Population structure and reproduction of the longtail grass shrimp Urocaris longicaudata (Decapoda,Caridea, Pontoniinae) in Laguna de Términos,SW Gulf of Mexico

The purpose of this study was to describe the population structure and some reproductive traits of Urocaris longicaudata collected in Laguna de Términos, Campeche, Mexico in October and December 2009, and February and April 2010. A total of 2977 specimens were collected of which 1596 were females (including 276 ovigerous) and 1381 were males. Females were larger than males (2.03 ± 0.63 vs. 1.97 ± 0.44 mm carapace length (CL), respectively). The overall sex-ratio differed significantly from 1:1. The reproductive period was apparently continuous, with most ovigerous females recorded from December 2009 to April 2010. The estimated size at sexual maturity in females was 2.90 ± 0.64 mm CL. A significant and positive linear relationship between CL and realised fecundity was estimated. The number of embryos ranged from 33 to 320. The average volume of newly spawned embryos was 0.038 ± 0.009 mm³ and that of those near hatching was 0.062 ± 0.012 mm³, representing a 63.15% increase throughout embryogenesis. The females lost on average 27.6% of the initially produced embryos during the incubation period, which favoured the survival of the remaining embryos. This is the first report on any biological trait of U. longicaudata along the southwestern Gulf of Mexico.     

Assessment of egg quality and realised fecundity of whiting Merlangius merlangus L. in captivity

Potential predictors of egg quality were assessed in whiting Merlangius merlangus L. permitted to spawn in a tank from which eggs were collected. These included fertilisation rate, the proportion of viable buoyant eggs, egg diameter, and egg wet and dry weights; all were influenced by temporal effects and were negatively correlated with days from start of spawning. The spawning period was protracted, from February to June. Mean daily egg production per female was 2.74 ± 2.43 g and 2338 ± 2075 eggs, equivalent to 14.6 ± 13.1 g kg^?1 day^?1 female^?1. Egg diameter was 1.21 ± 0.04 mm, egg wet weight 1.20 ± 0.21 mg, dry weight 0.10 ± 0.02 mg, and mean fertilisation rate and hatching rates were 76.8 and 73.3%, respectively. The incubation period ranged from 72 to 80 degree days and was dependent on temperature (x) and described by the equation y = 25.92 e^?0.1219x. Realised fecundity was also assessed to determine if this gave a more accurate measure of reproductive potential, and this was compared with potential fecundity estimated from predictive regressions on fish length from fisheries data. Realised egg production of 20 females of 185 g mean weight and 256 mm fork length was 4 444 360 (95% CL 4 093 961–4 743 018), similar to predicted seasonal egg production based on gravimetric fecundity measurements of wild caught fish.     

Reproductive output of the ornamental shrimp Lysmata vittata (Stimpson, 1860) (Decapoda: Caridea) in wild populations and under different maturation diets

ABSTRACT

Reproductive output parameters (fecundity and egg volume) of Lysmata vittata were examined in a population in northeastern Brazil. Effect of maturation diets on the reproductive output of these shrimp under laboratory conditions was evaluated. Reproductive output was estimated for 25 shrimp collected in the wild. Another 45 pairs of shrimp were used for diet experiments, 15 pairs per treatment (T1: industrialized food, T2: fresh food, T3: mixed diets). For wild population, mean fecundity and egg volume were differed between developmental stages of the eggs. Fecundity was significantly lower in the specimens subjected to T1 diet (267 ± 141 eggs) compared with shrimp from the wild population (393 ± 183 eggs). Egg volume was significantly lower in shrimp subjected to three diets tested compared with those from wild population. Egg loss during embryonic development in L. vittata may be caused by several factors (e.g. aborted development and maternal cannibalism). Fresh food proved to be important for improving reproductive output in L. vittata reared in culture. We emphasize the significance of improving nutritional value and palatability of diets to improve cultivation efficiency. Lysmata vittata can be used as a model organism for future studies aiming to improve the cultivation techniques for shrimp of the genus.

Abbreviations PSH: protandric simultaneous hermaphroditism; ARS: artificial refuge structures; CL: carapace length; EV: egg volume; L: largest diameter of the egg; S: smallest diameter of the egg; T1: industrialized pellets; T2: fresh ingredients; T3: mixed diets; ANCOVA: analysis of covariancr; SD: standard deviation.     

