Aquaculture in tropical Mexican lakes and dams: achievements and perspectives

Mexico, with highly diverse physiography, geology, soils and climate, is a country with a broad mosaic of aquatic ecosystems within 320 watersheds. This paper presents a brief picture of Mexican fresh waters, the distribution of rainfall and the potential for aquaculture. The main fish species and water bodies, dams and lakes, are highlighted. The country faces problems of surface water shortage which requires better management.

Fisheries potential of village dams in northern Ghana

Results of a twelve-month assessment of the fisheries and aquaculture potential of small waterbodies (SWBs) in the West Gonja District of Northern Ghana are presented. The primary objectives of the project were to established whether the fisheries within the reservoir basins in the West Gonja and Nanumba Districts (Northern Region) could be enhanced and aquaculture associated with the SWBs could be viable.

Morphometric characteristics and meristic traits of Tilapia zillii from three major dams of a southwestern state, Nigeria

Tilapia zillii was examined in three major dams in Ekiti State, Nigeria (Ureje dam, Ado, Egbe dam and Ero dam) for their morphometric characteristics and meristic traits. The results showed that the average body weight of the fish sampled were 145.86±50.06g in Ado, 30.19±9.35g in Egbe and 40.58±52.30g in Ero dam. Average total lengths were 21.29±3.20cm, 12.32±1.74cm and 11.24±1.56cm for Ado, Egbe and Ero dam respectively. The relationship between average weight and length of T. zillii showed that Y=15.202X-179.33 (R2=0.7181), Y=4.40049±-24.075 (R2=0.6708) and Y=2.6676X10.596 (R2=0.0063) for Ado, Egbe and Ero dam respectively. The results on headlength, total length, body weight and standard length and pre-pelvic distance are significantly different at 95% among the T.zillii of the three dams. There was no significant difference in the meristic traits of the T. zillii of the three dams. The population size of T.zillii in the three dams was just too small compared to other species of fish hence the need to assess the stock of fish in these dams critically for the encouragement of proper fishing activities in these dams.

Imminent Geologic and Hydrologic Hazards on Fort Ord BLM Land

The Bureau of Land Management acquired 7,500 acres of land as part of the re-use of the decommissioned Fort Ord Army base. A variety of geologic hazards exist on the landscape including gully erosion, mass wasting, and decaying earthen dams. This short report highlights a few critical areas that deserve closer evaluation and remediation. Of particular concern are decaying earthen dams and mass wasting of tall stream banks that may impact BLM infrastructure or adjacent urban development. (Document contains 13 paGES)

Tropical river fisheries valuation: background papers to a global synthesis

This report is a compilation of five regional reviews that document the global status of tropical rivers and inland fisheries in three continents: Latin America, Africa and Asia. It explores the role of ‘valuation’ methods and their contribution to policy-making and river fishery management. From the compilation, the best estimate of the global value of inland fisheries for those three continents is US$ 5.58 billion (gross market value), which is equivalent to 19 percent of the current value of annual fish exports from developing countries (US$ 29 billion) for 2004. The compilation shows that there is a general shortage of information on inland fisheries, especially derived from conventional economic valuation methods, though information from economic impact assessment methods and socio-economic and livelihood analysis methods is more widely available. The status of knowledge about the impact of changes in river management on the value of tropical river fisheries is weak and patchy. Although the impacts of large dams on the hydrology, ecology and livelihood support attributes of tropical rivers are well-recognized, there have been only few valuation studies of these issues. The document highlights the need for further valuation studies of tropical river and inland fisheries in developing countries. It underlines how vital it is for policy-makers and other stakeholders to understand the importance of these natural resources in order to make appropriate decisions concerning their role in development policy and illustrates why capacity building in valuation should become a major priority for agencies concerned with fisheries management and policy-making.

Review of river fisheries valuation in Central and South America

Unlike Africa and Asia, where a large part of the population are heavily dependent upon fishing for their livelihoods, fishing for a living in the interior of Central and South America (CSA) remains a marginal occupation for all but the most isolated of families. As such, the economics and management of fisheries on the continent have received little attention from within the continent and the rest of the world. This study shows that while a number of studies have been carried out on fishing in the region, they tend to be limited in their geographical focus and time scale. Although fishing of freshwater species may appear to be comparatively insignificant in the region, the rivers of CSA are very important. This report attempts to analyze the literature available on CSA river fisheries and attempts to draw out an economic value of these fisheries. It is divided into a number of sections. First, the authors describe the major river basins on the continent, characterize their fisheries, and place freshwater fisheries in CSA into a global context. Second, the authors provide a review of valuation techniques for fisheries and use this analytical framework to review the principal literature on freshwater fisheries in the region. Then they turn their attention to the economic impact of dams and water abstraction schemes, reviewing the available literature to ascertain how/if economic values are computed for the impact on fisheries. Finally, they offer some conclusions and recommendations on the direction for future studies of freshwater fisheries in CSA.

