Batch Fecundity Research Articles

Spatial and seasonal variability in reproductive investment of Baltic sprat

Fecundity of marine fish species is highly variable, but trade-offs between fecundity and egg quality have rarely been observed at the individual level. We investigated spatial differences in reproductive investment of individual European sprat Sprattus sprattus (Linnaeus 1758) females by determining batch fecundity, condition indices (somatic condition index and gonadosomatic index) as well as oocyte dry weight, protein content, lipid content, spawning batch energy content, and fatty acid composition. Sampling was conducted in five different spawning areas within the Baltic Sea between March and May 2012. Spawning sprat from the Kiel Bight were in a better nutritional condition compared to sprat from the Arkona Basin, Bornholm Basin, and the Gdansk Deep. These females were also producing up to twice as many oocytes, and invested significantly more energy in reproduction, than their counterparts sampled in the eastern part of the Baltic Sea. Still, oocytes produced by Kiel Bight sprat contained significantly lower fractions of the essential fatty acids 20:4 (n-6) and 22:6 (n-3). A seasonal trade-off between oocyte weight/lipid content and fecundity was found for Baltic sprat, albeit the gross energy invested into spawning remained constant. Observed spatial and seasonal differences in sprat reproductive investment may be linked to hydrographic conditions and food availability and will impact the survival probability of yolk-sac and first feeding larvae. These findings indicate that Baltic sprat is able to adapt its reproductive tactics to the highly variable pelagic habitat of the Baltic Sea.

Reproductive biology and space–time modelling of spawning for sailfish Istiophorus platypterus in the western Atlantic Ocean

ABSTRACTThis study presents data and estimates reproductive parameters of the sailfish Istiophorus platypterus (Shaw, 1792) in the western Atlantic, useful for future stock assessments of the species in the Atlantic Ocean. During the period 2006–2011, a total of 1132 fish were sampled by scientific observers on board Venezuelan and Brazilian longline vessels and from artisanal fisheries based out of Cumaná, Puerto La Cruz and Playa Verde, Venezuela and Cabo Frio, Rio de Janeiro, Brazil. The ovaries of 543 females were classified into five ovarian development phases based on microscopic analysis of the most advanced group of oocytes. Generalized additive models were applied to the gonadal index and sex ratio data in order to assess spatio-temporal trends of the reproductive activity and identify the spawning areas. Space–time effect was a significant factor contributing to changes in sex ratio and reproductive activity. Spawning activity was observed in two distinct areas. On the south-east Brazilian coast spawning peaked during December–February, while in the south-eastern Caribbean Sea spawning occurred between March and September, with its peak in March and April. Using a Bayesian approach, size at 50% maturity was estimated to be 146.12 cm (credibility interval of 95%, 138.45–152.09 cm). Batch fecundity ranged from 436,800 to 2,492,500 hydrated oocytes per female. This study confirms multiple aggregation spawning for this species in the western Atlantic Ocean.

Evidence of spawning among Pacific bluefin tuna, Thunnus orientalis, in the Kuroshio and Kuroshio–Oyashio transition area

Reproductive characteristics are one of the key factors for understanding population dynamics in fishes. This study describes the spawning habitat of Pacific bluefin tuna (Thunnus orientalis) in the Kuroshio and the Kuroshio–Oyashio transition area. A total of 551 adult fish (fork length > 120 cm) were collected during 1994–2007 (except in 2001 and 2003) and 2016. Based on a histological analysis of the gonads, we concluded that actively spawning females were mainly present in late May to early July. Relative batch fecundity was significantly lower than that reported in the Sea of Japan but was similar to that observed in the Nansei area. Whereas most spawning adults in the Sea of Japan are 3–6 years old and those in the Nansei area are over 10 years old, the majority of the specimens in this study ranged from 160 to 180 cm in length, which corresponds to 6–8 years of age. Our results indicate that Pacific bluefin tuna spawn in the study area and provide important data for understanding the spatiotemporal differences in spawning strategy with growth in this species.

