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Geography Of Lake Nicaragua, Jaime Incer

Investigations of the Ichthyofauna of Nicaraguan Lakes

The area surrounding Lake Nicaragua is discussed from the standpoints of its history, geological setting, climate and vegetation. A physical description of the lake itself is given, including the nature of its bottom, its shoreline, its islands and volcanoes.

The Status Of The Lake Nicaragua Shark: An Updated Appraisal, Thomas B. Thorson

Investigations of the Ichthyofauna of Nicaraguan Lakes

Since 1966, an extensive tagging program has demonstrated beyond any further doubt (Thorson, 1971) that the sharks move from the Caribbean Sea to Lake Nicaragua and vice versa. At the time of this writing, of 1450 post-juvenile sharks tagged at the various river mouths on the Caribbean Coast, ten have been recovered in Lake Nicaragua; and of 146 tagged at San Carlos, where the river leaves the lake, 28 have been recovered along the Caribbean Coast, most of them at the various outlets of the Rio San Juan. Except for these basic facts, the results of the tagging program have …

The Midas Cichlid In Nicaragua, George W. Barlow

Investigations of the Ichthyofauna of Nicaraguan Lakes

Cichlasoma citrinellum (Gunther), the Midas cichlid, is the most important food fish in the Great Lakes Basin of Nicaragua. It occurs in the majority of the lakes, where it is the most ubiquitous cichlid fish, but it is uncommon in the rivers. The fry are carnivorous while the juveniles and adults are omnivorous, eating mostly Aufwuchs, snails, and fish. The Midas cichlids suffer from a number of diseases in nature and in the laboratory, including lymphocystis and nocardiosis. Potential predators vary from sharks and sawfish in Lake Nicaragua, to just one cichlid relative in one crater lake; in Lake …

Calcium And Other Ions In Blood And Skeleton Of Nicaraguan Fresh-Water Shark, Marshall R. Urist

Investigations of the Ichthyofauna of Nicaraguan Lakes

The bull shark, Carcharhinus lellcas, employing archaic but effective means of regulating the physical-chemical composition of its body fluids, thrives in tropical fresh-water rivers and lakes. The ionic strength of the serum and the concentrations of total solutes, calcium, urea, and other ions are below the levels found in marine elasmobranchs but higher than the levels in teleosts. The patterns of the calcium deposits of the vertebrae are identical in marine and fresh-water subspecies.

Carcharhinus Nicaraguensis, A Synonym Of The Bull Shark, C. Leucas, Henry B. Bigelow, William C. Schroeder

Investigations of the Ichthyofauna of Nicaraguan Lakes

Nicaraguensis very closely resembles leucas by the following characters. The anterior margin of the eye is posterior to the front of the mouth by a distance equal to half its own diameter in nicaraguensis; the gill openings are relatively somewhat longer in nicaraguensis, the third being nearly as long as the distance between the nostrils; the free tip of the second dorsal is about two-thirds as long as its base in nicaraguensis.

Reproduction Of The Bull Shark, Carcharhinus Leu Cas , In The Lake Nicaragua-Rio San Juan System, Norman H. Jenson

Investigations of the Ichthyofauna of Nicaraguan Lakes

Carcharhinus leucas, the bull shark, or cub shark, is a member of a large family, the Carcharhinidae, sometimes called requiem sharks. It is of medium size, reaching a maximum of a little more than three meters in some parts of its range, but little more than two and one-half meters in my study area. It is euryhaline, able to live for extended periods of time in both freshwater and marine environments. It is a viviparous shark, retaining the young and nourishing them by means of a yolk-sac placenta.

Bottom Sediments Of Lake Nicaragua And Lake Managua, Western Nicaragua, Frederick M. Swain

Investigations of the Ichthyofauna of Nicaraguan Lakes

Lakes Nicaragua and Managua are large, rather shallow, fresh-water bodies that lie in a late Tertiary and Quaternary graben in western Nicaragua.
The bottom sediments comprise highly organic diatomaceous volcanic silts and clays in which quartz plagioclase feldspar, dioctahedral montmorillonite and volcanic glass are the principal constituents.
Organic nitrogen content of the lake sediments ranges from 0.3-1.2 percent, about the same range as in eutrophic lakes of higher latitudes. Bitumen content is rather low, much like that of oligotrophic lakes. Hydrocarbon fractions of bitumens are similar in amount to an alkaline lake of western U. S. Non-hydrocarbon bitumens are high …

Presence Of The Cichlid Fish Cichlasoma Managuense Gunther In Lake Xiloá, Nicaragua, Jime Villa

Investigations of the Ichthyofauna of Nicaraguan Lakes

Villa (1968) included C. managuense in the fauna of Lake Xiloá as a "recently introduced" species since the Ministerio de Agricultura y Ganaderia (Nicaragua) had introduced several hundred young individuals of this species from Lake Managua, hatched at the Estacion Experimental "La Calera." Apparently officials of the Ministerio did not determine whether or not C. managuense occurred in Lake Xiloá prior to its introduction.

