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Uma das práticas desafiadoras de manejo é aumentar a produção de arroz utilizando menos água. O experimento foi realizado nas safras de 2010/11 e 2011/12 na área experimental da Universidade Federal de Santa Maria, Rio Grande do Sul. O objetivo foi avaliar o rendimento de grãos e a eficiência do uso de água na semeadura no início e final da época recomendada. Os tratamentos foram as épocas de semeadura (01/10/10 e 01/12/10) safra 2010/11, e (27/09/11 e 07/12/11) safra 2011/12, com cinco repetições, e a cultivar utilizada foi a 'IRGA 424'. Não houve diferença no volume de água aplicado entre as épocas de semeadura, com volume médio de 5757 e 8420m³ ha-1, respectivamente, para safra 2010/11 e 2011/12. A época de semeadura afetou o rendimento de grãos, com rendimento de 13 e 24% a mais nas semeaduras do início da época (01/10/10 e 27/09/11), comparado às semeaduras do final da época (01/12/10 e 07/12/11), respectivamente. A semeadura realizada no início da época recomendada (início de outubro) proporciona maior rendimento de grãos e maior eficiência no uso de água. One of the challenging management practices is to increase rice production using less water. The study was conducted during the harvest of 2010/11 and 2011/12 in the experimental field of Universidade Federal de Santa Maria, Rio Grande do Sul State, Brazil. The objective was to evaluate the yield and water use efficiency at sowing at beginning and end of the recommended time. Treatments were at planting dates (10/01/10 and 12/01/10) 2010/11 harvest, and (9/27/11 and 12/07/11) 2011/12 harvest, with five replicates, the cultivar used was the 'IRGA 424'. There was no difference in the amount of applied water between sowing times, with an average of 5757 and 8420m³ ha-1, respectively for season 2010/11 and 2011/12. The sowing date affected grain yield, with yields of 13 and 24% more in the beginning of the sowing season (10/01/10 and 9/27/11) compared to the end of the sowing date (12/01/10 and 12/07/11), respectively. Sowing early in the recommended period (early October) provides greater yield and more water use efficiency.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Some process-based models, by using the Blackman s equation, the negative exponential, rectangular hyperbole, non-rectangular hyperbole, and the efficient use of the radiation were used as the central part in calculation of the carbon balance in order to estimate the variability of the productivity of both maize and bean crops in some mesoregions at Minas Gerais State, from the historic, meteorological and daily data relative to the period from 1975 to 2004. Some alterations in the productivity of the bean and maize crops were also simulated for the years 2020, 2050 and 2080, compared with the basis- year 2000, by considering the future climatic conditions, fertilization effect from CO2 and the technological advance. To quantify the effect of the climatic conditions on productivity of the crops, daily data projected for the A2 scenery based on the general atmosphere circulation model - HadCM3 were used. A simple empirical relationship was used to calculate the effect of the increasing CO2 concentration on the productivity of the crops. The effect of the technological advance on the future productivity was estimated by the tendency of the historical series of the IBGE productivity data, by considering the period from 1976 to 2004. The objectives of this study were: to calculate the potential productivity of the bean and maize crops for the mesoregions in Minas Gerais State, based on those different models previously mentioned; (b) to compare the results from the different models; and (c) to estimate the potential productivity and the yield gap (difference between the potential and real productivities), by taking into account the scenery A2 in the HadCM3 model, the effects from the CO2 fertilization and the technological advance. The potential productivity calculated by those models rather substantially differed. The percent difference between the model showing the highest productivity estimate and that one showing the minor estimate was 105% for bean and 108% for maize crops. The estimates showed an increased potential productivity in relation to the basis- year 2000, that is, from 35.04% to 114.66% for bean and 40.76% to 92.59% for maize crops, depending either on the estimated year and mesoregion. The technological advance showed to be the most important factor for such an increase. The results for the yield gap showed a decreasing tendency for both crops in all mesoregions, as distinguishing the Triângulo/Alto Paranaíba mesoregion. Modelos baseados em processos, utilizando as equações de Blackman, hipérbole retangular, exponencial negativa, hipérbole não retangular e uso eficiente da radiação, como parte central no cálculo do balanço