Aspects Of Reproductive Biology Research Articles

Aspect of Reproductive Biology of Fish of Commercial Importance in Sabke Reservoir, Katsina State

Aspects of the reproductive biology of the most economically important fish species in Sabke reservoir was investigated such as Fecundity for females, average egg diameter, Gonado Somatic Index (GSI), for a period of twelve month (from March 2009 to February 2010).Samples of fish were collected through both experimental gears and commercial catches from local fishermen fortnightly. Fecundity range of 222 – 9642, and mean of 14652 ± 2600, 197 – 4414, 1110 ± 1162, 77 – 2007, 712 ± 541, 183 – 3290, 1178 ± 901, 265 – 2467, 854 ± 677 was calculated for Clarias gariepinus, Lates niloticus, Tilapia zilli, Oreochromis niloticus and S. galilaeus respectively. Mean annual GSI and average egg diameter of C. gariepinus, L. niloticus, T. zilli, O. niloticus and S. galilaeus of 0.85mm, and 0.60mm, 0.63, and 0.84mm, 1.36 and 1.68mm, 1.83,and 2.02mm, 2.26, and 2.82mm respectively. In general Sabke reservoir indicates positive indices for high fisheries potential. Key words: Fecundity, egg diameter, Gonado Somatic Index

Effects of environmentally relevant concentrations of the xeno-androgen, methyldihydrotestosterone, on male and female mating behavior in Xenopuslaevis

Endocrine disrupting compounds (EDCs) are well known to interfere with the hormone system of aquatic vertebrates and to affect their reproductive biology. 17α-Methyldihydrotestosterone (MDHT) is a widely used model compound for the assessment of androgenic EDCs, because it binds with high affinity to nuclear androgen receptors. It was previously shown to affect various aspects of reproductive biology in aquatic vertebrates, however, evidence for MDHT affecting mating behavior of aquatic vertebrate species is lacking. In order to test the assumption that MDHT affects reproductive behavior of aquatic vertebrates, we exposed male and female Xenopuslaevis to three environmentally relevant concentrations of MDHT (30.45ngL−1, 3.05μgL−1 and 30.45μgL−1). In males, MDHT at all concentrations led to enhanced levels of advertisement calling and decreased the relative proportions of rasping, a call type characterizing a sexually unaroused state of the male, indicating an increase in sexual arousal of MDHT exposed males. Temporal and spectral parameters of the advertisement call itself, however, were not affected by MDHT exposure. In females, MDHT (30.45ngL−1) did not have any effects, while MDHT at 3.05μgL−1 increased female receptivity, increased the duration of time females spent close to the speaker playing male advertisement calls and reduced their latency to respond. MDHT at 30.45μgL−1, on the other hand, decreased female receptivity and increased their latency to respond. In summary, this study illustrates that exposure to environmentally relevant concentrations of the androgenic EDC MDHT affects male and female mating behavior of X. laevis. Hence, we suggest that nonaromatizable androgens might play a direct and predominant role in the physiology and regulation of reproduction not only in male but also in female frogs.

Materials on some aspects of reproductive biology of Whitson’s grenadier Macrourus whitsoni (Macrouridae) in the Ross Sea

Data on oogenesis, spawning, and fecundity of Whitson’s grenadier Macrourus whitsoni in the Ross Sea (Antarctica) are presented. During maturation of oocytes, their development becomes asynchronous, and their hydration occurs only in a part of the cells; thus, oocytes are released in batches. Spawning is observed in summer of the southern hemisphere. Based on a preliminary assessment, the average absolute individual fecundity reaches 28000 eggs, and average relative fecundity is approximately 11 eggs/g of the total body weight. The possibility of none-synchronous release of oocytes is discussed in other Antarctic fishes.

Development and characterization of a novel set of microsatellite markers for Arisaema serratum (Araceae)

We developed novel microsatellite markers in Arisaema serratum, a perennial herb that possesses pitfall flowers and exhibits labile sex expression, to facilitate research on parentage and pollination biology in this species. By using procedures for enrichment of desired microsatellite-containing fragments and PCR-based isolation of microsatellite arrays, we detected 18 novel microsatellite loci. Thirteen were highly polymorphic: the number of alleles per locus ranged from six to 46, the observed heterozygosities ranged from 0.320 to 0.940, and the expected heterozygosities ranged from 0.440 to 0.976. Nine of the 13 markers successfully amplified regions in congeneric species. These highly polymorphic markers will facilitate further studies on the mode of pollination and other aspects of reproductive biology in A. serratum.

