Profile soundings in lakes of the younger morainal area of Sleswick-Holstein with a sediment-echo-sounder of 30 kHz [Translation from: Wass.Boden 26, 135-138, 1974]

To be able to carry out physical, chemical and biological investigations on a lake, one needs a thorough knowledge of the volume of water and the shape of the lake basin. Little is known about the about the morphology of the lakes in Schleswig-Holstein and its ecological consequences. For this research a 30 KHz echo sounder with sediment transceiver was used to carry out profile determinations (echo soundings). This apparatus continuously records on paper the different reflexions and absorptions of the sediment and water body in the corresponding depth. By this, acoustically noticeable layers and different densities in the sediment and 'scattering layers' in the water body due to physical, chemical and biological reasons (e.g. plans and single fish) are made visible. Result are summarised here regarding the echo soundings in Blunker See.

The Younger Dryas and millenial-scale oceanographic variability in the Sulu Sea, tropical western Pacific

EXTRACT (SEE PDF FOR FULL ABSTRACT): A high resolution, AMS carbon-14-dated sediment record from the Sulu Sea clearly indicates the Younger Dryas climatic event affected the western equatorial Pacific. Presence of the Younger Dryas in the tropical western Pacific indicates this climatic event is not restricted to the North Atlantic nor to high latitudes, but is global in extent.

Production of the chironomids of the Uchinsk Reservoir. [Translation of: Methods for the estimation of production of aquatic animals. (Handbook and papers) (ed. G. G. Vinberg) p226-239. Minsk, Vysheishaya Shkola, 1968]

The method of E.V. Borutski was used for determining the production of chironomids, that is, the dynamics of the number and biomass of the larvae were analysed, their death, a calculation of emergence and the number of deposited egg layings was carried out. In addition to the method of Borutski, the authors also calculated the seasonal dynamics of the number of larvae of the younger age stages in the microbenthos.

Latitudinal and seasonal egg-size variation of the anchoveta (Engraulis ringens) off the Chilean coast

The anchoveta Engraulis ringens is widely distributed along the eastern South Pacific (from 4° to 42°S; Serra et al., 1979) and it has also supported one of the largest fisheries of the world over the last four decades. However, there are few interpopulation comparisons for either the adult or the younger stages. Reproductive traits, such as fecundity or spawning season length, are known to vary with latitude for some fish species (Blaxter and Hunter, 1982; Conover, 1990; Fleming and Gross, 1990; Castro and Cowen, 1991), and latitudinal trends for some early life history traits, such as egg size and larval growth rates, have been reported for others clupeiforms and other fishes (Blaxter and Hempel, 1963; Ciechomski, 1973; Imai and Tanaka, 1987, Conover 1990, Houde 1989). However, there is no published information on potential latitudinal trends during the adult or the early life history of the anchoveta, even though this type of information may help in understanding recruitment variability, especially during recurring large scale events (such as El Niño or La Niña) that affect the entire species range.

Involvement of fishermen children in fishing activities in Lake Chad region

Five fishing villages in Lake Chad Basin region of Borno State (Nigeria) were assessed for the roles of children in fishing activities in the area. The villages surveyed include: Bundaram, Yobe, Daba masara, Dumba and Doro. The results show that the children were largely between 12-18 years of age in the villages. Generally, the younger children (less than 12 years) participate in activities that require no technicality and little physical strength, while the older children (12 years and above) engage in skillful fabrication of gear and fishing activities. Some activities in the surveyed villages were gender specific. Such activities include fish processing (smoking) which is exclusive for female and few male children, who carry out preliminary cleaning of fish before any processing method is applied. 80% of the children in the five fishing villages claimed proper understanding of the techniques and procedure involved in most fishing activities. About 65% of the children sampled showed willingness to become full time fishermen while 22% were uncertain and claimed that they do not know what the future holds for them. 15% of them resolved to migrate to town so that they could live a city life

Parents aspiration and youth perception to sustainable fisheries development in Kainji Lake basin

Artisanal fisheries development in Nigeria, like in any other developing country of the world is characterized by subsistence level of operation using dugout canoe and paddle. This implies that parents and children constituted the labour in use since they only struggle for the upkeep of the family. A total of 240 questionnaires were used to solicit information from the respondents. This total was divided into 120 each for both parents and the youths respectively. Simple descriptive statistics such as frequency distribution and percentages were used to analyze their responses. Parents have strong aspiration for their children to succeed them hence, 78.3% of the parents expressed their aspiration for succession by the younger ones while 83.3% of parents tend to support their aspiration with persuasive strategies such as allowing their children to partake in fishing activities at will. On the part of the youth over 70% of them perceived fishing as a viable business where they can succeed their parents provided government can come to their aid in form of active involvement in the development of rural fisheries. It is therefore believed that fisheries development could achieve rapid improvement if the aspiration of the parents is balanced with perception of the youth and the government meets their expectation

