For the determination of iron (II) and total iron with 2,2'-dipyridyl in mineral waters. Reduction of iron (III) with ascorbic acid [Translation from: Zeitschrift fur Analytische Chemie 209 340-341, 1965]

The determination of bi- and trivalent iron in proximity, in mineral waters has gained in significance, on biological and technical grounds. This short paper describes the procedure of the determination of bivalent iron and total iron in a water sample.

Proceedings of the Learning Workshop on Livelihoods Analysis. Long An, Vietnam 19-20 November 2002

Sustainable Aquaculture for Poverty Alleviation (SAPA) is a strategy under the overall national program for hunger eradication and poverty reduction. This reflects high attention by the Ministry of Fisheries (MOFI) to the poor. Since the strategy was initiated, several actions have been taken. Recently, conferences and meetings were conducted in Hanoi, Thai Nguyen and Quang Tri. Consequently we also have workshops on a regional basis, and today we are pleased to conduct a workshop in Long An on livelihoods analysis. Now at the Ministry, there are more than 340 projects in aquaculture to attack poverty. The launch of SAPA has been given a high priority among support agencies. Recently Mr Gill of the World Bank and the Ministry agreed that they would act to strengthen aquaculture for poverty reduction. So today with the support of the Long An People’s Committee, NACA and STREAM we have a workshop to strengthen learning about livelihoods analysis. (PDF has 61 pages.)

Some features of the autecology and distribution of chaetognatha in the Eastern Tropical Pacific

ENGLISH: The Inter-American Tropical Tuna Commission, in cooperation with the Tuna Oceanography Research program of the Scripps Institution of Oceanography, is studying in the Eastern Tropical Pacific Ocean methods of identifying waters of different characteristics that may influence the distribution and behavior of the tropical tunas. One method of attacking the problem has been to attempt to use zooplankton species as biological indicators of water masses. It has been demonstrated that certain zooplankters have ecological affinities that make them useful for identifying and tracing the movements of water masses. In the Eastern Pacific Ocean, Bieri (1957), Lea (1955), Le Brasseur (1959), Sund (1959), and Sund and Renner (1959) have presented evidence that certain species of Chaetognatha possibly can serve as indicators. The present work reports on a study of the distributions of species of Chaetognatha, obtained from various depths by means of horizontal closing-net hauls, in relation to concurrent measurements of temperature, salinity, and dissolved oxygen. Analyses of these data have provided a basis for determining which species are of potential use as biological indicators within the area of the Eastern Pacific considered in this study. SPANISH: La Comisión Interamericana del Atún Tropical, en cooperación con el programa de la "Tuna Oceanography Research" de la Institución Scripps de Oceanografía, viene estudiando en el Océano Pacífico Oriental Tropical métodos para identificar aguas de características diferentes que podrían influir en la distribución y en el comportamiento de los atunes tropicales. Uno de los métodos para abordar el problema ha sido el de intentar la utilización de especies zooplanctónicas como índices biológicos de masas de agua. Se ha demostrado que ciertos organismos del zooplancton tienen afinidades ecológicas, merced a las cuales son útiles para identificar y trazar los movimientos de las masas de agua. Bieri (1957), Lea (1955), Le Brasseur (1959), Sund (1959) y Sund y Renner (1959) presentaron evidencia de que ciertas especies de quetognatos pueden servir, posiblemente, como tales índices en el Océano Pacífico Oriental. El presente trabajo informa sobre un estudio de la distribución de las especies de quetognatos obtenidos de distintas profundidades por medio de la red de plancton que se cierra en lanzamientos horizontales y en relación con mediciones concomitantes de la temperatura, la salinidad y el oxígeno disuelto. El análisis de estos datos ofreció una base para la determinación de las especies que son potencialmente aptas para ser usadas como índices biológicos dentro del área del Pacífico Oriental a la cual se refiere este estudio.

