Search

Tiger sharks (Galeocerdo cuvier) play an important ecological role as top predators, yet knowledge of their reproductive ecology is scarce. Here, the authors report the first observation of a potential neonate G. cuvier at Cocos Island, a predator-dominated oceanic island in the Eastern Tropical Pacific (ETP). The individual was detected using baited remote underwater video stations (BRUVS). The cameras also detected female individuals potentially pregnant, suggesting that parturition may take place at or near the island. Nonetheless, it is still unclear if the presence of a single neonate is an isolated event or evidence that the species is using the island for reproduction.

The oviducal gland is a specialised region of the elasmobranch oviduct that is thought to be a site of sperm storage, among other functions. The phenomenon of female sperm storage in elasmobranchs has implications for the understanding of their reproductive ecology and the management of exploited populations, but relatively little information exists on its taxonomic extent. In the present study, oviducal glands from 29 different species, of varying reproductive modes, from the northern Indian and North East Atlantic oceans were examined using light microscopy for the presence of sperm. The organisation of the gland into four fundamental zones; club, papillary, baffle and terminal, was conserved across all species, with slight variations in relative zone volume due to reproductive mode. Spermatozoa observed within the oviducal gland were not limited to a particular reproductive mode or maturity stage. Although spermatozoa were most commonly encountered in the terminal zone tubules, in some species they were also encountered elsewhere in the gland. The storage of sperm may be a vital reproductive strategy for many species and furthering our taxonomic understanding of which species employ this strategy will help to better inform fisheries managers and protect exploited low reproductive species.

Marine fish stocks are increasingly being exploited to unsustainable levels. Yet, knowledge of basic biological and ecological traits of species, required to sustain fisheries management at a local...

Major aggregations of nesting green turtles (Chelonia mydas) occur in the northern Red Sea, although little is known about the reproductive ecology of this endangered species in the region. To address this issue, we satellite-tracked 30 female green turtles to document their movements and to identify factors driving habitat use at two major rookeries in the Red Sea, Jazirat Mashabah (Mashabah Island) and Ras Al Baridi in Saudi Arabia. Between successive nesting events, turtles displayed high fidelity to nesting beaches and adjacent in-water habitats (inter-nesting habitats). Using generalized linear mixed models, we estimated the mean probability of nesting per beach emergence (nesting success rate) to be 0.628, and the mean duration between a successful nesting event and the successive emergence onto the beach (re-nesting interval) to be 10.8 days at each site. The nesting success rate was relatively high (>0.8) when the preceding daytime land surface temperature (LST) was lower than 37°C but decreased with elevated daytime LST (47°C). Re-nesting interval was longer at lower water temperatures and towards the end of the nesting season of individuals. Our study improves the robustness of abundance estimates from census data (e.g., track counts) and shows that the protection of nesting and inter-nesting habitats during a breeding season would be an effective conservation strategy for the species. We discuss how global warming could increase energy expenditure due to lowered nesting success, ultimately compromising the reproductive fitness of these populations.

Successful recruitment of endangered pallid sturgeon has not been documented in the upper Missouri River basin for decades, and research on the reproductive ecology of pallid sturgeon has been hindered by low sample size. A conservation propagation program was initiated in the 1990s, and the oldest age class of hatchery‐origin pallid sturgeon are becoming sexually mature increasing the number of reproductively‐active fish in the system. However, it is currently unknown how the reproductive ecology of hatchery‐origin pallid sturgeon relates to the few remaining wild fish. Following spring reproductive assessments, weekly relocations were recorded for each individual from late‐May to mid‐July to facilitate comparisons of spawning season movements among reproductive classifications and between spring hydrographs (2015 and 2016) for male pallid sturgeon. Mean total movement distances (±SE) were 104.5 km (18.9) for reproductively‐active wild males, 116.0 km (18.1) for reproductively‐active 1997‐year class males, and 20.6 km (3.0) for non‐reproductively‐active fish of unconfirmed sex. Movement characteristics of reproductively‐active males did not differ between 2015 and 2016 despite a difference of eight days in the timing of peak discharge and a difference of 79 m³/s (16.7%) in magnitude. Male aggregations were observed on the descending limb of the hydrograph in 2016 during temperatures suitable for spawning, but female pallid sturgeon underwent follicular atresia, similar to the other years of the study. Hatchery‐origin pallid sturgeon from the conservation propagation program appear to have retained reproductive characteristics from the wild broodstock, a key finding for a population where local extirpation of the wild stock is imminent.