Fecundity peaks prior to sex transition in a protogynous marine batch spawning fish, black sea bass (Centropristis striata)

Abstract Understanding the dynamic processes that contribute to reproductive output is vital to determine appropriate harvest controls and sustain marine fisheries. For sequential hermaphrodites, the process of reproduction is complicated by sex transition within the life history. We examined the reproductive dynamics of black sea bass (Centropristis striata), a protogynous serranid, within a major fishing region of the Northwest Atlantic during two consecutive spawning seasons to quantify the strength of size-dependence and the magnitude of temporal variation in several key traits. Specifically, we estimated the size-dependence of sex ratio, maturity, spawning capability, batch fecundity, and spawning frequency at both fine (weeks/months) and broad (years) temporal scales. We observed fecundity to be highest in females of intermediate body size, which was entirely a function of reduced spawning frequency among the largest females. Female fecundity peaked at sizes well below the estimated size at sex transition, and contrary to the pattern typically observed for gonochoristic fishes in which the largest females yield the greatest number of eggs. Among protogynous fishes, females may decrease egg production prior to sex change and instead allocate energy to somatic growth, benefitting from larger body size during the subsequent male phase. The production of fewer batches of eggs by larger females directly impacted estimates of annual fecundity. In addition, we detected large interannual differences in the proportion of spawning capable females, and also spawning frequency, which resulted in considerable variation between annual fecundity estimates. The inclusion of temporal and size-dependent variation in female egg production should produce more robust estimates of stock reproductive potential and its response to changing harvest scenarios.

Using oocyte essential fatty acid composition to assess spawner reproductive potential under hypersaline conditions

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 584:199-212 (2017) - DOI: https://doi.org/10.3354/meps12366 Using oocyte essential fatty acid composition to assess spawner reproductive potential under hypersaline conditions Julian Döring*, Werner Ekau Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359 Bremen, Germany *Corresponding author: julian.doering@me.com ABSTRACT: Inversion of estuaries in the dry tropics (i.e. salinity increases upstream) against the backdrop of a globally changing climate is forcing migratory clupeid fish species to adapt quickly to modifications in their spawning habitats to ensure reproductive success. Hatching success and survival probabilities of marine fish eggs and early life stages are prone to impairment under high temperature and elevated salinity conditions. Essential fatty acids affect osmoregulation in marine fish early life stages, and deficiencies can therefore be expected to cause elevated offspring mortality under hyperosmotic conditions, ultimately modifying a stock’s reproductive potential. Here we show that oocytes spawned by bonga shad Ethmalosa fimbriata inside a hypersaline estuary exhibited significantly higher 20:4 (n-6) proportions (1.6 ± 0.7% of total fatty acids) than oocytes spawned under marine conditions (0.6 ± 0.2%). Further, oocyte proportions in 20:4 (n-6), 20:5 (n‑3), and 22:6 (n-3) were positively correlated with water temperature, water salinity, and female reproductive investment (relative batch fecundity, gonado-somatic index, oocyte dry weight). Oocytes spawned during high temperature/high salinity conditions inside the estuary are therefore likely to develop normally under the prevailing conditions. Reproductive potential was determined to be highest in females spawning inside the estuary at the end of the wet season, when temperatures are high and salinities are less stressful due to freshwater input. Results lead to the conclusion that migratory clupeid fishes can maintain their reproductive potential in hypersaline estuaries and lagoons, which potentially allows for sustainable stock sizes. KEY WORDS: Arachidonic acid · Clupeidae · Fatty acids · Maternal effects · Salinity · Temperature · Inverse estuary · Reproductive investment Full text in pdf format Correction PreviousNextCite this article as: Döring J, Ekau W (2017) Using oocyte essential fatty acid composition to assess spawner reproductive potential under hypersaline conditions. Mar Ecol Prog Ser 584:199-212. https://doi.org/10.3354/meps12366 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 584. Online publication date: December 07, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Reproductive biology of female striped marlin Kajikia audax in the western Pacific Ocean.