Education and awareness programme on marine protected area management, Bar Reef Marine Sanctuary, Sri Lanka

The objectives of the education programme included: making the fishing community and the younger generation aware of the importance of conserving marine resources; to obtain their suggestions and opinions; and to identify gaps and needs to strengthen local participation.

Observaciones sobre la reproducción, desarrollo embrionario y larval de la anchoíta argentina (Engraulis anchoita)

The first studies on the problems related to the reproduction of marine fish in Argentina (SW Atlantic ocean) have been carried out with a species of great economic importance, the anchovy (Engraulis anchoita Hubbs and Marini). The spawning period of this species during the period 1963-64 has been determined. By the application of the quantitative collection method, it has been established that spawning commenced in the areas close to the coast during the first few days of September and at a water temperature of 10,3° C and reached its greatest intensity in October (up 1569 eggs/1 square metre surface water) at a temperature varying between 11,5-13,8° C. From the middle of November the anchovy continues to reproduce in a less intensive form and further out to Sea, up to at least the month of May. The intensity of reproduction reaches a peek in February, and at a water temperature of 20° C. It is believed that two physiologically distinct populations of Engraulis anchoita may exist, the first reproducing in Spring and the second in Autumn. It has been established that a daily spawning rhythm occurs, between the hours of 8 and 12 p. m. During this period it was possible to obtain mature females with which artificial fertilization was performed. The rate of development was determined, which at a temperature of 14-15° C is from 69-72 hours, and at a temperature of 19-20° C from 50-53 hours. A temperature of 49° C was found be lethal. The different embryonic and larval stages of development are illustrated diagramatically and individually described. The preliminary studies on the larvae and juveniles caught in the Sea during the period of reproduction led to the formulation of certain conclusions whith reference that the juveniles, as yet larvae, begin to group together at an early age, and the younger individuals the more uniform are the schoals whith regards to the total size of the specimens. It has shown that the anchovy during its first year of life tends to display littoral behaviour. RESUMEN EN ESPAÑOL: Los primeros estudios de los problemas referentes a la reproducción de los peces marinos en la Argentina (océano Atlántico sudoccidental) se han efectuado sobre una especie de gran importancia económica, Engraulis anchoita Hubbs y Marini. Se ha determinado la época de desove de la anchoíta en un período anual 1963-64. Aplicando el método de recolección cuantitativo se ha establecido que el desove de esta especie ha empezado en las zonas muy cercanas a la costa, en los primeros días de setiembre a la temperatura 10,3° C y ha alcanzado mayor intensidad en octubre (hasta 1569 huevos en 1 m2 de la superficie del agua) a la temperatura 11,5°-13,8° C. Desde mediados de noviembre la anchoíta sigue reproduciéndose en forma poco intensiva y más mar afuera, hasta por lo menos el mes de mayo. La intensidad de reproducción para este segundo período alcanza un pico, aunque muy pequeño en febrero a la temperatura 20° C. Se hace la suposición de que pueden existir dos de distintas características fisiológicas poblaciones de Engraulis anchoita una de reproducción primaveral y otra de reproducción otoñal. Además se ha establecido que existe un ritmo diario de desove que comprende las horas 20-24. En las horas de postura se pudo conseguir hembras maduras y con sus productos sexuales se efectuó la fecundación artificial. Se determinó la velocidad de desarrollo que a la temperatura 14°-15° C es de 69-72 horas y en la temperatura 19°- 20° C es de 50-53 horas. La temperatura 4° resultó ser letal. Se realizaron dibujos y descripciones correspondientes a los distintos estadios embrionarios y larvales. Los estudios preliminares de las larvas y juveniles de la anchoíta, capturados en el mar en la época de reproducción, permitieron sacar ciertas conclusiones sobre el crecimiento en sus primeros meses de vida. Se observó que los juveniles, larvas todavía, empiezan a agruparse muy temprano y cuanto más jóvenes son los individuos, tanto más uniformes son los cardúmenes en las dimensiones de los ejemplares. Se demostró que la anchoíta en su primer año de vida tiene costumbres muy costeras.