World Journal of Agricultural Sciences 5 (4): , ISSN The length-weight relationships (LWR) of fish are calcium in animal feeds and. Abstract. The parameters a and b of the length-weight relationship of the form W = a · Lb were estimated for 57 fish species sampled in São Sebastião Channel. 3(5) Length-Weight Relationships of Marine Ornamental Fish Threespot Humbug . in the world and forms a large part of the global solution to .
The length-weight relationship is one of the standard methods that yield valid biological information. It establishes the mathematical relationship between the two variables length and weight so that the unknown variable can be readily computed from the known variable.
Length and weight data are essential for estimating growth rates, age structure [ 5 ], for calculating the standing stocks biomass [ 6 ], condition indices [ 7 ] and several other aspects of fish population dynamics [ 8 ]. Length-length relationships LLRs are also important in fishery management for comparative growth studies [ 9 ]. Length-length relationships are still scarce for most tropical and sub-tropical fish species [ 61011 ], although LLRs are readily available for most European and North American freshwater and marine fishes [ 12 - 14 ].
The condition factor CF is an index reflecting interactions between biotic and abiotic factor on the physiological condition of fishes. It shows the welfare of the population during the various stages of the life cycle [ 15 ].
Length-weight relationship LWR and length-length relationship LLR of fishes can indicate species status in an environment and characterize patterns of growth [ 1617 ]. Despite the various studies on this subject for marine and freshwater fishes in Nigeria [ 18 - 29 ], there is paucity of information on length-weight relationships and lengthlength relationships of these commercially important fishes from Lake Alau. It is 22 Km from Maiduguri lying at a Latitude: The total area of the lake is about 56 Km2 with a maximum depth of 9m.
It has a distinct tropical savannah climate with a marked monsoonal effect with an average rainfall of mm, humidity The reservoir is characterized with loamy soil and a total storage capacity of 54, ha. The reservoir is a means of livelihood to rural populations who live nearby especially from Maiduguri and Konduga town. A large number of fishes including some commercially important species are fished by both small and large scale fishers throughout the year.
All sampled fishes were identified to species level using standard keys [ 132 ]. After blotting the specimens to remove excess water, total length TL and standard length SL of each fish were measured and body weight BW determined following Kareem et al.
The sex of each specimen was identified by examination of the gonads. The determination coefficient r2 was used as an indicator of the quality of the linear regression [ 34 ]. Tables and graphs were plotted with the use of MS Words and Excel Results and Discussion The sample size and sex distribution for the two-species investigated are shown in Figure 1.
Length-weight relationships of marine fishes from the central Brazilian coast
A total of specimens comprise of Six hundred and two Heterotis niloticus and Nine hundred and eighty-one Raimas senegalensis were collected and used for the length-weight and length- length relationship calculations.
Senegalensis consists of The observed sex distribution among the species showed preponderance of males over females in their population. The sex ratio recorded in this study is in compliance with the works of Achakzai et al. Sample size and composition of Heterotis niloticus and Raimas senegalensis collected from Lake Alau.
The result of the length-weight analysis for H. Senegalensis collected from Lake Alau was presented in Tables 1 and 2. The standard and total length range for H. In fish, condition factor K reflects through its variations and provides information on the physiological state of the fish in relation to its welfare and based on the hypothesis that heavier fish of a given length are in better condition Bagenal and Tesch, Some condition factors reported for fish species include; Clarotes lateceps from the fresh water reaches of the lower Nun river Abowei and Davies, Liza falcipinnis from Badagry creek Lawson et al.
The condition factor is usually influenced by age of fish, sex, season, maturity stages, etc. They were reared in three months in 3. The fish specimen were harvested randomly for this study with scoop net. The fish body weights were taken to the nearest 0.
Total length and standard length were measured with a measuring board taken to the nearest 0. The length-weight relationship was calculated by the least square method for male and female separately and also for combined sexes using the parabolic equation: The condition factor was determined by using the expression: Chi-squared test was carried out on the observed male and female specimens to show the level or proportion of differentiation from the expected 1: RESULTS The length-weight relationship and correlation coefficient r for the two sexes separately and combined relationship for both sexes was logarithmic transformation as depicted in Fig.
The correlation coefficients r were 0. The equations for the length-weight relationship in this study were as follows: The female grows faster by weight than the male as their exponential value was more Table 1.
Length-weight relationships of marine fishes from the central Brazilian coast - Aquatic Commons
The condition factor- length relationship for combined sexes together was represented in Fig. Length-weight relationship of Clarias gariepinus females reared in flow-through system Fig. Length-weight relationship of Clarias gariepinus males reared in flow-through system Fig.
Length-weight relationship of Clarias gariepinus combined sexes reared in flow-through system Fig. Condition factor-length relationship of Clarias gariepinus combined sexes reared in flow-through system Table 1: Regression co-efficient of Clarias gariepinus reared in flow-through system The condition factor for combined sexes ranged from 0.
Chi squared test analysis on sex ratio of Clarias gariepinus reared in flow- through system The chi-square test was used to determine if a population contains equal proportions of males and females and it is a test of how well a model fits the observed data.