Length and mass data for 1260 (536 females, 683 males, 41 sex unknown) striped marlin Kajikia audax were collected at the fish markets of Tungkang, Singkang and Nanfangao from July 2004 to September 2010. Of these samples, 534 gonads (236 females and 298 males) ranging from 95 to 206 cm in eye-to-fork length (LEF ) and 8 to 88 kg in round mass (MR ), were collected. Chi-square tests indicated sex ratios were homogeneous among months in 2004 and 2006-2008, but not in 2005, 2009 and 2010; and there were significant differences in sex ratio by size. The overall sex ratio (RS ) differed significantly from the expected 0·5. Kajikia audax are sexually dimorphic and the proportions of females increased with size between 140 and 210 cm LEF . Reproductive activity was assessed using a gonado-somatic index (IG ), external appearance of the gonads and histological examination and results indicated that the spawning season occurred from April to August with a peak in June to July. Based on histological observations and the distribution of oocyte diameters, K. audax are multiple spawners and their oocytes develop asynchronously. The estimated length-at-50% maturity (LEF50 ) was c. 181 cm (c. 4·8 years of age) for females. The proportion of reproductively active females in the spawning season with ovaries containing postovulatory follicles (0·27) indicated that they spawned every 3·7 days on average. The hydrated oocyte method estimated mean ± S.D. batch fecundity (FB ) to be 4·4 ± 2·02million eggs; average relative fecundity was 53·6 ± 13·9 oocytes g-1 MR ; and the average annual fecundity was 181·3 ± 48·3 million eggs. The parameters estimated in this study are key information for stock assessments of K. audax in the north-western and central Pacific and will contribute to the conservation, management and sustainable yield of this species.

Aspects of reproductive biology of the red gobyTrypauchen vagina(Gobiidae) from the Mekong Delta

This study provides knowledge on reproductive traits of Trypauchen vagina, a target fish for catching, based on data analysis of 701 individuals collected in the Mekong Delta from January to December 2015. The species is a multiple spawner depositing eggs in early wet season (June–August) since gonadosomatic index reaches a high point during this period, supported by the appearance of ripe and spent gonads at that time. Male and female fish matures firstly at 16.59 and 16.81 cm in total length respectively. The species displays high batch fecundity (4,000–12,750 eggs/female). Knowledge of length at first maturity and spawning season is essential for local authorities to set the suitable fish length and time for fishing. The results provide fundamental information on the reproductive biology and contributed to knowledge for fish population sustainable management.

Reproductive biology and management of two commercially important groupers in the SW Atlantic

The reproductive biology of Epinephelus morio (red grouper) and Mycteroperca bonaci (black grouper) were evaluated based on 533 specimens collected from artisanal fisheries landings in the Abrolhos Bank, Brazil, between May 2005 and September 2012. Sex ratio for the black grouper was 1:14 (n = 155 females and 11 males; 26.1–147 cm TL) and 1:10 for the red grouper (n = 334 females and 33 males; 15.0–96.0 cm TL). For both species, highest values of the gonadosomatic index (GSI) for females were recorded between July and October, indicating spawning during the austral winter. The length at first maturity (L50) for females was estimated at 62.0 and 47.0 cm TL for the black and red grouper, respectively. Batch fecundity based on TL and TW ranged from 2 to 15.4∗106 and 1.5 to 13.7∗106 for the black and red grouper, respectively. Interviews with experienced fishers revealed that spawning seasons of both groupers are largely unrecognized. Results demonstrate a positive relationship between GSI peaks, lower temperatures and stronger winds. The information provided herein may help decision-making regarding fisheries management and conservation for E. morio and M. bonaci at various levels of governance in the Abrolhos Bank, the region with the largest and richest coralline reefs in the South Atlantic.

Reproductive Traits of the Duckbill Sleeper Butis butis (Hamilton, 1822).

