Allometric Growth Pattern Research Articles

Length-Weight Relationship of Fishes in Some Rivers of Morang, Nepal

The length-weight relationship is a crucial aspect of fishery assessments, providing valuable biological information. The length-weight relationship is expressed by the equation W = aLb, where W represents the total weight of the fish and L denotes the standard length. The LWR equation was transformed into a linear form using logarithmic transformation: LogW = a + bLogL. The biometric data obtained from this study includes information on species, sample numbers (N), standard length range, total weight range, and the length-weight relationship constants (a and b) for each species. In this study, we estimated the length-weight relationship of 16 freshwater fish species from some rivers of Morang district, Eastern Nepal. A total of 1,600 fish specimens, representing 16 different species from 5 families were studied from September 2022 to February 2023. The fishes were captured from the river and preserved in 20% formalin for subsequent biometric measurements in the laboratory. Biometric measurements were taken as follows: for each fish, length measurements were listed as standard length or fork length (SL in cm) from mouth to where the caudal fin is lobate. Length measurements were taken with a regular ruler validated against a Vernier Calliper, with an accuracy of 0.1 cm. Weight measurements were obtained using an electronic digital balance with a precision of 0.01 g. While listing weight, a fish consistency was maintained concerning the degree of wetness of the body to ensure accuracy. Among the species listed in the Morang district, Puntius terio has the smallest range of standard length (2.7 cm - 7.4 cm) and total weight (1.07 g - 7.06 g) while Garra gotyla gotyla has the largest range of standard length (4.3 cm - 18.6 cm) and total weight (4.5 g - 15.6 g). These variations indicate the natural size differences among the species. The analysis of the length-weight relationships revealed that all the studied fish species exhibited a negative allometric growth pattern. This means that as the length of the fish increases, its weight increases at a slower rate. The findings of this study contribute to our understanding of the growth patterns of freshwater fish species in the study area.

Length-Weight Relationships and Condition Factors of Kawakawa Euthynnus affinis and Longtail Tuna Thunnus tonggol from Sarawak, Malaysia

Length-weight relationships (LWR) and condition factors (K) were determined for two neritic tuna species Euthynnus affinis and Thunnus tonggol, caught in Sarawak waters. Specimens were collected from five locations around Sarawak between 2016-2019. The r2 value of the LWR for each species re both close to 1 (>0.9), indicating a highly significant relationship attributed to the length and weight of the fish species . The K values are 1.94 and 1.97, and the values of b in the LW equation are 2.53 and 2.59 for E. affinis and T. tonggol, respectively. The b<3 values indicates negative allometric growth patterns, where the growth rate of body length is faster than the weight gain. These values fall within the published range of 2.50 to 3.50 for neritic tuna species in the region. The results of this study provide the basic life history parameters and the general condition of the two species, E. affinis and T. tonggol, useful for our tuna fish stock assessment efforts in Sarawak waters.

Biological parameters and spawning potential ratio of Longtail Tuna Thunnus tonggol landed in Kranji fishing port, Lamongan District, Indonesia

