shad, map 4; sturgeon, map 5. Regarding migration, for bleak is referred to map 6 and for twaide shad to map 7. The most threatened area with respect to illegal fishing is the south-east area, where the spawning area of carps is located and where illegal fishing methods are apllied, such as explosives, electric fishing, poison etc. Apart from their economic value, carps comprise in the entire area near the lake, including also the Shkodra city, a lot of species, which are valuable for both states.
|
Biodiversity Monitoring
The number of species (main groups): |
| Main groups |
Number of species
|
| Micro algae |
around 1100 as a whole lake |
| Higher Plants |
726 species - for all the area of Lake Shkoder |
|
1,900 species on the whole lake catchments area
|
| Aquatic macrophytes |
164 species - for all the area of Lake Shkoder |
| Invertebrates |
257 species, from which: |
| Molluscs |
54 species (Lake and waters of his depressions)
|
| Cladocera |
47 species |
| Copepoda |
18 species
|
| Fishes |
57 (on the whole lake catchments area) |
| Amphibians |
15 (on the whole lake catchments area)
|
| Reptiles |
30 (on the whole lake catchments area) |
| Birds |
271 (on the whole lake catchments area)
|
| Mammals |
7 ? (on the whole lake catchments area)
|
|
|
|
The number of endemic species:
Because Lake Shkoder is a relatively young lake, it is poor in endemic species.
|
| Main groups |
Number of species
|
| Microalgae |
2 (Cyclotella scadariensis, Cymbella scutariana)
|
| Oligochaeta |
1 (Peloscolex scodranensis) |
| Molluscs |
9 (2 on the lake) |
| Aquatic plants |
1 (Trapa longicarpa subsp. scutariensis) |
| Fishes |
2 (Pachychilon pictum, Salmothymus obtusirostris zetensis) |
| Amphibians |
1 (Rana shqiperica) |
|
Terrestrial plants many locally and for the Balkan endemic species
|
|
GEF IW:LEARN