Butis butis is a commercially important goby that is widely distributed in Indo-Pacific regions; however, its reproductive biology is poorly characterized. We condcted the present study in estuarine and coastline areas in the Mekong Delta from June 2015 to May 2016 to generate reproductive parameters for this species. The results of data analysis based on a collection of 173 individuals (74 females and 99 males) indicate that the sex ratio of this species is close to 1:1. Mature (stage IV) and ripe (stage V) gonads were found monthly during the study period, suggesting that Butis butis is an iteroparous fish that spawns in a year-round cycle. Male B. butis matures first at 8.97 cm total length (TL), which is longer than females (6.82 cm TL). Butis butis is well adapted to tropical monsoon regions due to its high batch fecundity (46,017 ± 6941 SE), ranging from 15,000 (8.6 cm TL and 5.71 g W) to 78,500 (15.8 cm TL and 42.24 g W) eggs. Batch fecundity increases with fish size due to a strong positive relationship between batch fecundity and fish size (TL and W). These results help fill the knowledge gap on the reproductive biology of Butis butis, and contribute crucial information relevant to sustainable management of fish populations in the study region.

Assessing maturity, fecundity and hermaphroditism in blue cod Parapercis colias

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 26:137-148 (2017) - DOI: https://doi.org/10.3354/ab00679 Assessing maturity, fecundity and hermaphroditism in blue cod Parapercis colias K. K. Brandt1,3,*, M. R. Dunn1, S. L. Brouwer2 1School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand 2Oceanic Fisheries Programme, Pacific Community (SPC), BP D5, Noumea 98848, New Caledonia 3Present address: 100–104 Stoke Newington High Street, London N16 7NY, UK *Corresponding author: kasper.k.brandt@gmail.com ABSTRACT: Macroscopic assessments of maturity from whole fish gonads are well established and routinely used in fisheries research and are important in the estimation of size-at-maturity and the impacts of size-selective fishing. Histological assessment of maturity is more accurate, but much slower, more expensive, and so less frequently conducted. We made a comparison between macroscopic and histological maturity classifications for a diandric protogynous hermaphrodite, blue cod Parapercis colias. The agreement between macroscopic and histological maturity classifications was low. Female and male L50 (length at which 50% of the fish are mature) was estimated from histological data as 23 and 26 cm, respectively. Female spawning frequency was 4.6 d, and mean ± SD relative batch fecundity was 6.5 ± 3.3 hydrated oocytes per gram body weight. A single gonad with both testicular and ovarian tissue was found. Many blue cod were assigned incorrect maturity classifications. These results warrant a study of early gonadal development in blue cod to elucidate if and how sex change takes place. Difficulties in determination of sex and maturity may be most pronounced for species, like blue cod, that have complex maturation patterns. For blue cod, a review of the macroscopic maturity classification key and more thorough technician training are called for. KEY WORDS: Maturity assessment · Length at maturity · Fecundity · Parapercis colias · Sex change · Histology Full text in pdf format PreviousNextCite this article as: Brandt KK, Dunn MR, Brouwer SL (2017) Assessing maturity, fecundity and hermaphroditism in blue cod Parapercis colias. Aquat Biol 26:137-148. https://doi.org/10.3354/ab00679 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 26. Online publication date: September 05, 2017 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2017 Inter-Research.

Ethmalosa fimbriata (Bowdich 1825), a Clupeid Fish That Exhibits Elevated Batch Fecundity in Hypersaline Waters

Little is known about the concerted influence of temperature and salinity on the fecundity of clupeid fishes. Due to a globally changing climate, both physical parameters might act as stressors, severely affecting the reproductive potential of clupeid fish populations inhabiting tropical estuaries. Differences in relative batch fecundities, the gonado-somatic index, and the condition index of bonga shad (Ethmalosa fimbriata) were analysed in individual females sampled at the Senegalese coast and inside the inverse Sine Saloum estuary, where salinity increases upstream in all seasons. Multiple linear regression models on fecundity and gonadal energy storage show that clupeids can adapt towards increasing their reproductive investment at temperatures (26–30 °C) and salinities (42–51), which by far exceed marine conditions, in an effort to maximize recruitment success. This reproductive strategy, however, is accompanied by a trade-off between reproductive effort and somatic growth, which ultimately limits the species’ reproductive potential inside the estuary. The observed high variability in batch fecundities might be a viable mechanism to adjust to fluctuating and rather extreme environmental conditions. Understanding the spawning biology of exploited clupeid fishes in drastically changing environments is crucial for evaluating the reproductive potential of stocks at the outer reach of their physiological performance curve.

