Introduction

Fishes are one of the cheapest sources of protein in the world which contains necessary and essential nutrition for body. Due to increasing population in all countries, fish may play an important role in economic development of countries in both aquaculture and the production of ornamental fish. No other group of invertebrate serves man in so many forms as fishes. Morphometric analysis provides a powerful complement to genetic and environmental stock identification approaches (Cadrin, 2000), length-weight relationships allow the conversion of growth-in-length equations to growth-in-weight for use in a stock assessment model. Information about individual body weight-length/width relationships in populations is important for estimating the population size of a stock, specifically for the purpose of its exploitation.

The Lenght measurement is aimed at comparing body shape in fishes as well as the relationship existing between these measurement in different species. These measurement include total lenght, standard lenght, body depth e.t.c. From the lenght – weight relationship, it is possible to determine whether the growth is isometric (that is, whether the lenght and weight of the fish are increasing at a proportional rate rate to the other) or allometric (that is, whether the increase in lenght is relative with increasing body size). The condition factor expresses the relative degree of robustness or wellbeing of fish and reflects the degree of nourishment and state of sexual maturity. Sex of fish, age of fish, type of fish species, maturity stage and season are some of the factors that influence the condition factor of fish, leading to variation in the condition factor (Anyanwu et al., 2007; William, 2000).

The assumption of the condition factor is that fish in better condition are heavier (Bagenal and Tesch, 1978). It also provides information on the physiological state of fish relating to fish welfare from the reproductive and nutritional perspectives and also provides useful information that can be used as age, growth and feeding intensity indices (Oni et al., 1983).

Condition factor (K-factor) provides information when comparing two populations living in certain feeding density, climate and other conditions (Weatherly and Gills, 1987). Thus, condition factor is important in understanding the life cycle of fish species and it contributes to adequate management of these species, hence, maintaining the equilibrium in the ecosystem. Condition factor compares the wellbeing of a fish and based on the hypothesis that heavier fish of a given length are in better condition.

Some reports on other fish species include; Alfred-Ockiya, (2000), Chana chana in fresh water swamps of Niger Delta and Hart, (1997), Mugil cephalus in Bonny estuary, Hart and Abowei, (2007), ten fish species from the lower Nun River, and Abowei and Davies, (2009), Clarotes lateceps from the fresh water reaches of the lower Nun river. They reported that, as a fish's condition increases, body water is replaced mainly by lipid and, to a lesser extent, protein while ash content remains relatively constant.

Study Area

The Badagry creek (Figure 1) is approximately 60 km long and 3 km wide, lies between longitudes 3°0′ and 3°45′ E and between latitudes 6°25′ and 6°30′ N. It is part of a continuous system of lagoons and creeks along the coast of Nigeria from the border with the Republic of Benin to the Niger delta. Most of the year it is characterized by fresh and slightly brackish water. The lagoon is approximately equidistant from the entrances of Lagos and Cotonou harbors. As a result, it is influenced by tides and floods from the Lagos Lagoon and Cotonou harbour through Lake Nokue and Lake Porto-Novo (Anyanwu and Ezenwa, 1988). The Yewa River with its tributaries, Isalu and Ijomo is the major river emptying into the lagoon. Creeks connected to the lagoon include Bawa and Doforo.  Badagry creek is foumd in Lagos state in the southwestern part of Nigeria. The creek impacts significantly on the lives of Lagosians. It is used for fishing, aquaculture, sand mining and as a means of transportation. The creek is also important in conservation terms because of the great diversity of endemic species. The Badagry creek is a long stretch of water body that runs parallel to the Atlantic Ocean in the south; it extends from Lake Nokue near Port-novo, Benin republic to Apapa area of Lagos before opening up into the Atlantic Ocean via Lagos harbour. Along the creeks the major occupation of the inhabitants is fishing, crop farming, and mat weaving. There is diversity of fin and shell fishes in the creek.

Figure 1 Administrative map of Nigeria (above) showing the Hydrological map of the Lagos lagoon complex. The sample stations A & B are indicated on the Badagry axis of the lagoon

Fish species such as Ethmalosa, Gobioides, Cynoglossus. and Pomadasys, Pseudotolithus, Tilapia, Mugil, Liza, Clarias, Selene, Macrobranchum, Callinectes Tillapia guinensis, Gymnarchus niloticus, Chrysichthys nigrodigitatus, Bathygobius soporator, Pomadasys peroteti, Marcusenius psittacus are common in Badagry creek. Reviews on fishes and fisheries of Badagry creek include that of Solarin and Kusemiju (1991), Lawal-Are and Kusemiju (2000), Chukwu and Kuton (2001), Lawal-Are (2001), Ajado and Edokpayi (2003), Kumolu-Johnson (2004), Akintola (2007), Soyinka et al. (2010). The surrounding vegetation is composed mainly herbs and shrub plants dotted by raffia palm (Raphia sudanica), oil palm (Elaeis guineensis) and coconut palms (Cocus nucifera). Floating plants such as the water lettuce (Pistia stratoites), duckweed (Lemna sp.) and water hyacinth (Eichhornia sp.) often cover some parts of the water surface (Akin-oriola et al. 2004).