They produce the sperm, but whose is it? The 11th Biology of Spermatozoa Meeting, September 5-9, 2011--Derbyshire UK

Sperm biology pervades numerous research areas from clinical research to evolutionary biology and animal conservation. Integrating these fields for a better understanding of each is one of the main goals of the Biology of Spermatozoa meeting, a conference held biennially outside of Sheffield in the United Kingdom. This September, at the 11th meeting, scientists from around the globe presented their ongoing research on numerous aspects of reproductive biology, from assisted reproduction in humans and animal conservation through stem cell research and proteomics to sophisticated evolutionary adaptations of ejaculates and female reproductive traits in order to bias paternity toward one or the other male in situations of female promiscuity. Throughout the conference, ethical controversies with reproductive applications (e.g., sperm banking) found their place just as much as novel clinical technologies (e.g., sperm quality assays) or major advances in understanding the mechanisms underlying fundamental processes of postcopulatory sexual selection (e.g., using transgenic animals that produce fluorescently labeled sperm). Across a wide range of different taxa, this meeting has presented a fascinating synthesis of current research and emerging directions in the study of sperm biology.

The biology and evolution of polyspermy: insights from cellular and functional studies of sperm and centrosomal behavior in the fertilized egg

Recent studies of centrosome biogenesis, microtubule dynamics, and their management point to their role in mediating conditions such as aging and cancer. Centrosome dysfunction is also a hallmark of pathological polyspermy. Polyspermy occurs when the oocyte is penetrated by more than one sperm and can be pathological because an excess of centrosomes compromises development. However, in some taxa, multiple sperm enter the egg with no apparent adverse effect on zygote viability. Thus, some taxa can manage excess centrosomes and represent cases of non-pathological polyspermy. While these two forms of polyspermy have long been known, we argue that there is limited understanding of the proximate and ultimate processes that underlie this taxonomic variation in the outcome of polyspermy and that studying this variation could help uncover the control and role(s) of centrosomes during fertilization in particular, but also mitosis in general. To encourage such studies we: 1) describe taxonomic differences in the outcome of polyspermy, 2) discuss mechanistic aspects of reproductive biology that may contribute to the different consequences of polyspermy, and 3) outline the potential selective events that could lead to the evolution of variation in polyspermy outcomes. We suggest that novel insights into centrosome biology may occur by cooperative studies between reproductive and evolutionary biologists focusing on the mechanisms generating variation in the fitness consequences of polyspermy, and in the taxonomic distribution of all these events. The consequent discoveries of these studies may lead to informative insights into cancer and aging along with other centrosome-related diseases and syndromes.

Reproductive biology and condition factor of the catfish Bagrus docmak (Forsskål) (Pisces: Bagridae) in Lake Chamo, Ethiopia

Some aspects of reproductive biology, length-weight relationship and condition factor of 534 (258 males and 276 females) Bagrus docmak (Forsskal) in Lake Chamo were studied from samples taken during February 1995 to February 1996. B . docmak had an extended breeding period from February to August, with peak spawning in May for both sexes, when 76.2% males and 78.3% females had ripe gonads. The main pulse in breeding activity occurred during the rainy months of April and May. The overall sex ratio (male: female) was 1:1.07 which did not deviate significantly from the hypothetical distribution of 1:1 ( x 2 =0.61, p>0.05). However, sex ratio was significantly different from 1:1 in the samples >90 cm fork length (FL) ( x 2 = 10.71, p 2 = 0.75, p 2 = 0.73, p 2 = 0.90, p B . docmak is best expressed by the equation TW= 0.0054FL 3.24 . Monthly Clark’s condition factor (mean +/- SE) ranged from 0.426± 0.011 to 0.489± 0.014 for males and from 0.449± 0.010 to 0.489± 0.012 for females.

