Effect of Diplostomum Species on Length Weight Relationship of Farmed Nile Tilapia in Kibos Area, Kisumu City, Kenya

Transcription

1 Fisheries an Aquaculture Journal, Vol. 03: FAJ-0 RESEARCH ARTICLE Effect of Diplostomum Species on Length Weight Relationship of Farme Nile Tilapia in Kibos Area, Kisumu City, Kenya

2 Fisheries an Aquaculture Journal, Vol. 03: FAJ-0 Effect of Diplostomum Species on Length Weight Relationship of Farme Nile Tilapia in Kibos Area, Kisumu City, Kenya Violet M Nea*, Ben O Aketch, Davi M Onyango Department of Zoology, Maseno University, P.O. Box , Maseno, Kenya. *Corresponence: vmmbone@yahoo.com Accepte: May 3, 03; Publishe: Jul, 03 Abstract Diplostomum species metacercariae are parasitic trematoes that pose significant economic threat to fish farming worl wie. Nile tilapia ranks the most commercialize fish in Kenya besies being a cheap source of highly nutritive protein. However, low prouction of pon reare Nile tilapia in western Kenya poses threats to initiatives by the Kenyan government to revamp the economy of resients in this region. Diplostomiasis infection has been scantly reporte in the region, however, comprehensive stuies on the effect of Diplostomum spp. on the health status of farme fish is lacking. This stuy examine the influence of Diplostomum parasites on the length-weight relationships an conition factor of farme tilapia in Kibos area near Kisumu City. 3 fish samples were collecte from three fish farms between December, 0 an February, 0. The values of the regression co-efficient obtaine for the length-boy weight relationship in all the farms was aroun the hypothetical value 3 whereas the correlation co-efficient was greater than. This suggests an isometric growth form in all the sample specimens. The conition factor compute exhibite values significantly greater than K n =.0. There was no significant statistical ifference (p>0.05) between parasitize an non-parasitize fish. Thus, it is clear the specimens were healthy an fingerlings (< 5cm) from the farms coul be use for commercial prouction. Keywors: Conition factor; length; weight; Oreochromis niloticus; pon.. Introuction Metacercariae of the igenean trematoe Diplostomum are common parasites of wil an culture fish in temperate an tropical climates []. Fish heavily infecte with these igenetic trematoes may experience loss of vision, reuce growth, emaciation [] or eformation of the vertebral column, brain tumour, cellular necrosis an eath [3]. It has been further shown that these parasites can reuce fish crypsis an escape response an thus increase fish susceptibility to bir preation [4]. Accoring to reports [5], farming of Oreochromis niloticus in western Kenya has graually increase from 4% in the year 003 to 9% by 00. This was as a result of the initiative by the Kenyan government to revamp the economy of communities in western Kenya through the Economic Stimulus Program (ESP) targeting fish farming. Kibos area near Kisumu City is locate within western Kenya an is largely enowe with black soil, which is suitable for aquaculture []. However, evience of ecline in fish prouction [] as well as the average size of fish (00gm-0gm) caught in fish farms in the area over the last 3-5 years has been reporte []. There are many possible reasons for the low prouction of tilapia, such as too early maturation, high stocking ensity, high mortality ue to preation, biotic an abiotic environmental changes such as socio-economic an ecological conition of the place [9; 0], lack of foo, an parasitism by both ecto an enoparasites []. Information on nutritional requirements [], environmental changes such as ph an temperature [3; 4] an aspects of tilapiine biology [5] have well been ocumente in previous stuies, however, there is scanty of information on the effect of parasitism on the growth of fish with particular relevance to the well-being of fishes in privately manage fish farms. Accoring to Machao et al. [3], Diplostomum parasites pose averse threats to growth an health status of fish. Recent stuies [; ] emonstrate over 40% prevalence rate of iplostomiasis among farme O. niloticus in western Kenya, however, comprehensive stuies on the effect of Diplostomum spp. on the health status of farme fish in the region is lacking. A clear unerstaning of the growth of farme fish is necessary for accurate preiction of prouction levels in fish farms. This is because weight-length relationships provie information on the conition an growth patterns of fish. In aition, the conition of tilapia broo-stock etermines the amount of see to be prouce for stocking of pons whereas the conition of juveniles is important as they are use in stocking of fish farms. Hence, this stuy investigate the influence of Diplostomum parasites on the length-weight relationships of farme tilapia in Kibos area near Kisumu City.. Methos. Stuy esign & stuy area A three months cross-sectional survey (December 0 - February 0) was conucte in Kibos area near Kisumu City, Kenya. Kibos is locate between latitues N/ 0 4'0.00"S an