Materials and Methods

Sample Collection: Fin-fishes used in this study were purchased weekly from fishermen at Badagry creek between November 2014 - June 2015 (8 months). A total of 1008 fin fish specimens were examined. They were caught principally with cast net and surrounding net, with 76mm mesh size. The fish were transported to the laboratory of Department of Fisheries, Lagos State University for analysis.

Sex Ratio Determination: The sex of each specimen was determined by visual examination of the genital openings using the naked eye and magnifying lens. The ratio of male to female specimen were determined and tested statistically by chi – square method.

The chi-square was expressed mathematically as Chi² = (O – E) ² / E. Where: O is the Observed sexes and E is the Expected sexes.

Lenght – Weight Relationship: Body weight was measured to the nearest 0.1 g using a sensitive electric digital scale, while Lengths were measured to the nearest 0.1cm using a meter rule in the laboratory as described by Olatunde (1978). The length-weight relationship was estimated using the equation: W = aLb Where: W=Weight of the fish in grammes, TL=Total lenght of the fish in centimeters.

a=Regression constant. b=Regression co-efficient. The parameters a (intercept) and b (slope) were estimated by linear regression based on logarithms: Log (W) = Log (a) + b Log (L). Where: W = weight (g) of the crabs, L = Total lenght of the fish in centimeters.

Condition Factor: The fulton’s condition factor for the fish specimen were calculated using the formula:  K = 100 ( W / L³). Where: K=Fulton’s condition factor, L=Total lenght of the fish in centimeters, W= Weight of fish in grammes

Results

A total of 1008 specimens were examined. The total length ranged from 12.85±1.54cm – 27.49±4.75cm, and the body weight ranged from 38.50±14.04g – 159.09±28.24g Oreochromis niloticus having the least and Marcusenius senegalensis having the highest. Table 1 shows the summary of results of the biology (e.g. Growth pattern) of all the species studied, with the mean condition (K) factor for the fish species ranging from 0.77 – 5.37, Marcusenius senegalensis having the least and Pomadasys peroteti having the highest. 75% of fish species sampled had K – factor greater than or equal to 1.

The value of the regression (b) showed that the pattern of growth was positive allometry (b > 3), except for only two (2) species within the population i.e. M. senegalensis (b =2.12) and G. niloticus (b =1.39) which shows that these two (2) species were not growing appropriately in relation to the body length (cm). However, most of the species have b values higher than 3, especially for Sarotherodon melanotheron with b value equals to 15.59. The co-efficient of regression r, ranged from 0.06 – 0.91, Tilapia mariae having the least. Positive values obtained for the correlation coefficient (r) shows that there is an increase in the body weight with increase in lengths. The length weight relationships of all the species are presented in Figures 2 – 13.

Table 1 Growth pattern of fish species in Badagry creek, Lagos

Figure 2 Length-weight relationship in Chrysichthys nigrodigitatus from Badagry creek

Figure 3 Nigeria; Length-weight relationships in Marcusenenius senegalensis from Badagry creek

Figure 4 Length-weight relationships in Tilapia zilli from Badagry creek

Figure 5 Length-weight relationships in C. longifilis from Badagry creek

Figure 6 Length-weight relationships in Pomadasys peroteti from Badagry creek

Figure 7 Length-weight relationships in C. longifilis from Badagry creek

Figure 8 Length-weight relationships in Pomadasis jubelini from Badagry creek

Figure 9 Length-weight relationships in Gymnacus niloticus from Badagry creek

Figure 10 Length-weight relationships in Sarotherodon melanotheron from Badagry creek

Figure 11 Length-weight relationships in Tilapia mariae from Badagry creek

In the present study, 478 male and 530 female specimens were caught representing 47.42% and 52.58% of the fish population respectively, giving the overall sex ratio of 1male:1.1 females (Table 4). A Chi–square revealed a significant departure from the theoretical 1male to 1 female ratio (X2 =2.68 > X2, 0.05=3.84). Sex ratios were generally in favour of females except in species such as Chrysichthys nigrodigitatus, Tilapia zilli, Tilapia guinensis, Sarotherondon melanotheron which were in favour of males. Chrysichthys auratus longifilis had a sex ration of 1:1.