The 9th International Charr Symposium convened on 18–21 June 2018, in Duluth, Minnesota, USA, to gather scientists with an interest in charr biology and management from the entire geographical range of the genus Salvelinus. The symposium was attended by 169 individuals from six countries, and included 99 oral and 32 poster presentations, 28 of which were published in the ensuing proceedings. Topic areas of presentations and publications included (1) cultural anthropology; (2) genetics, evolution, taxonomy, and systematics; (3) behavior, movement, and habitat; (4) reproductive ecology, developmental ontogeny, and physiology; (5) population ecology, dynamics, and life history; (6) trophic ecology, parasites, predators, toxicology, and pollution; and (7) management. Research reported in these proceedings has built upon the history of earlier symposiums and will be continued with the 10th symposium scheduled to convene in Nikko City, Tochigi Prefecture, Japan, in 2021.

Identifying complex behaviors such as spawning and fine-scale activity is extremely challenging in highly migratory fish species and is becoming increasingly critical knowledge for fisheries management in a warming ocean. Habitat use and migratory pathways have been extensively studied in marine animals using pop-up satellite archival tags (PSATs), but high-frequency data collected on the reproductive and swimming behaviors of marine fishes has been limited by the inability to remotely transmit these large datasets. Here, we present the first application of remotely transmitted acceleration data to predict spawning and discover drivers of high activity in a wild and highly migratory pelagic fish, the mahi-mahi (Coryphaena hippurus). Spawning events were predicted to occur at nighttime, at a depth distinct from non-spawning periods, primarily between 27.5 and 30°C, and chiefly at the new moon phase in the lunar cycle. Moreover, throughout their large-scale migrations, mahi-mahi exhibited behavioral thermoregulation to remain largely between 27 and 28°C and reduced their relative activity at higher temperatures. These results show that unveiling fine-scale activity patterns are necessary to grasp the ecology of highly mobile species. Further, our study demonstrates that critical, and new, ecological information can be extracted from PSATs, greatly expanding their potential to study the reproductive behavior and population connectivity in highly migratory fishes.

Se estudió la biología reproductiva y el ciclo de vida de la palometa pintada, Parona signata en Mar del Plata (38°00’S 57°33’O). Las muestras fueron obtenidas mensualmente desde enero de 2018, hasta febrero de 2019, provenientes de la pesca artesanal y/o de la flota comercial de la localidad Mar del Plata. Además, se llevó a cabo un análisis histológico y se estimaron los principales parámetros reproductivos tales como: la fecundidad, análisis de la distribución de la frecuencia de diámetros ovocitarios e índice gonadosomático (GSI) mensual. Tanto el análisis macroscópico como el microscópico permitieron afirmar que en los meses de marzo y noviembre existe actividad reproductiva. Se encontraron hembras en puesta, las cuales presentaron ovocitos hidratados en los cortes histológicos. Ambos, los análisis histológicos y de distribución de la frecuencia de diámetros oocitarios mostraron la presencia de todas las fases de maduración oocitaria en ovarios correspondientes a la sub-fase de desove activo, indicando que P. signata es un desovante parcial con fecundidad anual indeterminada. La fecundidad parcial osciló entre 36.426 y 126.035 oocitos hidratados/hembra. La fecundidad relativa varió entre 42 y 150 ovocitos por gramo de hembra libre de ovario. The reproductive biology and life cycle of Parona leatherjacket, Parona signata (Carangiformes), present in Mar del Plata (38°00′S 57°33′W) coast, was studied. Samples were obtained monthly since January 2018 to February 2019 from the artisanal fishermen and the commercial fleet of Mar del Plata. A histological analysis was carried out and the main biologic-reproductive parameters were estimated: fecundity, oocyte frequency distribution and gonadosomatic index (GSI). Both the macroscopic and microscopic analyses showed reproductive activity in March and November. Mature females were recorded, which showed hydrated oocytes, as was evidenced by the histological procedures. Both, the histological and the oocyte diameter distribution analyses showed the presence of all oocyte maturation stages in ovaries in active-spawning subphase, indicating that P. signata is a multiple spawner with indeterminate annual fecundity. Batch fecundity ranged between 36,426 and 126,035 hydrated oocytes/ female. Relative fecundity ranged between 42 and 150 oocytes/ g female ovary free. Fil: Bianchi, Santiago Julián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: González Castro, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Stock-recruitment relationships in elasmobranchs are uncertain due to a lack of data, especially regarding pre-recruit survivorship. A pre-recruit survival model for the early life history of elasmobranchs was developed and parameterized using biological data. Then, an existing age-structured model for the reproductive ecology of teleost fishes was modified for elasmobranchs and combined with the pre-recruit model. The combined model was then applied to the North Pacific blue shark (Prionace glauca). The stock-recruitment relationships of this species were clarified using the biological data collected from wide areas of the western North Pacific. The model provides a point estimate for steepness, which represents a fraction of the unfished recruitment when spawning stock biomass is 20% of the unfished spawning stock biomass. Numerical simulations were conducted to incorporate uncertainties in the biological parameters and produce the variance of steepness. The mean value and its standard deviation for steepness with the Beverton-Holt model were 0.584 (standard deviation = 0.099). The results suggest that the stock-recruitment relationship in North Pacific blue shark remains highly density-dependent and that its productivity is higher than that of other viviparous elasmobranchs.

