Maximum Reproductive Potential Research Articles

Virtually identical does not mean exactly identical: Discrepancy in energy metabolism between glucose and fructose fermentation influences the reproductive potential of yeast cells

The physiological efficiency of cells largely depends on the possibility of metabolic adaptations to changing conditions, especially on the availability of nutrients. Central carbon metabolism has an essential role in cellular function. In most cells is based on glucose, which is the primary energy source, provides the carbon skeleton for the biosynthesis of important cell macromolecules, and acts as a signaling molecule. The metabolic flux between pathways of carbon metabolism such as glycolysis, pentose phosphate pathway, and mitochondrial oxidative phosphorylation is dynamically adjusted by specific cellular economics responding to extracellular conditions and intracellular demands. Using Saccharomyces cerevisiae yeast cells and potentially similar fermentable carbon sources i.e. glucose and fructose we analyzed the parameters concerning the metabolic status of the cells and connected with them alteration in cell reproductive potential. Those parameters were related to the specific metabolic network: the hexose uptake - glycolysis and activity of the cAMP/PKA pathway - pentose phosphate pathway and biosynthetic capacities - the oxidative respiration and energy generation. The results showed that yeast cells growing in a fructose medium slightly increased metabolism redirection toward respiratory activity, which decreased pentose phosphate pathway activity and cellular biosynthetic capabilities. These differences between the fermentative metabolism of glucose and fructose, lead to long-term effects, manifested by changes in the maximum reproductive potential of cells.

Dependency of Crops on Pollinators and Pollination Deficits: An Approach to Measurement Considering the Influence of Various Reproductive Traits

Pollinators provide crucial ecosystem services, i.e., pollination, which determines crops’ reproductive fitness and yield. As pollinators decline, flowering crops might face pollination-deficit stress depending on their dependence on pollinators and pollinator availability. Here, we assessed the dependency of some crops (belonging to diverse plant families) on biotic pollinators based on their maximum reproductive potential in a supplementary pollination treatment and minimum reproductive success in a pollinator exclusion treatment. Additionally, we determined the pollen transfer limitation of the crops in open field conditions. We also determined the influence of the different reproductive traits with the index of dependency of crops on pollinators (IDP) and the coefficient of pollination deficit (D). Based on the values of IDP, members of Cucurbitaceae are obligatorily dependent on pollinators for their fruit set. Members of Brassicaceae and Rutaceae are highly reliant on pollinators. A few crops, like Lablab purpureus and Nigella sativa, are less dependent on pollinators. In open field conditions, most crops have a low pollination deficit, some without pollen transfer limitations, and only a few crops (Citrus × limon and Citrus maxima) show a higher pollination deficit. The IDP is negatively influenced by the pollen–ovule ratio, which also negatively affects the pollination deficit of the crops. This study will be useful in understanding and mitigating the effects of pollinator losses, as well as in choosing crops (those under pollination deficit stress and largely dependent on pollinators for fruit set) for supplemental pollination services to increase agricultural production.

Reproductive potential and stock status of the anadromous shad, Tenualosa ilisha (Hamilton, 1822): Implications for managing its declining fisheries in northern Bay of Bengal bordering India

The anadromous shad, Tenualosa ilisha is a fish of high economic importance in countries flanking the Bay of Bengal (BoB). Its fishery in the northern BoB bordering India and the associated Bhagirathi–Hooghly river system has been declining. Scientific explanations on the existing fishery management recommendations, especially the length at first maturity (Lm50), minimum legal size (MLS), minimum mesh size for fishing nets and stock status were limited, raising serious concerns on the sustainability of its fisheries. Through the examination of its reproductive cycle, using histological maturity identifiers, the Lm50 of males and females were redefined at 265 mm TL/ 1.0 year age and 305 mm TL/ 1.2 year age, respectively. The size-based fecundity, sex ratio and abundance revealed that females of 281–360 mm TL/ 1.0–1.6 year of age have maximum reproductive potential. In the catch, 45%–65% of males and females were below Lm50. The temporal progression of mean length in the catch (MLC) and female length at maturity showed declining trend. Application of length-based indicators (LBI) and stock assessment models showed the fishery in near full exploitation, less optimal and undergoing multi-generation, indiscriminate, size-selective overfishing. The spawning stock biomass (SSB) has declined to 26.8% of the virgin SSB, while the yearly spawning potential ratio (SPR) ranged from 0.04 to 0.29, which is lower than the SPR threshold (0.3) suggested for sustaining a fishery. The species is both growth and recruitment overfished. Though the mean annual catch is marginally lower than the estimated maximum sustainable yield (MSY) of 32,953 t, any increase in fishing effort would further impact the SSB. Based on the results, a MLS of 360 mm TL, minimum mesh size of 110 mm for fishing gear and a precautionary annual catch limit of 30,000 t suggested for management, and the potential impact of implementing these on fishers’ catches discussed.