Strategies of a successful new invader in European fresh waters: fecundity and reproductive potential of the Ponto-Caspian amphipod Dikerogammarus villosus in the Austrian Danube, compared with the indigenous Gammarus fossarum and G. roeseli

1. Fecundity of a Dikerogammarus villosus population at Spitz was studied in the Austrian Danube during the 3‐year period 2002–2004. Ovigerous females were absent in October and November, and extremely scarce in December when the reproductive season started again slowly. From January to September pre‐copulatory pairs and egg‐carrying females were present. The reproductive cycle lasted for 9–10 months. 2. Various pigmentation phenotypes of D. villosus have been described in the literature. However, no significant differences were found between the reproductive variables studied here and several colour morphs. Mating was size‐assortative; mean body length of males was about 1.3 times greater than that of their potential mates, and the wet weight was approximately twice as heavy. 3. The relationship between the number of embryos per clutch and the wet weight of females was described by a 3‐parameter power equation. The population mean was 43 eggs with a range of five to 194 eggs. Eighty‐two specimens from 1359 D. villosus females had more than 100 eggs: the smallest of these females was 12 mm long (30 mg) wet weight, and the largest, which was 18 mm long (91 mg), had 194 eggs in embryonic development stage 4. 4. Numbers of embryos in developmental stages 2 (early egg stage) and 7 (newly hatched neonates) differed significantly with body wet weight of ovigerous females (P < 0.05). For an average female in the range 10–12 mm (20–30 mg) the number of juveniles in the brood pouch was 74% of the number of stage 2 eggs. This value can be interpreted as the survival rate of eggs. 5. The overall mean egg volume (EV, ±95% CL) of stage 2 eggs of D. villosus was 0.05 ± 0.001 mm³, and EV increased significantly at each stage of development. At stage 6, egg volume had increased by a factor of 2.6, and averaged 0.13 ± 0.001 mm³. In comparison, G. fossarum and G. roeseli had significantly larger eggs in all developmental stages. 6. Mean egg size of D. villosus (0.063 mm³) was maximal in January. For D. villosus (and G. roeseli) the minimum mean egg size occurred in September. In contrast to G. fossarum and G. roeseli, a second peak in egg size was not observed for D. villosus, and egg size fell more or less successively from January to September. 7. A simple index of fecundity was calculated from the number of stage 2 eggs divided by the female's wet weight. The highest values were observed in April and May, when females from the overwintering generation grew to their maximum body size. Thus the release of a large number of neonates corresponds with the availability of plentiful food and rising water temperatures for juvenile growth in the spring. The lowest value occurred in December. In June the small females of a summer generation appeared, with a naturally low fecundity. 8. The relationship between brood development time and water temperature was studied in the laboratory at a series of constant temperatures. At 16 °C, mean brood development time was 14 days for D. villosus, compared with about 3 weeks for the indigenous species. At 10 °C, mean brood development time was 24 days in D. villosus, compared with 40 days in G. fossarum and 44 days in G. roeseli. At 4 °C it was 1.8 and 3.5 times longer in G. fossarum and G. roeseli. 9. The number of offspring produced by a single clutch from a large female D. villosus is considerably higher than the total numbers produced by the indigenous freshwater gammarids, such as G. fossarum, G. roeseli and G. pulex, during their life‐spans of 1.5–2 years in seven to nine successive broods. Only one or two large ovigerous D. villosus would probably be enough to start a new population. A potentially high reproductive capacity, comparatively small eggs, optimal timing to release the maximum number of neonates per female in April/May, and a long reproductive cycle, together with rapid development of eggs, rapid growth to sexual maturation, short life span, tolerance to a wide range of environmental conditions, and exceptional predatory capabilities, all give the invasive Ponto‐Caspian gammarid an opportunity to become globally distributed in freshwater ecosystems of the temperate climate zone.     