On the climatology, oceanography and fisheries of the Panama Bight

ENGLISH: Seasonal changes in the climatology, oceanography and fisheries of the Panama Bight are determined mainly by the latitudinal movements of the ITCZ over the region. Evaporation is about 980 mm annually. Rainfall is probably much less than previous estimates because of a discontinuity in the ITCZ. Freshwater runoff from the northern watershed varies from 22 X 109 m3/mo in October-November to 11 X 109 m3/mo in February-March; from the southeastern watershed it varies from 16 X 109 m3/mo in April-June to 9 X 109 m3/mo in October-December. Total annual runoff is about 350 X 109m3. A marked salinity front is found at all seasons off the eastern shore. In the northern part of the Bight temperatures in the upper layers remained fairly constant from May to November; by February the mean temperature had decreased by 4°C and sharp gradients existed in the geographic distributions. Salinities in the upper layers decreased steadily from May to November; by February the mean salinity had increased by 2.5‰. The mean depth of the mixed layer increased from 27 m in May to 40 m in November; by February upwelling decreased it to 18 m. Between November and February upwelling had doubled the amount of P04-P and tripled that of NO3-N in the euphotic zone; surface phytoplankton production and standing crop, and zooplankton concentrations also doubled during this period. Upwelling was about 1.5 m/mo during May-November and about 9.0 m/mo during November-February, the annual total is about 48 m, Mean primary production is about 0.3 gC/m2day during May-December and about 0.6 gC/m2day during January-April; annual production is about 140 gC/m2. A thermal ridge occurred in February running from the northern to the southwestern part of the Bight. Within this ridge was a marked thermal dome coinciding with the center of the cyclonic circulation cell. Upwelling in the dome averaged 16 m/mo in November-February. The fisheries of the Panama Bight annually produce about 30,000 metric tons of food species and about 68,000 m.t. of species used for reduction. Most attempts to further the understanding of tuna ecology were unsuccessful. The apparent abundances of yellowfin and skipjack in the northern part of the Bight appear to be related to the seasonal cycle of upwelling and enrichment, as abundances are greatest in April and May when food appears to be plentiful. The life-cycle of the anchoveta in the Gulf of Panama also appears to be related to upwelling; the species mass varies from about 39,000 m.t. in December to about 169,000 m.t, in April. About 19.1 X 1012 anchoveta eggs are spawned annually. The life-cycles of shrimp in the Panama Bight appear to be related to upwelling as catches are greatest in May-July, about 3-5 months after peak upwelling, and annual catches are inversely correlated with sea level. SPANISH: Los cambios estacionales en la climatología, oceanografía y pesquerías del Panamá Bight están determinados principalmente por el movimiento latitudinal sobre la región de la Zona de Convergencia Intertropical (ZCIT). La evaporación es de unos 980 mm al año. La pluviosidad es probablemente muy inferior a las estimaciones previas a causa de la descontinuidad en la ZCIT. El drenaje de agua dulce, de la vertiente septentrional, varía de 22 x 109m3/mes en octubre-noviembre hasta 11 x 109m3/mes en febreromarzo; el de la vertiente sudeste varía de 16 x 109m3/mes en abril-junio a 9 x 109m3/mes en octubre-diciembre. El drenaje total, anual, es alrededor de 350 x 109m3. En todas las estaciones frente al litoral oriental se encuentra un frente de salinidad marcada. En la parte septentrional del Bight las temperaturas en las capas superiores permanecieron más bien constantes de mayo a noviembre; en febrero la temperatura media había disminuido en unos 4°C y existieron gradientes agudos en las distribuciones geográficas. Las salinidades en las capas superiores disminuyeron constantemente de mayo a noviembre; en febrero la salinidad media había aumentado en 2.5‰. La profundidad media de la capa mixta aumentó de 27 m en mayo a 40 m en noviembre; en febrero el afloramiento disminuyó el espesor de la capa mixta hasta 18 m. Entre noviembre y febrero el afloramiento había duplicado la cantidad de PO4-P y triplicado la de NO3-N en la zona eufótica; la producción superficial de fitoplancton y la biomasa primaria y las concentraciones de zooplancton también se duplicaron durante este período. El afloramiento era cerca de 1.5 mimes durante mayo-noviembre y de unos 9.0 mimes durante noviembre-febrero, el total anual es de unos 48 m. La producción media primaria es aproximadamente de 0.3 gC/m2 al día durante mayo-diciembre y cerca de 0.6 gC/m2 al día durante enero-abril; la producción anual es de unos 140 gC/m2. En febrero apareció una convexidad termal que se extendió de la parte norte a la parte sudoeste del Bight. Dentro de esta convexidad se encontró un domo termal marcado el cual coincidió con el centro de la circulación ciclonal de la célula. El afloramiento en el domo tuvo un promedio de 16 mimes en noviembre-febrero. Las pesquerías del Panamá Bight producen anualmente de cerca 30,000 toneladas métricas de especies alimenticias y unas 68,000 t.m. de especies usadas para la reducción. La mayoría de los esfuerzos realizados con el fin de adquirir más conocimiento sobre la ecología del atún no tuvo éxito. La abundancia aparente del atún aleta amarilla y del barrilete en la parte septentrional del Bight parece estar relacionada con el ciclo estacional del afloramiento y del enriquecimiento, ya que la abundancia mayor en abril y mayo cuando parece que hay abundancia es de alimento. El ciclo de vida de la anchoveta en el Golfo de Panamá parece también que está relacionada al afloramiento. La masa de la especie varía de unas 39,000 t.m. en diciembre a cerca de 169,000 t.m. en abril. Aproximadamente 19.1 x 1012 huevos de anchoveta son desovados anualmente. Los ciclos de vida del camarón en el Panamá Bight parecen estar relacionados con el afloramiento ya que las capturas son superiores en mayo-julio, unos 3-5 meses después del ápice del afloramiento, y las capturas anuales se correlacionan inversamente con el nivel del mar. (PDF contains 340 pages.)