Competition Between Color Morphs Of The Polychromatic Midas Cichlid Cichlasoma Citrinellum, George W. Barlow

Investigations of the Ichthyofauna of Nicaraguan Lakes

The Midas cichlid, Cichlasoma citrinellum, is a polychromatic fish that occurs in Nicaragua. All of these fish start life as normally colored, cryptic individuals. In some populations a few fish change into conspicuously colored morphs, most frequently gold. When kept in unmixed color groups, golds and normals grow at the same rate; but when they are mixed, growth of the golds becomes taster and that of the normals slower. Golds dominate normals in contests over food, which accounts for their advantage.

Hemoglobin Stability In Bull Sharks, Jack D. Burke

Investigations of the Ichthyofauna of Nicaraguan Lakes

No significant differences in oxyhemoglobin affinity, or electrophoretic patterns of hemoglobin were found in 18 bull sharks collected in selected regions of Lake Nicaragua, the Rio San Juan, and the Caribbean Sea. The half-saturation of hemoglobin with oxygen (P50) was 11 and 17 mm Hg at pH 7.4 and 6.8, respectively (25° C, 3% hemoglobin solution, potassium phosphate buffer, 0.3 ionic strength). Electrophoresis resolved the hemoglobin into a minor and a major band. P1animetry of densitometric recordings showed that the major band constituted 54% of the total hemoglobin; the minor band, 46%. On the basis of these hemoglobin studies, no …

Body Fluid Solutes Of Juveniles And Adults Of The Euryhaline Bull Shark Carcharhinus Leucas From Freshwater And Saline Environments, Thomas B. Thorson, C. Michael Cowan, Donald E. Watson

Investigations of the Ichthyofauna of Nicaraguan Lakes

Since the discovery of the phenomenally high urea content of the body fluids of cartilaginous fishes by Staedeler and Frerichs (1858), the unique osmoregulatory system of this vertebrate class has been studied by many investigators. In broad outline, the mechanisms are essentially similar in all three of the major subtaxa: the selachians, the batoids, and the holocephalans. A single exception is the genus Potamotrygon (fresh-water stingrays of South America and Africa), which has apparently lost the ability to concentrate urea even when transferred to salt water.

Rectal Glands Of Marine And Fresh-Water Sharks: Comparative Histology, Mikio Oguri

Investigations of the Ichthyofauna of Nicaraguan Lakes

The rectal glands of elasmobranchs perform the function of salt-excreting organs. These glands are smaller and show regressive changes in specimens of the bull shark, Carcharhinus leucas, found in fresh-water environment, compared with specimens of this and other species from a marine habitat.

Observations On The Reproduction Of The Sawfish, Pristis Perotteti, In Lake Nicaragua, With Recommendations For Its Conservation, Thomas B. Thorson

Investigations of the Ichthyofauna of Nicaraguan Lakes

The presently known pristiform fauna of the western Atlantic consists of only two species, one each of Fowler's (1941) subgenera, Pristis and Pristiopsis. The former, characterized by the absence of a subcaudal lobe on the caudal fin, is represented by Pristis pectinatus; the latter, in which the subcaudal lobe is present, by Pristis perotteti. Although several features readily separate the two species, they can most easily be distinguished by the more slender rostrum of P. pectinatus and its larger number of rostral teeth, 24 to 32 on each side, as compared with 14 to 20 in …

The Feral Goat Herd Of Faure Island, W H J Clarke

Journal of the Department of Agriculture, Western Australia, Series 4

For just on a century there has existed on Faure Island, off the mid Western Australian coast, a herd of white feral goats.

The fleece of these animals, while similar in appearance to Angora mohair, has characteristics which somewhat resemble the luxury fibre cashmere, in that it comprises a fine dense undercoat, which sheds in early spring, as well as the hairy outcoat typical of all goat breeds except the Angora.

As there is little, if any, shedding in second or subsequent crosses, it would appear that the mating of Faure Island feral goats with traditional Angoras (or off-spring of …

Protecting Agriculture In 1976 : Three Sides Of An Apb Campaign, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

A quick look at three areas in which the A.P.B. are working with landholders to protect Western Australia from invasion.

Protecting our agriculture and wildlife is not only the APB's job— it is very much the community's job also. Any suspect birds or plants must be reported immediately to the Agriculture Protection Board.

A Survey Of Shearing Times, B R. Beetson

Journal of the Department of Agriculture, Western Australia, Series 4

When do farmers in W.A. shear their sheep, and why do they selest the times they do?

A Department of Agriculture survey attempted to answer these questions, which have important implications for the wool industry.