RELATIONSHIP BETWEEN BLOOD METABOLIC PROFILES AND MILK YIELD ASSOCIATED WITH PARITY AND STAGE OF LACTATION IN CROSSBRED DAIRY COWS IN BANGLADESH

Background: Cattle cross-breeding program has been launched throughout Bangladesh but this program has still focused mainly on biological rather than economic evaluation. Currently, 30000 dairy farms with mainly cross-bred cows are in operation throughout the country and this intensive dairy farming system with high milk yielding dairy cows is supposed to be associated with high incidence of sub-clinical nutritional and metabolic diseases. Objectives: The objective of this study was to detect the relationship between major blood metabolic profiles and milk yield associated with parity and stage of lactation in cross-bred dairy cows. Materials and Methods: Blood samples of 220 apparently healthy lactating cross-bred dairy cows (HF x L, n = 190; SH x L, n = 20 and JS x L, n = 10) of 10 dairy herds were collected for metabolic profile test (MPT) in Bangladesh during the period from July to November 2016. The major metabolic profiles which are associated with milk fever (calcium, phosphorus & magnesium) and ketosis (glucose) were considered in this study. These biochemical parameters were estimated to detect the influence of risk factors including herds, breeds, parities and lactation age of cross-bred lactating dairy cows by using the commercial kits in spectrophotometer method. Results: The evaluation of the biochemical constituents of 220 cross-bred lactating dairy cows revealed that 30% (n = 66) had hypocalcaemia and 20.45% (n = 45) had hypoglycemia. Significantly lower levels of average calcium (7.93 ± 0.36 mg/dl; p < 0.024) and glucose (43.44 ± 3.63 mg/dl; p < 0.0001) values were recorded in HF x L cross-bred dairy herd of BAUDF, Mymensingh in comparison to other investigated nine dairy herds. The highest milk yield was recorded at 7th parity (16 +- 0.91 liter / day) and 1st week of lactation (17.33 +- 1.09 liter / day) were associated with low mean calcium (8.09 +- 0.85 mg / dl; 6.68 +- 0.13 mg/dl) and glucose (36.45 +- 7.67 mg/dl; 32.31 +- 3.90 mg / dl) levels in comparison to the respective values of different parity and lactation weeks. Conclusions: A relationship between blood metabolic profiles and milk yield associated with herd, breed, parity and lactation stages was recorded in lactating crossbred dairy cows. The evaluation of blood metabolites at different stages of lactation cycle especially at transition period is required to detect the nutritional and metabolic health for optimum milk production and to achieve maximum reproductive potential of high yielding dairy cattle. The readily available milk samples could be used as a biological fluid to monitor the health and nutritional status of dairy cows by using mid-infrared (MIR) spectroscopy method to prevent sub-clinical metabolic disorders. Therefore, well developed laboratories with necessary equipment, test kits and reagent should be provided to perform MPT in both the blood and milk samples for practical uses. Keywords: Compton metabolic profile test, Metabolic profile, Lactating cross-bred cows, Calcium, Phosphorus, Magnesium, Glucose, Parity, Lactation stages

Elucidating fitness components of the invasive dermestid beetle Trogoderma granarium combining deterministic and stochastic demography.

The invasive dermestid khapra beetle, Trogoderma granarium, is an important pest of stored products that is subject to strict phytosanitary measures. In this study, we conducted a demographic analysis of this species at 30, 35 and 40°C, combining deterministic and stochastic approaches. The net reproductive rate, the intrinsic rate of increase, the finite rate of increase and the doubling time did not differ significantly between 30 and 35°C, while at 40°C we detected negative values of the intrinsic rate of increase and the doubling time. The Briere model fit the data well with respect to the intrinsic rate of increase. Females of roughly 63, 42 and 21 days old reached their maximum reproductive potential at 30, 35 and 40°C, respectively. The stochastic models of this study allowed for checking model fit and the characterization of the most suitable distribution for each component of the process. We expect these results to have bearing on the management of T. granarium since they could be combined with models related to international trade and climatic change, alerting specialists towards early detection strategies against this species.