Aspects of the biology of the big-handed crab,Heterozius rotundifrons (Decapoda: Brachyura), from Kaikoura,New Zealand

Abstract

From January 1975 to June 1976, samples of Heterozius rotundifrons A. Milne Edwards, 1867 were taken monthly from the intertidal zone at First Bay, Kaikoura Peninsula (42°25′S, 173°42′E). Small crabs (< 8 mm carapace width) were never common; they were either too cryptic to be collected in quantity, or have a different habitat from larger crabs. Ovigerous females were present in all months except February (in both 1975 and 1976), but generally formed less than 50% of the total sample of females each month. The number of newly deposited eggs (0.75×0.81 mm) carried by females increased with increase in carapace width according to the equation y = -1123.56+102.97x (r ² = 0.8213). Egg development lasted 3–5 months, and egg mortality during this period was almost 10%. The overall sex ratio for the 18-month sampling period was 1846 ♀ : 993 ♂, which suggests that females were approximately twice as numerous as males. However, when crabs were sorted into size classes it was evident that the sex ratio was not significantly different from 1:1 in crabs of 6–12 mm carapace width, whereas females significantly (P<0.001) outnumbered males in the 13–21 mm size range. The right and left chela were approximately equal in length in females of all sizes, but the right chela of large males was greatly enlarged compared with the left, and with the chelae of females of comparable carapace width. Increase in the growth rate of the males’ right chela commenced at a carapace width of approximately 11.0 mm. Since the smallest ovigerous female collected also had a carapace width of 11.0 mm, it is concluded that both males and females attain sexual maturity at this size.     

Female reproductive pattern of Callinectes sapidus Rathbun, 1896 (Brachyura: Portunidae) in Iskenderun Bay,Eastern Mediterranean

We studied the female reproductive pattern of Callinectes sapidus, which was introduced to the Mediterranean in the 20^th century. We assessed female size at first maturity, fecundity, and fecundity relationship to size in Iskenderun Bay, eastern Mediterranean, Turkey. Samples were collected between July 2014 and June 2015 using bottom trawling at depths ranging from 1 to 50 m. A total of 322 crabs were caught of which 308 (95.7%) were females including 116 ovigerous ones. The minimum carapace width of the mature females was 39.1 mm and the mean carapace width 123.8 mm. The carapace width of ovigerous females varied between 95.1 and 144.5 mm, with a mean of 120.3 mm. The highest number of ovigerous females was observed in July and August. Mean fecundity was 1.91 million (667,950–4,669,853) eggs per female. A weak positive linear relationship between fecundity and carapace width was noted, as well as a high correlation with total egg weight. In the eastern Mediterranean, maturity sizes of females were smaller than those in the native region of the species.     

Annual reproductive cycle and growth of the pen shell Atrina maura (Pterioidea: Pinnidae) on sand-bottom culture in the Ensenada Pabellones lagoon system,Gulf of California,Mexico

Abstract

The reproductive cycle and growth of the pen shell, Atrina maura, which was cultured in the Ensenada Pabellones lagoon system, Gulf of California, from March 2008 to March 2009, is described in this article. Histological techniques and the condition index were used to determine its reproductive condition. The sex ratio was 0.57 females:1.72 males within the population studied. There were no differences (χ², p < 0.05) in shell length (SL) between males and females. The mean length of the sampled specimens ranged between 50.99 ± 4.86 mm and 218.16 ± 8.87 mm. The histological results confirmed that A. maura is a gonochoristic organism that presents synchronic development of the gonads. The maturity and spawning phases were observed throughout the study period, with the exception of March and May 2008. The frequency of the gonad development stages obtained per month suggests that this species reproduced two times annually, with one important reproductive period from June to September, a minor reproductive period from November to February, and two resting periods as follows: July to August and January to February 2009.     