Cattle Fertility Not Harmed By Pour-On Insecticides, D J. Barker

Journal of the Department of Agriculture, Western Australia, Series 4

Pour-on insecticides have been a feature of lice and fly control on cattle for many years and in many countries, but it seems that only in Western Australia have they been suspected of lowering fertility.

Frequent reports of this effect have been received by the Department of Agriculture since the first pour-on insecticide was marketed in W.A. in the late 1960's, culminating in the research work reported below.

The work clears pour-ons as a cause of reduced fertility in herds.

Meat Marketing : The L.I.P.C. And Japan's Meat Import Controls, G C. George

Journal of the Department of Agriculture, Western Australia, Series 4

hardly a week passes without some reference to Japan's Livestock Industry Promotion Corperation (L.I.P.C.), and its effect on Australian meat exporters.

This article describes some of the functions of the L.I.P.C., and attempts to provide some insights into the Japanese meat market. The author, Gil George, recently returned from Japan after completing a Master's degree in Economics.

Availability Of Trypotophan In Some Feedstuffs For Swine, Pedro H. Rivera L., E. R. Peo, Jr., T. Stahly, B. D. Moser, P. J. Cunningham

Department of Animal Science: Faculty Publications

Two experiments were conducted to determine the availability of tryptophan (Try) from corn (NC), opaque-2 corn (OC), milo (M) and freeze dried alfalfa (FDA) when fed to swine. The first experiment consisted of a growth trial involving 96 baby pigs and eight treatments. The basal diet containing .06% Try and 24.5% protein was supplemented with .015%, .030% and .045% L-Try. These four diets were used to establish a standard curve for growth. The other treatments were formed by adding the feedstuffs as the source of Try to the basal diet. Availabilities were determined by comparing growth responses. Try availabilities from …

Some Remarks On The Fecundity Of Tilapia (T. Mossambica Peters) And Its Introduction Into Middle Central America (Nicaragua) Together With A First Contribution Towards The Limnology Of Nicaragua, Dietmar Riedel

Investigations of the Ichthyofauna of Nicaraguan Lakes

a. This paper presents an account of fecundity studies into T. mossambica under Middle Central American conditions and limnological investigations into Lake Moyua/Nicaragua which have been performed during 1961/62.

b. Data obtained as to fecundity of T. mossambica are discussed in the light of the term prolificy and with regard to ecological and biological characteristics of Nicaraguan waters and native fish fauna.

c. A more detailed contemplation about the possible effects of a spread out or transplantation of T. mossambica into other Nicaraguan waters concludes the paper.

Ichthyology Of The Lakes Of Nicaragua: Historical Perspective, Jaime Villa

Investigations of the Ichthyofauna of Nicaraguan Lakes

Scientific study of Nicaraguan freshwater fishes did not begin until Gunther described the first species from Lake Nicaragua in 1864, but actual accounts of several interesting fishes were written as early as the sixteenth century by the first historians of the New World. These accounts ranged from hearsay to rather detailed (for their time) descriptions and first-hand observations on the form and life of some species. In some cases these observations or conclusions have been doubted for many decades but confirmed and elaborated in recent years. Therefore I believe it may be of interest to examine the early chronicles.

Derivation Of The Freshwater Fish Fauna Of Central America, George S. Myers

Investigations of the Ichthyofauna of Nicaraguan Lakes

The nature, composition, and evolution of Centra) American freshwater fish groups are discussed in relation to the history and derivation of the faunal elements. It is concluded that the entire area between the Isthmus of Tehuantepec and eastern Panama was and always had been devoid of primary (obligatory) freshwater fishes prior to the very late Tertiary. Instead, secondary freshwater fishes evolved in this area during the Neogene and perhaps for a longer period, the Poeciliidae having probably had a longer history within the area than the Cichlidae. In the late Tertiary a very few North American immigrants entered the area …

Geographical Distribution Of Central American Freshwater Fishes, Robert Rush Miller

Investigations of the Ichthyofauna of Nicaraguan Lakes

The distribution of freshwater fishes in Central America is reviewed. Major parts of the region, especially in Honduras and Nicaragua, have yet to be explored ichthyologically, and systematic revision of important groups, notably the cichlids, is long overdue. The continental area from the Isthmus of Tehuantepec to the Colombian border contains approximately 456 species, of which over 75% comprise the Cyprinodontidae, Poeciliidae, Cichlidae, and marine invaders (peripheral fishes); about one-third of the latter (57 species) have taken up more or less permanent residence in fresh water. There are 104 primary species in 10 families, 165 secondary forms in 6 families, …

Geographic Distribution Of The San Juan Ichthyofauna Of Central America With Remarks On Its Origin And Ecology, William A. Bussing

