Multidisciplinary research and management: fisheries in the Central Delta of the Niger River (Mali)

This contribution gives an overview of the fisheries in the Central Delta of the Niger River (Mali) and highlights the results of a multidisciplinary research and management program conducted in the area to assess the status of the fisheries and improve their management. The importance of multidisciplinary approaches is emphasized to fully elaborate the problems impacting fisheries and the measures for their resolution. Directions for increased decentralization, participation of fishers and ecosystem preservation for improved management of the Central Delta fisheries are briefly discussed.

Potentials for different models for freshwater aquaculture development in the Red River Delta (Vietnam) using GIS analysis

This study was an attempt to apply land-based GIS analysis for freshwater aquaculture planning in the Red River Delta of Vietnam. It was based on diverse data sources in order to help decision makers at the site and also to contribute to the modelling of selection processes for aquaculture development planning in the region.

River fisheries in Africa: their relationship to flow regimes

River fisheries in Africa are important because of their contribution of animal protein to human diets. Such fisheries are highly dependent on hydrological regimes and show considerable year-to-year variation in response to natural climatic events. River flow regimes are being increasingly altered by withdrawals by man, principally for agriculture. The modification of hydrological regimes is leading to diminishing catches of fish and changes in the number and size of the species caught. Given that the trend to remove water from rivers for agriculture and power generation will continue, better appraisals of the impacts of such withdrawals are urgently needed so the policies for water allocation can be better defined. The development of tools to aid in such decision-making is equally important.

Rangia and Marsh Clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, in Eastern México: Distribution, Biology and Ecology, and Historical Fisheries

Rangia and marsh clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, occur in brackish waters along México’s eastern coast from the northern State of Tamaulipas to the southern State of Campeche. The clams were important to the prehispanic people in the southern part of the State of Veracruz, where they were used as food and as construction material. In modern times, they are harvested for food. The fishermen wade in shallow water and harvest the clams in soft sediments by hand. Annual landings of whole clams during a recent 5-yr period, 1998–2002, were 1,139–1,695 t. The only area with a substantial ongoing clam fishery is in the Lower Papaloapan River Basin, including Alvarado Lagoon, where as many as 450 fishermen are licensed harvesters. This fishery for the Rangia and marsh clams is the most important clam fishery along México’s Gulf Coast.

Modern dinoflagellate cysts found in surface sediments of Santa Cruz Island, Galapagos

Modern dinoflagellate cysts in surface sediments collected on Santa Cruz Island, Galapagos, are described, along with other palynomorphs such as microforaminiferal linings, tintinnid loricae, copepod eggs and acritarchs including Domasiella-like micro-remains and Halodinium spp. The dinoflagellate cyst assemblages mainly consisted of Spiniferites cf. scabratus (gonyaulacoid) followed by Brigantedinium spp. and Selenopemphix quanta (peridinioids). No gymnodinioid cysts were found. No remarkable differences in cyst composition and densities were recognized between stations. The cyst assemblages were characterized by low species diversity and low cyst concentrations in comparison with the Pacific coast of Guatemala and Peru. CDF Contribution Number 1019.

Autonomous adaptation to climate change by shrimp and catfish farmers in Vietnam’s Mekong River delta

The Mekong River delta of Vietnam supports a thriving aquaculture industry but is exposed to the impacts of climate change. In particular, sea level rise and attendant increased flooding (both coastal and riverine) and coastal salinity intrusion threaten the long-term viability of this important industry. This working paper summarizes an analysis of the economics of aquaculture adaptation in the delta, focusing on the grow-out of two exported aquaculture species—the freshwater striped catfish and the brackish-water tiger shrimp. The analysis was conducted for four pond-based production systems: catfish in the inland and coastal provinces and improved extensive and semi-intensive/intensive shrimp culture.

River Dart Scale Reading Investigation Report on the 1965 Season

This is the fourth River Dart Scale Reading Investigation Report on the 1965 season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All it summarized in tables, and figures are included plotting weight distributions for each age classes and frequency distributions.

River Dart Scale Reading Investigation Report on the 1966 Season

This is the fifth River Dart Scale Reading Investigation Report on the 1966 Season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All it summarized in tables, and figures are included plotting weight distributions for each age classes and frequency distributions. It also compares the results of previous reports.

River Dart Scale Reading Investigation Report on the 1967 Season

This is the sixth and final River Dart Scale Reading Investigation Report on the 1967 Season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All it summarized in tables, and figures are included plotting weight distributions for each age classes and frequency distributions. It also compares the results of previous reports and gives a full summary for the investigation (including previous reports).

River Dart Scale Reading Investigation Report on the 1962 Season

This is the first River Dart Scale Reading Investigation Report on the 1962 season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews briefly the theory and mechanics of the scale-reading technique, the life history of the salmon, and the methods used for the collection of scales and the examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All are summarized in various tables and figures are also included, plotting weight distributions for each age classes and frequency distributions.

River Dart Scale Reading Investigation Report on the 1963 Season

This is the second River Dart Scale Reading Investigation Report on the 1963 season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All are summarized in tables, and figures are alo included plotting weight distributions for each age classes and frequency distributions. The report also remarks the similarity of the results with those for 1962.

River Dart Scale Reading Investigation Report on the 1964 Season

This is the third River Dart Scale Reading Investigation Report on the 1964 season by the Devon River Board. The object of this investigation is to examine, by means of scale-reading, the general biology of the salmon population of the River Dart. It reviews the methods used for the collection of scales and examination of the materials. It shows the results of the survey and the number of scales studied from each of the various sea-age classes, time of running with distribution of the sea-age groups throughout the season, fish sizes and smolt ages at migration. All are summarized in tables, and figures are also included plotting weight distributions for each age classes and frequency distributions. After three years of the investigation a pattern is emerging which shows that the Dart salmon population is mainly composed of four year old fish, which have spent two years in the river and then two year or little longer at sea.

River Dart fisheries survey 1965

This is the first River Dart Fisheries Survey produced by the Devon River Authority; which was carried out from May to October 1965. The objective was to examine the distribution and relative abundance of salmonid fish in the River Dart, in order to assess the possibility or desirability, of increasing salmon smolt production of the river by artificial propagation or other means. Description, chemical, pollution and biological conditions of the River Dart along with fisheries catches, water extraction and spawning are briefly cited. The method includes the choice of sections and sampling techniques. The results go through the number/type/class of fishes counted while the survey took place, distribution patterns within the different transects/brooks, competition between salmon parr and trout and estimations of population. The section on the discussion and recommendations is introduced by a brief explanation of the bases for the Artificial Propagation Programme and the River Dart specific case-study. The annexes contains River Dart and tributaries maps, fish size distribution tables and figures, tables with totals of salmonid fish found and population density tables.