Age composition,growth, and reproductive biology of yellow catfish (<Emphasis Type="Italic">Peltobagrus fulvidraco</Emphasis>, Bagridae) in Ce Lake of Hubei Province,Central China

This study presents fundamental information on the reproductive biology, size and age composition, and growth of yellow catfish, Peltobagrus fulvidraco. Sampling was carried out monthly from Ce Lake in Hubei province from January 2004 and December 2004. Overall female/male (F/M) sex ratio was 1.08, not significantly different from expected 1.0 ratio. But sex ratio (F/M) of the spawning group was 1.14:1 with skewness towards females (p < 0.05). The smallest sexually mature male and female massed 20.51 and 16.93 g, and measured 100.1 and 94.3 mm in total length, respectively. Reproductive period for this species is from April to August when GSI is considerably higher than the rest months (p < 0.05). The highest GSI values were measured from May to July for both sexes and this period was presumably the peak spawn. First maturation occurred at age 1⁺ for both sexes. Fish of age 1⁺ and 2⁺ comprised the greatest portion of spawners. The absolute fecundity (AF) of P. fulvidraco ranged from 657 to 11,696 eggs per fish, with mean AF value of 3,570 ± 122 (S.D.) eggs per fish, varying considerably at given length, weight and age. The fecundity relative to total length (F/L) fluctuated from 58 to 680 eggs/mm, with a mean value of 246 ± 34 (SD) eggs/mm, and fecundity relative to total weight (F/W) varied from 29–133 eggs/g, with a mean value of 67 ± 7 (SD) eggs/g. P. fulvidraco is a single spawner, with low fecundity compared with other Bagrid fish.     

Insights of the life history in the porcellanid crab Petrolisthes armatus (Gibbes, 1850) (Crustacea: Anomura: Porcellanidae) from the Southwestern Atlantic coast

Petrolisthes armatus (Gibbes, 1850) life history was evaluated based on growth and reproduction. Specimens were captured at Ubatuba (Brazil), identified, sexed and measured: carapace (CL, length; CW, width), larger cheliped propodus (PL, length; PW, width; and PH, height), and 2th and 5th abdominal somite (AW₂ and AW₅, width). Relative growth was studied using CL as independent variable and its relation with other variables (dependents), to estimate puberty size and morphological maturity. Fecundity was represented by number of eggs vs. body size CL, with a better fit using a power function. Considering the 257 specimens analyzed, males were larger than females, and the overall sex ratio was 1:1, with some differences among size classes. Maturity (puberty size) was revealed by: AW₂ × CL (males: 8.6 mm CL; females: 7.6 mm CL); and AW₅ × CL (7.1 and 7.6 mm CL, respectively). Reproduction was continuous, but more intense in rainy season and recruitment occurring in dry season. Fecundity of this species was 228 ± 163 eggs, with better fit by a power function (R² = 0.72). Maturity size and growth differed when a pristine area (Ubatuba) was compared with a polluted area (São Sebastião), in the same Brazilian area (São Paulo State).     

Reproductive biology of blue sucker in a large Midwestern river

Efforts to protect or rehabilitate depressed blue sucker Cycleptus elongatus populations require an understanding of life‐history characteristics and reproductive biology to provide fisheries managers with the tools required for science‐based management. The objective of this study was to examine the reproductive biology of blue sucker in the Wabash River, Indiana, during March and April 2006. A total of 105 reproductively mature blue sucker (53 males, 52 females) was collected using boat electrofishing to examine size‐at‐maturity, absolute fecundity, gonadosomatic index (GSI), relative fecundity, and estimated egg size. Size‐at‐maturity was estimated at 515 mm total length (TL) for males and 568 mm TL for females. Mean absolute fecundity of females captured during the study was 150 704 eggs per female (range, 26 829–267 471 eggs per female) and was positively related to both TL (r² = 0.66) and wet weight (r² = 0.77). Mean GSI was 6.4% (range, 2–9.3%) for males and 17.2% (range, 4.3–23.4%) for females. Relative fecundity ranged from 15 331 to 65 887 eggs kg^?1 body weight (mean = 46 946 eggs kg^?1 body weight) and was strongly correlated with GSI (r² = 0.87). Mean estimated egg size was 278 eggs g^?1 (range, 229 364 eggs g^?1) and exhibited an inverse relationship to GSI (r² = 0.42). The results of our study provide information on the reproductive biology of blue sucker which can be used to aid in the identification of potential recovery threats for depressed populations.     