Chinook salmon spawner stocks in California's Central Valley, 1989: annual report

This report covers the 37th annual inventory of chinook salman, Oncorhynchus tshawytscha, spawner populations in the Sacramento-San Joaquin River system.-It is a compilation of reports estimating the fall-, winter-, late-fall-, and spring-run salmon spawner populations for streams which were surveyed. Estimates were made from counts of fish entering hatcheries and migrating past dams, froro surveys of dead and live fish and redds on spawning areas, and from aerial counts. The estimated 1989 total escapement of chinook salmon in the Central Valley was 205,990 fish. This total consisted of 181,864 fall-, 12,171 spring-, 539 winter-, and 11,416 late-fall-run spawners. All of the spring-, late-fall-, and winter-run salmon were estimated to be in the Sacramento River system, while 3,493 fish of the fall run were in the San Joaquin River system. Due to decreases of spawner populations in most Central Valley tributaries, the total 1989 salmon stock was 32% lower than in 1988; however, late-fall salmon in the upper Sacramento River had a run size similar to that of 1988. The winter run in the mainstem Sacramento River was at a record low level. (PDF contains 44 pages.)

Annual report chinook salmon spawner stocks in California's central valley, 1991

This report covers the 39th annual inventory of chinook salman, Oncorhynchus tshawytscha, spawner populations in the Sacramento-San Joaquin River system." It is a compilation of reports estimating the fall-, winter-, late-fall-, and spring-run salman spawner populatiens fer streams which were surveyed. Estimates were made from counts of fish entering hatcheries and migrating past dams, from surveys of dead and live fish and redds on spawning areas, and from aerial counts. The estimated 1991 total escapement of chinook salmon in the Central Valley was 147,080 fish. This total consisted of 132,571 fall-, 5,921 spring-, 190 winter-, and 8,398 late-fall-run spawners. All of the spring-, late-fall-, and winter-run salmon were estimated to be in the Sacramento River system, while 1,176 fish of the fall run were in the San Joaquin River system. Spawner populations in all individual tributaries (except the American River) and the Sacramento River mainstem were lower than in 1990; but it should be noted that fall run populations in the Feather and Yuba rivers, two of the larger tributaries, were not surveyed that year. The winter run in the mainstem Sacramento River was at a record low level. (PDF contains 42 pages.)

The past history and present trends in the fisheries of Lake Chad

Lake Chad is a very large, shallow eutrophic lake shared by Chad, Nigeria, Niger and Cameroun. It supplies approximately 13% of Nigeria's inland fish. It however lies in an unstable ecological environment characterised by intermittent period of rainfall and drought. This creates a very large draw down area. Consequently, the fisheries are affected by the oscillation in the size of lake due to the drought. Other factors affecting the volume of water are the numerous dams on the inflow rivers. The fishery is also subjected to intense overfishing and may be affected by pollution and other land use practices. The paper discusses changes that took place over the years as a result of the factors of drought, effect of dams on the inflow rivers. The fishery is also subjected to intense overfishing and may be affected by pollution and other land use practices. The paper discusses changes that took place over the years as a result of the factors of drought, effects of dams and overexploitation. Previous records of fish production, species composition and distribution, the status of the fish stocks, their sizes are compared with more recent data. The status of the fishery before and after the contraction of the lake is discussed. Suggestion for a national exploitation of the lake based on habitat improvement, increasing the volume of the water in the lake through controlled use of the influent rivers as well as reduction in overfishing are made

Biology and Management of the American Shad and Status of the Fisheries, Atlantic Coast of the United States, 1960

This paper summarizes current information on the American shad, Alosa sapidissima, and describes the species and its fishery. Emphasis is placed on (1) life history of the fish, (2) condition of the fishery by State and water areas in 1960 compared to 1896 when the last comprehensive description was made, (3) factors responsible for decline in abundance, and (4) management measures. The shad fishery has changed little over the past three-quarters of a century, except in magnitude of yield. Types of shad-fishing gear have remained relatively unchanged, but many improvements have been made in fishing techniques, mostly to achieve economy. In 1896 the estimated catch was more than 50 million pounds. New Jersey ranked first in production with about 14 million pounds, and Virginia second with 11 million pounds. In 1960 the estimated catch was slightly more than 8 million pounds. Maryland ranked first in production with slightly more than 1.5 million pounds, Virginia second with slightly less than 1.4 million pounds, and North Carolina third with about 1.3 million pounds. Biological and economic factors blamed for the decline in shad abundance, such as physical changes in the environment, construction of dams, pollution, over-fishing, and natural cycles of abundance, are discussed. Also discussed are methods used for the rehabilitation and management of the fishery, such as artificial propagation, installation of fish-passage facilities at impoundments, and fishing regulations. With our present knowledge, we can manage individual shad populations; but, we probably cannot restore the shad to its former peak of abundance.