Investigations of the Ichthyofauna of Nicaraguan Lakes

The scientific study of fishes of the Great Lakes of Nicaragua began in 1864 with the description by Gunther of Heros labiatus (=Cichlasoma labiatum) from Lake Managua. Subsequently, Gunther reported on several other species collected in the Great Lakes by Captain J. M. Dow. Astorqui (1967) reviewed the sparse ichthyological literature dealing with Nicaraguan fishes and pointed out the paucity of recent studies. Since then Villa (1971) has produced a provisional list of the freshwater and brackish water fishes of Nicaragua and Astorqui (1972) has analyzed the ichthyofauna of the Great Lakes Basin. Riedel (1972) discussed the geological …

Una Teoría Sobre El Origen De Los Peces De Xiloà, Jaime Villa

Investigations of the Ichthyofauna of Nicaraguan Lakes

A finales de 1965 v en conexion con estudios en curso sobre la herpetolog( a nicaragiiense colec te una pequena serie de peces de la Laguna de Xiloa que revelaron aspectos interesantes y me indujeron a realizar colecciones extensivas en toda la laguna; estas colecciones se realizaron durante 1966-68 y cons tan de varios cientos de ejemplares, depositados en la Universidad de Costa Rica y en mi coleccion particular. El material acumulado durante estos anos y las notas tomadas durante todo el tiempo en que se realizaron han sido suficientes para permitir una serie de conclusiones en diversos aspectos, algunas …

Some Speculations About "The Great Nicaraguan Lake", Jaime Villa

Investigations of the Ichthyofauna of Nicaraguan Lakes

The available evidence indicates that Lakes Managua and Nicaragua were broadly connected in the past, when most of the fish species invaded the "Great Nicaraguan Lake". Due to the lowering of the water level (caused perhaps by tectonic movements and/or erosion produced by the Rio San Juan), Lake Managua became separated from Lake Nicaragua in the Tipitapa area. Water movement from Lake Managua is achieved mostly by seepage through a porous dropoff which prevents the exchange of fishes between the lakes. At about the same time, if not earler, Lake Xilml also became separated. After the more or less permanent …

Peces De La Cuenca De Los Grandes Lagos De Nicaragua, Ignacio Astorqui

Investigations of the Ichthyofauna of Nicaraguan Lakes

El presente trabajo se basa en una coleccion de peces hecha en Nicaragua par el Profesor Luis R. Rivas y el autor des de el 11 de Junia hasta el 14 de Julio de 1960. El trabajo se limita a la cuenca de los Grandes Lagos y rios trio butarios (Fig. 1). La mayor parte del material procede de esta zona y no pre· ten de ser un trabajo ictio16gico definitivo acerca de Nicaragua.
Aspectos de la paleografia de Centroamerica, el origen de la fauna de los lagos y la historia de la ictiologia de Nicaragua se encuentran en un …

Lake Nicaragua Fishery Resources, William D. Davies

Investigations of the Ichthyofauna of Nicaraguan Lakes

Data collected during this survey indicated that the number of full-time fishermen has not increased appreciably over the past several years. However, it is likely that, if the demand for fish were to increase, a number of the present part-time fishermen would increase their effort to full-time. Indications are strong that the fish catch from this lake could at least be doubled by the existing population of fishermen, using the same gear, if market conditions were such as to encourage greater fishing effort.
The lake's overall fisheries resources are far from being exploited to their maximum, with the possible exception …

Informe Sobre Los Resultados Del Programa De Investigacion De Los Recursos Pesqueros Del Lago De Nicaragua, Instituto De Fomento Nacional

Investigations of the Ichthyofauna of Nicaraguan Lakes

E1 Instituto de Fomento Nacional (INFONAC), basado en los principios de su Ley Creadora y en la politica de desarrollo pesquero que se ha trazado, tome en el mes de Enero de 1971, la firme determinacion de iniciar el "Programa de Investigacion de los Recursos Pesqueros del Lago de Nicaragua" con una duracion estimada de tres (3) aiios, teniendo como base de operaciones la Ciudad de Granada.

An Investigation Into The Use Of Artificial Habitats As A Means Of Increasing The Fishery Productivity Of The Great Lakes Complex Of Nicaragua, Terrance M. Lim, Kenneth R. Mckaye, Douglas J. Weiland

Investigations of the Ichthyofauna of Nicaraguan Lakes

Protein deficiency is a major dietary problem in Central America where protein-rich foods are scarce and costly. Fish, however, represents a rich source of animal protein that is not being utilized to a significant extent. Moreover, it is a source that could be made available to large portions of the populations of these countries if improvements of the present fishing and distribution methods were realized. Prerequisite to expansion, however, is a basic understanding of the ecosystems and their components. It is at this preliminary stage that the situation presently lies. Once this understanding has been achieved, means of maximizing production …