Reproductive Biology of Red Pandora ( Pagellus bellottii Steindachner, 1882) from the Coast of Ghana and Implications for Management

: A total of 933 samples of Pagellus bellottii were obtained from the coast of Ghana between January and December 2019, from commercial catches to determine the sex ratio, maturity stages, spawning period


Introduction
The Red Pandora, distributed in the eastern Atlantic portion of the ocean, is mostly found between 10 m and 50 m (Kouame et al., 2018).It is an important component of the multispecies marine demersal fish in the Eastern Central Atlantic (Russell and Carpenter, 2014).P. bellottii is a commercially important demersal fish in Ghana, accounting for about 70% of the demersal fishes landed in Ghana (Lazar, 2017).However, from the coastal waters of Ghana, the catch size of the assessed species is currently on the decline since 2005 which demands proper management measures (Ayivi, 2012).For sustainable management of this species, there is the need for science-based information which largely precipitates from several biological studies including the reproductive studies (Adebiyi, 2012).Studies on reproductive biology of fishes is essential in fisheries management because it provides an understanding of the spawning behavior of the species, dynamics unpinning the dominance of a particular sex, seasonal variations in fish growth, physiological wellbeing of fishes and the dynamics controlling the addition of juveniles to the fish stock (Ismail et al., 2018;Shamsan et al., 2010;Sangun, Akamca, & Akar, 2007;Walker et al., 2005).
Despite the importance of studies on the reproductive biology of fishes to sustainable management, the only study published on Red Pandora in Ghana mainly revolve around population parameters (i.e.Amponsah et al., 2016).In addition, the only study on reproductive biology of P. bellottii is linked to Asare-Ameyaw (2000).The paucity of such important ecological information limits the options needed for sustainable management of this commercially important species.Thus, the objective of this was to provide an update on some aspects of reproductive studies of Red Pandora in Ghana.Such information is a necessary contribution to the ecologically based management of the species from the coast of Ghana.

Study area
The study focused on six fishing communities along the coast of Ghana, namely Elmina, Kpone, Tema, Prampram, Sakumono and Nungua fishing communities along the coast of Ghana (Fig. 1).Table 1 shows the geographical coordinates of the fish sampling communities used in the study.These fishing communities were selected based on the intensity of fishing activities and predominant landing of fish species in the Sparidae family.

Data collection
Samples were sourced from different types of artisanal fishing gears, particularly hook and line from January to December 2019 and identified in situ using Kwei and Ofori-Adu (2005) identification keys.Samples obtained were then preserved on ice and sent to the fish laboratory at the University of Ghana for further analysis.At the laboratory, total length of the samples was measured to the nearest 0.1 cm using a wooden measuring board.A digital balance was used to record body and gonad weight of the specimen to the nearest 0.01g.

Length-Weight Relationships (LWR)
The total length and body weight of fish were used for the Length-Weight Relationships.The Length-Weight relationships were represented using the log transformed procedure: Log W = a + b log TL (Pauly, 1984), where W = body weight (g), TL = total length (cm), a and b are constants for intercept and growth pattern respectively.

Condition factor (CF)
The condition factor (CF) indicates the physiological wellbeing of fishes.This was estimated monthly using the equation: fish weight *100/total length 3 (Froese, 2006).

Maturity stages
Macroscopical assessment for sex and maturity stages was done for each of the gonads obtained.Categorization of the maturity stages was as follows: I, immature; II, resting; III, ripe; IV, ripe and running; V, spent (Chaouch et al., 2013).

Sex ratio
Sex ratio provides information on the representation of male and female fish present in a population.The sex ratio was calculated as the proportion of males to females (Chaouch et al., 2013).

Length at first maturity
For the calculation of the length at which 50% of individuals were matured, only maturity stages III and IV were used.From the cumulative length frequency of matured individuals, 50 % on the cumulative axis was extrapolated to the length axis for the length at first maturity estimation.

Gonadosomatic index (GSI)
Determination of GSI aids in quantifying the changes in gonad weight during the annual sexual cycle and identifying the spawning season.The gonadosomatic index (GSI) was determined as gonadal weight * 100/eviscerated weight (g) (Analbery, 2004).

Data analysis
Variation in reproductive parameters such as GSI, length, and condition factor between male and female individuals were statistically analyzed using a T-test at a significance threshold of P < 0.05.Chi-square test was used to investigate the differences in sex ratio from an expected 1:1 ratio.

Length distribution
The length measurement ranged from 7 cm to 33.9 cm for female individuals with a mean length of 19.6 ± 0.2 cm (Table 2).For male individuals, the mean length was 19.4 ± 0.1 cm with minimum and maximum lengths as 7 cm and 32.3 cm, respectively (Table 2).

Length weight relationship (LWR)
In the LWR, the growth pattern (b) for male and female individuals of P. bellottii was 3.03 (Fig. 2) and 3.02, respectively (Fig. 3).The variation in log transformed length of both male and female individuals explained more than 96 % of the variation in log transformed weight (Table 3).

Condition factor
The condition factor spanned from 1.08 to 1.97 for female individuals and 0.68 to 2.02 for male individuals of P. bellottii.The mean condition factor was 1.36 for males and 1.38 for females, respectively (Table 4).

Sex ratio
A total of 542 males and 391 females were observed out of 933 samples obtained.Sex ratio in the study was favoured by males with a ratio of 1.39 male: 1 female.Chi-square analysis showed significant difference from the theoretical ratio of 1:1 between male and female individuals (Goodness of Fit Chi-square = 24.4,N =533, df=1, p-value <0.001).