Maturation is one of the most important ontogenetic transitions in an individual’s life. However, the reproductive ecology of the tropical anguillid eel genus Anguilla at the onset of oceanic spawning migration is poorly understood. To understand the reproductive ecology, the fecundity of the tropical eels Anguilla bicolor bicolor, A. bengalensis bengalensis and A. marmorata was examined using advanced migrating silver eels (Stage IV and V). A close linear relationship was found between total length and fecundity in A. bengalensis bengalensis. The fecundities of A. bicolor bicolor (0.55 to 4.96 × 106), A. bengalensis bengalensis (0.33–1.72 × 106) and A. marmorata (0.99 × 106) were within the range of those observed in temperate eels.

Deep-sea corals are of conservation concern in the North Atlantic due to prolonged disturbances associated with the exploitation of natural resources and a changing environment. As a result, two research cruises in the Gulf of Maine region during 2014 and 2017 collected samples of two locally dominant coral species, Primnoa resedaeformis and Paramuricea placomus, at six locations to investigate reproductive ecology. Remotely operated vehicles (ROVs) were used to collect specimens that were examined via paraffin histology, and coincident video surveys were used to determine size class distributions. Both species were identified as gonochoristic, and sampled locations exhibited dissimilarities in spermatocyst development and oocyte size except for those in close geographic proximity. Fecundities exhibited substantial ranges across sample locations and average oocyte sizes ( SD) were 140  117 m for P. resedaeformis and 64  46 m for P. placomus. In addition, colony size distributions were also significantly different across sampling locations. Notably, the Outer Schoodic Ridge sample location, with larger colony and oocyte sizes, was identified as a potential key source population of reproductive material in the Gulf of Maine. These data were used to calculate differences in reproductive potential based on relationships between colony morphology and reproductive output using height as a predictive proxy. Furthermore, calculated age at first reproduction, 7.6-19.8 years for P. resedaeformis and 20.7-37 years for P. placomus, which may be dependent on sex of the colony, provides a metric for estimating the amount of time these coral habitats will take to recover. This investigation, in response to historical population impacts and environmental change, links reproductive and morphometric relationships to inform population scale reproductive models, while also establishing an understanding of regional scale gametogenic variability within the Gulf of Maine region.

Climate change and land-use practices are causing widespread warming of streams, forcing resident species to adapt or migrate. For instance, in the John Day River, Oregon (Columbia River basin), rising temperatures are facilitating the range expansion of Smallmouth Bass Micropterus dolomieu into critical salmon rearing habitat. Understanding Smallmouth Bass reproductive ecology at its range boundaries is integral to understanding and ultimately predicting its upstream range expansion. We addressed this knowledge gap by exploring potential temperature-mediated effects on Smallmouth Bass reproduction at the leading edge of its nonnative riverine distribution in the Pacific Northwest. We used continuous snorkel surveys to characterize its upstream extent in the North Fork John Day River, where we observed spawning patterns and measured adult nest-guarding male size, fecundity, brood development, habitat attributes, and nest success over 2 years (2014, 2015). We found a pattern of asynchronous and pro...