3 Research Article longitues 34 0 E / 34 49' 0.00"E. Three farms were selecte for the stuy. These sites were selecte base on their location near a fry prouction centre which serves as the main supplier of fingerlings in western Kenya.. Fish sampling proceure an transportation Fish sample size for Nile tilapia O. niloticus L.5 use in this stuy was estimate accoring to the formula []. Sampling was one after every three weeks for a perio of three months (December 0 February 0). Sixty four (4) Nile tilapia fish were ranomly sample from each fish farm at every sampling time using a seine net of.5m iameter an mm mesh. Sample fish were then transporte in ice cool box at 0 C to Maseno University, Zoology Department laboratory for analyses..3 Laboratory proceures.3. Examination of fish specimens for Diplostomum parasites Fish eyes were issecte an then examine for metacercariae with a stereoscopic microscope using proceures as escribe by [9] an [0]. The metacercariae extracte from each eye were counte as separate lots, an place in a petri ish containing saline solution before storing in 95% ethanol..3. Examination of fish for length weight relationship The specimens were moppe on filter paper to remove excess water from their boy surfaces. Total an stanar fish boy lengths were then measure using a meter ruler an recore in centimetres. The total length was measure as the istance from snout to the tip of the caual fin while the stanar length was measure as the istance from the snout to the caual peuncle. The boy weight was taken using a Table top weighing balance to the nearest 0.g. Fish samples were recore accoring to their collection sites as F, F an F3..4 Data analyses Data was analyze using SPSS software package. For the length-weight ata, the least square metho base on Type I linear regression moel was use for the expression: log (W) = log (a) + b. log (TL). Where: W = Weight of fish (g); L = Total Length of fish (cm); a = exponent escribing the rate of change of weight with length (= the intercept of the regression line on the Y axis); b = the slope of the regression line (also referre to as the allometric coefficient). The entire relationship between length (L) an weight (W) of fish was expresse by equation: W = al b [] with the a an b values having been obtaine from the linear regression. The egree of ajustment of the moel stuie was assesse by the correlation coefficient (r ). Stuent s t-test was applie to verify whether the eclivity of regression (constant "b") presente a significant ifference of 3.0, inicating the type of growth: Isometric (b = 3.0), positive allometric (b>3.0) or negative allometric (b<3.0). The values of the compile growth exponent were use for the calculation of conition factor, K accoring to []: K n =00 W L b where: K n = Conition factor; W = Total boy weight (g); L = Total length of fish (cm) an b = regression coefficient. Mean K n values obtaine were compare with the stanar K n =.0 by Stuent s t-test. The inepenent-samples t-test was use to test for ifferences in the K n values between parasitize an unparasitize hosts. In all cases a statistical significance of 5% was aopte. 3. Results Figures,, an 3 inicate that parasitize fish with greater stanar lengths (> 0. cm) in all the farms ha relatively lower K n values compare to smaller size fish ( 0.0 cm). In aition, inepenent-samples t-test conucte to compare K n of parasitize an un-parasitize fish among the class groups reveale no significant ifference in the relative conition factor values; t (4) =., p = 0.34 in farm I, t (5) = , p = 4 in farm II an t () = 0.4, p = in farm III. Accoring to results epicte in Table, parasitize iniviuals were on average bigger (greater mean total length) an heavier than non-parasitize fish with an exception of farm I. Mean relative conition factor values were significantly greater than K n =.0 for parasitize iniviuals of farm I an farm III with an exception of farm II. However, all iniviuals combine exhibite relative conition factor values significantly greater than K n =.0. Unpaire t test compute to etermine any significant ifference in the mean K-factor between parasitize an non-parasitize fish in general inicate that there was not statistical significance between the groups (p = 0.53) an the ifferences between conition means were likely ue to chance.

