The History, Present Condition, and Future of the Molluscan Fisheries of North and Central America and Europe: Volume 2, Pacific Coast and Supplemental Topics

Over 100 molluscan species are landed in Mexico. About 30% are harvested on the Pacific coast and 70% on the Atlantic coast. Clams, scallops, and squid predominate on the Pacific coast (abalone, limpets, and mussels are landed there exclusively). Conchs and oysters predominate on the Atlantic coast. In 1988, some 95,000 metric tons (t) of mollusks were landed, with a value of $33 million. Mollusks were used extensively in prehispanic Mexico as food, tools, and jewelry. Their use as food and jewelry continues. Except in the States of Baja California and Baja California Sur, where abalone, clams, and scallops provide fishermen with year-round employment, mollusk fishing is done part time. On both the Pacific and Atlantic coasts, many fishermen are nomads, harvesting mollusks wherever they find abundant stocks. Upon finding such beds, they build camps, begin harvesting, and continue until the mollusks become so scarce that it no longer pays to continue. They then look for productive beds in other areas and rebuild their camps. Fishermen harvest abalones, mussels, scallops, and clams by free-diving and using scuba and hooka. Landings of clams and cockles have been growing, and 22,000 t were landed in 1988. Fishermen harvest intertidal clams by hand at wading depths, finding them with their feet. In waters up to 5 m, they harvest them by free-diving. In deeper water, they use scuba and hooka. Many species of gastropods have commercial importance on both coasts. All species with a large detachable muscle are sold as scallops. On the Pacific coast, hatchery culture of oysters prevails. Oyster culture in Atlantic coast lagoons began in the 1950's, when beds were enhanced by spreading shells as cultch for spat. (PDF file contains 228 pages.)

Die Bedeutung biologischer Daten aus der deutschen Seelachsfischerei für Bestandsabschätzung und Management

Since 1999, the ICES Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak assesses the saithe stock in the North Sea, Skagerrak and west of Scotland as a single stock unit. The sampling, evaluation and role of biological data from the German saithe fishery in the assessment are described. The German data showed similar trends as observed in French and Norwegian series. Based on these estimates, the spawning stock recovered to more than 200 000 t due to reductions in quotas and exploitation rates. Thus, the production of the stock increased also in combination with good recruitment and positive trends in spawning stock size and landings were projected for 2002. The biological data derived from the German saithe fishery dominated the assessment of stock size, structure and exploitation. This fact encourages a continuation of the described analyses based on sampling onboard fishing vessels and fish markets by the Institute for Sea Fisheries. The successful collaboration with the saithe fishing industry is judged as an important contribution to the sustainable management of fish stocks.

Preliminary studies of the dual role of cotton-seed cake as fish feed and fish pond fertilizer in aquaculture

Many locally available fish feeds have been tried in fish culture. These include guinea corn, soya bean, groundnut cake and rice bran. Cotton seed cake has been successfully used as a fishpond organic fertilizer at Ado-Ekiti Government fish farm. Three fishponds stocked respectively with common carps, Heterotis, Tilapia spp., Clarias lazera and Heterobranchus were fed with cotton seed cake. Carps, Tilapia and Heterotis increased rapidly in weight and length while the catifishes did not grow

Lehia ez perfektua-ri buruzko notak

Para quien es de utilidad: - Alumnos de Tª Microeconómica IV, curso 3º LE. - Alumnos de las asignaturas de Tª de Juegos y Organización Industrial del Máster en Economía: Instrumentos del Análisis Económico. Estas notas sobre competencia imperfecta están dedicadas al estudio de estructuras de mercado caracterizadas por la existencia de poder de mercado. Se estudia en primer lugar el monopolio, dedicando una atención especial a los diferentes tipos de discriminación de precios. A continuación se presenta la Tª de juegos no cooperativos y se muestra su utilidad para analizar diferentes fenómenos económicos caracterizados por la interdependencia estratégica. Finalmente, se estudian diferentes modelos de competencia oligopolística y la estabilidad de los acuerdos colusivos.

An integrative view of aggressivenss in adolescence : development of a new measure and assessment of parenting and attachment effects

128 p. Retirada a solicitud de la autora 03/03/2016

Preliminary studies on bamboo floating cage and net enclosure culture in Kainji Lake basin

The main objective of this paper is to introduce bamboo floating cage and net enclosure fish culture technology aimed at producing fish from almost all available inland bodies of water in Nigeria. The experimental approach embarked upon at Kainji Lake Research Institute is discussed. Results obtained from these experiments would help in identifying the inherent problems of this culture system and in determining the urgently needed information that will serve as management and production guidelines for adapting the technology to local conditions of varying ecological characteristics in Nigeria. Ultimately, the project is aimed at increasing the productivity of fishermen/fish farmers and hastening the development of rural communities

An evaluation of the artisanal fisheries resources of the Cross River State of Nigeria

The Cross River State (Nigeria) marine and freshwater artisanal capture fisheries are divided into 4 categories according to the type of resources being exploited. Schaefer's production model is applied to each of the fisheries to estimate the maximum sustainable yields (Ymax). The total potential yield for all the fisheries in natural waters is 178,650 tonnes/year. This potential is unlikely to be achieved as more fishermen are abandoning the occupation due to the scarcity of boats, outboard engines and nets. Even if the full potentials were realized the production would still be short of what the State should produce by about 30.5%. Investment opportunities which, if effected can help to narrow the gap between the available and the desired level of production are enumerated

Utilization of non-piscine pituitary extract in the breeding of Clarias gariepinus

