Reproductive Phenology and Size Structure Characteristics of <i>Hypseleotris agilis</i> (Herre, 1927) in Lake Mainit, Philippines

Hypseleotris agilis locally known as Bugwan is a native species and one of the most abundant fishes of commercial value in Lake Mainit, Philippines. A total of 1,584 H. agilis from Lake Mainit near the mouth of Kalinawan and Puyo River were caught from May 2018 to February 2019 to determine the length-weight relationship (LWR), condition factor (K), gonadosomatic index (GSI) and hepatosomatic index (HSI) of this species. Positive allometric growth was observed for both sexes (b>3). Sex ratio indicated the dominance of males over females as much as 58.7%. The number of ripe males and gravid females was observed throughout the months of the collection, which indicates the ability of the fish species to spawn continuously throughout the year. Determination of GSI in both sexes showed higher values during November (males) and December (females). However, HSI values were relatively low during the spawning season, which would indicate the usage of energy for gonadal maturation. The K factor showed high values during the peak spawning months, directly proportional to GSI values. This study provides updated information for management and conservation of this important fishery resource in Lake Mainit.

The length – weight relationship (LWR), condition factor (K), sex ratio, gonadosomatic index (G S I) and hepatosomatic index (H S I) of 412 specimens of Pseudotolithu s s enegalensis (Valenciennes, 1833) from Tombo , a coastal fishing community in the western rural district of Sierra Leone were studied for twelve months . Samples used for the study were collected from the catches of artisanal fishers and measurement s of length and weight of samples were done in situ using the facilities of the Ministry of Fisheries and Marine Resources. Samples for the reproductive study were preserved in an ice box and taken to the laboratory of the Department of Aquaculture and Fisheries Management, Njala University , Sierra Leone for analysis. The parameters "a" and "b" of the length - weight relationship were estimated using the equation described by Ricker ( W = aL b ) while the condition factor was calculated using Fulton`s equation (K = W1 00 / L 3 ) . The reproductive biology of the fish was estimated using Gonadosomatic index ( GSI ) and Hepatosomatic index ( H S I ) . The combined LWR for both sexes showed that a, b and r values were – 2.57 , 3. 3 5 and 0. 899 , respectively. The r – values obtained show a strong linear relationship between the length and weight of the species. The length - weight relationship indicated allometric growth for P . senegalensis in the study area. The condition factor (K) varied from 0.64 – 1.0 ; this may be attributed to environmental conditions of the water . The species clearly exhibited a positive allometric growth pattern ( tα ( 2) , 0.05, 411 > 1.965) . The sex ratio of males to females was 1:1. 15 and was not significantly different from the expected 1:1 ratio. Estimation of GSI and HSI was carried out from December, 2010 to May, 2011 to determine the spawning behaviour of P. senegalensis . The mean GSI obtained indicate d that March and April , respectively are the two peak spawning period for the species . Gonado somatic index ranged between 1.1 % and 2.8% for the females. The results of this study revealed that P. senegalensis doe s not have obligatory spawning month but exhibit multiple spawning behaviour. T he length - w eight relationships and condition factor of the study indicated that the fish were thriving very well in the coastal water of Sierra Leone. Sustainable management of the species , therefore , require s that the environment be protected against anthropogenic pollution and imposition of closed fishing season especially during the t wo peak spawning period is recommended to enable the species recruit effectively.