4 Fisheries an Aquaculture Journal, Vol. 03: FAJ-0 3 Figure : Effect of Diplostomum spp. on Mean K n Factor of culture O. niloticus in relation to fish class size in farm I. Figure : Effect of Diplostomum spp. on Mean K n Factor of culture O. niloticus in relation to fish class size in farm II. Figure 3: Effect of Diplostomum spp. on Mean K n Factor of culture O. niloticus in relation to fish class size in farm III.

5 4 Research Article Table : Descriptive statistics an estimate parameters of length-weight relationships for parasitize an nonparasitize O. niloticus caught in three fish farms in Kibos area, Kisumu City. Farm Status N Total length characteristics Mean Wt ± SE Mean K n ± SE Stuent s t test Parameter of the relationships Farm I Parasitize Nonparasitize Both (4.5%) 44 Mean Ls ± SE Min. Max. 3.± ± ±0. ±.4.5± ±.4.0±0.3.00±0..0 ±0.0 p = 0.00* p = p = 0.0* a b r t test b = 0 3* b = 3* b = 3* Farm II Farm III Parasitize Nonparasitize Both Parasitize Nonparasitize Both 3(39. %) 4 (9.%) ± ±.0 0.4±0.4.±4.3.33±3..± ± ±. 3.4± ± ± ±.09 9±0..04±0. 5.±0.0.09±0. 4±0. 3.0±0. p = 0.5 p = 0.0 p = 0.0* p = 0.004* p = 0.0 p = 0.0* b<3n s b=3* b=3* b<3n s b=3* b=3* Prevalence - in parenthesis; (K n) Mean values of the relative conition factor; (SE) Stanar error; (Min) Minimum; (Max) Maximum; (N) the sample size; (a) the intercept of the relationship; (b) the slope of the relationship; (r ) coefficient of correlation; (t) growth t test. *Significant (P<0.05), ns = not Significant (P>0.05). Table : Summary of length-weight relationship of Oreochromis niloticus from 3 fish farms in Kibos area, Kisumu City. Farm number Number of fish Exponential equation r Growth t test examine Farm I 4 Wt = 0.54 (TL) b = 3* Farm II 4 Wt = 0.0 (TL).0 b= 3* Farm III 4 Wt = 0.40 (TL) 3. b = 3* *Significant (P<0.05) Results from the log transforme ata to stuy the length weight relationships gave a regression equation of Log w = log a + b log L. Linear regression conucte on the ata confirme that there was a strong significant relationship between length an weight of fish with p values <0.00. In aition high egree of positive correlation between total length an total weight of all iniviuals was inicate by high values of correlation coefficient (r ) ranging 0 to 9. This implies that the exponential moel applie woul provie reliable preictions of the weight of fish in the farms. The estimate values of the exponent b range from.3 to 3.. Parasitize fish in farm II an III ha b values less than 3 (b<3; p<0.05) implying a negative allometric growth whereas non parasitize fish in farm I an III showe positive allometric growth (b>3; p<0.05). In summary, the exponent b values were aroun the hypothetical value 3 showing isometric growth for the farme fish (Table ). 4. Discussion Conition factor is a quantitative inicator of fish fitness reflecting recent feeing conitions an is obtaine using the length-weight relation of the iniviual [3]. Analysis to etermine the effect of Diplostomum on the growth conition of examine fish inicate that there was no statistical significance between parasitize an non-parasitize fish (p = 0.53; > 0.05) hence, there was not sufficient evience to inicate that the relative conition factor (K n ) was ifferent between the groups in the stuy area. On the contrary, parasitize