The use of synthetic and non-synthetic hormones have been reported in different regions with the recommendation of different doses. The adaptability of these findings have however not been very successful due to the high cost of building and maintaining hatchery, high cost of synthetic hormone (when available) and high level manpower required. It is obvious that adaptive research in the past ten years in developing countries like Nigeria have been geared towards utilization of resources that are equally effective but cheap and ready to come by. This paper reports the utilization of the pituitary extract of bull frog (Rana adspersa) and the toad (Bufo regularis) in the induced breeding of the African catfish, Clarias gariepinus. The extraction and dosage are discussed alongside the preliminary rearing of fries in outdoor hatchery tanks. Human chorionic gonadotrophin (HCG) and Clarias pituitary extracts were used as control

Evaluation of toxicity effect of Datura innoxia root extract to Clarias gariepinus fingerlings

Clarias gariepinus fingerlings were exposed 96 hours under laboratory conditions using static bioassays with continuous aeration to determine acute toxicity of Datura innoxia root extract. The LC sub(50) of the exposed fingerlings was 128.83 mg/L. The fish exhibited loss of balance, respiratory distress and swam erratically just prior to death

Internationale Konferenz über Fischinspektion und Qualitätskontrolle. Eine weltweite Bestandsaufnahme

27 Jahre nach Durchführung der ersten Internationalen Konferenz über Fischinspektion, die von der FAO in Halifax, Kanada, 1969 veranstaltet wurde, war das Nationale Fischerei Institut der USA in Kooperation mit anderen Institutionen Sponsor und Organisator einer zweiten Konferenz über Fischinspektion und Qualitätskontrolle. Diese Konferenz fand vom 19. - 24. Mai 1996 in Arlington, Virginia, statt. An 3 Tagen war die Konferenz durch eine Ausstellung begleitet, auf der 26 Aussteller, Consulting-Firmen, Handelslaboratorien und Universitätsinstitute, ihr know how und ihre Dienste auf dem Gebiet der Fischinspektion und Qualitätskontrolle offerierten. Die Konferenzteilnehmer hatten während der Konferenzpausen auf diese Weise die Möglichkeit, sich über Neuheiten und Leistungsangebote zu informieren.

Angular distribution and conversion of multi-keV L-shell X-ray sources produced from nanosecond laser irradiated thick-foil targets

An experimental study on the angular distribution and conversion of multi-keV X-ray sources produced from 2 ns-duration 527nm laser irradiated thick-foil targets on Shenguang II laser facility (SG-II) is reported. The angular distributions measured in front of the targets can be fitted with the function of f(theta) = alpha+ (1- alpha)cos(beta) theta (theta is the viewing angle relative to the target normal), where alpha = 0.41 +/- 0.014, beta = 0.77 +/- 0.04 for Ti K-shell X-ray Sources (similar to 4.75 keV for Ti K-shell), and alpha = 0.085 +/- 0.06, beta = 0.59 +/- 0.07 for Ag/Pd/Mo L-shell X-ray Sources (2-2.8 keV for Mo L-shell, 2.8-3.5 keV for Pd L-shell, and 3-3.8 keV for Ag L-shell). The isotropy of the angular-distribution of L-shell emission is worse than that of the K-shell emission at larger viewing angle (>70 degrees), due to its larger optical depth (stronger self-absorption) in the cold plasma side lobe Surrounding the central emission region, and in the central hot plasma region (emission region). There is no observable difference in the angular distributions of the L-shell X-ray emission among Ag, Pd, and Mo. The conversion efficiency of Ag/Pd/Mo L-shell X-ray sources is higher than that of the Ti K-shell X-ray sources, but the gain relative to the K-shell emission is not as high as that by using short pulse lasers. The conversion efficiency of the L-shell X-ray sources decrease, with increasing atomic numbers (or X-ray photon energy), similar to the behavior of the K-shell X-ray Source.

Studies of the effects from extracts from two local plants (Tephrosia vogelii and Parkia clappertoniana) on Clarias gariepinus (Tengels)

Studies were carried out using 96hr static toxicity bioassay to determine the effect of lethal concentrations of extracts from two local plants Tephrosia vogelii and Parkia clappertoniana which are known fish poison, on a species of mud fish. Clarias gariepinus Phytochemical analysis of the plant extracts was done and the extract from T. vogelii was found to contain alkaloids, tannins and flavonoids, while the extract from P. clappertoniana was formed to contain alkaloids tannins and saponins. Experimental fish were exposed to test water separately polluted by varying concentrations of extraction of both plant species ranging from 0.50mgl super(-1), 1.50mgl super(-1), 2.50mgl super(-1), 3.0mgl super(-1), 5.00mgl super(-1), 10.00mgl super(-1) in the case of T. vogelii and 5.00mgl super(-1), 7.50mgl super(-1), 10.00mgl super(-1), 15.00mgl super(-1), 20.00mgl super(-1) and 30.00mgl super(-1) in the case of P. clappertaniana. Behavioural hispathological and heamatological examinations were made. Both plant extracts were found to have lethal effects at the higher concentrations, affecting the gills and the central nervous system as well as having a depressive effect on the total count and increasing platelet and white blood cell count. Symptoms of toxicosis observed include, initial inactivation agitated swimming, tumbling movement air gulping, increased opercular beat and period of quiescence/knockdown before death. Marked differences were also observed in the hematological and histopathological analysis of poisoned fish. Lower concentrations of the extracts had sub lethal effects on the fish, which manifested as zigzag movement air gulping increased opercular movement etc. None of these effects were observed in the control experiment