Reproductive performance in captivity of Austropotamobius pallipes in Abruzzi Region (central Italy)

Austropotamobius pallipes juveniles for restocking should originate from native breeders to preserve the genetic integrity of the populations. We compared the reproductive performance in captivity of A. pallipes populations of four drainage basins of the Abruzzi Region to assess their reproductive efficiency and improve their aquaculture. The broodstock were collected before the breeding season and reproduction took place in an experimental hatchery. The female carapace length ranged from 35.4 to 59.0?mm. Spawning occurred in 84% of females (range 69–93%) and the mean number of eggs per female was 89 (range 80–104). No significant differences were observed among the groups. Close to hatching, two groups maintained a high percentage of egg-bearing females (52%) and a high number of eggs, while the other groups lost most of their eggs. At the end of the cycle, the stage 2 juveniles obtained represented 19.5% of the initial egg number. The efficiency for stage 2 juvenile production ranged from 48.2 to 0.1%, and the mean number of stage 2 juveniles per female ranged from 42.2 to 1. These differences were not attributable to maternal size, but the characteristics of the brooks of origin might have influenced the reproductive performances of crayfish in the hatchery.     

Size at the onset of sexual maturity in the anomuran crab, Aegla uruguayana (Aeglidae)

The size at maturity was studied in the crab Aegla uruguayana from the Areco River (31°14′ S, 59°28′ W), Argentina. Size at sexual maturity was determined according to three criteria: morphometric (change in the relative growth of reproductive characters), histological (first maturation of gonads) and functional (capability to mate and carry eggs). Regarding females, morphometric maturity occurred at a carapace length (CL) of 11.50 mm, considering abdomen width as a reproductive character. Gonad maturity of females could be observed at a minimum size ranging from 15 to 17 mm CL. The smallest ovigerous female observed in the field was 15.60 mm CL, although a relevant population incidence of ovigerous females (86.6%) has just been observed at values higher than 17 mm CL. As for males, the relative growth of the left chela length changed at a value of 15.40 mm CL, while morphological changes in sexual tube occurred between CL of 14 and 16 mm. Testicular maturation occurred at a CL ranging from 17 to 19 mm. The smallest size of males having spermatozoids in their vasa deferentia was 18.70 mm CL. The results obtained indicated that, in both sexes, functional maturity occurred after morphometric maturity and at a size similar to that of gonad maturity. Comparing sexes, females acquired sexual maturity (morphometric, gonad and functional maturity) at sizes statistically smaller than those of males.     

Notes on the biology of Cancer bellianus (Brachyura, Cancridae) around the Canary Islands

Information on biometric and biological parameters of Cancer bellianus Johnson, 1861 (Crustacea, Decapoda, Brachyura, Cancridae) off the Canary Islands is given. Crabs examined were collected during experimental fishing surveys during 1974–1998. Carapace length, carapace width, total wet weight, sex and ovigerous condition were determined. This species was caught at depths from 153 to 750 m, the deepest ever recorded. Size frequency distributions were assembled and size-weight relationships were estimated by sex. Sex-ratio as a function of size and depth was determined. The size at first maturity was calculated by analysing the relative growth between the carapace length and the left chela width: 103.5 mm CL in males, 101.2 mm CL in females. Ovigerous females, egg size and fecundity estimates are reported apparently for the first time.     

Reproductive biology of the rock shrimp Sicyonia dorsalis (Decapoda: Penaeoidea) from the southeastern coast of Brazil

Summary

Sicyonia dorsalis is not commercially exploited in Brazil, but it forms a critical link in marine food chains by converting detritus food sources into microorganism biomass that is available for higher trophic levels. We examined the reproductive biology of this species, sampled for five and a half years in a tropical locality, the southeastern coast of São Paulo (23° S), Brazil. Monthly samples were taken from January 1998 to June 2003 at depths of 5 to 45 m. Degree of ovarian development was used to examine breeding in adult females. Recruitment was estimated by changes in proportion of individuals in juvenile size classes of carapace length (CL #8.2 mm) in relationship to the total number of individuals. The largest immature female measured 9.2 mm CL, but 75% of females were smaller than 7.3 mm CL. The largest immature male measured 6.8 mm CL. The relative frequency of reproductive females was negatively correlated with the relative frequency of recruitment (p <0.001). Reproductive females were found in every season, with peaks in December-February following the recruitment peak in March-June, and a second peak of spawning in May-July and of recruitment in September-November. The continuous reproductive pattern observed for S. dorsalis, combined with the hypothesis that during spring and summer the phytoplankton production is higher, when the South Atlantic central water mass intrudes into the region during upwelling events, suggests that food availability for protozoeal and mysis larvae may be an important selective factor shaping the seasonal breeding pattern for S. dorsalis. The classical paradigm of continuous reproduction at lower latitudes, with increased seasonality of the breeding period at higher latitudes, seems to be valid for this species.     