6 Fisheries an Aquaculture Journal, Vol. 03: FAJ-0 5 iniviuals were, on average, heavier in weight an of larger sizes (greater mean stanar length) than nonparasitize iniviuals (Table ). This may be attribute to the fact that perhaps, these host species o not epen essentially on vision for localization an capture of foo. Tilapiines exhibit a iversifie feeing routine [3]. They are omnivorous grazers that fee on phytoplankton, periphyton, aquatic plants, small invertebrates, benthic fauna, etritus an bacterial films associate with etritus. They are also filter feeers where suspene particles such as phytoplankton an bacteria are entrappe on mucous buccal cavity [3]. As such, the touch of foo on the lips of the fish can be enough for it to sense presence of foo within its vicinity [4]. It may also be as a result of the recore parasite intensity in the eyes ranging 5 to 4 parasites per fish, which probably i not affect the vision of the fish. Similarly, Marcogliese et al. [5] observe no significant effect of Diplostomum parasitism on the conition of fish espite the number of parasite intensity observe ranging 4 parasites per host. Variation in conition factor by size (length) classes was not statistically significant (p = 0.34 in farm ; p = 4 in farm II an p = in farm III; >0.05). Nevertheless, larger size fish (> 0. cm) ha relatively lower K n values compare to smaller size fish ( 0.0 cm). This coul be attribute to the resources transferre to the gonas in the latter stages of the life history of a fish for purposes of reprouction or construction of the gonas. [3; 4; ] similarly observe relatively lower values of conition factors for large sizes of fish, while relatively higher values of conition factors for rather small size fish in Brycinus nurse, characi an tilapia fish species, respectively. A number of other factors (e.g. sex, seasons, environmental conitions, stress, an availability of foo) also affect the growth conition of fish however; these were not consiere in the present stuy paving way for more research to ascertain the influence of ecological factors, sex an iet to the health status of fish. In totality, fish specimens in this stuy were observe to be healthy as the conition factor values were higher than one (K n = ). On the contrary, the K n values for fish species in this stuy (range..) coul not be compare to values of.5 obtaine for Brycinus nurse fish species in Volta lake [],. an.3 in Sassanra an Bagoe rivers in northern Nigeria []. Lower K n values of fish in this stuy coul be explaine by the fact that pon fish culture preisposes fish to stress an iseases as a result of high stocking ensity compare to the natural water systems. It may also be conclue that fingerlings (<5cm) examine in this stuy were suitable for commercial prouction. 4. Length-weight relationships The length-weight relationship (LWR) of the sample fish inicate that the weight of the fish increase logarithmically with an increase in length, with the b values lying between.5 an 3.5. The regression coefficient for isometric growth is 3 an values greater or lesser than 3 is an inication of positive or negative allometric growth, respectively []. Similar to growth conition, the length-weight relationship in fish is affecte by a number of factors incluing ecological factors such as temperature, foo supply (quantity an quality), spawning conitions an other factors, such as sex, age, gona maturity, stomach fullness, health, season an habitat [9]. Parasitize fish in farms II an III (Table ) in the present stuy showe values of b significantly lower than 3 (p< 0.05) which is an inication of negative allometric growth i.e. the fish grows but is slener. Negative allometric growth is an inication of slow growth which might be ue to non-availability of foo as suggeste by [30]. Similarly, the K n values of these fish specimens were lower (9 an.09 respectively) than values reporte by [] an [], which range 3.4. Parasitize fish in farm I ha the b values at 3 inicating an isometric growth which characterize the fish as portraying unchanging boy form an unchanging specific gravity [3]. Non-parasitize fish showe b values greater than 3 (Table ) implying a positive allometric growth. Rapi growth might be an inication of abunant foo supply an other favourable conitions as suggeste by [30]. The overall b values of fish in all the farms were aroun the hypothetical value of 3 ranging between.0 to 3. (Table ). These results are analogous with the range of a values an b values usually encountere in fin fishes, which lie between an 4 accoring to []. Recently, Froese [3] confirme the exponent b shoul normally fall between.5 an Conclusion In conclusion, finings from this stuy regaring the length weight relationships of fish emonstrate that Diplostomum parasite species i not appear to have any effect on the conition factor of heavily infecte O. niloticus as the compute K n values were higher than. Regression coefficients inicate isometric growth for all the sample fish as the b values were approximately 3. However, Diplostomum can inirectly cause severe losses in fish populations. It is for this reason that we have to take parasitic infection in hatcheries an pons seriously. In aition, the current stuy i not consier the iet, gonaal evelopment an stomach fullness