Gonadosomatic index (GSI)
The mean GSI for matured female individuals ranged from 0.54 in Octoberto 5.14 in July, with the major spawning peak in July and a minor spawning peak in May (Fig. 4).

Length at first maturity
The size at which 50% of female and male individuals mature was 20.0 cm (Fig. 5) and 20.8 cm (Fig. 6), respectively.

Discussion
Growth pattern of fish species is an essential length weight parameter for managing fish species (Ndiaye et al., 2022).The LWR of P. bellottii from the study showed an isometric growth pattern for both male and female individuals which implies equal growth in length and weight.The implication of the growth pattern (b) for both male and female individuals of the Red Pandora from the study resonated with findings by other researchers such as Pauly (1984); Froese (2006) and Amponsah et al. (2017).Studies by Mansaray and Konomiya, (2020) from the coastal waters of Sierra Leone recorded a negative allometric growth pattern (b > 3.0) for male Red Pandora individuals and isometric growth pattern (b = 3.0) for female individuals.The variation in growth pattern for male individuals may be linked to factors such as seasonal effect, habitat type, stomach fullness level, obtainability of feed items, size variations, weight of species, environmental conditions, maturation stage, health status, and population size (Ndiaye et al., 2022).Nonetheless, the recorded "b" value for both sexes was within the suggested range of 2.5 to 3.5 by Thomas et al., (2003) for most tropical fish species.
The mean condition factor of both male and female individuals of the assessed species was above 1.0 which implies the existence of conducive environmental factors in the marine environment of Ghana.This suggests the relatively sound physiological well-being of both male and female individuals of the assessed fish species.Furthermore, this assertion has been confirmed by other scholars such as Ayode (2011) and Adebiyi (2013).Mansaray and Konomiya (2020) recorded higher condition factor for males than females of Red Pandora which was consistent with finding from this study.The variation in condition factor between male and female individuals may be due to the rate of growth in both sexes and the weight of the individual fishes (Oliveria et al., 2017;Agbugui, 2013).
In the present study, males were numerically more than females, leading to violation of the theoretical ratio of 1:1 for males and females.Findings from the study was similar to studies by Mansaray and Konomiya (2020) and Kouame et al., (2018) from the Ivorian waters and Asabere-Ameyaw (2000) from the Ghanaian waters.The higher number of male individuals than females could be due to high vulnerability of males than females to fishing gears (Vicentini and Araujo, 2003).In addition, spatial or vertical variation of sexes may have contributed to higher number of males than females (Sims et al., 2001).Furthermore, Ali Ben Smida and Hadhri (2014); Benina (2015); Mahdi et al., (2017) and Dobroslavić et al., (2017) have inferred that one of the sexes of fish species will always be predominant.
The most important biological parameter for determining the breeding season of fish as well as their gonadal maturity is the gonadosomatic index (Bindu et al., 2012;Raghavan et al., 2016).The GSI increases with maturity and decreases with the end of gonadal activity after spawning (Jan et al., 2014;Geremew et al., 2015).In the study, a minor spawning period was observed from November -January and a major spawning from March to September based on the variation in GSI.This was similar to studies by Asabere-Ameyaw (2000) who documented minor and major spawning phases in January-February and June to September, respectively.Nonetheless, the relatively small breeding activities observed in all months of the study could suggest a continuous spawning behavior (Lazar, 2017).In addition, ICE (2004) has inferred P. bellottii to be a multi-spawner species fish due the presence of matured individuals all year round.In this study, females reached first maturity earlier than males which was in accordance with findings by Kouame et al., (2018), Ndiaye (2014) from Senegalese waters and Asabere-Ameyaw (2000).Zarrad et al. (2010) attributed difference in size at first maturity to growth differences of populations influenced by temperature and food quality and availability.Also, changes in length at first maturity may be directly connected to demographic density, environmental conditions, differences in reproductive biology, growth rates, fishing catches, availability of food, and hydrological conditions (Perez-Palafox et al., 2021).Nonetheless, the size at first maturity for both males and female individuals was similar to those estimated by Asabere-Ameyaw ( 2000), but higher than the estimates by Amponsah et al. (2016) which may be due to differences in the scientific approach used in the estimation process.Size at sexual maturity (L50) is an essential parameter for fisheries management as it gives the authorities to decide on mesh size in fishing zones and therefore, to avoid fishing juveniles (Hossain et al., 2013).The use of appropriate meshes will prevent the capture of immature individuals and therefore, sustain the potential for reproduction (Lin et al., 2013).

Conclusion
This study sheds light on some aspects of the reproductive biology of the Red Pandora in the coastal waters of Ghana.The results revealed that male and female individuals of Red Pandora exhibit isometric growth with a mean value of condition factor greater than 1.0.The sex ratio of individuals in the study favored males.GSI studies displayed two spawning periods.This information will contribute to knowledge essential for sustainably managing the population of P. bellottii in Ghana.

Figure 2 .Figure 3 .
Figure 2. Linearized length weight relationship (LWR) of female individuals obtained during the study period

LogFigure 4 .Figure 5 .Figure 6 .
Figure 4. Monthly estimated GSI of individuals obtained during the period of sampling

Table 1 .
Geographical coordinates of sampling locations

Table 2 .
Descriptive statistics of length distribution of male and female individuals of P. bellottii

Table 3 .
Regression output for LWR of male and female individuals of P. bellottii obtained during the study period

Table 4 .
Descriptive statistics of condition factors of P. bellottii