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Morphometric relationships and condition factors are essential for understanding any marine species' development process, which aids in designing appropriate strategies for management and articulating their balance in the ecosystem — and this includes shrimps. Since only a few studies on these characteristics have been done in Penaeus semisulcatus over the last thirty years, constant updating of these criteria is required to successfully manage the shrimp fishery in Palk Bay. The CL-TW relationship demonstrates negative allometric growth in both males and females, whereas the TL-TW relationship exhibits positive allometric growth. In this present investigation, significant differences in slopes and elevations of the carapace length-total weight, total length-total weight, carapace length-total length, and total length-carapace length have been observed between sexes; considering the condition factors shown in the present investigation, the shrimps in Palk Bay were in good growing condition. This study has demonstrated that updated information on morphometric relationships would help fishery managers effectively manage the fisheries. [ABSTRACT FROM AUTHOR]

The green tiger shrimp, Penaeus semisulcatus , is a commercial species supporting important fishery along the Palk Bay coasts. It is a much sought-after seafood commodity influencing the livelihood of the local fishers. This study aims to investigate the fecundity of the species in relation to its morphometry. Fecundity is an index of reproductive capacity used to calculate a stock's reproductive potential and the egg's survival. The absolute fecundity of the shrimp ranged from 26 100 to 750 000 ova alive per female, and the mean absolute fecundity from 59 100 to 583 000 ova alive per female. The relationship between fecundity and the morphometric measurements showed a positive exponential correlation. One-way ANOVA indicated a significant difference in the different size classes' carapace length, total weight, ovary weight, absolute fecundity, stomach weight, and gastrosomatic index. There was no significant difference between the relative fecundity and the gonadosomatic index. This study provides insight into the reproductive potential of P. semisulcatus for efficient management of the resource in Palk Bay, Tamil Nadu, India. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the spatial and temporal distribution of shrimp species in the Lake Nokoué-Cotonou Channel complex for an efficient management of the fishery. The results of one year sampling from five stations (North, South, East, Central and West) in the complex revealed the following proportions: Penaeus notialis 73.68%, Macrobrachium macrobrachion 13.81%, Macrobrachium vollenhovenii 5.36%, Penaeus monodon 2.68%, Macrobrachium felicinum 2.20%, Penaeus kerathurus 1.72%, Macrobrachium cf. zariquieyi 0.27%, and Macrobrachium equidens 0.27%. The species M. cf. zariquieyi and M. equidens were never reported from Benin, but are now found in Lake Nokoué. Spatially, Penaeus (Penaeus notialis) are more abundant in the west (Acadja concentration zone), while Macrobrachium (Macrobrachium macrobrachion) are more dominant in the east (near the Ouémé entrance) and north (near the Sô entrance) of the lake. Penaeus are strongly present in the lagoon complex from January to August, while Macrobrachium are more abundant in Lake Nokoué from September to December. Spearman's correlation analysis revealed that increasing salinity, pH, transparency and total dissolved solids (TDS) positively influenced the abundance of P. notialis , while increasing salinity, pH, transparency, and TDS negatively influenced the abundance of M. macrobrachion at the 5% significance level. For an efficient management of the shrimp fishery, it is desirable that the shrimp fishery in Lake Nokoué, mainly in the Cotonou Channel, which is a very sensitive area for their seasonal migrations, benefits from at least three months of respite per year, from November to January. This period corresponds to the strong migration of juvenile Penaeus towards the lake. This should allow many Penaeus to grow up and breed at least once in their lives, according to the species' life cycle presented. [ABSTRACT FROM AUTHOR]