Reproductive structures of the seagrass, Halodule wrightii Ascherson (shoal grass) are cryptic and ephemeral, but were found on several occasions at several sites over more than a decade in the subtropical Laguna Madre (USA). Structures align with descriptions for H. wrightii. Male, but no female flowers were found, but the numerous fruit-bearing shoots imply the occurrence of pistillate flowers. Mean seed bank density was 890 seeds m-2 (1900–5200 m-2). Sexual reproduction in H. wrightii is more common than previously believed and the seed bank reserve may contribute to its ecological role as a colonizer of disturbed sediments.

International audience; Studying gamete biology can provide important information about a species fertilization strategy as well as their reproductive ecology. Currently, there is a lack of knowledge about how long sea bass Dicentrarchus labrax eggs can remain viable after being activated in seawater. The objectives of this study were to understand the effects of pre-incubation of fresh and overripe sea bass eggs in seawater and to determine the duration of egg receptivity. Pooled eggs (fresh and overripe) from four females were pre-incubated in seawater for 0 min (control), 0.5 min, 1 min, 3 min, 10 min and 30 min and then fertilized by pooled sperm from four males. The fresh eggs had a higher fertilization success than overripe eggs. Our results revealed a significant effect of pre-incubation time for both the fresh (P < 0.01) and overripe eggs (P < 0.01). Fertilization success of eggs significantly declined for both these treatments after 3 min of pre-incubation, which clearly indicates that sea bass eggs are able to be fertilized by sperm for up to 3 min after release into seawater. This study has particular importance for understanding fertilization strategies, reproductive potential, as well as reproductive ecology of sea bass.

The reproductive ecology of European eel (Anguilla anguilla) is poorly understood, though information on life-history traits such as fecundity is necessary for appropriate management of this critically endangered species. During the growth period of the life cycle, yellow-phase eels can be resident in different habitat types (e.g. salinity ranging from freshwater to marine) over a wide geographic distribution. Consequently, maturing silver-phase eels migrating back to the oceanic spawning grounds can display considerable variation in certain life-history traits depending on their habitat and/or geographic origin. Few fecundity estimates are available from wild A. anguilla, and no investigation of the effects of habitat type (i.e. salinity) or geographic location on variation in fecundity has been undertaken. To assess the former, we examined silver-phase eels which had predominantly been resident in freshwater (Lake Mälaren, Sweden) or brackish (Baltic Sea) habitats. Despite Lake Mälaren eels generally being larger, there was no difference in the fecundity–body size relationship between these salinity zones. Second, we determined if fecundity differed between silver-phase eels sampled from different geographic locations: Lake Mälaren and the Baltic Sea outlet in Sweden, the River Shannon in Ireland (northwest Europe) and Vistonis Lake in Greece (eastern Mediterranean). Our results showed that silver-phase eels from Sweden (Lake Mälaren and Baltic Sea outlet) and Greece were significantly more fecund at a given body size than those from Ireland. Spawner models and conservation policies should therefore take account of eel geographic origin in particular when incorporating this life-history parameter.

This study examined the reproductive ecology of eight Eastern Pacific deep-sea octocorals, collected from Washington to Southern California. The sexuality, reproductive mode, oocyte size, and fecundity of each species were identified using histological techniques. This research increases the knowledge of basic life histories of deep-sea corals.Swiftia simplexhad the highest total fecundity of 42.53 (±9.82 SE) oocytes per polyp. Mean oocyte diameters inS. simplexandS. pacificafemales differs among sample months.Swiftia pacificaandS. kofoidihad the lowest total fecundity: 4.6 (±2.06 SE) and 3 (±1.53 SE) oocytes per polyp, respectively.

Can the reproductive traits of

Commercial catches of barfin flounder Verasper moseri, an important target flatfish for stock enhancement programs in northern Japan, have recovered remarkably since the large-scale release of seedlings from Hokkaido in 2006. However, their reproductive ecology remains unclear. Our study of 2008–2012 investigated seasonal changes in the maturity of stocked female barfin flounder (n = 4,123) off the Pacific coast from Hokkaido to Tohoku (35.7°–43.4°N). Histological observation of ovaries revealed that fish undergoing vitellogenesis were observed mainly off Hokkaido and partially off northern Tohoku during August–January (40.2°–43.4°N). However, fully matured or spawning fish were not found near those areas. They were observed only in southern Tohoku. Ongoing spawning was observed off southernmost Tohoku (35.8°–37.5°N around 300 m depth) from early February through late April, when commercial landings had decreased drastically off Hokkaido. Spent fish were caught only rarely off southern Tohoku, but were observed frequently off Hokkaido during April–June. These results demonstrate that spawning grounds form at the upper continental slope off southernmost Tohoku during February–April. Relations between maturation traits and seasonal landings strongly suggest that female barfin flounder repeatedly migrate more than 700 km from feeding grounds off Hokkaido to spawning grounds off southern Tohoku.

