Suchergebnisse

Pre-larvae hatching fecundity and ovarian fecundity of narrow-clawed crayfish populations were estimated in the lakes and reservoirs of Belarus. Statistically significant differences in the fecundity of females from various water bodies were noted only for Lake Kichino. For all other water bodies, the fecundity dependence on the length of females did not differ statistically and was described by one equation. The greatest loss of eggs was noted during the spawning period (oviposition), insemination and attachment to pleopods of the female. During this short period (2–3 hours), egg mortality of females 120 mm TL is 30 %, it decreases for small females and increases for large ones. During the gestation period, egg mortality averages 8 %.

SummaryData on the fertility of mothers and daughters in 10,931 mother–daughter pairs were obtained from family reconstitution studies based on English parish registers between the sixteenth and nineteenth centuries. These data indicate that there is no association between the fecundity of daughters and that of their mothers.

We determined seasonal patterns of fecundity and diet of roof rats (Rattus rattus) snap-trapped in
an orchard of macadamias (Macadamia integrifolia), and assessed the implications for controlling
rat damage to macadamia nuts. In all, 903 males, 756 females, and 16 rats of unidentified sex
were captured between June 1990 and April 1991. Sex ratios varied from 1 : 1 only during August,
when males outnumbered females (P < 0.05). Subadult rats were present throughout the study
and comprised 31% of captures. Adult male roof rats were in reproductive condition throughout
the year, and females bore young during every month of the study. Average monthly pregnancy
rates varied from 8% to 54% and were highest in April. Mean prenatal litter size ranged from
3.0 to 6.5 among months. Macadamia nut was the dominant food item throughout the study,
and was present in all 199 stomachs inspected, with a mean relative frequency of 85%. Insect
fragments, primarily lepidopteran larvae, occurred in 66% of the stomachs, with a mean relative
frequency of 8%. Moss was found in 48% of the stomachs, with a mean relative frequency
of 4%. Grass seeds, fruit seeds and non-insect animal material were present in small amounts.
These results show that, in areas with prolonged macadamia flowering and subsequent extended
periods of nut availability, roof rats breed throughout the year on a diet consisting mostly of
macadamia nuts. In such situations, growers may need to apply control measures throughout the
crop cycle to keep rat damage at acceptable levels.

10 páginas, 8 figuras, 1 tabla ; To estimate productivity of a fish stock, the precise determination of fish fecundity is essential. The stereological method accurately estimates fecundity from histological images of a fish gonad. For that purpose, a hexagonal grid is overlaid on the histological image and the number of grid points associated to each oocyte (reproductive cells) category and the number of oocytes in each category is counted. This process is done manually often using off-the-shelf software, but it is very time-consuming, requires specialized technicians, and does not allow to review the calculations. In this paper, we describe and evaluate the software Govocitos, which offers an easy and automatic way to estimate fecundity using the stereological method. Govocitos contains a module to automatically detects the matured oocytes in the slice (nearly 80% of oocytes are correctly detected) and a module to automatically classify the oocytes according to the presence/absence of nucleus (with 84% of accuracy) and to three development stages (with 87% of accuracy). It also provides a user friendly GUI that allows the experts to modify the outlines and classifications of oocytes, to calculate diameters, areas and roundness, to build diameter frequency histograms, to count the points and objects inside the grid, to estimate partial and potential fecundity and to export the data to files and into a database. In addition, Govocitos provides the possibility of varying grid characteristics, it can be trained to work with different species and it allows to check and supervise the calculations whenever needed including in a later point in time. Govocitos is a free software that can be downloaded from http://lia.ei.uvigo.es/daeira/software/govocitos or http://citius.usc.es/w/govocitos. ; This investigation was partly supported by the Xunta de Galicia (regional government) Project PGIDIT08MMA010402PR ; Peer reviewed