The deep-water rose shrimp, Parapenaeus longirostris (H. Lucas, 1846), is the most dominant shrimp species on the Algerian west coast. In that area, the diet of P. longirostris was studied between July 2020 and June 2021. This approach to the diet of the rose shrimp was based on analysis of the stomach contents and determination of the ingested prey. A seasonal sampling was carried out in the main fishing ports (Béni Saf, Bouzedjar, Oran and Mostaganem). The results obtained showed that the shrimp feed intensively in spring and increasingly less in winter and summer. Crustaceans, foraminiferans, polychaetes, and molluscs constituted the most frequent preys in the diet, with respective frequencies of 58.85, 55.95, 36.63 and 32.04%. Small microplancton and mesoplancton prey (radiolarians, copepods, and various larvae) were less important in the diet of P. longirostris. Fish and echinoderms constitute accidental prey, of which the frequency is less than 10%. Résumé: La crevette rose profonde, Parapenaeus longirostris (H. Lucas, 1846), est l'espèce de crevette dominante sur la côte algérienne occidentale. Son régime alimentaire a été étudié, dans cette zone, pour une meilleure compréhension de sa stratégie alimentaire. Cette approche est fondée sur l'analyse des contenus stomacaux et la détermination des proies ingérées. Un échantillonnage saisonnier, entre juillet 2020 et juin 2021, a été effectué dans les principaux ports de pêche de l'Ouest algérien (Béni Saf, Bouzedjar, Oran et Mostaganem). Les résultats obtenus ont montré que les crevettes se nourrissent intensivement au printemps et beaucoup moins en hiver et en été. Crustacés, Foraminifères, Polychètes, et Mollusques constituent les proies les plus fréquentes, avec des fréquences respectives de 58,85%, 55,95%, 36,63% et 32,04%. Les petites proies du microplancton et du mésoplancton (Radiolaires, Copépodes et diverses larves) sont moins importantes dans le régime alimentaire de P. longirostris. Les Poissons et les Echinodermes constituent des proies accidentelles, dont la fréquence est inférieure à 10%. [ABSTRACT FROM AUTHOR]

In Mexico, shrimp catch is the main fishing activity, and the second important species is the blue shrimp, Penaeus stylirostris. Specimens of P. stylirostris collected in 2016-2018 from inland waters (bay) and offshore (littoral) in the Santa María la Reforma lagoon (SMLR) system were analysed. The sexes were separated, and then individuals were measured in total length (L , mm) and weighed (W , g). The data were transformed into a natural logarithm and were adjusted to seven candidate models with a multi-model approach (Linear, Quadratic, Cubic, Broken stick, Two segments, Three segments and Four segments: the last two proposed in this study as new equations). A total of 30 439 specimens were analysed. Statistical differences were found in L between areas (KS test, p < 0.0001). Positive and negative allometry was observed according to biometric relationship and sex. The best model was selected with the lowest value of the Akaike information criterion, resulting in the choice of the Four segments model. Resumen: En México la captura de camarón es la principal actividad pesquera y la segunda especie en importancia es el camarón azul Penaeus stylirostris. Se analizaron especímenes de P. stylirostris en aguas interiores (bahía) y exteriores (ribera) del sistema lagunar Santa María la Reforma de 2016 a 2018. A los organismos se les determinó la longitud total (L) en mm y su peso (P) en g. Los sexos se diferenciaron por dimorfismo sexual. Los datos fueron transformados a logaritmo natural y fueron ajustados a siete modelos candidatos con un enfoque múlti-modelo (Lineal, Cuadrático, Cúbico, Línea Rota, Dos segmentos, Tres segmentos y Cuatro segmentos). En total se analizaron 30 439 organismos. Se encontraron diferencias estadísticas en L entre las zonas de captura (prueba KS, p < 0.0001). Se observó una alometría positiva y negativa de acuerdo con la relación biométrica y sexo. El mejor modelo se seleccionó con el menor valor del criterio de información de Akaike, resultando ser el de Cuatro segmentos. [ABSTRACT FROM AUTHOR]