Variations in the sizes of gonads,eggs and larvae of the dace,Leuciscus leuciscus

Synopsis Prespawning female dace were examined in 7 successive years; in 6 years mean egg size (mm³) and egg number were inversely related and hence the ovary weights of equivalent-sized females were constant. Fecundity increased logarithmically with fish length, and an index of reproductive effort (ovary weight ÷ length cubed) also increased. The number of eggs per gram of ovarian tissue decreased with fish length; this was because mean egg size (mm³) increased and not because of a change in the proportion of connective tissue in the ovary. But in 1977, both egg number and mean egg size were low, although very high somatic growth had occurred in the previous, very warm, summer of 1976. Eggs from different-sized female dace were artificially fertilized, and incubated at a constant temperature. Dry weights of larvae, egg dry weights, mean egg size and larval starvation times showed linear correlations with each other and with parental (female) lengths. The progeny from the very smallest parent died several days earlier than those from the other parents. Size-related predation rates may be of more consequence than starvation death in natural populations. The optimum position of dace along the continuum between many small eggs and fewer larger eggs may vary at different levels of reproductive effort.     

Reproductive strategy of the snapping shrimp Alpheus armillatus H. Milne-Edwards, 1837 in the South Atlantic: fecundity,egg features,and reproductive output

Summary

The family Alpheidae, composed by shrimps of relatively small size, popularly known as snapping shrimps, is the one of the most diverse decapod groups. These shrimps are found worldwide and occur in tropical and subtropical waters, from the intertidal zone to great depths. We investigated reproductive aspects of Alpheus armillatus, in order to gather information on egg production, aiming to enhance knowledge of its reproductive strategies in a population in an intertidal area of the South Atlantic. Ovigerous females were collected under rocks, in May and July 2006 (dry season) and in November 2006 and March 2007 (rainy season). Egg production and reproductive output were analyzed and compared seasonally and during the period of embryonic development. Females measured on average 11.28 mm CL, with a mean of 763 eggs and 0.10 mm3 egg volume. The egg volume of this population was smaller than previous estimates for other species of snapping shrimps, but the mean egg number was higher. The volume of eggs doubled during the incubation period, but despite this increase, no significant loss of eggs was observed. Alpheus armillatus invests on average about 12% of body weight in reproduction. The proportional investment in egg production is significantly higher in the rainy season when compared with the dry season (17.9% vs 4.8%), correlated with higher temperatures and increased food availability at this time. Our results corroborated the hypothesis of a pattern of egg production influenced by environmental conditions and intraspecific variability among the family Alpheidae, as a function of the biogeographic region.     

Egg production of the burrowing shrimp Callichirus seilacheri (Bott 1955) (Decapoda, Callianassidae) in northern Chile

The thalassinidean shrimp Callichirus seilacheri is a common species in the intertidal zone of the South American Pacific coast. However, our knowledge of its reproductive ecology is rather limited. The present study was carried out between January and December 2003 at Las Machas, northern Chile. Although ovigerous females were encountered almost throughout the study period, they were particularly abundant between May and September when water temperatures were lowest and sediment coverage of the burrow entrances was highest. Females of C. seilacheri produced numerous (17,450 ± 3,796 eggs) and small (0.884 ± 0.080 mm; 0.262 ± 0.054 mm³) eggs when compared to other thalassinidean shrimps for which such information is available. Fecundity was positively correlated with female size; however, correlations were allometric, which might be related to the elasticity of the abdomen. Egg volume increased by 41.2% during embryogenesis, and egg loss during the incubation period was on average 8%. Females inverted on average 14.9% of their dry weight into egg production.     