de carbono, foram utilizados para estimar a variabilidade da produtividade das culturas de milho e feijão, em algumas mesorregiões do Estado de Minas Gerais, a partir de dados diários meteorológicos históricos de 1975 a 2004. Também foram simuladas alterações na produtividade das culturas do feijão e do milho, para os anos de 2020, 2050 e 2080, comparadas com o ano-base 2000, considerando-se as condições climáticas futuras, o efeito fertilização por CO2 e o avanço tecnológico. Para quantificar o efeito das condições climáticas na produtividade das culturas, foram utilizados dados diários projetados para o cenário A2, pelo modelo de circulação geral da atmosfera, HadCM3. Uma relação empírica simples foi usada, para calcular o efeito da crescente concentração de CO2 na produtividade das culturas. O efeito do avanço tecnológico na produtividade futura foi estimado, por meio da tendência da série histórica dos dados de produtividade do IBGE, considerando-se o período de 1976 a 2004. Foram objetivos deste trabalho: (a) calcular a produtividade potencial das culturas do feijão e do milho para as mesorregiões do Estado de Minas Gerais, com base nos diferentes modelos citados anteriormente; (b) comparar os resultados dos diferentes modelos; e (c) estimar a produtividade potencial e a perda de produtividade (a diferença entre as produtividades potencial e real), considerando o cenário A2 do modelo HadCM3, o efeito fertilização por CO2 e do avanço tecnológico. A produtividade potencial, calculada pelos diferentes modelos diferiu substancialmente. A diferença percentual entre o modelo de maior estimativa de produtividade e o de menor foi de 105% para a cultura do feijão e de 108% para a cultura do milho. As estimativas mostraram um aumento na produtividade potencial em relação àquela no ano-base 2000, para a cultura do feijão de 35,04% a 114,66%, e de 40,76% a 92,59% para a cultura do milho, dependendo do ano estimado e da mesorregião. O efeito da tecnologia foi o mais importante para tal aumento. Os resultados da diferença entre as produtividades potencial e real apresentaram tendência decrescente para as duas culturas, em todas as mesorregiões, com destaque para a mesorregião do Triângulo/Alto Paranaíba.

El uso de variedades de trigo con genes enanizantes ha permitido lograr grandes incrementos en la producción. Sin embargo, aún esta poco claro cómo estos genes afectan el rendimiento y la fisiología de trigo. Los objetivos de este trabajo fueron evaluar el efecto de la altura de planta sobre el rendimiento, la estabilidad del rendimiento y la distribución de los asimilados a los distintos componentes del rendimiento. Se utilizó el trigo harinero cultivar Santa Helena y once líneas cercanas a isogénicas derivadas de este cultivar y portadoras de los genes enanizantes Rht1 y/o Rht2. El ensayo se evaluó durante tres temporadas, dos en México y una Chile. Las isolíneas semienanas rindieron 21% más que los otros grupos en todos los medioambientes, mientras que la línea alta sólo rindió sobre el promedio en los medioambientes más pobres. A su vez, las plantas semienanas obtuvieron la mayor biomasa (13.746 y 12.974 kg; P < 0,05) y el mayor índice de cosecha (0,40; P < 0,05). Este mayor rendimiento se debió a un aumento en el número de granos por espiga (22%), lo que implicó un mayor número de granos por metro cuadrado. Sin embargo, no se observaron diferencias entre isolíneas en la tasa de acumulación de biomasa ni en la magnitud de la radiación interceptada en el período de crecimiento de la espiga. El peso de los granos disminuyó al disminuir la altura de la planta. Las isolíneas enanas demoraron en promedio 4 días más en llegar a espigadura y antesis que la isolínea alta y 2 días más que las semienanas. The use of wheat varieties with dwarfing genes has permitted the achievement of great increases in production. Nevertheless, it is still unclear how these genes affect the yield and the physiology of the wheat. The objectives of this study were to evaluate the effect of plant height on yield, the stability of yield and the distribution of the assimilates of the distinct components of yield. The bread wheat cultivar Santa Helena and eleven close lines to isogenetic derivatives of this cultivar and carriers of the dwarfing genes Rht1 and/or Rht2 were utilized. The trial was evaluated over three seasons, two in Mexico and one in Chile. The semi-dwarf isolines yielded 21% more than the other groups in all environments, while the tall line only yielded above the average in the poorest environments. As well, the semi-dwarf plants obtained greater biomass (13,746 and 12,974 kg; P < 0.05) and a greater harvest index (0.40; P