The yellowlegs shrimp Penaeus californiensis is an oceanic species that approaches the coastal zone for its reproduction. However, in the southern Gulf of California, this species also enters coastal lagoons to grow and reproduce. To test the hypothesis that the growth of P. californiensis differs between these two environments, monthly samplings of shrimp were made in the interior of the Navachiste coastal lagoon and its adjacent marine area. To determine growth, age groups were identified using the size structures over time. Five cases of the Schnute model were adjusted to the data, and the best case was selected using a multi-model selection approach. A sigmoid-shaped curve best represented the female data (case 2), and the inverted exponential curve (case 5; equivalent to the Von Bertalanffy growth function) was best for males. Average growth differed between sexes (p = 0.0097) but not between environments (p = 0.559). Resumen: El camarón café, Penaeus californiensis , se considera oceánico que se acerca a la zona litoral para su reproducción. Sin embargo, en el sur del Golfo de California se ha observado que también ingresa a lagunas costeras para crecer y reproducirse. Para probar la hipótesis de que el crecimiento de P. californiensis difiere en estos dos ambientes, se realizaron muestreos mensuales de camarones en la zona litoral y al interior de la Laguna de Navachiste. Para determinar el crecimiento se identificaron grupos de edad en las estructuras de tallas a través del tiempo. Cinco casos del modelo de Schnute se ajustaron a los datos y se seleccionó el mejor usando selección multi-modelo. La curva de forma sigmoidea es la que mejor describió los datos de las hembras (caso 2) y la exponencial invertida (caso 5; equivalente a la función de crecimiento de Von Bertalanffy) fue la mejor para machos. El crecimiento promedio difirió entre sexos (p = 0.0097) pero no entre ambientes (p = 0.559). [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the patterns in the spatial distribution, size structure, morphometric relationships, and relationships of biomass and size to sampling depth and distance to the coast of Penaeus notialis in the Colombian Caribbean. The biological data were collected on board a shrimp trawler. The females were larger and heavier than the males, which indicated distinct sexual dimorphism in body size. The cephalothorax length at 50% maturity in females was 26.49 mm, and in males, it was 15.13 mm. Relatively high biomass values were found in the southern zone of the study area at depths between 25.6 and 49.3 m and between 3.94 and 7.80 nmi (= 7.29-14.45 km) from the coast. We found a clear spatial structure of biomass and size in relation to depth, so that the fishing effort can be directed to the locations of the adult population. Resumen: El objetivo de este estudio fue evaluar los patrones de distribución espacial, estructura de tallas, relaciones morfométricas, y relaciones de la biomasa y tallas con la profundidad y distancia de la costa de Penaeus notialis en el Caribe colombiano. Los datos biológicos fueron tomados a bordo de un barco camaronero arrastrero. Las hembras fueron más grandes y pesadas que los machos, mostrando un distinto dimorfismo sexual en tamaño. La longitud al 50% de madurez del cefalotórax en hembras fue 26.486 mm y en machos 15.134 mm. Valores relativamente altos de biomasa fueron encontrados en la zona sur del área de estudio, en profundidades entre 25.6 y 49.3 m y distancia de la costa de 3.94 a 7.80 nmi (= 7.29-14.45 km). Se encontró una clara estructura especial de la biomasa y las tallas relacionadas con la profundidad, para que el esfuerzo se pueda dirigir donde la población adulta está localizada. [ABSTRACT FROM AUTHOR]

An abnormal bifid rostrum is reported for the first time for a wild-caught subadult female (carapace length = 22.5 mm) of the pink shrimp Farfantepenaeus duorarum (Burkenroad, 1939) from Celestun lagoon, Yucatan, southern Gulf of Mexico. A review of registers on morphological abnormalities in shrimps of the family Penaeidae is provided. Resumen: Se reporta por primera vez un rostro bífido anormal para una hembra subadulta silvestre (longitud del cefalotórax = 22,5 mm) del camarón rosado Farfantepenaeus duorarum (Burkenroad, 1939) de la laguna costera Celestún, Yucatán, sur del golfo de México. Se proporciona una revisión de registros sobre anormalidades morfológicas en camarones de la familia Penaeidae. [ABSTRACT FROM AUTHOR]

This study was to examine the immunomodulatory effects of oxytetracycline (OTC) on the white shrimp Litopenaeus vannamei (Boone, 1931). Immune parameters were not suppressed by OTC treatment in haemocytes in vitro. A total of 96 healthy shrimp were divided into four groups. Group 1 was the control group. Group 2 received 50 mg OTC/kg body weight/day. Group 3 received 1 g β -glucan/kg feed. Group 4 received 50 mg OTC/kg body weight/day and 1 g/kg β -glucan. OTC residues were more highly accumulated in the hepatopancreas than in muscle tissue during the rearing period, and the addition of β -glucan prolonged the retention time of OTC in the muscle tissue. Additionally, dietary administration of OTC in combination with β -glucan facilitated the excretion of OTC from the hepatopancreas. Shrimp that orally ingested OTC alone had an elevated total haemocyte count, phagocytosis, superoxide anion production and prophenoloxidase activity, and these immunostimulatory effects were further enhanced in shrimp receiving OTC in combination. [ABSTRACT FROM AUTHOR]

The species composition of the Decapoda suborder Dendrobranchiata in waters around and off the Canary Islands has received increasing attention in recent years (Landeira & Fransen, 2012; González & Santana, 2014; Landeira & González, 2018). Shrimps were caught as by-catch of the local artisanal fishery of the striped soldier shrimp I Plesionika edwardsii i (Brandt, 1871) with multiple semi-floating shrimp traps (Arrasate-López et al., 2012; Pajuelo et al., 2018). The checklist of the dendrobranchiate shrimps from the Canary Islands has been recently published by Landeira & González (2018), where a total of 49 species were listed. [Extracted from the article]