Sexual dimorphism on a macroscopic scale is unusual within Phaeophyceae. In this paper we report for the first time on macroscopic sexual dimorphism in F. radicans. During field collections it was ...

Smallmouth Bass (Micropterus dolomieu) and Largemouth Bass (M. salmoides) are congeneric species that co-occur in many lentic and lotic systems, but have never been documented to hybridize in the wild. In 2003, a long-term study of reproductive ecology of M. dolomieu encountered a nest defended by a male M. dolomieu with two distinctly different size sets of eggs. The size range of one set of eggs was consistent with that observed for M. dolomieu, but the size range of the second set of eggs was too small for M. dolomieu and was within the size range for M. salmoides. A sample of fin tissue from the male guarding the brood and a subsample of both size classes of offspring were collected. Molecular genetic techniques (protein electrophoresis, microsatellite analysis, and RFLP analysis of mtDNA) confirmed that progeny from the larger eggs were from a mating between the nest-guarding male and a female M. dolomieu and that those from the smaller eggs were from a mating between the nest-guarding male ...

Fishing can induce evolutionary changes in individual life history traits, leading to fish that mature smaller and younger and with larger gonads, so that they reproduce more intensely. The steepness of a stock–recruitment relationship is commonly defined as the fraction of recruitment of an unfished population obtained when the spawning stock biomass is 20% of its unfished level. We use a model of harvest-induced evolutionary change to understand how the steepness of the stock–recruitment relationship changes due to fishing. If the true spawning stock biomass is known, the stock–recruitment relationship changes little under fishing-induced evolution and there is little concern for fisheries management. When management is based on a total biomass – recruitment relationship, recruitment may be underestimated, which is also of little concern from a sustainability perspective. However, when the number of spawners – recruitment relationship is used to forecast recruitment, management practice that ignores the evolution of steepness may overestimate recruitment and therefore recommend catches that exceed safe biological limits. Using outdated maturity ogives underestimates spawning stock biomass, which results in steeper and higher stock–recruitment relationships as life histories evolve. Although of little concern for sustainability, this may pose challenges for practical fisheries management.

The sperm allocation pattern of a copulating marine cottid fish, Alcichthys alcicornis, was investigated. A total of 86 mating events using six males were conducted in aquarium tanks over 10 days, and in 36 of them, spermatozoa were collected using a false copulation method. Males released 3–8 × 108 spermatozoa in early events, with the number decreasing gradually during subsequent mating events. This sperm allocation was represented as an “early investment and tapering” pattern. It was discussed why males have significantly higher sperm release in early spawning events. The reproductive behavior consists of spawning and subsequent copulation. Spermatozoa have the ability to fertilize eggs from multiple clutches, and in earlier produced clutches the level of sperm competition should be relatively low. In addition, if early spawn happens to be the first spawn with a female, spermatozoa that are released into the water column after spawning are responsible for fertilizing the female’s first clutch. The probability of this occurring should decrease dramatically as the season progresses, due to the highly synchronous seasonal spawning of females. All of these factors should select for high sperm numbers in early ejaculates. Based on such reproductive ecology of A. alcicornis we hypothesize that this sperm allocation pattern is an adaptive reproductive strategy in response to egg availability and sperm competition occurring within the ovarian cavity.

Congrids inhabit the warm and temperate seas of the world, from the coastline to the slope of various continents. Many of its species are much valued by commercial and artisan fishing; nevertheless, at world level, there is great ignorance about the life cycle of the members of this genus. Some species of the genus, such as those from the North Atlantic, appear to be semelparous, for they cease feeding, decalcify, loose their teeth and migrate to deep waters to spawn. Specimens of the southern conger eel Conger orbignianus were examined for the purpose of learning about their biology in waters of the western South Atlantic. Histological sections were analysed from ovaries of coastal conger specimens from the North Argentina coastal littoral, the Argentine Sea deep waters, and the giant congers from southern Brazil. Two oocitary generations have been observed in coastal females typical of total spawners, with a previtellogenetic batch that does not reach maturity, and a vitellogenetic batch that does it together with its size, completely surrounded by adipose tissue. The ovaries of fish captured in deep waters occupied the whole abdominal cavity, with scarce adipose tissue and degraded body. The giant congers from southern Brazil were captured in very deep waters, healthy, with few atretic oocytes and abundant adipose tissue. Evidence of semelparity was found in the southern conger eel; the asistosis stage, the body degradation during the reproductive migration and gigantism might be common attributes in other species of the genus.