Protracted volitional spawning of pinfish Lagodon rhomboides and changes in egg quality and fatty-acid composition throughout the spawning season.

Spawning performance of pinfish Lagodon rhomboides without use of hormonal aids was monitored over an extended season. Nearly three million eggs were obtained from 75 spawns collected over a 90-day consecutive period from a single population of four brood fish (1M:1F). A mean ± s.d. batch fecundity of 30·27 ± 22·64 eggs g-1 female was estimated with 98·0 ± 0·06% of the batch composed of floating eggs which were 1·04 ± 0·04 mm in diameter and 85·71 ± 27·59% fertile. Floating eggs successfully hatched 54·65 ± 29·13% of the time which yielded larvae that were 2·59 ± 0·24 mm in length. Fatty acids within floating eggs were largely represented by polyunsaturated fatty acids (45·30 ± 2·14% of total fatty acids) of which linoleic acid [(c18:2n-6cis) 3·49 ± 1·69% trifluoroacetic acid (TFA)] and docosahexaenoic acid (DHA) [(c22:6n-3) 28·47 ± 1·48% TFA] represented the majority of fatty acids for n-6 and n-3 polyunsaturated fatty acids, respectively. The strongest correlations between fatty acids and hatching success and larval survival to first feeding were observed for the DHA:EPA (eicosapentaenoic acid; c20:5n-3) ratio and total n-6 polyunsaturated fatty-acids levels, respectively. These data demonstrate potential for producers to rely on natural spawns for extensive egg production and provide a baseline for future development of natural spawning protocols of captive L. rhomboides.

Diplectrum radiale (Quoy & Gaimard, 1824) (Serranidae): A rare case of simultaneous hermaphroditism in a teleost fish

AbstractThis study generates, for the first time, information on the reproductive traits of the simultaneous hermaphrodite Diplectrum radiale. The specimens were captured bimonthly in two distinct ecosystems along the south‐eastern Brazilian coast. The mature ovotestes were removed, preserved in formalin and examined using histological techniques. The results revealed indeterminate fecundity with asynchronous ovarian organization. All spermatogenesis occurs within cysts, and the spermatogonial distribution indicated an unrestricted testicular type. The testicular and ovarian tissues were separated from each other by different ducts, indicating no possibility of internal self‐fertilization. The hydrated oocytes were stored in the accessory reproductive structure for at least 24 hr. The presence of atretic hydrated oocytes within this structure and the positive periodic acid–Schiff reaction of the villi‐like projections revealed the function of the ovary sinus as absorbing unspawned oocytes. The relative batch fecundity ranged from 62 to 209 oocytes/g (126 ± 42) for specimens from the coast and from 52 to 203 oocytes/g (113 ± 57) for those sampled in the estuary. The potential batch fecundity was linearly related to size, weight, and the gonadosomatic and hepatosomatic indices, revealing that these parameters significantly affect the reproductive potential of D. radiale.

Reproductive life history characteristics of invasive red lionfish (Pterois volitans) in the northern Gulf of Mexico

With invasive lionfish (Pterois spp.) increasing throughout the western North Atlantic Ocean and Gulf of Mexico (GOM), it is important to define life history characteristics to help understand the invasion and potential effects on receiving ecosystems. Although some aspects of reproduction are known elsewhere in the invaded range, little is known in the northern GOM [nGOM; Florida Keys (24.66°N) to south Texas (26.00°N)]. In the present study, gonadosomatic index (GSI) calculations were based on 4527 red lionfish Pterois volitans (Linnaeus, 1758) specimens (April 2012–March 2015). Male and female GSI peaked from May to October, corresponding with macroscopic gonadal assessments of reproductively active females. Histological examination of ovaries from 355 females found they were spawning capable during all months. Males (n = 211) were spawning capable in all months except March, the only month in which no actively spawning females were present. A significantly higher percentage of reproductively active females was found from May to December. Lionfish reached 50% maturity at a small size (166.6 mm TL, females; 145.2 mm TL, males). Mean relative batch fecundity (n = 71) was 92 eggs g–1 gonad-free body weight (GFBW) and was highest in August (207 eggs g–1 GFBW). The population spawning frequency was estimated to be every 2.5 d over 11 mo in the nGOM, corresponding to a maximum potential annual output of 2,332,490 eggs for an average sized (188.6 g) female. These reproductive characteristics are similar to invasive lionfish in tropical waters, although nGOM reproductive output appears higher. Our results represent the most comprehensive reproductive data on lionfish in their invaded range, and provide a baseline for management in the nGOM.

