Biological campaign with snails as first intermediate host for Diplostomum by Tench Tinca tinca
Identification of fresh water snails in area as first intermediate host of Diplostomum and survey of snails feeding by Tench Tinca tinca and its role in biological control of Diplostomiasis via cutting its life cycle was studied. During four steps sampling (May to August 2001), 771 specimens of all kinds of fresh water snails of Sefidroud Fisheries Research Station (place of survey), as sample of fresh water snails in area was identified. Totally 3 Genus and 4 Species based on abundance consisted of Physaacuta (77.04%), Limnaea Limnaea stagnalis (6.87%) & Planorbis planorbis(6.36%) were identified. The most abundance of snails was seen in May with average 57.5% and the least abundance was in August average 37.75% and number of snail was between 45-47 specimens/m2 that was scattered in depths of O to 80cm. Furthermore the most number of snails was seen in depths of O to 30 cm and from deeper than 80 cm there was no snail due to lacking of aerobic condition. During 2001-2002, practical survey of feeding of snail by juvenile and adult Tench (2 & +3 years old) were conducted treatments (fiberglass tanks treatments 1&2 and fish culture pond treatments 3&4) under equal physical and chemical conditions with presence of GFC (Growth Food Carp) in treatments 2&4 and without GFC in treatments 1&3..survey on adult Tench (+250gr) in the first treatment confirmed the snail was fed. In second treatment, 4% of Tench biomass, GFC was distributed and only 30% from it was fed by Tench in the other hand all of snails were fed. The abundance of snails in third treatment was 45 specimens/m2 which after stocking Tench reduced to 8 specimen /m2 or 82% decreased. In the fourth treatment before stocking the Tench, average abundance of the snails was 47 specimens/m2 and based on 4% biomass of Tench 500gr GFC was given which in the end 40% concentrated food was used while abundance of snails decreased to 12 specimens/m2 or 75% decreased. The results of Tench (+15gr) feeding survey in separately in 2002 confirmed the feeding of snails as in first treatment 80% of snails fed by tench and in second treatment 15% of Tench biomass GFC was distributed and 78% of artificial food and 65% of snails consumed too. The abundance of snails in third treatment was 36 specimens fm2 which after stocking Tench reduced to 13 specimens/m2 by the 64% decrease and in forth treatment before stocking the Tench, average of abundance the snails was 41 specimens/m2 and in this treatment similar second treatment based on 15% biomass of Tench, GFC was given daily which at the end 65% GFC was used while abundance of snails decreased to 43% .Juvenile Tench (2 years old) in contract with adult Tench (+3 years old) had no ability to use different sized of snails and only can use of juvenile and small size (5mm) of snails. At the beginning, inclination of Tench to use of snail was further than using of GFC. Statistics test (T-student & Z test) confirmed the results were significant. The results of this survey showed that snail feeding by Tench is instinctive character and this species can control snails (Diplostomum first intermediate host) and increase production in fish pond culture.
| Main Authors: | , , , |
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| Format: | Report biblioteca |
| Language: | Persian |
| Published: |
Iranian Fisheries Science Research Institute
2005
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| Subjects: | Snail, Diplostomum, Tinca tinca, Species, Specimens, |
| Online Access: | http://hdl.handle.net/1834/14265 |
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