Reproductive plasticity in <Emphasis Type="Italic">Petrolisthes armatus</Emphasis> (Anomura,Porcellanidae): a comparison between a Pacific and an Atlantic population

The porcellanid crab Petrolisthes armatus, with a known geographic distribution covering a wide range of latitudes, was selected to conduct a comparative study on egg production and reproductive output between two populations from Pacific and Atlantic coasts. Ovigerous females were collected between September and November 2005 in Punta Morales, Pacific coast of Costa Rica (n = 137) and from March 2005 to July 2006 in Araçá region, São Paulo, Brazil (n = 46). The mean size of females was statistically different between both populations with larger females from Brazil than Costa Rica (7.9 ± 1.31 and 6.6 ± 0.95 mm CW, respectively). Likewise, egg production was significantly different in both populations and started in Pacific Costa Rica at a smaller female size than in Brazil. Specimens from Pacific Costa Rica produced roughly three times more eggs than equally sized females from Brazil, while newly extruded embryos were larger in Brazil than in Costa Rica (0.045 and 0.039 mm³, respectively). Egg volume increased during embryogenesis by 112.8 and 164.5% in Costa Rican and Brazilian populations, respectively. The egg water content increased steadily in both populations; however, eggs produced in Brazil contained always more water than those from the same developmental stage in Costa Rica. Average reproductive output (based on dry weight) was substantially lower in Brazil (0.031) than in Costa Rica (0.065). Our results confirm an impressive intraspecific plasticity of reproductive features in an intertidal decapod. The observed phenotypical variability might be related to local environmental conditions as well as to the location of the studied population concerning its geographic range of distribution.     

Reproductive cycle of seabob shrimp Xiphopenaeus kroyeri (Crustacea,Penaeidea) from the northeast coast of Brazil

The reproductive cycle of Xiphopenaeus kroyeri north-eastern Brazil was described to contribute to the sustainable management of this stock in the region. Specimens were collected monthly from August 2011 to July 2012 using a local vessel of the artisanal fleet. A total of 1201 individuals were analyzed (673 females and 528 males) with a mean carapace length (CL) of 1.88 ± 0.16 cm and total length (TL) of 9.00 ± 1.22 cm. The lowest CL and TL of mature females were 1.33 and 6.5 cm, respectively, and all females above 2.44 cm (CL) and 11.5 cm (TL) were mature. Ovarian maturation was classified into four stages: I (immature), II (maturing), III (mature) and IV (spawned). Individuals of all maturational stages were present throughout the year. Considering the macro and microscopic analysis, it was suggested that this species in north-eastern Brazil has a continuous reproductive cycle, with two seasonal peaks, November/December and February (austral spring and summer). A positive correlation between the percentage of mature females and temperature was observed, and a higher percentage was reported in the warmer months of the year. This suggests that the reproductive peaks can be triggered by water temperature variation throughout the year.     

On the biological characteristics of Capoeta fusca Nikolskii, 1897 in eastern Iran

It is hypothesized that Capoeta fusca might display specific life‐history traits that differ from other species of this genus. To test this hypothesis a total of 354 specimens of C. fusca (listed by ICUN in the category DD = data deficient) were caught in the Qanat of Shadmehr (a well‐known active man‐made water well system in eastern Iran) on a monthly basis to cover fully the reproductive season from April to October 2007. Based on opercula readings the maximum ages of the population were 5+ years for both sexes. Sizes ranged from 57 to 190 mm total length (weight 2.14–84.76 g). Length‐weight relationship implied that the growth was negatively allometric for males and isometric for females. The von Bertalanffy growth model was estimated as L_t=18.74(1‐e^{?0.33(t+0.473)}) and L_t=22.35(1‐e^{?0.32(t+0.333)}) for males and females, respectively. Sex ratio was 1 : 2.42 in favour of females. The GSI indicated that reproduction of the fish in the qanat system occurred between May and August, with the highest average value of 6.12 for males in June and 9.55 for females in July. Oocyte diameters ranged from 0.30 to 2.05 mm, with a mean value of 0.92 mm. Absolute fecundity ranged between 506 and 22 800 eggs, with a mean of 4961 eggs. Fecundity relative to total weight fluctuated from 34 to 583, with a mean value of 133 eggs per g. Absolute fecundity and oocyte diameter to fish size (length and weight) were significantly correlated.