Reproductive Characteristics of Double-Crested Cormorants (Phalacrocorax auritus) in the Eastern United States: Demographic Information for an Intensely Managed Species

Abstract. Double-crested Cormorants (Phalacrocorax auritus) are intensely managed through culling in North America to reduce presumed damage to commercial and natural resources. To evaluate this management, there is a critical need to understand the reproductive biology of Double-crested Cormorants. Gonadal development, reproductive potential and breeding status were determined by necropsy for 1,781 Double-crested Cormorants salvaged each month of the year from control programs in their wintering and breeding ranges in seven States in the USA. Gonadal development of males peaked earlier in the year than females. Mean and maximum reproductive potential was five and 13 ovum, respectively. The average proportion of non-breeding female Double-crested Cormorants culled from breeding colonies was 14.9% (n = 202) and from foraging flocks on the breeding grounds was 22.1% (n = 358). This demographic information should be considered when evaluating and modeling effects of Double-crested Cormorant management in Nor...

ASSESSMENT OF FECUNDITY AND GONADO-SOMATIC INDEX OF POND REARED CIRRHINUS MRIGALA (HAM., 1822)

Mean body weight for both the sexes was 1270.9±10.96 g with mean total length of 473.95±11.92 g. GSI (%) values ranged from 0.23 to 7.93 in male with peak value in July (7.93) and 0.83 to 16.9 in female with peak value in July (16.09).The gonads attained maximum weight of 472.5 and 124.41g for females and males, respectively in the month of July and minimum in November. The fish has only one spawning season extended from May to August as indicated by the peaks of GSI with peak season between July-August. The relative and absolute fecundity varied from 69,244 to 2, 15,680/ kg and 74,783 to 4, 14, 416, respectively. Fecundity showed a significant positive correlation with total length (0.749), gonad weight (0.747) and body weight (0.807) of the sampled fish. C. mrigala exhibited maximum reproductive potential and fecundity in the month of July compared to June and August in the eco-climatic conditions of Eastern Uttar Pradesh. Key words: Gonado-somatic index, fecundity, Cirrhinus mrigala, Eastern Uttar Pradesh

Life Table Analysis ofPropylea quatuordecimpunctata(Coleoptera: Coccinellidae) at Constant Temperatures

AbstractA life table analysis of the 14-spotted ladybird beetle, Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae), reared on bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae), was conducted at four constant temperatures (17, 20, 25, and 30 ± 1°C). A temperature dependence in the coccinellid's net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time, and doubling time was detected. Estimated values of intrinsic rate of increase were 0.065, 0.095, 0.166, and 0.190 females per female per day at 17, 20, 25, and 30°C, respectively, where Lactin model indicated that the maximum value is achieved at 29.23°C. Females of ≈75, 50, 45, and 20 d old reach their maximum reproductive potential at 17, 20, 25, and 30 ± °C, respectively. In addition, temperature affected the risk of death of immature and female adults, as the survival curves at the examined temperatures were significantly different. The mean survival times decreased from 19.9 to 8.0 d and 123.1 to 33.5 d from 17 to 30°C for entire immature stages and female adults, respectively.

Culture studies on early development of Lessonia trabeculata (Phaeophyceae, Laminariales): Seasonality and acclimation to light and temperature

SummaryLessonia trabeculata is an important economic and ecological algal resource of Chile. Due to intense use in abalone and alginate industries, severe problems of over‐harvesting are emerging. We compared sporophyte‐initiation and ‐growth in two populations from northern and southern Chile (Bahía Inglesa and Maicolpué) under laboratory conditions. Irradiance and temperature were the most important factors affecting gametophyte development. Meiospores harvested in spring exhibited maximum reproductive and growth potential, while spores released during autumn were moribund, and died within a few days. In both study sites, we found evidence for acclimation: Meiospores collected in summer required higher levels of irradiance and temperature for maximum development than winter spores. Juvenile sporophytes from both localities responded similarly to temperature and/or irradiance. The best conditions for recruitment of sporophytes from both localities were 15°C and white fluorescent light of 40–70 μmol m−2 s−1. Although due to its low growth potential L. trabeculata is not a good candidate for mariculture, our results provide the necessary knowledge for laboratory‐based seedling production, which is needed for restoration and repopulation projects in damaged areas.