Abstract. Harlyan LI, Rahman MA, Rihmi MK, Abdillah SFA. 2023. Biological parameters and spawning potential ratio of Longtail Tuna Thunnus tonggol landed in Kranji fishing port, Lamongan District, Indonesia. Biodiversitas 24: 6527-6535. Longtail Tuna (Thunnus tonggol), one of the small-pelagic tropical fisheries in the Fisheries Management Area (FMA-712), is important in supporting global food security. Therefore, to ensure its sustainability, this fishery is applying for fishery certification to be an ecolabel fishery by the Marine Stewardship Council (MSC). However, limited information about Longtail Tuna's biological parameters and stock status in this management area will lead to failure in certification completion. This study aims to provide biological parameters and stock status of Longtail Tuna landed in the Kranji fishing port, Lamongan, Indonesia. Length, weight, and gonad weight of female Longtail Tuna individuals which landed in the Kranji fishing port were conducted from January to April 2023. Several analyses were carried out to figure out the biological parameters of Longtail Tuna, such as length-weight relationship, length at first maturity ( ) and length at first capture ( ) estimation. Length-Based Spawning Potential Ratio (LB-SPR) analysis was conducted to estimate fish exploitation. Results showed that the Longtail Tuna landing in the Kranji fishing port exhibited a negative allometric growth pattern with the length-weight relationship model W = 0.0433 FL2.7608. A comparison between (43.9+0.11cm) and (43.6+0.04cm) indicated that most female Longtail Tuna landed in the Kranji fishing port are mature (60% of the total samples). The LB-SPR analysis showed moderate exploitation status (SPR = 34%). Fishing activities are still manageable in this situation by focusing on stock sustainability. An overlapping fishing ground occurs in the Kranji water, showing the domination of two species landed in the Kranji fishing port, Longtail Tuna and Eastern Little Tuna (Euthynnus affinis). Therefore, Longtail Tuna fishery management might also consider fishery management of Eastern Little Tuna or other species with overlapped habitats.

Population structure of Indian river shad, Gudusia chapra (Hamilton, 1822) from the Rupsha River, south-west Bangladesh

The Indian river shad, Gudusia chapra, is a well-known species of potamodromous fish belonging to the Clupeidae family. The main focus of this study is to state the sex ratio, growth pattern, length-length relationship, form factor, Fulton’s condition factor and relative weight of G. chapra harvested from the Rupsha River (south-west Bangladesh). Altogether 300 specimens (male=166 and female=134) were harvested with the help of commercial fisher folks on seasonal basis (summer, rainy and winter) during 2022. Body weight and length of individual specimen were recorded with digital balance and measuring board. Total length varied between 12.7 to 16.5 cm for males and 13.0 to 17.3 cm for females. Further, body weight ranged between 15.82 to 42.48 g for male and 18.36 to 46.65 g for female. As a whole, both sexes revealed positive allometric growth pattern (b>3.00). Moreover, the length-length relationships were found highly correlated for both sexes. The estimated form factor was 0.0087 indicated fusiform body shape for G. chapra population. The mean Fulton’s condition factor was recorded close to 1 indicated a pleasant health condition for this species. Further, mean relative weight revealed a sound ecological atmosphere regarding prey-predator status. The research outcomes would be helpful to execute a sound management policy in the Rupsha River and connected ecosystem in the south-west Bangladesh.
 

Length-Weight Relationships (LWRs) of Four Loach Species of the Cobitidae Family from the Surma River, Bangladesh

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.

Morphological Character and Percentage of Hotate Clams (Patinopecten Yessoensis) Meat Weight in the Growing Phase, in Funka Bay, Hokkaido, Japan.

This study focuses on the growth and meat weight percentage of Hotate clams (Patinopecten yessoensis) during the rearing phase in Funka Bay, Hokkaido, Japan. Japan, as a major producer of seafood, including Hotate clams, plays a significant role in global seafood consumption. The objective of this study was to analyze the length-weight relationship of Hotate scallops and assess their meat weight percentage during the rearing phase. The research method involved observations using a random sampling technique during the period from August to October 2022. Samples were taken in Funka Bay, with coordinates between 42°20'-42°40' North and 140°00'-141°00' East at a depth of 43 meters. Results showed that the length-weight relationship of Hotate clams during August to October exhibited a negative allometric growth pattern, with the highest constant reaching 2.640. This means that length growth is faster than body weight. The percentage of Hotate clam (P. yessoensis) meat weight during the rearing phase ranged from 31.03% to 35.70%. This study provides important insights into the growth and meat composition of Hotate clams during critical phases in their culture in Funka Bay, Hokkaido, Japan. It can serve as a valuable information foundation for the management and maintenance of sustainable and productive Hotate clam aquaculture in the future.