Reproductive Biology of Freshwater Murrel, Channa punctatus (Bloch, 1793) from River Varuna (A Tributary of Ganga River) in India

Aspects of reproductive biology such as sex ratio, size at first maturity, spawning, gonadosomatic index, ova diameter and fecundity of Channa punctatus from river Varuna were investigated for a period from March 2007 to February 2008. On the basis of monthly variation, the overall sex ratio (M: F) was 1: 1.33. Chisquare test showed no significant departure in sex ratio. Five stages of maturity were recognized in both the sexes. For the population, 50% of individuals belonging to the size of 125 mm were mature for the first time. The spawning season extends from June to October. Gonadosomatic index reaches maximum in August. Only one batch of ova is produced to be released in one spawning act. Absolute fecundity varied from 3,678- 27,853 with an average value of 12,546 in the individuals ranging between 116-231mm in length and 18-139.8 g in weight. Length wise, the average relative fecundity recorded was 708 eggs/mm body length and weight wise it was 175 eggs/g body weight of the fish. Relative fecundity per mm of ovary length was 2,729 and per gm of ovary weight was 5,449. Mean absolute fecundity increased with total length, body weight, ovary length, ovary weight and exhibit linear regression equation derived from the logarithmic transformed data. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. punctatus in its natural habitat.

Estimation of Dietary Composition and Fecundity of African Carp, <i>Labeo Coubie</i>, Cross River, Nigeria

Dietary composition and aspect of reproductive biology (fecundity and sex ratio) of African carp was investigated for 12 months. Specimens were collected from artisenal fishermen, measured for Length (cm) and weight (g), examined for genital papilla in the male and the stomach removed for food analysis. The main food categories were crustaceans, rotifers, insects, worms, plant parts and mud. The index of relative importance (IRI) values indicated that 13 out of the 21 food items were major diet components. The prominence of detritus in the diet indicated that L. coubie is a bottom feeder and is euryphagus. Fifty eight (58) 28.6% out of the 205 females had matured gonads. Absolute fecundity ranged from 679 to 15073 eggs. The relative fecundity ranged from 40 to 793eggs/Length (cm) and 64 to 286 eggs/weight (g). Spawning was between the months of May through August. The Length – Weight yielded significant results for female than male indicating that, females were in better condition than the males. The overall sex ratio of L. coubie was 1:1.67 in favour of females. The wide food range and high fecundity made L. coubie suitable for pond culture. @ JASEM J. Appl. Sci. Environ. Manage. December, 2010, Vol. 14 (4) 19 - 24

The prevalence of helminthofauna and fecundity studies in west African lungfish, <i>Protepterus annectens</i> Owen, 1839 (Dipteriformes: Lepidoserinidae) in river Anambra, Nigeria

An investigation was conducted on the helminthofauna and some aspects of reproductive biology of the West African lungfish, Protopterus annectens in River Anambra, Nigeria, between May and July, 2008. The sample comprised forty two fishes purchased from fishermen and fish mongers at Otuocha fish market, a major fish landing location in the Anambra River Basin. The sex composition of the sample which was 1:41 (male: female) is thought to reflect a preponderance of female fish in the natural population of P. annectens in the river system. Heterorchis protopteri, a digenean, was the only helminth parasite recovered, infesting 6 (six) out of the 42 fish.33 worms were recovered, giving a prevalence of 14.29 %, mean intensity of infection of 5.5 and mean abundance of 0.8 for the parasite in the fish population. The infection parameters increased with size of fish (weight and length). No parasite was recovered from the lone male fish examined, and this could be attributed to sample size. H. protopteri is reported from P. annectens in Nigeria for the first time. All the female fish examined were gravid while the lone male fish had ripe testes which indicate that P.annectens spawns in the river system in the wet season. Fecundity of the species was estimated to be about 1423 eggs per female and P. annectens is categorized as a mesofecund species. It is suggested that some form of regulation of cropping of P. annectens in the river system should be put in place pending a clearer understanding of its ecology, in order to reduce the chances of harming the recovery capacity of the species.Keywords: Protopterus annectens, River Anambra, Heterorchis protopteri, fecundity, spawning.

Aspects of Reproductive Biology in Mudskipper, Periophthalmus papilio from Mangrove Swamps of Lagos Lagoon, Lagos, Nigeria