Seminal Characteristics in Spanish Purebred Stallions: A Retrospective Study

In this work, we studied retrospectively the influence of several factors on semen quality of the Spanish Purebred (SPB) stallion. Among these factors, we considered stallion age, season, and interval between two consecutive collections. The semen was collected from 11 SPB stallions (634 ejaculates). Semen quality was evaluated based on volume, concentration, and motility of the ejaculates. Results showed that the semen collected in autumn and winter was more concentrated in comparison with that collected in spring and summer, when the volume of ejaculate was the highest. Those ejaculates collected from younger stallions were characterized by having the smallest volume and the highest sperm concentration. When incorporating an SPB stallion into a program of artificial insemination, it is important to take into account all of these factors to achieve the maximum reproductive potential of the animal.

The EU Common Fisheries Policy in light of the precautionary principle

According to the EU's 2009 green paper on the reform of the CFP, 81% of European fish stocks are overfished despite the fact that the EU has repeatedly committed itself under both international and EU law to maintaining and restoring its fish stocks to levels capable of producing MSY. Here we argue that the EU's repeated enactment of TACs exceeding maximum reproductive potential has violated the precautionary principle and as such constitutes a breach of European and international law. As a policy decision, a precautionary approach to fisheries management requires a continuous examination of scientific evidence. Furthermore, although the EU is endowed with exclusive competence in regard to marine conservation, this competence must be exercised in accordance with the rule of law. Judicial review is an essential component in ensuring the accountability of institutions, however the highly politicized nature of fisheries policy hinders Member States and EU institutions from challenging non-sustainable TACs. Despite efforts to expand stakeholder participation in fisheries policy-making, environmental organizations such as WWF-UK have been denied standing to challenge EU fisheries policy in European courts, leaving potential violations of the precautionary principle unaddressed and denying judicial protection guaranteed under the Aarhus Convention. The ECJ's 2011 decision in BUND v. Bezirksregierung Arnsberg (“Trianel”) may represent a turning point in the Court's interpretation of direct and individual concern in regard to cases instituted by environmental organizations in a precautionary context. Rather than merely developing new policy tools, genuine and comprehensive reform of the CFP also requires an operable legal framework to ensure that violations of the precautionary principle by EU institutions in enacting fisheries policies can be addressed.

Piping Plover Chick Foraging, Growth, and Survival in the Great Plains

Abstract: We tested the hypothesis that piping plover (Charadrius melodus) habitat quality and chick survival on the Missouri River, USA, were lower on a cold‐water reservoir and downstream from a hypolimnetic (cold‐water) release dam with diel water fluctuations (Garrison Dam) than downstream from an epilimnetic dam (Gavins Point Dam). Plovers in adjacent alkali wetlands provided an index to the maximum reproductive potential in the region. Chicks gained weight more rapidly in the alkali wetlands than on epilimnetic and hypolimnetic river reaches. Invertebrate numbers and biomass were higher in the wetlands and epilimnetic reach, but chick survival was lower on the epilimnetic reach. Thus, piping plovers adapted to a variety of prey densities, and other factors, likely predation, reduced survival rates in the epilimnetic reach. Temporal and spatial variability in site quality indices suggests the need for a regional management strategy with different strategies at each site. Managers can minimize effects of local fluctuations in resource abundance and predators by ensuring protection of or creating geographically dispersed habitat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):682–687; 2008)

<![CDATA[<B>What does determine gonad weight in the wild kissing bug <I>Mepraia spinolai</i></B>]]>

Female fecundity increases with body size in a variety of insects, but it is unknown if this generalization applies for kissing bugs. In this study, we evaluate whether gonad weight in the bloodsucking insect Mepraia spinolai correlates with body size, or determined by nutrition or developmental time. We found that the investment on reproductive tissue correlates positively and significantly with body size and with the amount of ingested blood by female insects along their lifespan. Total molting time did not significantly affect gonad weight. We suggest that under optimal feeding conditions M. spinolai females could express their maximum reproductive potential.

What does determine gonad weight in the wild kissing bug Mepraia spinolai

Female fecundity increases with body size in a variety of insects, but it is unknown if this generalization applies for kissing bugs. In this study, we evaluate whether gonad weight in the bloodsucking insect Mepraia spinolai correlates with body size, or determined by nutrition or developmental time. We found that the investment on reproductive tissue correlates positively and significantly with body size and with the amount of ingested blood by female insects along their lifespan. Total molting time did not significantly affect gonad weight. We suggest that under optimal feeding conditions M. spinolai females could express their maximum reproductive potential.