Some biological aspects of indian mackerel (Rastelliger kanagurta Cuvier, 1817) in Bali Strait waters

Indian mackerel (Rastrelliger kanagurta Cuvier, 1817) is a small pelagic fish species which is the main catch commodity in purse seine and jukung fleets in the Bali Strait waters. Sustainable management is urgently needed for indian mackerel populations in Bali Strait waters to remain sustainable fishery. The availability of basic information such as biological aspects is very important as a fundamental resource in the management of indian mackerel in Bali Strait waters. The aims of this study were to reveal several biological aspects of mackerel such as growth patterns, condition factors, sex ratio, and size at first maturity of indian mackerel in Bali Strait waters. Sampling was carried out in May-September 2018. Samples of fish were taken from purse seine and jukung fleets using trawl nets and gill nets. Fish sample was measured, weighed and dissected to observe the sex and the gonadal maturity stage. The total number of indian mackerel samples was 167 individuals. Mackerel in the Bali Strait waters has a positive allometric growth pattern with fish in good condition. The sex ratio was in an unbalanced condition with the number of male fish being more than the female fish. The size at first maturity was 19.34 cm for male fish and 19.76 cm for female fish.

Ichthyofauna of Merbau River, Leuser Ecosystem Area, Indonesia: species composition, diversity, biometric condition, potency, and conservation status

The Leuser Ecosystem Area (LEA) is one of the largest conservation areas in Southeast Asia. However, the explorations of ichthyofauna at LEA are still relatively scarce compared to other vertebrates fauna. We report the first ichthyofauna studies of the northern river of LEA in Aceh Province. This study aimed to determine the composition, diversity, biometric condition, potency, and conservation status of freshwater fish in Merbau River, LEA, Indonesia. Fish sampling was carried out at six research stations using selective gill nets, throwing net, hook, tray net, and scoop net. A total of 434 individual fish belonging to 21 species, nine families and six orders were collected from the sampling location. Cyprinidae was the predominant family obtained, namely 42.9%. Based on their conservation status, 85.7% of collected fish were categorized as Least Concern, 9.5% as Data Deficient, and 4.8% as Near Threatened. A total of 14 fish have the potential as consumption fish, two species have the potential as ornamental fish, and five others have the potential both as consumption and ornamental fish. All fish species collected had negative allometric growth patterns with growth coefficient values (b) ranging from 1.17–2.51. The diversity and evenness index of fish was categorized as moderate (H’ = 2.52) with stable conditions (E = 0.85).

POPULATION PARAMETERS OF RED SNAPPER (Lutjanus malabaricus) IN ARAFURA SEA FMA 718

The utilization of red snapper (Lutjanus malabaricus) in Arafura waters is already at its optimum point and is classified as over-exploited. Information on population parameters is needed so that management can be sustainable. This study aims to determine several aspects of population parameters (Lc, Lm, L, t0, K, Z, M, F, E). The data collection method uses red snapper sampling including sex, length, and total weight in the 2021-2022 fishing period at PPP Mayangan, Probolinggo. The total number of red snapper samples was 3,077 with the smallest length being 19 cm and the largest being 89 cm. The results showed a relationship between length and weight W = 4,106.10-2 L1,730 with a value of b = 1,730, meaning that b < 3 indicates a negative allometric growth pattern. Average length caught (Lc = 50 cmTL) < Average length at maturity (Lm = 52 cmTL). Based on the Von Bertalanffy model formula, the growth parameter values are obtained, namely asymptotic length (L∞) = 96 cm, growth coefficient (K) = 0.72 per year, and age at zero length (t0) = -0.789. The growth equation is Lt = 96[1-e-0,72 (t-(-0,789))]. The value of natural mortality (=M) is 1.04 per year and the value of mortality due to fishing (=F) is 1.39 per year so the total mortality (=Z) is 2.43 per year. The exploitation value/utilization rate (=E) is 0.57. This shows that the utilization level has experienced more capture and reached the optimum level.