Length-weight relationship (LWR), condition factor, sex ratio, gonadosomatic index (GSI) hepatosomatic index (HSI) of the smooth blaasop puffer fish Lagocephalus inermis (Temminck and Schlegel, 1850), an emerging fishery resource along south-eastern Arabian Sea were studied from 1,722 samples collected during August 2017-May 2019 from Mangalore Fishing Harbour, Karnataka, India. LWR indicated negative allometric growth [W = 0.034805L2.76 (males); W = 0.033574L2.78 (females), W = 0.033979L2.77 (pooled)] and significant difference was observed in the b value of the fishes. Sex ratio was 1:1.08. The ratio was unusually high during post-monsoon and Chi-square test revealed that the monthly sex ratio did not vary significantly throughout the year except for December and January (p<0.01). Condition factor (K) and relative condition factor (Kn ) also were not significantly different between sexes. Two peak spawning seasons were identified - NovemberFebruary and August. The GSI was highest in August (female = 8.08 and male = 5.82) and lowest in May (female = 3.32 and male = 3.49). The HSI value was found to be inversely related to GSI and was highest in May (5.21) and lowest in August (3.99). These parameters are essential pre-requisites for stock assessment and sustainable management of the fishery resource.

This study describes the Condition factor, Length-Weight relationship, Gonadosomatic index and sex ratio of Indian mackerel (Rastrelliger kanagurta) which is an important fish in the Kuantan coastal water, Malaysia. Data were obtained from December 2011 to May 2012. A total of 1064 Indian mackerel specimens were studied for this research. Result showed that male was significantly more than female (χ2 = 7.91; P <0.01) in the Indian mackerel population in the Kuantan coastal area. Length-Weight relationship of each month was significant (P<0.01) with all coefficients of determination (R2) values being higher than 0.72. The allometric coefficients (b) of length-weight relationship varied between 2.5128 (April) and 3.0807 (May). A negative allometric growth of Indian mackerel was observed in January, March and April. An isometric growth was observed in December and February, while a positive allometric growth was observed only in May. The b-value of the of the length-weight relationship of Indian mackerel in April was very low compared to other month. The condition factor ranged from 1.0499 to 1.1320. Condition factor was significant different between months (P< 0.05). The significantly lowest mean condition factor was found in December and the highest in February and April. Overall higher mean condition factor was observed in smaller fish of both sex. Overall mean condition factor of female was better than male. Gonadosomatic index of Indian mackerel in February was higher than thouse observed in March and April and followed by May. Gonadosomatic index rapidly increased after January and reached at peak in February. After February gonadosomatic index was declining again. A positive relationship was observed between gonadosomatic index and condition factor of Indian mackerel. The peak spawning season of Indian mackerel in Kuantan coastal water was from February to April. The spawning season of Indian mackerel in Kuantan coastal water falls within the period between end of January and end of May.

The length-weight relationship (LWR) plays an important role in fishery management as it can be used to estimate the average weight of a specific length group. The results of the current study revealed that the mean values of regression coefficient b for both sexes of Schizothorax labiatus (McClelland) in the Jhelum River indicated positive allometric growth, while in the Sindh River, the b value for males indicated positive allometric growth and for females negative allometric growth. The value of coefficient of determination r2 for both sexes of S. labiatus was equal to or greater than 0.90 in both water bodies, except for females in the Sindh River. Higher significant (P &lt; 0.05) average values of Fulton’s condition factor (K) and the hepatosomatic index (HSI) for both sexes of S. labiatus were noted in the Jhelum River than in the Sindh River. In contrast, higher significant (P &lt; 0.05) values of the gonadosomatic index (GSI) were recorded in the Sindh River. The data generated during the current study provide basic information for researchers and fish biologists for the conservation and sustainable management of this commercially important food fish species in the Kashmir Valley.