The present study was conducted on aspects of reproductive biology of mudskipper, Periophthalmus papilio (Bloch and Schneider 1801) from the mangrove swamps of Lagos lagoon in Nigeria. P. papilio is an economically valued fish species, both as food for the populace and baits for industrial or offshore fisheries in Nigeria and the entire coasts of West African sub-region. 2167 individual fish were caught from the lagoon with non return valve traps between May 2006 and May 2008. Data on sex, total length (TL), gonad (GW) body weight (BW) measurements were carried out on individual specimen. These data were used in the determination of sex ratio, gonadosomatic index (GSI), and maturation in this species. The sex ratio of 1 male to 1.42 females was observed but was not significantly different (X 2 =57.04>X 2 1, 0.05=3.84) but a departure from the theoretical 1male:1female sex ratio. Females population were more than the males. The GSI values varied from 0.01 to 0.48% in males and between 0.11 and 8.40% in females. 0.104±0.004 (in males) and 2.69±0.03% (in females) of the body mass were used in gonad development. The eggs were as small as 0.20mm and as big as 0.50 mm (mean = 0.36±0.01 mm) in diameter for average fish of 116 mm TL.. Seven (7) stages of maturity: immature, immature and developing, ripening, ripe, ripe running, spent, and resting/representing the pre-, spawning and post spawning period were encountered in this study. The fish were identified as male at 70 mm TL and as females at 60mm but riped at 90mm TL. The maturity of females was earlier than the males. The maturity stages obtained from the present study were in conformity with those reported in other teleosts though with modifications. Therefore, the sex ratios, egg diameters, gonadosomatic index and maturation of the species in Lagos lagoon were investigated to provide baseline data for future ecological and biological studies of this species and other species within the Nigerian mangrove swamps, estauaries and coastal waters. (LAWSON Emmanuel O. Aspects of reproductive biology in mudskipper, Periophthalmus papilio from mangrove swamps of Lagos lagoon, Lagos, Nigeria. New York Science Journal 2010; 3(11):103-110). (ISSN: 1554-0200).

Reproductive biology aspects of two species of the genus Gavilea (Orchidaceae, Chloraeinae) in populations from Central Chile

El alcance al cual las plantas dependen de polinizadores para el transporte de polen para los exocruzamientos es uno de los temas claves en ecologia reproductiva de las plantas. Evaluamos el sistema reproductivo potencial, despliegue foral y polinizacion natural en dos orquideas del Cono Sur de Sudamerica, Gavilea araucana y G. venosa, efectuando cuatro ensayos de polinizacion manual (agamospermia, autogamia, geitonogamia y xenogamia) y contando cada for y fruto producidos por las plantas en condiciones naturales. La produccion de frutos difrio signifcativamente dependiendo del origen del polen asi como de la presencia de un vector polinico. Ninguna de las especies produjo frutos en las pruebas de agamospermia indicando, por lo tanto, que ellas requieren de la presencia de polen en los estigmas para producir frutos. Por el contrario, solamente G. araucana fue capaz de producir frutos siguiendo la prueba de autogamia demostrando, por ende, que esta orquidea no necesita depender de polinizadores para producir frutos. Ademas, G. araucana y G. venosa produjeron un 100% de frutos por geitonogamia y xenogamia, indicando esto, que ambas plantas son autocompatibles. El numero promedio de fores por planta fue 2,1 veces mayor en G. venosa con respecto a G. araucana; sin embargo, el exito en la fructifcacion natural fue de 28,8% y 98,9%, respectivamente. Ademas, mientras el incremento en el exito de la fructifcacion se correlaciono positiva y signifcativamente en G. araucana, en G. venosa estas variables no estuvieron relacionadas. Ciertamente, estudios adicionales referidos a las estrategias reproductivas de las orquideas del sur de Sudamerica son de gran importancia.

Population growth, trophic level, and reproductive biology of two congeneric archer fishes (Toxotes chatareus, Hamilton 1822 and Toxotes jaculatrix, Pallas 1767) inhabiting Malaysian coastal waters

Population growth, trophic level, and some aspects of reproductive biology of two congeneric archer fish species, Toxotes chatareus and Toxotes jaculatrix, collected from Johor coastal waters, Malaysia, were studied. Growth pattern by length-weight relationship (W=aL(b)) for the sexes differed, and exhibited positive allometric growth (male, female and combined sexes of T. chatareus; female and combined sexes of T. jaculatrix) and isometric growth (male samples of T. jaculatrix only). Trophic levels of both species were analyzed based on 128 specimens. The results show that, in both species, crustaceans and insects were the most abundant prey items, and among crustaceans the red clawed crab Sesarma bidens and Formicidae family insects were the most represented taxa. The estimated mean trophic levels for T. chatareus and T. jaculatrix were 3.422+/-0.009 and 3.420+/-0.020, respectively, indicating that they are largely carnivores. Fecundity of T. chatareus ranged from 38 354 to 147 185 eggs for females with total length ranging from 14.5 to 22.5 cm and total body weight from 48.7 to 270.2 g, and T. jaculatrix 25 251 to 150 456 eggs for females with total length ranging from 12.2 to 23.0 cm and total body weight from 25.7 to 275.0 g. Differences in values of gonadosomatic and hepatosomatic indexes calculated for both species in this study may have resulted from uneven sample size ranges.