Chinese cities exhibit diverse allometric growth patterns in material metabolism

AbstractRapid urbanization boosts the material demand of cities and leads to serious environmental problems, such as water shortage and air pollution. To achieve better governance of cities, stakeholders need to deeply understand urban material utilization. Taking 327 cities in China as examples, this study analyzes the urban material characteristics from a metabolic perspective. We investigated the spatiotemporal changes in the material base of these cities from 2000 to 2020, including material flow and material stock. We further explored the allometric growth patterns of urban material flow and material stock at different scales (e.g., individual, group, and community). Results show that cities have metabolic processes as natural organisms; they differentiate into many types and exhibit allometric growth patterns. There is a consistency of material metabolic patterns in most cities. The growth of material flows (+43%) and material stocks (+135%) was evident in all cities during 2000–2020. However, the material metabolism of Chinese cities exhibits diverse allometric growth patterns across the individual, group, and community scales. This study can provide simple but effective quantitative indicators for the investigation of urban material utilization, and can support distinct policy implications for sustainable urban material‐based planning and management.

Relationship Between Length and Weight and Habitat Conditions of Several Fish Species in Tondano Lake, Minahasa, North Sulawesi

The snake-head gudgeon or payangka fish (Ophieleotris aporos), tilapia fish or mujair (Oreochromis mossambicus), and marble goby or betutu fish (Oxyeleotris marmorata) are economically important fish in Lake Tondano. However, numerous community activities can disrupt aquatic biodiversity, declining Lake Tondano environmental conditions, and other factors. This study aimed to determine the relationship between length and weight and the habitat conditions of Ophieleotris aporos, Oreochromis mossambicus, and Oxyeleotris marmorata. The method used in this study was purposive sampling with research stations located at Remboken (station 1), Kakas (station 2), and Tondano Estuary (station 3). Sampling was carried out 5 times in every 10 days. The weight and length of the fishes caught in Lake Tondano were 2-60 g and 1-8 cm (Ophieleotris aporos); 9-180 g and 6-25.5 cm (Oreochromis mossambicus); and 16-30 g and 2.6-26.5 cm (Oxyeletotris marmorata), all of them have an allometric growth pattern. Oreochromis mossambicus is the most commonly caught fish in all research stations. The research station with the best level of water fertility is Remboken Station. The habitat characteristic of Lake Tondano was 25-290C of water temperature; brightness of 1.34-2.66 m; depth of 4.23-11.8 m; pH of 6.7-7.8; and dissolved oxygen of 2.27-6.31 mg/L, which still supports the well-being of the fish.

Length and Weight Relationship of Mackerel Fish (Auxis rochei) at Fish Collector Markets in Ampenan, Lombok

Lisong tuna (Auxis rochei) is one of high economic potential value of fish because of its abundance and often found in the fish market in Ampenan. Evaluating the impact of fishing to the growth pattern of length-weight of tuna is needed to ensure the sustainability of lisong tuna population. It is feared that the high intensity of tuna (A. rochei) fishing can cause growth disturbances and a decrease in local tuna populations. This study aimed to determine the relationship between the weight and length of lisong tuna (A. rochei) to their growth patterns in the fish market of Ampenan. Thirty individuals of lisong tuna were collected from two fish markets, Bintaro and Kebon Roek, in Ampenan. The equation of Linear Allometric Model is used to evaluate the length and weight relationship in growth patterns of lisong tuna. This study resulted in the positive allometric growth pattern of lisong tuna with slope value more than 3 (b=3.79). It indicated that the lisong tuna which were collected in Bintaro and Kebon Roek markets have a weight growth rate faster than their length growth rate. It means that the lisong tuna sold in Ampenan markets is quite fleshy and has a good growth rate.