The Peruvian moonfish (Selene peruviana) is an important fisheries resource that is landed in the main fishing harbors of Ecuador. At the local level, little information is available regarding the biology of this species, which hinders the development of management plans. The present study evaluates the reproductive characteristics of S. peruviana such as the size at sexual maturity and reproductive cycle. Specimens were obtained from artisanal and industrial catches from January 2017 to December 2018. The morphometric characteristics, sex, and maturity stage of 886 specimens were determined, and the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn) were estimated. The length-weight relationship and length at sexual maturity (L50) were evaluated with an allometry equation and multi-model analyses, respectively. The mean capture size (total length, TL) was 23.62 cm for males and 22.97 cm for females. A sex ratio (M:F) of 0.70:1.00 (χ2 = 26.28, P &lt; 0.05) was obtained. The allometric factor of the length-weight relationship for both sexes (b) was 2.63 (t = 12.16, P &lt; 0.05), and the coefficient of determination (r2) was 0.89, which suggests that negative allometric growth was present. The L50 (TL) was estimated to be 22.61, 23.86, and 23.27 cm for males, females, and sexes combined, respectively. The monthly GSI, HSI, and Kn values were significantly different (K-W, P &lt; 0.05) among study months. The maximum GSI values were observed in February and March, which constituted the period of highest reproductive activity. The HSI and Kn values exhibited similar trends. The size at sexual maturity was similar to the average catch size, which could indicate that S. peruviana is currently at the limit of its optimal catch size.

This study examined the population dynamics and seasonal variation (winter-summer) in the biological characteristics of black sea bream (Acanthopagrus schlegelii) in Zhanjiang coastal waters, China. Key growth parameters were estimated using the von Bertalanffy growth model, revealing an asymptotic length (L∞) of 505.05 mm and a growth coefficient (K) of 0.26 year-¹, with an estimated longevity of 11.24 years. Mortality analysis showed a total mortality rate (Z) of 0.35 year-¹, primarily driven by natural causes (M = 0.33 year-¹) with minimal fishing impact (F = 0.02 year-¹), resulting in a low exploitation rate (E) of 0.05. Length-weight relationship (LWR) analysis indicated positive allometric growth in females and nearly isometric growth in males, with significant seasonal variations in condition factors (K). Yield Per Recruit (YPR) analysis identified a maximum sustainable exploitation rate (Emax) of 0.421, with a conservative management approach suggested at E0.1 = 0.355. Seasonal variations in reproductive indices, with higher Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) in winter, highlight the species’ reproductive cycle. The findings suggest that Acanthopagrus schlegelii is stable, with low fishing pressure. Seasonal GSI and HSI variations suggest fisheries management should time fishing to reduce impacts on reproductive success. Maintaining exploitation rates below Emax is essential for sustainable management, contributing valuable insights for fisheries conservation in coastal China.

Although common in the Mediterranean, the morphological and biological characteristics of the moray eel Muraena helena are largely unknown. This study, based on 310 specimens caught using a longline at a depth of 50–100 m, addresses this knowledge gap for northern Tunisia, which is a stronghold of the species. There were significantly more males than females, with a sex ratio of 1:1.5. The number of vertebrae between individuals were variable, especially abdominal and caudal vertebrae (range 56–72; 70–84, respectively). Overall, the total number of vertebrae was less variable (138–146 ± 3.6 SE) and similar between males and females. The length-length relationship recorded for M. helena is provided for the first time, with the pre-anal length (paL), pre-dorsal length (pdL) and the head length (hL) growing faster than the total length (TL). According to the weight-length relationship (WLR), positive allometric growth was established for males (b = 3.6), females (b = 3.46) and combined sexes (b = 3.54). The relative condition factor (CF) did not show significant differences between seasons. The gonadosomatic index (GSI) indicated a significant difference between the seasons for females, whilst the hepatosomatic index (HSI) highlighted a significant difference between seasons for both males and females.

In Ecuador, Peprilus medius is an important fishery resource whose destination is for local consumption and export. There are few local studies on its reproductive biology, and its capture is not regulated. Therefore, this study evaluates the most relevant aspects of its reproductive activity. Samples were obtained monthly from January to December 2017 from the capture of the purse seine fleet and the artisanal gillnet fleet landing near Manta. The morphometric analysis included the length-weight relationship, estimated using the allometry equation. The size at sexual maturity is based on the L50 criterion; the reproductive cycle was determined according to the monthly analyses of the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn). A total of 334 specimens were analyzed, with average sizes of 22.0, 21.87, and 21.91 cm of total length (TL), for males, females, and combined sexes, respectively. Sex ratio was 1.17M: 1F (P &gt; 0.05), while the length-weight relationship showed negative allometric growth for both males and females (b = 2.58; CI95% 2.48-2.72). Size at sexual maturity L50 was estimated at 21.84 and 21.23 cm TL for males and females, respectively. The GSI and HSI values and Kn showed significant differences among months (P &lt; 0.05), with a marked seasonality during the single reproductive period. Mean size at first capture of 21 cm TL is recommended.