Growth response and survival of F1 hybrid fry of Heterobranchus longifilis and Clarias gariepinus reared in glass aquaria and plastic basins

The growth response of F1 hybrid fry of female Heterobranchus longifilis and male Clarias gariepinus were investigated under laboratory conditions in glass aquaria glass tanks and plastic basins. The larvae were produced artificially after inducement with Ovarptim. The hatching percentage was very high. Weekly mean length and weight were monitored for 6 weeks. The average length increase was higher in aquaria glass tanks than in plastic basins. However, there were depressed and irregular weight increases in both types of rearing troughs while significant weight increase (P<0.05) was recorded at week 6 in the plastic basin. Generally, the growth rate and survival in both containers were not significantly different

The production of freshwater fish for food

It has been estimated that in England and Wales fresh water covers some 340 square miles of which about one quarter is inhabited mainly by salmon and trout; in Scotland the lakes cover an area of 340 square miles. The principal object of this publication is to make available in handy form some of the methods, especially those involving the use of manures, by which crops of fish from water can be increased. The cultivation of water which this implies may be compared directly to the cultivation of farm land: the conditions for growth are made as favourable as possible, the seed is sown in the form of young fish, and after one or perhaps two growing seasons the crop is harvested. There are however many waters about the country where marketable fish are already available and can be removed without prejudice to, and indeed to the advantage of, sporting fisheries. In such cases it is necessary only to remove the fish and to rely on the natural processes of reproduction of those which are left to repopulate the water. Farming waters in the true sense is the concern of the greater part of this publication; the removal of crops of otherwise unwanted fish is considered in the last two sections on perch trapping and eel fisheries.

Length-weight relationship of some marine fish species in Reunion Island, Indian Ocean

The length-weight relationship of 29 marine fish species form Reunion Island (SW Indian Ocean) belonging to 14 families were computed. Data from 5,340 individuals were used for this purpose. Fish were sampled using different techniques, mainly with rotenone poisoning on coral reef flats, beach seine and handlines on shallow coastal bays, and longline fishing in the nearby open sea.