Ageing and the extinction of large animals

In the modulation of longevity by natural selection there is a trade-off between the investment of resources in the maintenance of the body, or soma, and the investment in reproduction. There is accumulating evidence that long-lived mammalian species have much more efficient maintenance than short-lived ones. It is also clear that short-lived ground-living mammalian species reproduce very much more quickly than larger long-lived species, and in all mammals there is an inverse relationship between maximum reproductive potential and maximum longevity. These features of life-history strategies very strongly support the disposable soma theory of the evolution of ageing. Slow development and large size are associated with delayed ageing. If the environment changes, for whatever reason, small rapidly breeding species are able to adapt and survive much more easily that large slow breeding species. This can explain the very well documented extinction of many large mammalian species during the Pleistocene. In an environment which remains constant for a long period of time, selection favours the evolution of larger species, but these are put at risk if the environment becomes less favorable. Fluctuating environments are more likely to promote the evolution of small short-lived species with high fecundity.

Lifetime reproductive success in a population of female red kangaroos Macropus rufus in the sheep rangelands of western New South Wales: Environmental effects and population dynamics

Female reproductive success and the recruitment of offspring to the next generation are key components of animal population dynamics. With an annual commercial harvest of between 13 and 22% of the red kangaroo (Macropus rufus) population, it is increasingly important that these processes are understood. We used data on the reproductive success of 33 free-ranging female M. rufus on Fowlers Gap station in far western New South Wales to determine the expected lifetime reproductive success (LRS) of females within an unharvested population. We also designed a model to generate predictions about female LRS incorporating empirical relationships between a mother?s reproductive success and maternal age, environmental conditions and the sex and survivorship of a previous reproductive attempt. Results from observations on female LRS (calculated from annual weaning rates) and those generated by the model predict that female M. rufus on ?Fowlers Gap? wean, on average, 3.7 young in a lifetime (ranges 0 - 11 and 0 - 20, respectively); representing only 41% of their maximum reproductive potential. Manipulation of initial starting conditions allowed the effect of varying environmental conditions on female LRS to be explored. The condition of the environment when females commence breeding does not appear to significantly affect their overall lifetime reproductive output. However, the occurrence of drought does. Females experiencing two droughts in a lifetime did not live as long and weaned fewer offspring and grandoffspring (from their daughters) than those females experiencing only one drought in a lifetime. In addition to the adverse effect of drought on the reproductive success of female M. rufus in this study, we suggest that, given the relatively high and stable population densities of M. rufus on ?Fowlers Gap?, other mechanisms (acting primarily on juvenile survival) must exist which limit population growth.

Reproductive variability over a four-year period in the sea urchin Evechinus chloroticus (Echinoidea: Echinodermata) from differing habitats in New Zealand

The endemic New Zealand echinoid, Evechinus chloroticus (Valenciennes), was sampled approximately monthly from September 1990 to October 1994 at three sites in Tory Channel, Marlborough Sounds, New Zealand. These channel sites (outer, mid and inner) were up to 20 km from the open ocean and differed in their shore type, exposure to wave action and macrophyte abundance. E. chloroticus showed an annual reproductive cycle at each site, with gametogenesis commencing in the late austral winter and spawning in summer. Maximum gonad indices (reproductive potential) varied spatially, with the outer site generally having higher maximum gonad indices than the inner site, and temporally, with maximum gonad indices occurring earlier in 3 of the 4 seasons at the outer site than the inner site. The mid and inner sites showed much greater variation in maximum gonad indices (range 15.83 to 26.99% and 11.87 to 20.90%, respectively) than the outer site (range 19.31 to 22.95%). Reproductive output (weight of gametes released per gram echinoid) also varied, with the different sites showing significantly different outputs in the different years. A regression of maximum reproductive potential against reproductive output was significant ( p < 0.001), and had a positive slope with an r 2 of 0.79. While, the initiation of gametogenesis was relatively synchronous between sites and years, and is possibly cued by increasing daylength, it progressed at different rates among populations. Spawning did show spatial and temporal variability, occurring near the time of highest sea-surface temperatures (∼15 °C). The observed variations in reproductive cycle may be related to small-scale variability in diet and environmental conditions. Furthermore, asynchronous spawning, variable spawning duration, and variable reproductive output are likely to strongly influence annual recruitment variability in E. chloroticus, with different larval subpopulations contributing unequally in different years. The ecological consequences of this, both for the ability of E. chloroticus to propagate itself in space and time and for the management of the developing E. chloroticus fishery in New Zealand, are discussed.