Parapenaeus fissuroides Crosnier, 1985 is an emergent fisheries shrimp resource in the benthic community of Kagoshima Bay. The growth pattern and longevity of P. fissuroides were estimated from monthly length-frequency distributions. Carapace length (CL) ranged from 7.7-27.1 mm in males and 6.4-36.1 mm in females. Both males and females were recruited during late autumn and winter. Growth was best described by Pauly & Gaschütz's growth equation as Lt = 25.6(1 - exp(-1.011(t/12 + 0.539) - (0.641/2π) sin(2π(t/12 - 0.577)))) for males and Lt = 34.3(1 - exp(-0.941(t/12+0.227)-(0.581/2π) sin(2π(t/12-0.603)))) for females. Females grew faster and reached larger sizes than males of the same age group. The life-span of P. fissuroides was estimated to be around 2 years for males and 2.5 years for females. [ABSTRACT FROM AUTHOR]

The genus Parapenaeopsis Alcock, 1901 was divided into eight genera by grouping the species included, based on generic features, under Alcockpenaeopsis, Arafurapenaeopsis, Batepenaeopsis, Ganjampenaeopsis, Holthuispenaeopsis, Kishinouyepenaeopsis, Mierspenaeopsis, Parapenaeopsis (then sensu nov.) (Sakai & Shinomiya, 2011a, b). The genus Batepenaeopsis Sakai & Shinomiya, 2011 is currently known to include two species, B. tenella (Spence Bate, 1888) and B. venusta (De Man, 1907). However, in the present paper P. acclivirostris Alcock, 1905 from the Persian Gulf near Kuwait, and a new species, B. moresbyensis sp. nov. from the Central Province, Port Moresby, Papua New Guinea, are presented as new members of the genus Batepenaeopsis Sakai & Shinomiya, 2011. [ABSTRACT FROM AUTHOR]

To select the model that allows the growth curves of juvenile and sub-adult shrimp to be described more accurately, a study was carried out in a coastal lagoon in the south of the Gulf of Mexico on the species Farfantepenaeus brasiliensis (Latreille, 1817) and Farfantepenaeus duorarum (Burkenroad, 1939). The data were obtained from 11 monthly samplings, taken between April 2011 and February 2012, applying the catch strategies used by the local fishermen, including the fishing gear used. The carapace length (CL)-total weight (TW) relationship was estimated for both species. Frequency analyses were performed in order to follow the best represented cohorts over time and fit three non-asymptotic growth models: Power, Generalised Schnute and the Indeterminate Tanaka model. The CL-TW relationship of juvenile and sub-adult F. brasiliensis was TW = 3 Ã-- 10â '5CL3.75 and TW = 8 Ã-- 10â '5CL3.50 for F. duorarum, both of which presented positive allometric growth. In both species the Indeterminate Tanaka model proved to be the best fit to the modal groups of the juvenile and sub-adult shrimp due to its ability to describe the seasonal oscillations in shrimp growth. [ABSTRACT FROM AUTHOR]

The article presents the taxonomic study of the shrimp specie Metapenaeopsis kyushuensis as a senior synonym of the specie Metapenaeopsis lata Kubo. It describes the results of the author's study of the syntypes and topotypic specimens of M. kyushuensis from around Kyushu which reveals that M. kyushuensis is a senior synonym of Metapenaeopsis lata Kubo, 1949. Illustrations are also presented which depict the features of the syntypes of Leptopenaeus kyushuensis Yokoya, 1933.

he species composition and variation in density (postlarvae m-3) of penaeid shrimp postlarvae were surveyed every 14 days in two zones of the Mexican Pacific coast; in the north (Mazatlán, 23°N 106°W) and south (Gulf of Tehuantepec, 15°N 95°W). Sampling coincided with full moon and new moon, and they were carried out with plankton net (0.3 m mouth diameter and 450 μm mesh size). Average sea surface temperature (SST) for 1985-1995 increased from Mazatlán (26.2 ± 0.2°C) to Tehuantepec (28.3 ± 0.5°C). The difference in SST between the coldest and warmest month was 7.8°C in Mazatlán and 3.3°C in Tehuantepec. Four species of penaeid shrimp postlarvae were identified: Litopenaeus vannamei (Boone, 1931), L. stylirostris (Stimpson, 1874), Farfantepenaeus californiensis (Holmes, 1900) and F. brevirostris (Kingsley, 1878). There was a regional variation in the species composition. L. vannamei was abundant at both coasts with 40% and F. californiensis varied from south to north from 45 to 36%; the less representative species were L. stylirostris and F. brevirostris, which varied from south to north from 15 to 24%. The occurrence period near Mazatlán is seven months, and it is year-round in Tehuantepec. This study suggests that warm water and low seasonal SST variability facilitate the presence of the shrimp larvae over a longer period. [ABSTRACT FROM AUTHOR]

