LENGTH-WEIGHT RELATIONSHIP, CONDITION FACTOR AND SPECIES ABUNDANCE OF SOME ECONOMIC IMPORTANT - PowerPoint Presentation

1. LENGTH-WEIGHT RELATIONSHIP, CONDITION FACTOR AND SPECIES ABUNDANCE OF SOME ECONOMIC IMPORTANT FISHES IN EPE LAGOON, EPE LAGOS.Taiwo Abdulkareem Babatunde and Salaudeen Fatimah ModupeolaDepartment of Human Kinetics, Sports and Health Education Lagos State University Ojo

2. INTRODUCTIONFish plays an important role in supply of dietary protein to Nigerians. It is one of the cheapest source of animal protein available to the teaming population of the country.Length-Weight relationship is an important fishery management parameter in assessing the relative well being of fish population. It is of great importance in fishery management. Length–Weight relationship is the rate of weight gain relative to growth in length i.e the rate at which weight increases for a given increase in lengthCondition factor is the measurement of the general health condition of fish as calculated by the ratio of body weight to body length

3. INTRODUCTION Cont.The condition factor of fish can be affected by a number of factors such as stress, sex, season, availability of feeds, and other water quality parameters (Khallaf et al., 2003) Previous works on the fish fauna in south-western Nigerian lagoons concentrated on aspects of the biology of some of the species and ecological conditions of the lagoons. There is a dearth of information of length-weight relationships and condition factors ‘K’ of most coastal/brackish water fishes that could form a good data base which could be assessed for estimation of biomass and population dynamics of Nigerian aquatic ecosystems (Bolarinwa 2015)

4. MATERIALS AND METHODSDESCRIPTION OF STUDY AREAEpe lagoon lies between latitudes 03050’-04010’N and longitudes 005030’ – 005040’E is fed by River Oshun, it has a surface area of more than 243 km2 (about 225 km2) and a maximum depth of 6 m though a large area of the lagoon is relatively shallow with a minimum depth of 1 m, and the vegetation surrounding the Lagoon is of the mangrove swampy type (Balogun, 1987).COLLECTION OF FISH532 samples of three fish species: Pseudotolithus senegalensis, Chrysichthys nigrodigitatus and Tilapia species were collected fortnightly for three months from the local fisher folks at landing jetty in Epe

5. MATERIALS AND METHODS Cont.The Total Length and Weight of the fishes were recorded.The Total Length was measured using a measuring ruler to the nearest 0.01cm for each of the fish samples. The total length was measured from the snout to the tip of the caudal fin The regression of weight against Total length was computed by the conventional formula described by Le cren (1951). W = aLb ………… (eqn. 1)

6. MATERIALS AND METHODS ContEquation (1) was transformed to logarithms of the formLog W= Log a + b Log LWhere W = Weight in grams (g), L = Total length of the fish in centimeters a = Regression constant; b = Regression coefficientThe Condition Factor for each fish was calculated using the conventional formula described by Worthington and Richard (1930). K = 100W/L3 Where; K = Condition factor, W = Body weight in grams (g) L = Average length in centimeters (cm)

7. RESULTS Chrysichthys nigrodigitatus Fig 1: Relationship between the length and weight of Chrysichthys nigrodigitatus

8. RESULTS Cont. Pseudotolithus senegalensis Fig 2: Relationship between the length and weight of Pseudotolithus senegalensis

9. RESULTS Cont.Tilapia species Fig 3: Relationship between the length and weight of Tilapia species

10. DISCUSSIONChrysichthys nigrodigitatusThe total length of Chrysichthys nigrodigitatus ranged from 16.5cm to 67.5cm with mean of 37.6cm and weight ranged from 56g to 2900g with mean of 798.9. The condition factor is 1.50. this is higher than the value (1.08) reported by Bolarinwa 2015 from Epe lagoon, although falls outside the range recommended range 2.4-4.8On log transformation, the overall length-weight was represented by Log W=2.24-0.15 Log TL showing a negative allometric growth pattern. This result is in sync with the report of Johnson et al., (2010), who reported negative allometric growth for Chrysichthys nigrodigitatus in Ologe Lagoon.There was a positive correlation of +0.71 which is significant exists between the total length and weight.