The present study describes the length-weight relationships (LWRs), length-length relationships (LLRs), Fulton's condition factor (KF), size at first sexual maturity, spawning season, sex ratio and fecundity of the Morari Aspidoparia morar (Hamilton, 1822) (Cyprinidae). Sampling was done using traditional fishing gear jhaki jal (cast net) from July 2010 to June 2011. Total length (TL), fork length (FL) and standard length (SL) were measured with digital slide calipers. Individual body weight (BW) and gonad weight (GW) were determined to an accuracy of 0.01 g for all specimens. The gonadosomatic index (GSI) was calculated and size at first maturity for males and females estimated using GSI and TL as indicators. Female ≥ size at first maturity was used to determine fecundity. A total of 1200 specimens (males = 552, females = 648) ranging from 4.06–12.84 cm TL and 0.53–16.75 g BW were analyzed. The overall coefficient b for the LWR indicated positive allometric growth (>3.00) in males and isometric growth in females (~ 3.00). ancova (analysis of covariance) revealed significant differences between males and females (P < 0.001). All LLRs were highly correlated (r2 > 0.973, P < 0.001). Sizes at first sexual maturity for males and females were 6.0 and 7.0 cm TL, respectively. KF changed little throughout the year and GSI peaked in November to April, indicating the spawning season (GSImax = 15.0 in females, 2.0 in males). Mature females were dominant during the entire spawning season except in April. Mean total fecundity was 6700 ± 3500, ranging from 1860 to 19680. In addition, relative fecundity ranged from 190 to 1200 (mean 560 ± 235) in the Jamuna River. To ensure sustainable management of this species, the protection of mature individuals during the peak spawning season is highly recommended.

Monthly changes of hepatosomatic index (HSI), gonadosomatic index (GSI), and plasma testosterone (T) levels in the reproductive season of male golden rabbitfish (Siganus guttatus) in captivity were investigated by sampling the liver, testis, and blood. HSI and GSI were estimated as percentage of relative weight of liver and testis to total body weight, respectively. Plasma T levels were measured using enzyme immune assay (EIA). Fragments of the testis were embedded in paraffin, cut to 5μm thickness, and stained with Harris' hematoxylin and eosin. The results included seasonal changes in HSI, GSI, T, and testicular stages. The plasma T levels were observed high at spermation stage and during February-March and May-June. The values of HSI were monthly fluctuations, but no significant differences between testicular stages were observed. The GSI values continuously exhibited a significant increase from December to April and maintained at high levels until June. GSI continuously increased from stage II (immature testis) to stage V (spawning testis). There was correlation between GSI and testicular stages. Histological sections showed that male golden rabbitfish are multiple spawners and spawning season starts from March to June. These results contribute to further understanding of reproductive biology in golden rabbitfish, which can be implicated for artificial propagation.

This study describes some biological traits (allometric relationship, reproductive biology and condition factor) of pikeperch Sander lucioperca at the southern edge of its range. Data were compiled from field studies between January 1997 and January 2009 in three Tunisian reservoirs. Overall, 1497 fish were caught, from which 1308 specimens were sampled and dissected. Sexually undetermined, male and female fish from the different sites exhibited similar allometric growth, expressed through the equation M(T) = 5 × 10(-6) L(T) (3·06) , where M(T) is the total mass and L(T) is the total length. The exponent value is slightly but significantly greater than 3, indicating positive allometric growth. Sex ratio (males:females) was 47:53 but remained balanced only up to 55 cm L(T) and changed with increasing size towards female dominance. Spawning occurred in March and early April according to the changes in female size-adjusted gonad mass or corresponding gonado-somatic index (I(G) ) values. Thermal conditions seemed favourable in February, but March corresponded to the period of equal day and night lengths and the switch towards longer days in terms of photoperiod. Changes in both size-adjusted M(T) or Fulton's condition factor and size-adjusted liver mass or hepato-somatic index (I(H) ) were clearly associated with reproduction. Reserves were consumed during spring in association with spawning efforts. Nevertheless, the delay before the reconstitution of reserves seemed relatively long (from early spring to late summer) although both thermal and trophic conditions could be considered favourable for active feeding of the fish.

