Esclusas de peces en la represa de Salto Grande. Consideraciones acerca de su funcionamiento

Fishlocks at Salto Grande Reservoir. Considerations about its functioning. The Salto Grande dam, has in its structure two Borland type fishlocks. The fish passage efficiency is low, and it is limited by the original system design, the management of the dam and the Uruguay river hidrology. Thus, in the 1984-1986 period, on annual average, the fishlocks were out of service 53 o/o of the time, while in the two periods when higher observed fish accumulation occur, march-april and september-october, the passages were closed 72 o/o and 54 o/o of the time, respectively. (PDF has 55 pages.)

Status and management of the sea cucumber fishery of La Grande Terre, New Caledonia

From October 2006 to May 2008, The WorldFish Center coordinated a ZoNéCo project to provide support to the Southern and Northern Provinces for decisions about how best to manage the sea cucumber fishery around La Grande Terre. We collected data during underwater population surveys, questionnaire-based interviews with fishers and processors, and landing catch surveys. A core aim was to furnish the Provinces with ‘ballpark’ estimates of the abundance and density of commercially important sea cucumbers on 50 lagoon and barrier reefs. Analysis and synthesis of the ecological and sociological data provide the basis for informed recommendations for fisheries management. Counts of trochus and giant clams on the reefs allow us to also describe the general status of those resources. We propose 13 recommendations for management actions and fishery regulations and advocate an adaptive management approach. This multidisciplinary study should serve as a useful template for assessing other fisheries, and we provide a series of generic ‘lessons learnt’ to aid future programmes. (PDF has 140 pages.)

Whales and Sonar: Environmental Exemptions for the Navy's Mid-Frequency Active Sonar Training.

Mid-frequency active (MFA) sonar emits pulses of sound from an underwater transmitter to help determine the size, distance, and speed of objects. The sound waves bounce off objects and reflect back to underwater acoustic receivers as an echo. MFA sonar has been used since World War II, and the Navy indicates it is the only reliable way to track submarines, especially more recently designed submarines that operate more quietly, making them more difficult to detect. Scientists have asserted that sonar may harm certain marine mammals under certain conditions, especially beaked whales. Depending on the exposure, they believe that sonar may damage the ears of the mammals, causing hemorrhaging and/or disorientation. The Navy agrees that the sonar may harm some marine mammals, but says it has taken protective measures so that animals are not harmed. (PDF contains 20 pages)

Reproductive biology of male franciscanas (Pontoporia blainvillei) (Mammalia: Cetacea) from Rio Grande do Sul, southern Brazil

The reproductive biology of male franciscanas (Pontoporia blainvillei), based on 121 individuals collected in Rio Grande do Sul State, southern Brazil, was studied. Estimates on age, length, and weight at attainment of sexual maturity are presented. Data on the reproductive seasonality and on the relationship between some testicular characteristics and age, size, and maturity status are provided. Sexual maturity was assessed by histological examination of the testes. Seasonality was determined by changes in relative and total testis weight, and in seminiferous tubule diameters. Testis weight, testicular index of maturity, and seminiferous tubule diameters were reliable indicators of sexual maturity, whereas testis length, age, length, and weight of the dolphin were not. Sexual maturity was estimated to be attained at 3.6 years (CI 95% =2.7–4.5) with the DeMaster method and 3.0 years with the logistic equation. Length and weight at attainment of sexual maturity were 128.2 cm (CI 95%=125.3–131.1 cm) and 26.4 kg (CI 95% =24.7–28.1 kg), respectively. It could not be verified that there was any seasonal change in the testis weight and in the seminiferous tubule diameters in mature males. It is suggested that at least some mature males may remain reproductively active throughout the year. The extremely low relative testis weight indicates that sperm competition does not occur in the species. On the other hand, the absence of secondary sexual characteristics, the reversed sexual size dimorphism, and the small number of scars from intrassexual combats in males reinforce the hypothesis that male combats for female reproductive access may be rare for franciscana. It is hypothesized that P. blainvillei form temporary pairs (one male copulating with only one female) during the reproductive period.

Systematic study of the blue green algae of Ceylon kept at the herbarium of the Royal Botanical Gardens, Peradeniya

The collection of blue green algae kept at the herbarium of the Royal Botanical Gardens, Peradeniya, was collected by Ferguson more than 70 years ago. Since then many changes have taken place in the taxonomy of the blue green algae. West (1902), Lemmermann (1907), Wine (1915), Crow (1923), Bharadwaja (1934) and Holsinger (1935) had described some of the blue green algae of Ceylon. While examining the collections of blue green algae kept at the herbarium, the authors found that most of the identifications were incorrect and required revision. In the present paper 20 blue green algae are described. The classification and key to the species are based on the characters given by Desikachary (1959). Blue green algae are important to fisheries since Chanos larvae feed on them.