Rapid rates of sperm DNA damage after activation in tench (Tinca tinca: Teleostei, Cyprinidae) measured using a sperm chromatin dispersion test

Spermatozoal haplotypic DNA is prone to damage, leading to male fertility problems. So far, the assessment of sperm DNA breakage has been challenging because protamines render the nuclear chromatin highly compacted. Here, we report the application of a new test to quantify DNA fragmentation in spermatozoa of an externally fertilizing teleost fish. The sperm chromatin dispersion (SCD) test uses a species-specific lysing solution to generate controlled protein depletion that, followed by DNA-specific fluorescent labelling, allows an easy morphological discrimination between nuclei affected by DNA damage. Using tench (Tinca tinca) as our model, we first trialled the test against established, but more technically demanding, assays employing in situ nick translation (ISNT) and the comet assay. The SCD test showed high concordance with ISNT, comet assay measures and a chromatin-swelling test, confirming the application of this straightforward SCD technique to various aspects of reproductive biology. Second, we examined between-male variation in DNA damage, and measured changes through time following spermatozoal activation. Between-male variation in the basal levels of average DNA damage ranged from 0 to 20% of sperm showing damage, and all showed increases in DNA fragmentation through time (0-60 min). The rates of DNA damage increase are the fastest so far recorded in sperm for a living organism, and may relate to the external fertilization mode. Our findings have relevance for broodstock selection and optimizing IVF protocols routinely used in modern aquaculture.

SISTEMAS DE ACASALAMENTO E BIOLOGIA REPRODUTIVA EM AVES AQUÁTICAS NEOTROPICAIS

The present paper reviews the published information on the mating systems and reproductive biology of Neotropical waterbirds. Thirty-four scientific articles were included, which were divided into two main themes: “mating systems” (10 articles) and “reproductive biology” (24 articles). Extra-pair copulation and/or fertilization were reported to occur in 60% of the Neotropical species investigated, while monogamy was reported in 22%, bigamy in 11% and nest parasitism in 11%. General aspects of reproductive biology of 30 species were more extensively reviewed, of which 20 were seabirds and 10 were lacustrine species. Aspects most frequently described were reproductive chronology (73% of species), clutch size (80%) and reproductive success defined by the number of hatched eggs (73%). Only one species in Sulidae (Sula leucogaster) and one in Threskiornithidae (Eudocimus rubber) were studied for both, mating system and reproduction. A global analysis of the available data revealed that seabirds and Ciconiiformes birds were most intensively studied in terms of reproductive biology, while their mating systems remain largely uninvestigated.

513. LOSS OF BETAGLYCAN DISRUPTS SOMATIC CELL DIFFERENTIATION IN THE FETAL MOUSE OVARY

Betaglycan (TGFBR3) is an accessory receptor that modulates the activities of members of the TGF-beta superfamily of growth factors which regulate many aspects of reproductive biology. We reported the presence of betaglycan on somatic and germ cells in fetal murine ovary from 12.5 dpc [1]. However, the role of this receptor in early ovarian development is poorly understood. We hypothesised that, given its expression pattern, betaglycan could serve as a TGFb accessory receptor on both oogonia and somatic cells during early ovarian development. In the current study, we examined the Tgfbr3 (betaglycan) null and wildtype ovary from 11.5–14.5 dpc. During this window of development, no overt morphological phenotype was detected, and cell proliferation (PCNA immunostaining) and apoptosis (active caspase 3 immunostaining) were unchanged in the null ovary. To determine whether somatic and/or germ cell markers were altered in the absence of betaglycan, quantitative real time PCR analysis was conducted using total RNA derived from 11.5–14.5 dpc betaglycan wildtype, heterozygous, and null ovaries (n=3 at each age/genotype). From 12.5 dpc, genes associated with the differentiation of the female somatic lineages Wnt4, Fst, Bmp2 were significantly decreased in the null ovary by 30%–50% (P<0.05) while germ cell markers (Oct4, Mvh) showed no significant changes compared to wildtype ovary. Genes associated with the testis-differentiation pathway (e.g. Sox9, Cyp11a1, Cyp17a1, Hsd3b, Insl3, Dhh) were not aberrantly expressed in betaglycan null or heterozygous ovary, with expression levels very low to undetectable. Collectively, these data suggest that while betaglycan does not appear to play a key role in establishing the structure of the ovary, loss of this receptor results in a disruption to the differentiation of ovarian somatic cells.

