EXPERIMENTAL INVESTIGATION OF SOCIAL BEHAVIOR ONTOGENESIS OF ARVICOLA AMPHIBIUS L. IN THE EARLY POSTNATAL PERIOD

The paper explores the influence of littling sex and age, as well as mother’s body weight, size and sex composition of breed onto the ontogenesis of social behavior of water vole Arvicola amphibius L. The authors conducted experiments and explored the relation among the littlings of each breed in two key periods of postnatal ontogenesis. The authors explored behavior ontogenesis of 88 water voles’ littlings in 19 breeds. The behavior was recorded conducting the tests by means of placing the littlings on a neutral arena; first time it was conducted when the littlings aged 10 days and then at the age of 20 days. The researchers evaluated motor activity and elements of peaceful and aggressive behavior. The results showed that females more often demonstrate peaceful forms of social behavior than males. Negative relationship between frequency of peaceful contacts among the littlings on the mother’s body weight after birth and the proportion of males in the breed. When water voles age 20 days, the frequency of peaceful contacts among the littlings decreases, and the frequency of aggressive contacts increases. Inter-sex differences in the frequency of aggressive contacts have not been detected. The authors found out that aggressive contacts among sibs are initiated by females. The frequency of theses contacts relates to the number of breeds in which they were born and grew up, while the aggressiveness of males does not depend on the amount of their breeds.

TWO SONS AND A DAUGHTER: SEX COMPOSITION AND WOMEN'S REPRODUCTIVE BEHAVIOUR IN MADHYA PRADESH, INDIA

SummaryThis article examines how the sex composition of women's current children at the start of a pregnancy interval influences both fertility desires and the full range of reproductive actions women may take to realize them, including temporary contraception, abortion and sterilization, in Madhya Pradesh, India, where popular notions of ideal family size and sex composition are dominated by son preference. The analysis is conducted using a dataset of 9127 individual pregnancy intervals from a 2002 statewide representative survey of 2444 women aged 15–39 with at least one child. The results indicate that women's preferences go beyond a singular preference for male children, with the preferred composition of children being two boys and one girl. Women with this composition are 90% less likely to report having wanted another pregnancy (OR 0.097, p<0.01) relative to those with two girls. These preferences have significant implications for reproductive actions. While sex composition has no statistically significant effect on the use of temporary contraception, those with the preferred sex composition are twice as likely to attempt abortion (OR 2.436, p<0.01) and twelve times more likely to be sterilized (OR 12.297, p<0.01) relative to those with two girls only.

Size and sex composition of two species of the genus Atlantoraja (Elasmobranchii, Rajidae) caught by the bottom trawl fisheries operating on the Uruguayan continental shelf (southwestern Atlantic Ocean)

In this work we analyzed the spatial and seasonal variation of length distribution, sexual proportion and mature dominance for Atlantoraja cyclophora and A. castelnaui, at the Uruguayan continental shelf. There were significant differences in total length (TL) composition between sexes, being females bigger than males for both species. Atlantoraja cyclophora showed a relatively uniform length distribution between inner and outer shelf. There were no major variations in the sex compositions and in the mature dominance between seasons, suggesting no temporal variation. Atlantoraja castelnaui showed a significant variation in its spatial and seasonal distribution. Individuals were smaller in inner shelf, pointing out the existence of juvenile zone in areas up to 50 m depth. A tendency to capture smaller individuals towards the end of the year was observed. In all seasons over 50% of females were caught below the estimated size at maturity, suggesting that this species is highly susceptible to exploitation.