The need for integrated and widely accessible sources of species traits data to facilitate studies of ecology, conservation, and management has motivated development of traits databases for various taxa. In spite of the increasing number of traits-based analyses of freshwater fishes in the United States, no consolidated database of traits of this group exists publicly, and much useful information on these species is documented only in obscure sources. The largely inaccessible and unconsolidated traits information makes large-scale analysis involving many fishes and/or traits particularly challenging. We have compiled a database of > 100 traits for 809 (731 native and 78 nonnative) fish species found in freshwaters of the conterminous United States, including 37 native families and 145 native genera. The database, named Fish Traits, contains information on four major categories of traits: (1) trophic ecology; (2) body size, reproductive ecology, and life history; (3) habitat preferences; and (4) s...

– We used a combination of methods to study the reproductive ecology of the imperiled smalleye shiner Notropis buccula Cross in the Brazos River, Texas between April 2003 and March 2005. Patterns in oocyte development, gonadosomatic index and oocyte size distribution indicate that reproduction occurs over a 6-month period between April and September and that the population spawns asynchronously with individual fish spawning small batches of ova throughout the reproductive season except during periods of elevated streamflow when spawning becomes more intense and is synchronised within the population. This combination of asynchronous spawning and episodic synchronous spawning in the same species challenges the current paradigm of an exclusive association between spawning and periods of elevated streamflow for pelagic, broadcast-spawning cyprinids in North American Great Plains Rivers. The combination of asynchronous and synchronous spawning that we observed for the smalleye shiner is likely widespread among pelagic, broadcast-spawning cyprinids and limitations of the methods commonly used to assess reproductive ecology likely contributed to an incomplete understanding of the relationship between spawning and streamflow. An accurate understanding of this relationship is necessary to design and implement appropriate conservation and management strategies for the smalleye shiner and other imperiled broadcast-spawning cyprinid fishes.

1. The main reproductive parameters of exotic Trachemys scripta elegans in established populations from two ponds in southern Spain are described. 2. Females were found to reproduce at 5 years of age, although sexually mature individuals of 4 and 3 years of age were also detected. Annual reproductive frequency was estimated to be 80-86% of reproductive females. Mean clutch size was 11.5 eggs and was not correlated with maternal body size. 3. The number of follicles of different size in ovaries suggested that four or more clutches could be laid per season. Eggs were laid from April to June (inclusive) mainly during morning hours, when females were easily detected during nesting trips. 79.5% of eggs were fertile. 4. Reproductive parameters of this species in southern Spain were of similar or even higher values than in native areas, thus placing them among chelonian species of earlier maturity. 5. Although chelonians might never be considered explosive breeders, the number of T. s. elegans individuals could surpass that of native aquatic chelonians in southern Spain, where T. s. elegans reach maturity earlier, are more fecund and their eggs are more fertile. Copyright © 2008 John Wiley & Sons, Ltd.

Three yellow sandshell mussels, Lampsilis teres (Rafinesque, 1820), were observed in Lake Tuscaloosa, Alabama, and the temporal display pattern of their mantle-flap lures was investigated in situ. All three gravid females fully displayed their mantle-flap lures after dark during each nighttime visit (N = 3) but none displayed their lures during daytime (N = 3). An encounter between a mantle-lure and a largemouth bass was observed. These observations are the first reported of in situ mantle-flap lure displays and fish host encounters for L. teres, and support previous studies of diel display patterns in other mantle-lure displaying mussels. This diel lure display may be related to the ecology of the fish hosts they seek to attract. Future daytime and, especially, nighttime field observations of bivalve mussels with mantle-flap lures may greatly improve understanding of their reproductive ecology.

The male slimy sculpin Cottus cognatus guards a nest rock and provides parental care for the offspring of one or more females, which deposit all their eggs into the male's nest. The purpose of our research was to determine the timing of nest acquisition, spawning, and hatching and to describe biological (number of eggs) and physical characteristics of the nest. In total, we monitored 77 nests during the 2004 spawning period (April-June). Females' egg masses contained an average of 106 eggs. Males guarded an average of 239 eggs; most guarded two or three females' egg masses. Most males (60%) began guarding nests in early May, about a week before egg deposition, and left the nest by the end of June. Males tended to use cobble in shallow water as nests. These findings suggest that slimy sculpin may be sensitive to changes in natural flow conditions during their reproductive period.