The small penaeid shrimp Metapenaeopsis goodei (Smith, 1885) is widely distributed along the Atlantic Ocean, yet information on its morphometric features is scarce or non-existent. This study evaluated differences in the morphometric relationships between sexes of juvenile (carapace length mean: 6.8 mm, range: 3 to 10.5 mm) in a nursery ground of northeastern Yucatan peninsula, Mexico. The morphological features studied were carapace length (CL), total length (TL), rostrum length (RL), relative rostrum length (RL/CL ratio), and total wet weight (W). About 19% of females (n = 207) and 54% of males (n = 167) had size classes of complete sexual maturity reported for this species, i.e., >8 and >6mm CL, respectively. Analysis of covariance detected significant differences between sexes for the TL-CL, RL-CL, RL/CL-CL and CL-W relationships. The coefficient b (slope) of the morphometric relationships decreased about 4 to 20% in females relative to males. The TL-CL, RL-CL and CL-W relationships showed positive allometry for both sexes, but more strongly in males, suggesting that as juveniles increase in CL the males become larger, heavier, and with longer rostrum than females, although males did not reach the same maximum mean CL as females. The positive allometric growth for the CL-W relationship suggests that weight increases more than length, probably because of the abundant food supply on the nursery ground. Results from the current study indicate that separation of morphometric relationships for females and males is necessary for M. goodei that inhabit nursery grounds. Sexual dimorphism in morphometry appears to reflect development to sexual maturity of juveniles in shallow inshore nursery grounds, before migrating to offshore adult habitats. [ABSTRACT FROM AUTHOR]

The article offers information on the first record of the Jinga shrimp. It states that in the Levant Basin, eastern Mediterranean, nine species of alien penaeid prawns are found which include Marsupenaeusn japonicus, Metapenaeus monoceros, and Melicertus hathor. It notes that the mentioned specie of prawns are known from the Turkish coast. It discusses the characteristics and qualities of above mentioned prawns.

A new species of penaeid, Metapenaeus motohi sp. nov. is described based on material from the Philippines. This new species is most closely similar to M. ensis (De Haan, 1844) from Japan in the morphology of the thelycum, but differs in that the rostral teeth mostly number 8-9, the P2, P3, and P5 are elongate, and the distal portion of the petasma forms a narrow lobule with a small genital pore. [ABSTRACT FROM AUTHOR]

This study examines the impact of shrimp trawling on the multi-species shrimp and prawn fishery in the northeastern Mediterranean. Fishing trials were carried out on a commercial prawn trawler between 18 and 23 September 2006. Data were collected with a conventional trawl net, designed specifically for prawns. During six valid trawl hauls, 32 species were caught in total and of the 17 species regarded as commercially valuable, individuals of all sizes of 12 species and those of the relatively larger sizes of 5 species were retained. The other 15 species were discarded as these are regarded as non-commercial due to a lack of market demand. The discard ratio was calculated as 2.37 : 1 for this fishery. The length-frequency distribution of the targeted penaeid prawn, Marsupenaeus japonicus, shows one peak at about 33 mm CL, and the larger specimens, over 35 mm, are all females (25%). However, the also targeted Penaeus semisulcatus shows two major peaks, at 29 and 39 mm CL, and the approximate size ranges connected with those peaks extend from 26 to 32 mm and from 36 to 40 mm CL, respectively; larger specimens, over 34 mm, are all females (37%). The female-male ratio was 1.07 : 1 for M. japonicus and 1.99 : 1 for P. semisulcatus. In the framework of by-catch and discard evaluation, this fishery should be defined as having high by-catch and discard rates. For this reason, gear-based and management-based solutions or measures should be developed to secure those resources for the future, and also to decrease the impact of fisheries on non-targeted species and their stocks. [ABSTRACT FROM AUTHOR]

The size structure of the commercially important rose shrimp, Parapenaeus longirostris, was compared between populations in the Sea of Marmara and the Aegean Sea. The analysis was based on data collected during trawl selectivity surveys carried out in November and December 2006. Growth showed no similar pattern, and in additions differences were found in length frequency distribution, sex ratio, and recruitment pattern of the P. longirostris populations in these two areas. [ABSTRACT FROM AUTHOR]