Co-treatment with androgens during artificial induction of maturation in female eel, Anguilla anguilla: Effects on egg production and early development

Inclusion of sustained-release androgen implants into fertility treatment regimes of female freshwater eels has been proposed to benefit artificial maturation outcomes. This study sought to test whether co-administration of the androgen 17-methyltestosterone (17-MT) in combination with ‘traditional’ hypophysation of female European silver eels would affect egg quality and subsequent larval survival. Implants, containing 1mg 17-methyltestosterone (17α-methyl-4-androsten-17β-ol-3-one in a matrix of cholesterol:cellulose=95:5), were administered twice, at 1 and 5weeks after onset of experimentation (MTA- and MTB-groups); control eels (Ctrl) were given a blank implant. Female eels received weekly injections with carp pituitary homogenates (CPH) from either Week 1 (MTA- and Ctrl groups) or Week 5 onwards (MTB-group). First 4 injections were made with 10mgCPH/kg body weight (BW) in sterile physiological saline (0.9% NaCl); the subsequent 12 injections with 30mg/kg CPH and thereafter, 40mg/kg CPH was injected until fish were considered ready for induction of final maturation. Bi-weekly blood samples were collected (Day 0 onwards) and analyzed for levels of testosterone (T) and estradiol-17β (E2) by radioimmunoassay. After reaching maturity, fertilized eggs were obtained upon spontaneous spawning of co-housed breeders and egg performance (fertilization, hatching, survival rates) was recorded. No differences were observed between eels from the MTA- and MTB-groups; however, egg performance was notably better in eels treated with 17-MT+CPH compared to eels receiving CPH only, with hatching rates reaching mean values as high as around 70% for both 17-MT and CPH co-treated groups, but only averaging 21.0±8.4% for eggs from the Ctrl-group. Furthermore, 17-MT treated eels displayed a more distinct pre-spawning peak for levels of plasma T and E2 and for body weight, the latter being indicative of increased batch fecundity. We conclude that androgen co-treatment holds promise for future development of eel captive breeding technologies. Statement of relevanceArtificial propagation of the European eel is increasingly urgent to release the strain on natural populations. This study presents a novel approach to artificial maturation of female eels: centered around the incorporation of androgens during fertility treatment. Accordingly, increased performance was observed in terms of fertilization, hatching and survival rates, which contributes to completing the life cycle of this fish in captivity.

Spawning cycle and fecundity of a multiple spawner round herring Etrumeus teres off southern Japan: Oocyte growth and maturation analysis

The spawning characteristics of round herring Etrumeus teres remain unclear despite its commercial and ecological importance. The oocyte growth and maturation during the spawning cycle of round herring were examined based on the samples collected at different hours of the day off southern Japan during their 2015 spawning season. The ovarian histological analysis showed that germinal vesicle migration (GVM) and subsequent germinal vesicle breakdown occurred from the afternoon to the next morning. The appearance of hydrated oocytes indicated that round herring spawned between midday and evening. Degeneration of post-ovulatory follicles and the ovarian developmental stage suggested that individual round herring did not spawn on consecutive days but rather spawned at an interval of at least 2days. The oocyte diameters of the second clutch (subsequent spawning batch) increased gradually when the first clutch (spawning batch) underwent GVM and hydrated, but oocytes in the second clutch increased significantly in size immediately after spawning, suggesting that vitellogenesis of the second clutch may be accelerated for the next spawning. Size at maturity in all females was estimated to 17.6cm in body length (BL), and batch fecundity was 1409–21,023 oocytes (15.7–24.0cm in BL). Our findings provide a foundation for conducting stock assessment studies on round herring using an egg production method.