Elevated CO2 affects the interactions between aphid pests and host plant flowering

Summary1 Broad beans (Vicia faba L.) were grown at either ambient (350 μL/L) or elevated (700 μL/L) CO2. Elevated CO2 increased shoot weight by 14% and root weight by 24% compared to ambient, but did not affect flowering.2 A single pea aphid (Acyrthosiphon pisum (Harris)) and its progeny decreased shoot and root weights by 20 and 24%, respectively, at ambient CO2 after 20 days, but did not affect flower number. At elevated CO2A. pisum decreased shoot and root weights by 27 and 34% and flower number decreased by 73%.3 A single glasshouse and potato aphid (Aulacorthum solani (Kaltenbach)) and its progeny had no effect on the growth of bean plants after 20 days at ambient CO2. At elevated CO2, A. solani decreased shoot and root weights by 20 and 18%, and flower number by 60%.4 The large reduction in flowering caused by aphids at elevated CO2 suggests a change in resource allocation within the plants to compensate for aphid infestation.5 Aphid density was unaffected by elevated CO2, although there were significant effects of CO2 on the resulting population structure of both A. pisum and A solani. We suggest that at elevated CO2, aphids appear not to achieve their maximum reproductive potential and their populations are limited by the lower carrying capacity of their host plants.

Rapid selection effects in a short-lived semelparous squid species exposed to exploitation: inferences from the optimisation of life-history functions

The short life span of cephalopods suggests a potential for high sensitivity to the artificial selective effects of human exploitation. To explore the effects of such selection life-history optimisation was applied using data for a semelparous squid, Illex argentinus with a life span of one year. Survival and fecundity functions were combined to generate a life time reproductive potential function. The maximum reproductive potential identified the optimum age for the squid to mature. In a situation of a constant mortality rate the maximum reproductive potential was achieved at an earlier age of maturation as mortality rate increased. The exact age when the optimum maturation occurs is sensitive to the rate of mortality and the form of the assumed growth curve but covers the age range when maturation is known to occur in this species. A more realistic seasonal fishing mortality function produced a more complex fitness curve with a temporally more restricted optimal age of maturity. The selection effects will be stronger in a seasonal fishery suggesting potentially very rapid evolutionary rates. Developing analyses specifically considering frequency-dependence and environmental-feedbacks will be valuable to clarify the potential of squid to show rapid evolutionary responses to selection. Strong selection for early age of maturation could affect the yield from the fishery but more importantly, could also make the migratory strategy, on which the fishery is based, an unviable option, resulting in collapse of the fishery that exploits the migratory component of the species.

Distribution, Biology, and Population Dynamics of Aristaeomorpha Foliacea (Risso, 1827) (Decapoda, Natantia, Aristeidae) in the North-Western Ionian Sea (Mediterranean Sea)

The distribution, biology, and population dynamics of Aristaeomorpha foliacea (Risso, 1827) have been investigated in the north-western Ionian Sea (middle-eastern Mediterranean). A total of 9,637 specimens, 5,570 females and 4,067 males, was collected during twelve trawl surveys carried out between 350 and 750 m of depth. Aristaeomorpha foliacea is found on muddy bottoms with the highest densities generally in the upper 600 m and in a zone where canyons cross the bottoms. A spatio-temporal distribution correlated to bio-ecological aspects was shown in the population. An increase in males on the fishing bottoms was shown during winter when maturity of this sex begins and shortly after mating occurs in the population. During the winter-spring season the whole population migrates to the upper slope. After the mating peak, in summer, when spawning is at its maximum, the population is again displaced to the deeper grounds. The ovary maturation period is between May and September and the largest specimens are the first to mate and reach sexual maturity. The size of maximum reproductive potential is 37.11 mm carapace length. Recruitment occurs in spring and the stock is mostly represented by young individuals. Both female and male growth rates fit a Von Bertalanffy function. Both female and male stocks appear to be mortality-dominated (Z/k > 1). Estimates of the exploitation ratio (E = F/Z) are between 0.43 and 0.62 in females and between 0.46 and 0.65 in males.