The vertical distribution of penaeoid shrimp larvae along a 24 hr cycle was analysed from two samplings carried out in distinct periods, i.e., summer and autumn 1993 in the southern Gulf of Mexico. A total of 7238 larvae belonging to the genera Solenocera and Sicyonia, and to the family Penaeidae was collected. In summer, the abundance of shrimp larvae was comparatively lower, with a total of 1062 individuals. The very low number (33 individuals) of Sicyonia larvae collected during this period did not allow detecting a clear vertical migration pattern. In the larvae of the genus Solenocera (837 specimens) and of the family Penaeidae (192 specimens), a typical vertical migration pattern was observed, in which larvae concentrated in shallow strata at dusk, while at dawn they moved toward deeper areas. During autumn, the highest abundance of larvae was obtained, with 6176 individuals captured. Larvae of the family Penaeidae adjusted to the typical vertical distribution pattern of meroplanktonic larvae, with a higher abundance near the surface during the day, and toward deeper strata at night. The Solenocera mysis (1685 individuals) showed a reverse behaviour, with high concentrations between 10 and 45 m depth. The Sicyonia mysis larvae (2465 specimens) increased their dispersion pattern along the water column at night. The distribution of the various penaeid larvae suggests a different vertical distribution behaviour for each group, with some overlap. The Solenocera's tend to remain mainly in the middle of the water column sampled, while Sicyonia larvae show a larger dispersion in that column, and the Penaeidae tend to concentrate near to the surface between 0 and 10 m depth. [ABSTRACT FROM AUTHOR]

In this study, cod end mesh selectivity of braided polyethylene for the deep-water rose shrimp, Parapenaeus longirostris was investigated in the Aegean Sea. Fishing trials were carried out on the commercial trawler, "Hapuloğlu" between 9 and 12 December 2006. Data were collected by a diamond mesh cod end of the 1200 mesh trawl net commercially used. The mean mesh size of the cod end meshes (nominal 46 mm) was measured near to 50 mm by using a calliper rule. Selectivity data were collected by the covered cod end method and analysed by means of a logistic equation with the Maximum Likelihood method. The mean selectivity curves were estimated from the individual hauls that were fitted taking into account the variation between hauls. The 50% retention length and the selection range of combined (male + female) P. longirostris were estimated as 19.6 mm (carapace length) and 6.2 mm, respectively, and there was no significant difference between the L50 values of the male and female sexes (p < 0.05). Consequently, the cod end showed relatively better selectivity considering the size at 50% sexual maturity of the species, and the effect of increased mesh size and of the material used are of great importance in enhancing the size selectivity and reducing the amount of undersized P. longirostris caught in this fishery. [ABSTRACT FROM AUTHOR]

Most studies of the reproductive period of shrimps are based on the percentage of mature females (PMF). The objective of this work was to determine the reproductive period of penaeid shrimp by applying an egg production index (EPI), combining fecundity, size structure, and density of mature females. We also intended to make a comparison with the PMF method. The months of maximum maturity obtained with PMF did not match those of the actual maximum egg production period. This is because PMF does not take into account the abundance, but rather the proportion of mature females. It is concluded that, in order to define the period of maturity of penaeid shrimp, we need at least three indices (fecundity, size structure, and density of mature females) as proposed here, and as comprised in the EPI. [ABSTRACT FROM AUTHOR]

The purpose of this article is to present an overview of the digestive enzymes of penaeid shrimp. The review also covers the effects of circadian rhythms and variations according to moulting cycles on the activities of the various digestive enzymes. [ABSTRACT FROM AUTHOR]

Mortality and yield parameters of the rose shrimp, Parapenaeus longirostris were compared with length frequency data collected from the beam trawl fishery in the Sea of Marmara. Von Bertalanffy parameters were estimated as L∞ = 16.28 cm and K = 0.490 year-1. The rates of total (Z), natural (M), and fishing (F) mortalitiy were calculated as 2.83, 0.97, and 1.86 for a 32 mm PE (polyethylene) cod end. The Z and F rates for two other cod ends, 32 mm PA (polyamide) and 36 mm PA, were, respectively, 2.13 and 1.16, versus 1.57 and 0.60. A study on the relative yield per recruit shows that maximum yield can be obtained at an exploitation rate (E) of 0.53, 0.52, and 0.45, respectively, for 32 PE, 32 PA, and 36 PA cod ends, whereas the current E values are 0.65, 0.54, and 0.38. Consequently, 32 mm PE and PA cod ends cause overfishing pressure on the stock of P. longirostris. [ABSTRACT FROM AUTHOR]