Goosefish Lophius americanus fecundity and spawning frequency, with implications for population reproductive potential.

To improve knowledge of goosefish Lophius americanus' reproductive biology, females were collected during 2009-2012 from the Mid-Atlantic Bight shelf region of the U.S. east coast. Batch fecundity increased with total length (LT ), from 229 100 to 2 243 300 mature oocytes per female (LT range: 55·5-112 cm; n = 54). This estimate of fecundity at LT is lower than one derived from a sample collected during 1982-1985. Examination of whole oocyte diameters in different months indicated that L. americanus is a serial spawner, releasing more than one egg veil per spawning season, as suspected or observed for other Lophius species. Seasonality of spawning was evident from whole oocytes and gonad histology, and from larval fish surveys spanning the U.S. north-east shelf, and confirmed a protracted (c. 6 months) spawning period. Peak spawning activity progressed northward from spring to autumn. The population-level implications of these results were explored by estimating population reproductive potential (PRP ), which considered the value of both current and future per capita reproduction using decade-specific age structure and fecundity at length. PRP is now more than 50% lower compared with the historical period (1982-1985), a result of the lower proportions of large females and reduced fecundity across all sizes. Mechanisms that could explain this loss of stock productivity are fishing-induced size-age truncation or regime shifts in egg production caused by changes in energy density of common forage species.

Three new decapods (Aristeidae, Chirostylidae, Pandalidae) from the Cape Verde Islands (NE Atlantic)

In the present article three benthic decapods, Aristeus varidens Holthuis, 1952 (Aristeidae), Gastroptychus formosus (Filhol, 1884) (Chirostylidae) and Plesionika longicauda (Rathbun, 1901) (Pandalidae), are recorded for the first time from the Cape Verde Islands. This is the southernmost record of G. formosus, as well as the northernmost of P. longicauda ever recorded from the eastern Atlantic. Preliminary data on batch fecundity and egg size of the pandalid shrimp are provided. Studied specimens were caught in the frame of a scientific trapping survey.

Reproductive potential of Pagrus pagrus (Perciformes: Sparidae) in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34º-39ºS)

ABSTRACT The reproductive potential of red porgy in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34º-39ºS) was studied by means of a macroscopic and histological analysis of the gonads. Length and age at first maturity were determined, and fecundity, spawning frequency and egg quality were estimated. The spawning season extended from spring through summer between October and January with a peak of spawning in December. Length and age at maturity for sexes combined was 24.5 cm TL and 1.54 years, respectively. Batch fecundity ranged from 6,974 (25 cm TL) to 110,725 (39 cm TL) hydrated oocytes and showed significant linear relationships with total length and ovary-free weight. Relative fecundity ranged from 16 to 172 oocytes per female gram (ovary free). Spawning frequency was 58.5% during January 2011, indicating that females spawned once every 1-2 days at the peak of the spawning season. The life history of red porgy in Argentina and Uruguay was characterized by a young age at first maturity and partial, almost daily, spawning in a bounded time period, a life history strategy that would facilitate population expansion or colonization of new areas, and high population recovery rates or growth (r).

Reproductive Biology of Albacore Tuna (Thunnus alalunga) in the Western Indian Ocean.

The reproductive biology of albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male albacore were sampled. A bias in sex ratio was found in favor of females with fork length (LF) < 100 cm. Using histological analyses and gonadosomatic index, spawning was found to occur between 10°S and 30°S, mainly to the east of Madagascar from October to January. Large females contributed more to reproduction through their longer spawning period compared to small individuals. The L50 (mean ± standard error) of female albacore was estimated at 85.3 ± 0.7 cm LF. Albacore spawn on average every 2.2 days within the spawning region and spawning months, from November to January. Batch fecundity ranged between 0.26 and 2.09 million oocytes and the relative batch fecundity (mean ± standard deviation) was estimated at 53.4 ± 23.2 oocytes g-1 of somatic-gutted weight. The study provides new information on the reproductive development and classification of albacore in the western Indian Ocean. The reproductive parameters will reduce uncertainty in current stock assessment models which will eventually assist the fishery to be sustainable for future generations.