Some aspects of reproductive biology of gangetic ailia, \(\textit{Ailia coila}\) (Hamilton, 1822) in Bangladesh

The present study was conducted by Bangladesh Fisheries Research Institute, Floodplain Sub-station to investigate the reproductive biology of Ailia coila in the northern region of Bangladesh. A total number of 100 fish samples were collected on a monthly basis from the Atrai River and Jamuna River during the period from January 2022 to December 2022. The highest mean value of the gonado-somatic index (GSI) was recorded in July (8.78 ± 1.95%), whereas the lowest was found in December (0.15 ± 0.09%). The highest individual fecundity (2,450 ± 570) and ova diameter (0.38 ± 0.07 mm) was also observed in July. From the histological observation of the ovary, the highest percentages (75%) of mature oocytes were observed during the month of July. Based on the GSI, fecundity and gonadal histology, the breeding season of A. coila was observed from June to August with a remarkable peak in July. In the case of length weight relationship (LWR), the coefficient of determination value (r2) was found 0.96 and the slope was found b = 1.50 which indicated the pattern of negative allometric growth of this species as b < 3. In contrast, an increase was recorded in the fecundity associated with the rise of total length, body weight and gonad weight showed a significant linear relationship. This study would assist in the development of induced breeding techniques and provide valuable information for the sustainable management of this population in the inland open ecosystem.

Unraveling the mating system of the burrowing shrimp Lepidophthalmus siriboia (Decapoda Callichiridae) based on life history traits

Natural history studies are important in helping to understand the origin and evolution of social organization as well as the evolution of specialized morphological structures linked to mating behavior of animals. Here we describe the burrow use pattern, sex ratio, and sexual dimorphism of the burrowing shrimp Lepidophthalmus siriboia to test a series of evolutionary hypotheses. To this end, a total of 259 individuals of L. siriboia were collected from the northeast region of Brazil. No shrimp pairs or burrows inhabited by more than one shrimp were detected during the study period. A solitary habit is a non-random behavior in this species because single shrimps were found with a greater frequency than expected by chance. All ovigerous females were found living solitarily, which suggests that males abandon these females shortly after insemination. Contrary to the expectations of an anisogamous species, L. siriboia produced a female-biased operational sex ratio (OSR), contradicting the hypothesis that only males compete for mates. The latter was supported by the existence of sexual dimorphism in cheliped size, a condition that argues in favor of female–female competition in this species. In the same line of reasoning, heterochely was present in adult males, although it was also present to a lesser degree in adult females. Female asymmetry of chelipeds suggests the evolution of an unconventional role in female major cheliped use. The major cheliped showed a positive allometric growth pattern through the ontogeny of both sexes. However, when growth patterns of the major and minor chelipeds were compared, the fitted regression lines for each sex had different slopes, indicating that the cheliped could be an appendage sexually selected by individuals of the opposite sex during mating.

SEX RATIO AND BIOMETRIC INDICES OF PAMA CROAKER, OTOLITHOIDES PAMA (HAMILTON, 1822) FROM THE BAY OF BENGAL, SOUTH-WEST BANGLADESH

The Pama croaker, Otolithoides pama is a prominent marine species under Sciaenidae family. This Sciaenid fish is a popular table food and a perceptible protein source for Bangladeshi rural people. Our research highlights a comprehensive description of the biometric indices of O. pama sampled from the Bay of Bengal, south-west Bangladesh, together with sex ratio, length-frequency distribution, growth pattern, form factor, Fulton’s condition and prey-predator status. Overall 252 specimens (male = 171 and female = 81) were sampled by gill net during 2022 on seasonal basis (summer, rainy and winter). Length and weight of the sampled fish were assessed with measuring board and digital balance. While the sex ratio (male: female = 1.00:0.47) deviated from the conventional ratio of 1:1, total length varied from 13.0 to 26.7 cm for pooled data. Both sexes revealed negative allometric growth (b < 3.00) pattern as a whole. Form factor (a3.0) was found 0.0074 which stated that the fish possessed a fusiform body shape. The mean Fulton’s condition factor denoted an indecorous state of health. Alternatively, prey-predator status was found quite suitable for O. pama population. The outcomes of our research would be highly effective for executing sound management policy in the marine water of Bangladesh.