7 Research Article of the sample fish. These factors may influence the length weight relationships of fish an therefore, future stuies pertaining to seasonal or annual ata are necessary to verify this hypothesis. Competing Interests There are no "financial competing interests" or other "non-financial competing interests" involving political, personal, religious, ieological, acaemic, intellectual, an commercial or any other to eclare in relation to this manuscript. Authors' Contributions VMN conucte the research, of which the results are reporte in the manuscript as well as rafte the manuscript. BOA participate in reviewing the manuscript as well as statistical analysis. DMO supervise the entire work, rea the manuscript an provie laboratory as well as financial support. Acknowlegement We woul like to acknowlege the help from Maseno University s Zoology Department staff an in particular Phillip Ochieng, James Ojienga an Job Pira for their technical support. We are grateful to Vincent Ochieng from Moi University for his technical assistance in ientification of Diplostomum parasites in the laboratory. References. Chappell LH, Harie LJ, Secombes CJ, 994. Diplostomiasis: the isease an host parasite interactions. In Parasitic Diseases of Fish. Eite by Pike AW, Lewis JW. Otley: Samara Publishing Limite, 59.. Niewiaomska K, 99. The genus Diplostomum taxonomy, morphology an biology. Acta Parasitologica, 4: Machao PM, Takemoto RM, Pavanelli GC, 005. Diplostomum (Austroiplostomum) compactum (Lutz, 9) (Platyhelminthes, Digenea) metacercariae in fish from the flooplain of the Upper Parana River, Brazil. Parasitology Research, 9: Seppälä O, Karvonen A, Valtonen ET, 005. Manipulation of fish host by eye flukes in relation to cataract formation an parasite infectivity. Animal Behaviour, 0: Musa S, Aura MC, Owiti G, Nyonje B, Orina P, Charo-Karisa H, 0. Fish farming enterprise prouctivity program (FFEPP) as an impetus to Oreochromis niloticus (L.) farming in Western Kenya: Lessons to learn. African Journal of Agricultural Research, (): Bowman JR, Seim KW, 995. Characterization of soils from potential PD/A CRSP sites in East Africa. Interim Work Plan, Africa Stuy 4. Fourteenth Annual Technical Report.. Magare J, 00. Economic Stimulus Programme. Link Newspaper, Special Report, pp 4 an 9. Issue No Otieno Z, 00. Results of tilapia fingerling prouction by private farmers. Technical cooperation programme Kenya, Paper No.. 9. Lèveque C, 00. Out of Africa: the success story of tilapias. Environmental Biology of Fishes, 4: Chakraborty SB, Banerjee S, 009. Culture of monosex Nile tilapia uner ifferent traitional an non-traitional methos in Inia. Worl Journal of Fish an Marine Sciences, (3): -.. Paperna I, 99. Parasites, infections an iseases of fishes in Africa: An upate. Page 3 in F.D. Repository. CIFA Technical Papers - CIFA/T3, Hebrew Univ. of Jerusalem, Rehovot (Israel).. Salama ME, 99. Effects of sex ratio an fee quality on mass prouction of Nile tilapia, Oreochromis niloticus (L.), fry. Aquaculture Research, (): Lizama MAP, Ambrósia AM, 00. Conition factor in nine species of fish of the Characiae family in the upper Paraná River flooplain. Brazilian Journal of Biology, : Anene A, 005. Conition factor of four cichli species of a man-mae lake in Imo State, South eastern Nigeria. Turkish Journal of Fish an Aquatic Sciences, 5: Galemoni e Graafi GJ, Huisman EA, 999. Reprouctive biology of pon reare Nile tilapia Oreochromis niloticus L. Aquaculture Research, 30: Matolla GK, 009. Parasites of Tilapia (Oreochromis niloticus) in Chepkoilel-Fish farm of Moi University, Eloret, Kenya. In Proceeings of the sixth framework programme on BOMOSA projects: Integrating BOMOSA cage fish farming system in reservoirs, pons an temporary water boies in Eastern Africa: n 4 th September, 009, Machakos, Kenya. Eite by Drexler SS, Waibacher H: Vienna, Austria,.. Fioravanti ML, Florio D, Konecny R, Lorber J, Wathuta EM, Magana A, et al., 009. Preliminary ata on the parasitofauna of wil an culture fish from Kenya an Ugana. In Proceeings of the sixth framework programme on BOMOSA projects: Integrating BOMOSA cage fish farming system in reservoirs, pons an temporary water boies in Eastern Africa: n 4 th September, 009, Machakos, Kenya. Eite by Drexler SS, Waibacher H: Vienna, Austria, 4-.. Daniel WW, 999. Biostatistics: A Founation for Analysis in the Health Sciences. th eition. New York: John Wiley an Sons.

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