Figure 12 Length-weight relationships in Oreochromis niloticus from Badagry creek

Figure 13 Length-weight relationships in Bathygobius soporator from Badagry creek

Table 4 Sex ratio and Chi2 analysis of fish species from Badagry creek, Nigeria

Discussion

From the length- weight relationship (b ranging from 0.19 – 15.59) when compared with b values 2.79- 3.21 reported by Fafioye and Oluajo (2005), who studied the length weight relationship of five species in Epe Lagoon; 2.61 – 3.25 recorded by Agboola and Anetekhai (2008), where they studied the length-weight relationship of 35 fish species from Badagry creek and 2.01 – 2.99 recorded by Kumolu-Johnson et al. (2010) on length – weight relationship of Ologe lagoon, the creek could be said to support a wide range of species exhibiting different growth patterns. All the fish species showed positive allometric growth (b > 3) except G. niloticus (b=1.19) and M. senegalensis (b=2.12) which shows negative allometric growth i.e. b = 3. Pomadasis jubelini showed an isometry growth (b approximately 3). When the value of the regression coefficient b showed that the pattern of growth is negative allometry (b < 3) it indicates that fish are lighter than their body length (Wooten 1998) which implies poor growth of length than weight, but a positive allometric growth (b > 3) favours weight than length. Marcusenius senegalensis showed a negative allometric growth having b value of 2.12.  Chrysichthys longifilis also showed a different growth pattern having a regression coeffiecient of 7.5 indicating positive allometric growth. The length-weight relationships of the grunters Pomadasys jubelini and Pomadasys peroteti reflected an isometric and positive allometry growth respectively. The value of the regression coefficient b showed that the pattern of growth was positive allometric (b < 3) for P. peroteti and issometric for P. jubelini. It can be inferred that growth was more in body weight than in body length. Results of negative allometric growth were also reported for P. jubelini from the Badagry Creek (b = 2.91) (Agboola & Anetekhai, 2008) and from the Qua Iboe estuary (b = 2.81) (King, 1996), Nigeria.

The correlation of coefficient (b) values for the Cichlids Tilapia zilli, Sarotherondon melanotheron, Tilapia guinensis, Tilapia mariae and Oreochromis niloticus ranged from 4.73 – 15.59 showing a positive allometry growth indicating growth being more in body weight than in body length. S. melanotheron had the highest and T. mariae had the least. Frill fin fish (Bathygobius soporator) showed positive allometry growth (b = 6.82) while Gymnarchus niloticus showed negative allometry having correlation coefficient of 1.39. Similar observation was made on Callinectes amnicola in Badagry, Lagos State and Warri River, Niger Delta Nigeria respectively. Although, a positive allometry was reported for Chrysichthys nigrodigitatus and Schilbe intermedius from Owalla and Eko –ende reservoirs. The reason for differences in growth patterns could be attributed to availability of food, poor environmental conditions and competition along the food chain.

The condition factor (K) reflects, through its variations, information on the physiological state of the fish in relation to its welfare. From a nutritional point of view, there is the accumulation of fat and gonad development (Le Cren, 1951). From a reproductive point of view, the highest K values are reached in some species (Angelescu et al., 1958). K also gives information when comparing two populations living in certain feeding, density, climate, and other conditions; when determining the period of gonad maturation; and when following up the degree of feeding activity of a species to verify whether it is making good use of its feeding source (Weatherley, 1972).

Condition factor is a morphometric index used to evaluate physiological status of fish based on the principle that those individual of a given length which have a higher mass are in better ‘condition’. In this study, the condition factor (K) ranged from 0.90 – 4.65. The condition factor could be influenced by differences in size or age. 75% of fish species sampled had K – factor greater than or equal to 1. According to Langler (1978), it has been found that the value of K is not constant for individual species or populations but it is subject to wide variations for fish of average natural condition. The K – factor should be equal to 1 while less than or greater than 1 indicate below and above average conditions respectively. Wade (1992) stated that condition factor greater or equal to one is good. All the fish had condition factors greater than one except the catfishes (Chrysichthys nigrodigitatus, Chrysichthys auratus) and Marcusenius senegalensis.

A closer examination of the condition factors revealed that 91.67% (11 out of 12 fish species) of the fish species had their K values outside the range (2.9-4.8) recommended as suitable for matured fresh water fish by Bagenal and Tesch (1978). This could have been caused by adverse environmental factors (Anene, 2005). This suggests that the condition of Badagry creek in comparison to fresh water bodies may be un-favourable to fishes in the creek. The causes of these adverse conditions may range from influx of industrial effluents from satellite industrial estate; sand mining activities currently taking place in the creek; and massive road construction taking place along the creek etc. Therefore, there would be need for more studies on the physico-chemical properties and the condition factors of other fish species in Badagry creek to be able to establish the suitability of the creek for fish survival.