Kajian Bioekologi Ikan Dominan Sebagai Bioindikator Kesehatan Lingkungan Di Muara Sungai Kumbe Kabupaten Merauke

River estuaries are a habitat for various aquatic-associated organisms both in the water, on the soil surface and that immerse themselves in the soil. The purpose of this study was to study the bioecology of fish as a bioindicator of environmental health in the Kumbe River Muara, Merauke Regency. This research took place from September to November 2022, carried out along the Kumbe River estuary, Merauke Regency. The data collection method was carried out by purposive sampling and interviews. The results showed that the most abundant species found was snapper (Lates Calcarifer) while the least found was parang fish (Chirocentrus dorab). The diversity index shows the medium category, the uniformity value shows the community is stable and the dominance index shows the dominance value in the area is high. The environmental parameters measured were pH, temperature and salinity. The results showed that it was still in accordance with the quality standards for aquatic biota. The long-weight relationship based on representative fish was found to be dominant, namely snapper (Lates Calcarifer), tilapia (Oreochromis niloticus) and spiny fish (Arius sp.) showing a negative allometric growth pattern. Allometric growth shows that the length growth is not balanced with the weight growthKeywords : Bioecology, Fish, Kumbe River

Length-Weight Relationship and Condition Factor of Oreochromis niloticus (Linnaeus, 1758) in Selected Tropical Reservoirs of Ekiti State, Southwest Nigeria

In Ekiti State, southwest Nigeria, Oreochromis niloticus is significant to live. This investigation was conducted to improve its sustainable management and access the length-weight relationship and condition factor of O. niloticus across important reservoirs in Ekiti State from November 2017 to October 2019. Collected specimens were weighed to the nearest gram, while the entire lengths were measured to the closest centimetre. Log-transformed regression was used to determine the fish's growth pattern in the reservoirs. The gradient comparison was done using the T-test. The length and weight of the species in the reservoirs showed a significant association. All length-weight relationships had r2 values greater than 0.8150 and were significant at P < 0.05. In the length-weight relationship of O. niloticus, the values of the exponent b in Egbe, Ero, and Ureje reservoirs varied from 2.45 to 2.87, 3.02 to 3.20, and 2.45 to 2.82, respectively. The results of regression coefficient b obtained showed that in the combined season, male, female and combined sexes from the Ero reservoir had isometric growth patterns with growth exponent b values of 3.18, 3.20 and 3.19 respectively that were not statistically different from 3. These results contradicted the negative allometric growth pattern in the Egbe and Ureje reservoirs. The condition factor during the dry season ranged from 1.93-2.05, 2.05-2.11, and 1.93-2.03 for fish in Egbe, Ero, and Ureje reservoirs, respectively while in the rainy season, it ranged from 2.00-2.02; 2.08-2.09 and 1.96-2.01 respectively. The fish species studied in the reservoirs lived above- average life and thus indicate that the prevailing ecological conditions in the reservoirs were not beyond the forbearance range for the fish species since their condition factors were within the range considered adequate for freshwater fishes in tropical waters.

Length-Weight Relationship and Condition Factor of Porogobius schlegelii and Bathygobius soporator from Buguma Creek, Rivers State, Nigeria

The present study investigated the length-weight relationship and condition factor of two fish species Bathygobius soporator and Porogobius schlegelii, in Buguma Creek. Over a three-month period (March – May 2018), 2000 different size fish samples each of B. soporator (1000) and P. schlegelii (1000) were collected by artisanal fishermen in Buguma Creek. The study collected total length and total weight data using a meter ruler and a digitally sensitive scale (Sartorius Model H987) for each species allowing determination of the growth exponent(b), coefficient of determination (r2) and mean condition factor values for the fish species. The study found that B. soporator ranged in total length from 7.00 to 18.80cm and from 2.00 to 14.70g, while P. shlegelli measured 4.50 to 11.50cm and weighed 1.30 to 7.10g. The growth exponent (b) ranged from 1.77 to 2.64 for B. soporator and 1.26 to 2.41 for P. schlegelli, indicating a negative allometric growth pattern for the two species, while the r2 values for B. soporator ranged between 0.61 and 0.89 and for P. schlegelli between 0.52 and 0.81 in Buguma Creek. The mean condition factor values for B. soporator ranged from 0.88 to 1.51, while for P. schlegelli it ranged from 0.38 to 0.39, suggesting that B. soporator had a higher condition factor than P. schlegelli, indicating better health and body condition for B. soporator and raising concern for the health of the P. schlegelli population in Buguma Creek. There is therefore an urgent need to establish conservation areas or fishing restrictions to allow the P. schlegelli fish population to recover and maintain a healthy population of the creek.