Understanding the environmental processes determining the timing and success of reproduction is of critical importance to developing effective management strategies of marine fishes. Unfortunately it has proven difficult to comprehensively study the reproductive behavior of broadcast-spawning fishes. The use of electronic data storage tags (DSTs) has the potential to provide insights into the behavior of fishes. These tags allow for data collection over relatively large spatial and temporal scales that can be correlated to predicted environmental conditions and ultimately be used to refine predictions of year class strength. In this paper we present data retrieved from DSTs demonstrating that events putatively identified as Atlantic cod spawning behavior is tied to a lunar cycle with a pronounced semi-lunar cycle within it. Peak activity occurs around the full and new moon with no evidence of relationship with day/night cycles.

A total of 312 adults of matrinxã were captured bimonthly, between 2011-2012, in two sites of the rio São Francisco: immediately downstream of the Três Marias Dam (site 1) and in the confluence with the rio Abaeté (site 2). Specimens of Brycon orthotaenia from site 2 presented higher values of total length (32.24 ± 5.70 cm for females and 26.64 ± 3.79 cm for males) and body weight (506.66 ± 332.17 g for females and 267.36 ± 145.84 g for males), when compared with the site 1. In site 2 was registered the highest GSI means (9.97 ± 2.96 for females and 0.93 ± 0.52 for males), compared with the site 1 means. Reproduction period occurred from October to February. Unlike site 2, no spawned females or spent males were captured in site 1. Significant differences were found between females and males in site 2 (χ2 = 26.84, df = 1, P < 0.05). Physical-chemical parameters of the water presented higher values in site 2. The canonical correlation test indicated that the reproduction of males is less susceptible to environmental factors than that of females. These results show that B. orthotaenia finds favourable conditions to reproduction just in site 2. Um total de 312 adultos de matrinxã foram capturados bimestralmente entre 2011-2012, em dois pontos do rio São Francisco: imediatamente a jusante da barragem de Três Marias (ponto 1) e na confluência com o rio Abaeté (ponto 2). Exemplares de Brycon orthotaenia do ponto 2 apresentaram maiores valores de comprimento total (32,24 ± 5,70 cm para fêmeas e 26,64 ± 3,79 cm para machos) e peso corporal (506,66 ± 332,17 g para fêmeas e 267,36 ± 145,84 g para machos) quando comparado com peixes do ponto 1. No ponto 2, foi registrado as maiores médias de IGS (9,97 ± 2,96 para fêmeas e 0,93 ± 0,52 para machos) em comparação com o ponto 1. O período reprodutivo ocorreu de outubro a fevereiro. Ao contrário do ponto 2, fêmeas desovadas e machos espermiados não foram capturados no ponto 1. Foram encontradas diferenças significativas entre fêmeas e machos no ponto 2 (χ2 = 26,84, gl = 1, P < 0,05). Parâmetros físico-químicos da água apresentaram maiores valores no ponto 2. A análise de correlação canônica indicou que a reprodução de machos é menos susceptível a fatores ambientais do que de fêmeas. Estes resultados mostram que B. orthotaenia encontra condições favoráveis para a reprodução apenas no ponto 2.

– The reproductive activities of two dominant fish species, roach Rutilus rutilus and rudd Scardinius erythrophthalmus were investigated from August 2000 to July 2002 in an oligotrophic lake, Lake Sapanca, in the northwest of Turkey. A total of 907 roach and 593 rudd individuals were examined. Macroscopic appearance of ovary, gonadosomatic index and oocyte diameter frequency distribution suggested that the spawning season of roach and rudd were from early April (13 °C) to late May (18 °C) and from early May (17.5 °C) to late June (23.5 °C), respectively. The spawning cycles of both species showed the same tendency in two successive years. The estimated mean total lengths at first maturity (LT50) were 12.26 and 14.98 cm for male and female roach, respectively, and 7.12 and 8.10 cm for male and female rudd, respectively. The sizes at 50% maturity corresponded to 3 years for roach and 1 year for rudd, for both sexes. The ratio of males to females was 1.3:1 and 1.2:1 for roach and rudd, respectively. The average condition factor K was 1.21 for rudd and 1.14 for roach, and it was not affected by sex or reproductive effort. Absolute fecundity varied from 7829 to 95,387 eggs between ages 3 and 9 for roach and from 1807 to 35,629 eggs between ages 1 and 7 for rudd. Comparisons of these results with earlier studies from more northern regions revealed that spawning of both species in this area started earlier, but spawning temperature and the duration of spawning was approximately the same.