References 

Agboola, J. I., and Anetekhai, M. A. (2008). Length-weight relationship of some fresh and brackish water fishes in Badagry creek, Nigeria. Journal of Applied Ichthyology, 24, 623-625.

http://dx.doi.org/10.1111/j.1439-0426.2008.01079.x

Ajado, E. O. and Edokpayi, C. A. 2003. Comparative racial study of Clarias gariepinus (Burchell, 1822) from River Niger and Badagry Lagoon, Southwest Nigeria. Nig. J. Fish., 1, 41.48.

Alfred-Ockiya, J.F. (1996). Studies on the Ichthyofauna of Kolo creek River State, Niger Delta Biologia. 1:24-28.

Anyanwu, A. J. and Ezenwa, B. I. O. (1988). Incidence of parasitic infection of pond raised Tilapia spp. and some cultivable fish species from three ecological areas of Lagos state. Nigeria Institute of Oceanography and Marine Research, Technical Paper No. 32.

Anyanwu, P. E., Okoro, B. C., Anyanwu, A. O., Matanmi, M. A., and Ebonwu, B. I. (2007). Length-weight relationship, condition factor and sex ratio of African mud catfish (Clarias gariepinus) reared in indoor waters recirculation system tanks. Research Journal of Biological Science, 2, 780-783.

Bagenal, T.B. and F.W. Tesch, (1978). Age and Growth. In: Methods for Assessing of Fish Production in Freshwaters. Bagenal, T.B. (Ed.). 3rd Edn. No. 3, Blackwell Scientific Publication Ltd., pp: 101-136.

Cadrin, S. X.(2000). Advances in morphometric identification of fishery stocks. Reviews in Fish Biology and Fisheries, 10: 91-112.

http://dx.doi.org/10.1023/A:1008939104413

Chukwu, L. O. and Kuton, M. P. (2001). The bio-ecology of the goby, Eleotris lebretonis (Steindachner) (Pisces: Eleotridae) from a eutrophic creek in southwestern Nigeria. J. Sci. Tech. and Environ., 1, 67.76.

Fafioye, O. O., and Oluajo, O. A. (2005). Length-weight relationship of five fish species in Epe Lagoon, Nigeria. African Journal of Biotechnology, 4, 749-751.

Fagade, S. O. and Olaniyan, C. I. O. 1974. Seasonal distribution of the fish fauna of the Lagos Lagoon. Bull. De I..I. F. A. N. T., Ser. A, 36(1), 244.252.

King, R. P (1996). Length-weight relationships of Nigerian coastal water fishes. NAGA. The ICLARM Quarterly, 19, 53-58.

Lagler, K.F., (1968). Sampling and Examination of Fishes. In: Methods for Assessment of fish Production in Freshwaters. W.E. Ricker, (Ed.). IBP, Handbook III, pp: 7-45.

Lawal-Are, A. O. 2001. Aspects of the biology of the lagoon crab, Callinectes amnicola (De Rocheburne) in Badagry, Lagos and Lekki Lagoons, Nigeria. In Proceedings of the 16th Annual Conference of Fisheries Society of Nigeria, Maiduguri, 4th.9th Nov., 2001  (Eyo, A. A. and Ajao, E. A., eds), pp. 215.220. Fisheries Society of Nigeria (FISON), Apapa.Lagos.

Lawal-Are, A. O. and Kusemiju, K. 2000. Size composition, growth pattern and feeding habits of the blue crab, Callinectes amnicola (De Rocheburne) in the Badagry Lagoon, Nigeria. J. Sci. Res. Dev., 5, 169.176.

Le Cren, E. D. (1951). The length-weight relationship and seasonal cycle in gonad weight and condition in perch Perca fluviatilis. Journal of Animal Ecology, 20, 201-219.

http://dx.doi.org/10.2307/1540

Le Cren, E. D. (1951). The length-weight relationship and seasonal cycle in gonad weight and condition in perch Perca fluviatilis. Journal of Animal Ecology, 20, 201-219.

http://dx.doi.org/10.2307/1540

Oni, S. K., Olayemi, J. Y., and Adegboye, J. D. (1983). Comparative physiology of three ecologically distinct freshwater fishes, Alestes nurse Ruppell, Synodontis schall Bloch and S. schneider and Tilapia zilli (Gervais). Journal of Fish Biology, 22, 105-109.

http://dx.doi.org/10.1111/j.1095-8649.1983.tb04730.x

Solarin, B. B. and Kusemiju, K. 1991. Day and night variations in beach seine catches in Badagry creeks, Nigeria. J. West Afr. Fish., 5, 241.248.

Soyinka, Olufemi, Olukolajo and Ebigbo, Chikezie Hillary Species Diversity and Growth Pattern of the Fish Fauna of Epe Lagoon, Nigeria. Journal of Fisheries and Aquatic Science, 2012 ISBN 1816-4927.