Frequency of spermatophore production and regeneration in the males of Tityus (Atreus) magnimanus Pocock, 1897 (Scorpiones, Buthidae)

The frequency of spermatophore production and the amount of time between matings for laboratory-reared males of Tityus (Atreus) magnimanus to regenerate spermatophores were examined. Males attain sexual maturity at the fifth or sixth instar (after a period of 137 to 155 days) and can produce initial spermatophores shortly after maturation. After mating, males can regenerate spermatophores within a single 24-hour period and remate. The present contribution represents the first report on an aspect of reproductive biology in this species and is part of a continuing study of the life history and post-embryonic development of Tityus (Atreus) magnimanus.

Systematics, phylogenetic relationships and conservation of the taxa of Anchusa (Boraginaceae) endemic to Sardinia (Italy)

Sardinia is a major centre of diversity of Anchusa, but the systematics, phylogenetic relationships and conservation status of the taxa endemic to the island are still poorly known mainly because of their remarkable rarity. We present a study on these endemics based on the results of field research focusing on the distribution, the number and size of the populations, the characteristics of the habitat and the factors of threat. Combined with observations on aspects of reproductive biology, on wild populations and cultivated plants, we evaluate the conservation status of the taxa and propose Red List IUCN categories of vulnerability. Original descriptions, nomenclatural types and karyological data are added. The following Anchusa taxa are endemic to Sardinia: A. capellii, A. crispa ssp. crispa, A. crispa ssp. maritima, A. formosa, A. littorea, A. sardoa and A. montelinasana sp. nov. The latter is described, based on the discovery of a morphologically distinct entity on a mountain in southwest Sardinia. Anchusa littorea was found at a single site after c. 25 years from the last record and 7 years of unsuccessful field research; this species is at the brink of extinction due to the extremely reduced size of the only remaining population. Our complete collection of taxa allowed an analysis of phylogenetic relationships based on DNA sequences from the ITS1 ribosomal genome. In spite of the low variation, this marker produced Maximum Parsimony and Neighbour‐Joining phylograms suggesting that the group is monophyletic and that the split between the two clades of the mountain and coastal endemics has been a key evolutionary event. We assume the three mountain species to be relict schizoendemics ancestral to the coastal taxa, and the Paleozoic siliceous massifs of central and south Sardinia as the centre of origin of the group.

Differential Sensitivity of Mouse Strains to an N -Alkylated Imino Sugar: Glycosphingolipid Metabolism and Acrosome Formation

This review deals with the pharmacological properties of an alkylated monosaccharide mimetic, N-butyldeoxynojirimycin (NB-DNJ). This compound is of pharmacogenetic interest because one of its biological effects in mice - impairment of spermatogenesis, leading to male infertility - depends greatly on the genetic background of the animal. In susceptible mice, administration of NB-DNJ perturbs the formation of an organelle, the acrosome, in early post-meiotic male germ cells. In all recipient mice, irrespective of reproductive phenotype, NB-DNJ has a similar biochemical effect: inhibition of the glucosylceramidase beta-glucosidase 2 and subsequent elevation of glucosylceramide, a glycosphingolipid. The questions that we now need to address are: how can glucosylceramide specifically affect early acrosome formation, and why is this contingent on genetic factors? Here we discuss relevant aspects of reproductive biology, the metabolism and cell biology of sphingolipids, and complex trait analysis; we also present a speculative model that takes our observations into account.

Determination of batch fecundity in Uranoscopus scaber Linnaeus, 1758 from the Aegean Sea, Turkey

Summary This work focuses on reproductive biology aspects of Uranoscopus scaber from the coast of the Aegean Sea. In total, 175 U. scaber specimens were collected in Izmir Bay using trawl nets from January to December 2005. The reproduction period according to gonadosomatic index (GSI) values extents from March to September, with a peak in May (6.32 ± 1.2). Oocyte diameters taken from 59 mature gonads ranged from 62 to 1860 μm. Maximum batch fecundity (BF) was 58091 (mean: 11556 ± 1445) in large oocytes in May, and 8408 (mean: 2821 ± 945) in hydrated oocytes in September. The BF increased with total length and body weight, excluding the ovaries. Total length (TL)–BF relationships and fish weight–BF relationships were BF = 0.0034TL4.6248 (r = 0.47) and BF = 59.166W−3101 (r = 0.49), respectively, according to the oocyte size frequency method. There was a linear relationship between BF and fish size.