Fish and fisheries in the Sesan River Basin: catchment baseline, fisheries section

The present report was prepared for the Water and Food Challenge Program project “Optimizing the management of a cascade of reservoirs at the catchment level” (MK3). It constitutes the baseline assessment of fish and fisheries in the Sesan River Basin. The objective of the MK3 project is to contribute knowledge and recommendations so that cascades of reservoirs corresponding to hydropower dams in the Mekong Basin are managed in ways that are more fair and equitable for all water users. This project seeks to understand at the catchment scale the cumulative upstream and downstream consequences of management decisions taken for multiple reservoirs. Revised rules for water storage infrastructure management will in particular take into account fisheries and agricultural potential as well as hydropower gen

A historical review of the shad fisheries of North America

A review of the relative productivity and value of the shad fisheries of North America as reflected in recorded commercial catches. A review of reasons for the decline that are biological and socioeconomic. Factors that have been held responsible are: pollution; destruction or impairment of spawning and nursery areas; overfishing; hydroelectric and canal dams; natural fluctuations in abundance. Natural catastrophes, parasites, and predators are not considered important in causing the decrease in commercial production. Attempts to rehabilitate the fisheries by various means of stocking artificially-reared fry and pond-reared fingerling shad, appear to have failed in every instance. Introduction of shad fry on the Pacific Coast has resulted in a major fishery. The most significant program is a controlled catch management plan, operating at this time [1953] only in Maryland.

Impactos negativos en las pesquerías de lisas (Pisces, Mugilidae) en Cuba de 1971 a 1995 y recomendaciones para incrementar su producción

Se presenta la situación actual de las lisas (Pisces, Mugilidae en Cuba, espacialmente respecto a los daños sufridos en sus pesquerías de 1971 a 1995. Se revisan las especies marinas presentes en aguas cubanas y sus características generales, así como las principales zonas, artes y épocas de pesca. Se presentan las capturas por regiones y se analizan los desembarques por categorías, de acuerdo con su composición por espec1e. Se revisa la Situación del grupo en los últimos años, cuyas capturas han disminuído a sólo un 5% del nivel más alto alcanzado, debido a los perjuicios ambientales de las lagunas y áreas costeras aledañas causadas por acciones antrópicas, que se describen, así como por disminuciones en el esfuerzo pesquero. Se presentan las relaciones entre las capturas y la capacidad de agua embalsada acumulada en el país, así como entre la talla media de las hembras de Mugil liza y el año en el periodo de 1981 a 1989 en la localidad históricamente más importante. Se analizan propuestas para incrementar la producción de los mugílidos en Cuba relacionadas con las pesquerías y la aplicación de técnicas de "Vallicultura integrada" como única vía para rehabilitar el medio ambiente lagunar con un balance adecuado de costo-rentabilidad. ABSTRACT The present status of the mullets (P1sces, Muglhdae),Cuba is rev1ewed, spec1ally in relation to their físhery between 1971 end 1995. The manne spec1es, Cuban waters, the1r general characterst1cs, as well as the main zonas, gears and flshmg Matons are shown. The captures by reg1ons and the landings by category and by specíes compositton are anatysed . The 11tuat10n ol the group in recent years is rev1ewed , in which the captures decreased to only 5% of the h1ghest leve! attamed due to envuonmental damages to coastal lagoons and nearby areas causad by human actions and by a lower flsh1ng effort. The retau onsh1ps are shown between captures and the country's cumulatíve capacitv of water dams, as well as that of the average s11e of Mugilliza tamales m the years between 1981 and 1989 ín the most historically important locat1on •. Proposals to mcrease mullet production in Cuba m relat1on to fisheries and establishment of "i ntegrated Vallicultura• as the only wav of restonng the tagoon environment with a good cost-benefi t balance are analysed.

A report on frame and catch assessment surveys on Lake Nakuwa, Lake Kyoga Basin, Uganda

Lake Nakuwa is one of the large lakes among the Kyoga drainage system lakes, located 132 km north east Off Jinja town, at 01° 091N 33° 21 1 E, an elevation 1037 m, surface area of 200 km2 and an average depth of 3.3 m. The lake is shared by the districts of Kamuli, Pallisa and the newly created district of Kaliro. howerever 80% of the landing sites are in Kaliro and less than 20% are shared between the districts of Kamuli and Pallisa. The lake is free of submerged and floating macrophytes, with lots of floating papyrus (sudds). Papyrus, hippo grass and reeds dominate the shoreline vegetation. Lake Nakuwa like the main lake Kyoga was stocked with the Nile perch and the tilapiine species namely Oreochromis niloticus, Oreochromis leucostictus and Tilapia zillii in the general stocking exercise of small lakes alild dams in the early 1970's.