Length-Weight Relationship and Condition Factor of Ethmalosa fimbriata (Bowdish, 1825) and Mugil cephalus (Linnaeus, 1758) in Coastal Waters of Ondo State

The study aimed at examining the Length-Weight Relationships (LWRs) and Condition factor of M. cephalus and E. fimbriata. 240 fish specimens were collected from November 2021 to April 2022 from Obi, Idiegbin, Okesiri and Araromi following standard methodologies subjected to length-weight relationship and condition factor analysis. The results showed that the mean total length of M. cephalus ranged from 30.96 ± 0.56cm (Araromi) to 23.80 ± 1.16cm (Okesiri) and weight ranged from 118.86 ± 9.36g (Araromi) to 71.32 ± 18.12g (Okesiri). E. fimbriata total length ranged from 21.04 ± 0.74cm (Araromi) to 13.96± 0.38cm (Okesiri) and weight ranged from 150.90 ± 1.14g (Araromi) to 70.54 ± 5.76g (Okesiri). The regression coefficient (b) revealed that both M. cephalus (2.19-1.97) and E. fimbriata (2.06-1.05) sampled in Araromi, Okesiri, Idiegbin and Obi respectively exhibited negative allometric growth. Condition factor range (2.41-1.50) recorded for E. fimbriata was higher than (0.50-0.45) range value recorded for M. cephalus. The study concluded that the two species exhibited negative allometric growth pattern and the environment was for conducive for E. fimbriata than for M. cephalus. The variations in growth of the species could be attributed to prevailing ecological conditions of the environment. Therefore, sustainable fish stock management should be carried out.

Growth pattern and population status of the sea urchin Paracentrotus lividus (Lamarck, 1816) on the Mediterranean coast of Egypt

The present study was carried out to evaluate the growth pattern and population status of the sea urchin Paracentrotus lividus (Lamarck, 1816) in the Egyptian Mediterranean coast off Alexandria City. A total number of 2575 specimens were collected from their fishing grounds during 2017 to 2018. The size classes ranged from 9–57 mm with a mean value of 34.27 mm. Classes from 27 to 41 mm represented about 81.44% of the total collected catch. The length-weight relationship (Wt = 0.0039 L2.3839) reflected a pattern of negative allometric growth. Age was determined using the Bhattacharya’s method based on the length frequency data. Six age or cohort groups were recognized. The Von Bertalanffy growth equations for length and weight were found to be Lt = 71.17[1 – e-0.215(t +0.130)] and Wt = 102[1 – e-0.215(t +0.130)]2.3839. The estimated longevity tmax for the Egyptian urchin was 13.96 years. The growth indices for length and weight were Φ’L = 3.04 and Φ’Wt = 0.67. The values of total mortality (Z), natural mortality (M), and fishing mortality (F) were 1.767, 0.47, and 1.297, respectively. The Egyptian urchin population showed an exploitation ratio of 0.73, indicating an over-exploitation status. The results of the yield per recruit and the relative yield per recruit emphasized the urgent need of fishery management strategies to control the fishing practices of the edible purple sea urchin P. lividus for future sustainability of its wild population off the coast of Alexandria. Further work is also needed to investigate other P. lividus populations along the Egyptian Mediterranean coast and assess their health status.