Three new species of the genus Megokris, M. manihine sp. n. and M. halli sp. n. from the South China Sea and the East China Sea, and M. motohburiorum sp. nov. from the Philippines, are described. In these three new species, the rostral teeth as well as the dorsal carinae on abdominal somites 2-6 are very similar to the corresponding structures in Megokris granulosus (Haswell, 1879) from Torres Strait, Queensland, and M. pescadoreensis (Schmitt, 1931) from Taiwan. However, the thelycum and petasma are characteristically different: in M. halli sp. n., the anterior plate of the thelycum bears a longitudinal middle protuberance, which is largely concave laterally in its middle region, and elevated with a round projection in its posterior part; and the anterior plate of the thelycum does not reach the posterior margin of the seminal receptacle. In M. manihine sp. n., the anterior plate of the thelycum bears a median longitudinal protuberance with a median ridge, the posterior part of which is conspicuously elevated with a pair of lateral swellings; the anterior plate of the thelycum does not reach the posterior edge of the seminal receptacle. In M. motohburiorum sp. n., the prominent median protuberance of thelycum is narrow in its anterior half and broadened with an elevation in its posterior half, while the posterior margin is rounded; the anterior plate of the thelycum is connected with the posterior edge of the seminal receptacle. [ABSTRACT FROM AUTHOR]

Some biological aspects of Melicertus kerathurus, a shrimp of high commercial value, were studied in İzmir Bay from April 2004 to December 2004. A seasonal reproduction pattern was observed from April to September with a high percentage of mature females occurring between May and July, when water temperature was relatively high. During the study, a total of 1050 specimens was captured: 612 (58.3%) females and 438 (41.7%) males. The largest female and male were 22.7 cm and 17.0 cm, respectively. The minimum size attained at first maturity was estimated to be 3.9 cm carapace length (CL) and 14.1 cm total length (TL). Sexual differences related to the length-weight relationship were noted. The onset of sexual maturity for females was estimated to be CL50% = 4.6 cm and TL50% = 16.5 cm. [ABSTRACT FROM AUTHOR]

Age, growth, and mortality of the karamote shrimp, Melicertus kerathurus (Forskål, 1775) [formerly: Penaeus k.], were determined for the native population in Amvrakikos Gulf (Ionian Sea; western Greece). Sampling was carried out on a monthly basis between June 1999 and May 2001. Carapace length ranged between 22 and 62 mm. Based on the carapace length frequency distribution, the Gulf population is composed mainly of individuals belonging to the first age class (0 and 1), and only a few from the other two expected age classes. Length frequency distributions and weight-at-age data were used to estimate the parameters of the Von Bertalanffy growth equations. For females, these were: CL∞ = 69.704 mm, TL∞ = 309.14 mm, W∞ = 123.01 g, K = 1.062 year-1, t0 = 0.238 years. For males: CL∞ = 62.658 mm, TL∞ = 274.18 mm, W∞ = 115.979 g, K = 1.253 year-;1, t0 = 0 years. Von Bertalanffy parameters for pooled data were: CL∞ = 59.695 mm, t0 = 0 and K = 1.047 year-1 and TL∞ = 246.79 mm, t0 = 0.410 and K = 0.629 year-1 and W∞ = 92.88 g based on TL. The overall length-weight relationship was: log W = -1.767 + 2.037 log TL (r2 = 0.842, N = 5505). Total mortality Z and natural mortality M rates for combined sexes were 2.26 year-1 and 1.15 year-1, respectively. The exploitation ratio E was estimated to be 49%. [ABSTRACT FROM AUTHOR]

Two new penaeid shrimp, Megokris akademik sp. nov. and M. ghamrawyi sp. nov., are described from the Persian Gulf (= Arabian Gulf). These new species are most closely similar to M. granulosus (Haswell, 1879) from Darnley Island, Torres Strait, in the morphology of the thelycum, with an anterior median concavity, and in the petasma, with an anterolateral projection of an ox-horn shape, tapering at the tip, and directed forward. However, M. akademik and M. ghamrawyi differ from M. granulosus in the posterior margin of the anterior plate of the thelycum, which in the two new species is not fused with the posterior plate as it is in that latter species; also, in M. ghamrawyi the ventromedian process of the petasma has a rounded distal end, whereas in M. granulosus the petasma bears a triangular projection at the distal end of its ventromedian process. [ABSTRACT FROM AUTHOR]