11. DISCUSSION Cont.Pseudotolithus senegalensisThe total length of Pseudotolithus senegalensis ranged from 20cm to 126cm with mean of 35.7cm and weight ranged from 10g to 7600g with mean of 824.3. Condition factor of 1.81 was recorded. This falls within the range 0.64 and 1.99 reported by Fafioye and Oluajo (2005) for five fish species at Epe Lagoon, Nigeria On log transformation, the overall length-weight was represented by Log W = -2.32 + 3.09 Log TL showing a isometric growth pattern. Mogoriola et al, 2011 recorded ‘b” value less than 3, showing negative allometric growth There was a positive correlation of +0.71 which is significant exists between the total length and weight.

12. DISCUSSION Cont.Tilapia SpeciesThe total length of Tilapia species ranged from 14cm to 35cm with mean of 25.02cm and weight ranged from 37g to 1900g with mean of 396.5 The condition factor is 2.5. The ‘k’ value recorded is similar to what was recorded by Bolarinwa 2015 in Epe Lagoon, it is also within the range recorded by Mahomoud et al. (2011) but comparatively smaller than those obtained by Anene (2005). On log transformation, the overall length-weight was represented by Log W = -1.89 + 3.06 Log TL showing a positive isometric growth pattern.There was a weak positive correlation of +0.47 which is significant exists between the total length and weight.

13. CONCLUSIONThe study revealed the growth pattern and condition factors of Pseudotolithus senegalensis, Chrysichthys nigrodigitatus and Tilapia species in Epe Lagoon. The ‘b’ values recorded show that most of the fishes collected were of positive isometric growth pattern except for Chrysichthys nigrodigitatus which exhibit negative isometric growth pattern.The results also reflect the level of wellbeing of these economic important fishes which are highly consumed by inhabitants of Lagos State. Epe Lagoon is still favourable to fishes but there is a need for constant monitoring of the water. Therefore, there is need for more in-depth investigation that contain a larger volume of data of length and weight, the condition factors of other fish species and the physiochemical properties of Epe lagoon

14. REFERENCESAnene, A., (2005). Condition factors of four cichlid species of a man-made lake in Imo state,Southeast, Nigeria. Turk. J. Fish. Aquat. Sci., 5: 43-47.Balogun, J.K., (1987). Studies on some aspects of the Biology of Pellonulaafzeliusi (Johnels) in Epe Lagoon, Nigeria. Arch. Hydrobiol., 109: 517-530Bolarinwa, J.B (2015): Length- Weight Relationships and Condition Factors of Tilapia zilli and Chrysichthys nigrodigitatus in Epe Lagoon, Nigeria. Science and Engineering Perspectives SEP. Vol. 10,Fafioye,O.O and Oluajo, O. A (2005). Length-weight Relationships of 5 species in Epe lagoon, Nigeria, African Journal of Biotechnology4(7): 749-751.

15. REFERNCES Cont.Khallaf, E., Galal, M., Athuman, M (2003). The biology of Oreochromis niloticus in a polluted canal. Ecotoxicology. 12:405-416Kumolu-Johnson, C. A and Ndimele, P.E (2010). Length-Weight relationships and condition factors of twenty-one fish species in Ologe lagoon, Lagos, Nigeria, Asian Journal of Agricultural Sciences 2(4):174-179.Le Cren ED. 1951. The length-weight relationship and seasonal cycle in the gonad weight and condition in yhe perch (perce fluviatilis). J. anim. Ecol.,20:201-219.

16. REFERENCES Cont.Mahomoud, W.F., Amin, A.M.M., Elboray, K.F., Ramadhan, A.M., El-Halfawy M.M.K.O (2011). Reproductive biology and some observation on the age, growth, and management of Tilapia zilli ( Gerv , 1848 ) from Lake Timsah, Egypt. International Journal. 3:15-25Omogoriola.H.O., Solarin.B.B., Williams.A.B., Ayo-Olalusi. C.., Edah Bernard (2011): Length- weight Relationships and Relative Condition Factor (Kn) of Sciaenids, Pseudotolithus Senegalensis (Valenciennes, 1833) and Pteroscion peli (Bleek,1863), in Nigerian Coastal water. Internet Journal of Food Safety, Vol.13, 2011, p.81-87