Decadal trends in shark catches and effort from the New South Wales, Australia, Shark Meshing Program 1950 - 2010

The New South Wales (NSW) government has operated a program of netting beaches for the protection of swimmers and surfers against shark attack since 1937 in Sydney, and since 1949 in Newcastle and Wollongong. The scope and directives of the Shark Meshing Program have remained constant since its inception, with operational modifications in net specifications in 1972, changes in spatial deployment in 1972, 1987 and 1992, and the elimination of winter netting since 1989. This markedly increased meshing effort in 1972, and again in 1987. In the present study, we examine the trends in catch and effort for the period from 1950–1951 to 2009–2010 over this 200-km section of the NSW coast. Significant temporal trends in species, size and sex composition are described herein. Catches were consistently dominated by three shark taxa, hammerhead sharks (Sphyrna spp.), whaler sharks (Carcharhinus spp.) and Australian angel sharks (Squatina australis), although their relative contributions to catches varied over time. Catch per unit effort has significantly declined for five of the most abundant shark taxa over the study period, increasing only for a single taxon, the sevengill shark (Notorynchus cepedianus). Catches of larger, potentially dangerous white sharks (Carcharodon carcharias) and tiger sharks (Galeocerdo cuvier) saw fewer large animals being caught over time. This pattern was not observed across other taxa. Four different monthly trends were observed in landings of the most abundant eight taxa, reflecting differences in the biology of the catch species. The current study also provides useful information on catches and sizes of grey nurse (Carcharias taurus) and white sharks before and after their protection in NSW waters in 1984 and 1998, respectively.

Spatial variation in abundance and catch composition of Cancer pagurus in Norwegian waters: biological reasoning and implications for assessment

The edible crab (Cancer pagurus), which is abundant along the Norwegian coast north to Troms County, has been exploited in Norway since the start of the 20th century. The main fishery is in Mid-Norway and Helgeland (63°–67°N), which together land 75% of the Norwegian catch. The fishery is regulated by season, minimum legal size, and the discarding of soft or ovigerous females. Catches have never been systematically described, so this study presents data collected over 4 years by a reference fleet of professional fishers reporting the catch from four standardized trial traps set among their ordinary traps. Catch rate, catch composition, and size distribution from Mid-Norway/Helgeland are compared with the smaller crab fishery in Rogaland (59°N) and with new crab grounds off Vesterålen (69°N). Local variations in size and sex composition between and within region seemed partly to be caused by differences between exposed and sheltered regions, and between heavily and newly exploited grounds. Size distribution is used as an indicator to determine a suitable sampling strategy. The most efficient survey design is seemingly the collection of relatively small samples from many boats to reduce the between-vessel component of variation. A suggested strategy to obtain an abundance index would be to collect daily catch rates from all commercial landings.

Pod Characteristics of Migrating Humpback Whales (Megaptera Novaeangliae) Off the East Australian Coast

The size and sex composition of migrating humpback whale pods were investigated off the east Australian coast. Two hundred and thirty one singletons, 257 pairs, 63 trios, 7 quads and 4 pods containing more than 5 individuals were observed during two land-based surveys carried out throughout the northward migration in 1991 and 1993. Generally humpback whales migrated northward towards the breeding area in pods of I or 2 individuals. In 1992, a biopsy study was carried out throughout the northward and southward migrations. Pods migrating southward (mean = 2.59, SE = 0.19) towards the feeding areas were significantly larger than those travelling north (mean = 1.75, SE = 0.03). The sex of 134 individuals in 63 complete pods was determined by molecular analysis of skin biopsies. Male humpback whales were found in larger pods than females. The most common pod type observed was the male-female pair, which is suggestive of either mating on migration and/or mate-guarding. Males were found associated together frequently. Competitive behaviour was observed during both the northward and southward migrations. The sexing of all individuals within 8 competitive pods indicated that not all contained a female. Although competitive behaviour was observed during the migration, most male-male associations were charactcrised by non-agonistic and occasionally cooperative interactions. We suggest there is a behavioural continuum on migration between the feeding and breeding grounds which is not governed solely by spatial proximity to the terminus. The pod characteristics of humpback whales on their return migration to the feeding grounds showed greatest similarity to those observed on breeding grounds elsewhere. In conclusion, our study showed that the migration of humpback whales is more