The diet composition of adult and juvenile individuals of the penaeid shrimp, Melicertus kerathurus was determined, based on the analysis of 145 and 48 specimens, respectively, collected off and inside Pinios estuary (N.W. Aegean Sea). The adult individuals displayed a diversified diet, mainly based on Mollusca, Crustacea, and Polychaeta. The diet of the juvenile individuals is also diverse, with Crustacea being the most dominant prey category. Feeding activity of the juvenile M. kerathurus, which are also active predators, seems to be higher than that of the adults. Multidimensional analyses demonstrated that the diets of the juvenile and adult individuals were significantly different. This should probably be attributed to corresponding differences in the composition of the benthic assemblages of the open sea (adult individuals) and inside Pinios estuary (juveniles), as well as to developmental differences between the adults and the juveniles that affect their feeding behaviour. [ABSTRACT FROM AUTHOR]

The penaeid shrimp, Parapenaeus investigatoris Alcock & Anderson, 1899 is widely distributed in the Indo-West Pacific. In the present study, the occurrence of this species was reported for the first time in Japanese waters, based on five male specimens collected in Kagoshima Bay, southern Japan, at 229-230 m depth, using a simple experimental trawl net. One live specimen of P. investigatoris was photographed, and the important morphological characters and body coloration of the live specimens were noted. Kagoshima Bay is now considered to be the northernmost locality in the known distribution of this species. [ABSTRACT FROM AUTHOR]

Methods of length frequency analysis were used to study the growth of the shrimp, Penaeus kerathurus in the Gulf of Gabes. In this area, six trawl surveys were carried out to collect specimens for a series of length frequency distributions. Different techniques (Bhattacharya, Normsep, and Mix) have been used to separate these distributions from their Gaussian component and to determine the average length of the various cohorts. An age was assigned to each mean length (cohort) on the base of previous information regarding the period of spawning and the date of sampling. Growth parameters were calculated using the growth model of Von Bertalanffy (1938) and the data of age and mean length. The mean values of L∞ (mm),K (year), and t0, and their standard deviation (sd) would be for females: 203.43 (sd 15.46), 0.60 (sd 0.16), and -0.88 (sd 0.23), and for males: 157.17 (sd 12.81), 0.78 (sd 0.36), and -1.00 (sd 0.50), respectively. [ABSTRACT FROM AUTHOR]

The penaeid shrimp, Metapenaeopsis sibogae (De Man, 1907) was previously known only from deep waters in Indonesia and the Philippines. In the present study, the occurrence of this species was reported for the first time from Japanese waters, based on twenty-one specimens collected from Kagoshima Bay, southern Japan, between 130 and 148 m depth. As a result of morphological examination, the ratio of rostrum length to carapace length was found a useful character to distinguish M. sibogae from the sympatric species, M. lata Kubo, 1949, and subspecies, M. provocatoria owstoni Shinomiya & Sakai, 2000. The body colouration of live specimens of M. sibogae is also described. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to examine the effects of various starvation-and-refeeding cycles on the growth, food intake, food conversion efficiency, and body composition of the Chinese shrimp, Fenneropenaeus chinensis fed on the polychaete worm, Neanthes japonica. Five groups of shrimp with an initial wet weight of 2.189 ± 0.087 g (mean ± SE) were established: the control (C40) fed ad libitum throughout the experiment; the four treatment groups were subjected to repetitive cycles of starvation-and-refeeding (1 : 4, 2 : 8, 4 : 16, and 8 : 32 days for groups S1F4, S2F8, S4F16, and S8F32, respectively), with each treatment group experiencing 8-day food deprivation and 32-day refeeding during the course of the experiment. Within the same feeding period (32 days), the shrimp subjected to periods of starvation-and-refeeding showed a higher mean percentage weight gain than those fed ad libitum continuously (P < 0.05), however, at the end of the experiment all the treatment shrimp failed to catch up the controls in body weight. This indicated that compensatory growth occurred only partially in the present study. Increased appetite was displayed by the shrimp experiencing cyclic 'nutritional stress', of which those in group S1F4 showed significantly higher food intakes (FIs) in terms of wet weight, dry matter, protein, and energy content than the controls (P < 0.05). Food conversion efficiencies (FCEs) in the most frequently starved and refed group (S1F4) were significantly lower than those in the control group (P < 0.05), while these indices in the other three treatment groups were similar to those in the control group. Feeding regimes significantly affected body lipid content but not water, protein, ash, or energy content. At the end of the experiment, the shrimp in the group S8F32 had the highest lipid content, while those in the S1F4 and the control group had the lowest. All the above results suggest that the Chinese shrimp regulate their appetite and growth rate in relation to different feeding regimes. [ABSTRACT FROM AUTHOR]