Four loaches, namely, Lepidocephalichthys guntea (Hamilton, 1822), Lepidocephalichthys annandalei (Chaudhuri, 1912), Lepidocephalichthys thermalis (Valenciennes, 1846), and Lepidocephalichthys berdmorei (Blyth, 1860) from the Cobitidae family, were collected from the Surma River, Bangladesh. Of the total 376 speciminia, 193 males (51.32%) and 183 females (48.67%) in number; were collected with the support of local fishermen using a variety of nets at 15-day intervals from November 2022 to April 2023. The length-weight relationship (LWR) parameters were analyzed using the equation W = a L b . L. annandalei displayed a notable isometric growth pattern, with a condition factor (K) ranging from 0.725 to 0.734. In addition, L. thermalis exhibited isometric growth among males, while females showcased positive allometric growth with a condition factor (K) varying between 0.697 and 0.714. L. guntea exhibited a consistent positive allometric growth pattern across all aspects, with a condition factor (K) ranging from 0.729 to 0.738. In contrast, L. berdmorei demonstrated positive allometric growth, but males and females both exhibited a negative allometric growth pattern. The condition factor (K) for L. berdmorei ranged from 0.699 to 0.702. This suggests a complex growth pattern influenced by both length and weight in every experimental loach. The research underscores the importance of recognizing gender-specific variations in growth patterns within species.

El bagre marino Bagre panamensis es un recurso pesquero que se explota a lo largo de todo el año y sin restricción alguna en el sureste del Golfo de California. Para manejar de manera adecuada la pesquería comercial de algún recurso, es importante conocer aspectos de su biología básica como la reproducción. En el presente estudio se estimó el periodo de reproducción a través de los índices gonadosomático (IGS), hepatosomático (IHS) y el factor de condición de B. panamensis. Las muestras fueron obtenidas mensualmente entre noviembre de 2015 y octubre de 2016 de la pesca comercial del área de San Blas. Se recolectaron 346 ejemplares de los cuales 182 fueron hembras y 164 machos. Las tallas (longitud total y peso) encontradas no mostraron diferencias entre sexos. La proporción sexual no fue diferente de 1:1 para el total de las muestras. La relación peso-longitud mostró que ambos sexos presentaron un tipo de crecimiento alométrico positivo. De acuerdo al índice gonadosomático (IGS) y el hepatosomático (IHS) se observó que esta especie presenta un periodo de reproducción al año, que va de mayo a agosto. Con base en estos resultados, se podría proponer una estrategia de manejo para esta pesquería en el sureste del Golfo de California.

The present study encompasses studies on the seasonal variation in various biological parameters of snow trout, Schizothorax esocinus collected from River Jhelum. The exponent 'b' of the length-weight relationship depicted positive allometric growth type. Condition factor (K) was significantly ( P<0.05 ) highest in autumn while lowest values were observed in spring and winter. Gonadosomatic Index (GSI) in both sexes was significantly ( P<0.05 ) highest during the spring season (spawning phase) while the lowest value was observed during summer season (spent phase). Hepatosomatic Index (HSI) was significantly ( P<0.05 ) highest in both sexes during the autumn season while as the lowest value was observed during winter season. The study provides information on health status and reproductive cycle of S. esocinus that could help in augmenting the production along with development of appropriate conservation and management strategies.