Age, growth, mortality, and radiometric age validation of gray snapper (Lutjanus griseus) from Louisiana

The gray snapper (Lutjanus griseus) is a temperate and tropical reef fish that is found along the Gulf of Mexico and Atlantic coasts of the southeastern United States. The recreational fishery for gray snapper has developed rapidly in south Louisiana with the advent of harvest and seasonal restrictions on the established red snapper (L. campechanus) fishery. We examined the age and growth of gray snapper in Louisiana with the use of cross-sectioned sagittae. A total of 833 specimens, (441 males, 387 females, and 5 of unknown sex) were opportunistically sampled from the recreational fishery from August 1998 to August 2002. Males ranged in size from 222 to 732 mm total length (TL) and from 280 g to 5700 g total weight (TW) and females ranged from 254 to 756 mm TL and from 340 g to 5800 g TW. Both edge analysis and bomb radiocarbon analyses were used to validate otolith-based age estimates. Ages were estimated for 718 individuals; both males and females ranged from 1 to 28 years. The von Bertalanffy growth models derived from TL at age were Lt = 655.4{1–e[–0.23(t)]} for males, Lt = 657.3{1–e[– 0.21(t)]} for females, and L t = 656.4{1–e[– 0.22 (t)]} for all specimens of known sex. Catch curves were used to produce a total mortality (Z) estimate of 0.17. Estimates of M calculated with various methods ranged from 0.15 to 0.50; however we felt that M= 0.15 was the most appropriate estimate based on our estimate of Z. Full recruitment to the gray snapper recreational fishery began at age 4, was completed by age 8, and there was no discernible peak in the catch curve dome.

The U.S. Gulf of Mexico Pink Shrimp, Farfantepenaeus duorarum, Fishery: 50 Years of Commercial Catch Statistics

U.S. Gulf of Mexico, pink shrimp, Farfantepenaeus duorarum, catch statistics have been collected by NOAA’s National Marine Fisheries Service, or its predecessor agency, for over 50 years. Recent events, including hurricanes and oil spills within the ecosystem of the fishery, have shown that documentation of these catch data is of primary importance. Fishing effort for this stock has fluctuated over the 50-year period analyzed, ranging from 3,376 to 31,900 days fished, with the most recent years on record, 2008 and 2009, exhibiting declines up to 90% relative to the high levels recorded in the mid 1990’s. Our quantification of F. duorarum landings and catch rates (CPUE) indicates catch have been below the long-term average of about 12 million lb for all of the last 10 years on record. In contrast to catch and effort, catch rates have increased in recent years, with record CPUE levels measured in 2008 and 2009, of 1,340 and 1,144 lb per day fished, respectively. Our regression results revealed catch was dependent upon fishing effort (F=98.48df=1, 48, p<0.001, r2=0.67), (Catch=1,623,378 + (520) × (effort)). High CPUE’s measured indicate stocks were not in decline prior to 2009, despite the decline in catch. The decrease in catch is attributed in large part to low effort levels caused by economical and not biological or habitat related conditions. Future stock assessments using these baseline data will provide further insights and management advice concerning the Gulf of Mexic

Pacific Hagfish, Eptatretus stouti, and Black Hagfish, E. deani: The Oregon Fishery and Port Sampling Observations, 1988-92

In 1988, the Oregon Department of Fish and Wildlife began sampling and monitoring the development of a new fishery for Pacific hagfish, Eptatretus stouti, and black hagfish, E. deani. Hagfish landings by Oregon trap vessels have ranged from 11,695 kg in 1988 to 340,774 kg in 1992. Whole frozen fish were shipped to South Korea for the "eel skin" leather market. From 1988 through 1989, I sampled 924 Pacific hagfish and 897 black hagfish from commercial and research catches. Mean length of fish sampled from commercial landings was 39.6 cmf or Pacific hagfish and 34.5 cm for black hagfish. Weight-length relationships (W=aLb) were calculated for males and females of both species. Fifty percent maturity for male and female Pacific hagfish was 35 cm and 42 cm, respectively, while 50% maturityf or male and female black hagfish was 34 cm and 38 cm, respectively. Examination of gonads for both species indicated that spawning either occurs throughout the year or the spawning period is protracted. Mature females of both species had from one to three distinct sizes of eggs, but they usually carried only one group of eggs over 5 mm in length. Mature Pacific hagfish females averaged 28 eggs over 5 mm in length, and black hagfish females averaged 14 eggs over 5 mm in length. Hermaphroditism was found in 0.2% of the Pacific hagfish examined.