Zoology and Botany Department Sao Paulo State University, Rua Cristovao, Colombo, 2265, 15054-000 Sao Jose do Rio Preto, SP

The Kemp's Ridley (Lepidochelys kempii) is one of the most endangered sea turtles in the world, and it possesses temperature-dependent sex determination (TSD). Sex ratios produced under TSD can vary widely and can affect the reproductive ecology of a population. Therefore, sex ratios produced from TSD are of ecological and conservation interest. The current study validated and utilized a testosterone radioimmunoassay (RIA) to examine the sex ratio of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee, Florida. Testosterone levels were measured in blood samples collected from juvenile Kemp's Ridleys captured over a three-year period. Results of this study indicate that a significant female bias (approximately 3.7:1) occurs in the aggregation of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee.

The Bluemask Darter, Etheostoma (Doration) sp., is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Little is known about the life history of this species, and an understanding of its reproductive ecology is necessary to implement management and recovery actions. Spawning behavior and habitat were studied from 29 May to 1 July 2002 in the Collins River. Spawning events (n = 247) averaged 7.6 ± 0.1 sec, and intervals between spawning events averaged 127.0 ± 5.0 sec. Some age 1 individuals were sexually mature, but the majority of the reproductive population was comprised of older fish. Microhabitat use differed among nonspawning females, nonspawning males, and spawning pairs. Depths and water velocities differed significantly (P < 0.05) between areas occupied by lone females (n = 37), lone males (n = 45), and spawning pairs (n = 63). Spawning transpired in runs at mean water depths of 21.4 ± 0.4 cm, bottom velocities of 18.9 ± 0.4 cm/...

The life cycle of the nine-spined stickleback Pungitius pungitius from Airolo Lake, Alaska, was studied using samples taken during 1993-1994 and 1997-1998. Pungitius pungitius was actively reproducing in late May and ceased reproductive activities by late June. Spawning adults were 2+ years old. Contrary to an earlier report, the data indicate that an individual female oviposits all of her ovulated eggs (i.e. an entire clutch) into a male's nest during one spawning episode. There was a trade-off between clutch size and egg size without concomitant variation in clutch mass between two years. The results are compared to those from other studies.

Although stunting is a common phenomenon in fish populations, the consequences of stunted body size on the reproductive ecology of individuals has received little attention. The present study compares the reproductive ecology of bluegill in established stunted and non-stunted populations. Three ponds (two non-stunted and one stunted) were monitored for spawning activity throughout the summer. Parental male bluegill from both non-stunted populations were older, larger, and had greater mating success (number of eggs or fry within nests) than parental males in the stunted population. Stunted bluegill also experienced a shortened reproductive season owing to the delay in onset of spawning. The present study demonstrates that individual size and population size structure can have a marked influence on the reproductive ecology of bluegill.

It is well known that water temperature directly affects fish reproduction. The aim of this study was to develop a predictive model to determine water temperature conditions on a typical Pampas shallow lake (Chascomús, 35°36′S, 58°02′W) from local climate variables (specifically air temperature and rainfall). In addition, this model was used to assess the variability of local climate and water temperature conditions in this lake over the last 47 years, and predict possible effects on pejerrey reproductive phenology. The temperature model showed a good fit demonstrating a direct influence of the local climate into the lake water temperature. As consequence of a demonstrated warming in Chascomús City, an average increase of 1.4°C was evident in Chascomús lake over the analyzed period, which was mainly due to a thermal increase during the warmer seasons (spring, summer, and autumn). This pattern of warming drove to a shortening in the pejerrey spawning season length, estimating a decrease of 19 days over the period of 47 years. Thus, this study showed that a tight association between the climate variability and the change in fish reproductive phenology can occur in species inhabiting shallow lakes. Fil: Elisio, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús (San Martin); Argentina Fil: Vitale, Alejandro José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Universidad Nacional del Sur; Argentina Fil: Miranda, Leandro Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús (San Martin); Argentina