Se realiza una sinopsis del estado de situación de los recursos pesqueros del Golfo San Matías, de sus pesquerías y especies asociadas a las mismas y del ecosistema marino. El objetivo de este informe es presentar información histórica y actualizada sobre los recursos pesqueros y las pesquerías marinas de Río Negro, a los fines de su empleo como guía de análisis para la evaluación de las mismas con vistas a la potencial certificación de una gestión sustentable de las mismas a partir de los estándares del Marine Stewardship Council (MSC). Se presenta información sobre la organización y estructura del sector institucional y del marco legal en el que se desarrolla la actividad. Se desarrolla una caracterización de las pesquerías a partir de diferentes aspectos: historia, ámbito geográfico, flotas y artes de pesca, investigación y evaluación de los efectivos pesqueros, tendencias en las capturas y en la biomasa, medidas de manejo, sistema de administración, control y fiscalización, problemas de manejo, mercados y productos. Se anexa una caracterización biológica de las principales especies de importancia comercial. PROGRAMA: PROMARPES. Instituto de Biología Marina y Pesquera Almirante Storni (San Antonio Oeste, Argentina) Published Eco-labelling, Marine Stewardship Council, MSC, moluscos bivalvos, vieira tehuelche, Aequipecten tehuelchus, mejillón, Mytilus edulis platensis, almeja púrpura, Amiantis purpurata, peces costeros, calamar, Illex argentinus, merluza, Merluccius hubbsi, palangre, recursos potenciales, moluscos gasterópodos, almeja panopea, cangrejos, pulpito patagónico

Within the frame of the National Program (PNM), 'Assessment of Marine Tunisian Resources' (1996-1999), two prospecting surveys on small pelagic fishes, have been led in narrow collaboration with French Institute IFREMER. Their objectives were to specify the relative fishes abundance, their spatial-temporal variability but also to quantify the maximum sustainable yield (MSY) of this resource. A third important goal was to familiarize a Tunisian scientist team, with numerical methods and data processing used during the cruises (reading of echograms, treatments of data, etc.) in stocks assessment. It is known that the indirect stocks assessment methods of small pelagic species is not reliable, reason for which we opted to apply echo - integration techniques. Those campaigns revealed that for all the Tunisian waters, and despite of possible sources of errors in the estimation of the MSY and considering the level of exploitation that turns to best around 35.000 tons, we assume the possibility of increasing captures to a reasonable level. That level was fixed empirically to 75% of the calculated value, to 60.000 Tons. But it will be recommended more accuracy in the calculation of the minimum rate of exploitation to be supported by small pelagic stocks. A regular sampling of professional landings in the main harbours would permit the available estimation of the different dynamic parameters of the main exploited species. Deux campagnes de prospection sur les petits pelagiques s'inscrivant dans le cadre du Programme National Mobilisateur (PNM), "Evaluation de ressources pelagiques et demersales des eaux tunisiennes" (1996-1999) ont ete menee en etroite collaboration avec l'Institut Francais de Recherche et d'Exploitation de la Mer (IFREMER). Ces campagnes ont pour objectifs de preciser l'abondance relative des petits pelagiques et leur variabilite spatiaux-temporelles mais egalement de quantifier les potentiels exploitables des stocks des animaux aquatiques prealablement definis, et surtout de familiariser l'equipe des scientifiques tunisiens, aux methodes numeriques et informatiques utilisees en participant a la lecture des echogrammes et aux traitements des donnees des campagnes en mer en vue d'evaluer les stocks. Il est connu que les methodes d'evaluation indirectes des stocks s'ajustent mal a des especes telles que les petits pelagiques, raison pour laquelle on fait recours pour l'estimation de leur biomasse a la prospection acoustique en utilisant les techniques de l'echo-integration. Les dites prospections ont revele que pour toute la Tunisie et malgre les sources possibles d'erreur dans le calcul du potentiel exploitable et compte tenu du niveau d'exploitation qui tourne au mieux autour de 35.000 tonnes, nous pouvons affirmer la possibilite d'accroitre les captures a un niveau raisonnable que nous le fixons empiriquement a 75% de la valeur calculee soit a un plafond de 60.000 tonnes. Mais il sera fortement recommande plus de precision dans le calcul du taux minimum d'exploitation susceptible d'etre supporte par le stock pelagique. Aussi un echantillonnage regulier des debarquements des professionnels dans les principaux ports permettrait l'estimation rigoureuse des differents parametres dynamiques des principales especes exploitees. Published

Deux campagnes de prospection sur les petits pélagiques s'inscrivant dans le cadre du Programme National Mobilisateur (PNM), "Evaluation de ressources pélagiques et démersales des eaux tunisiennes" (1996-1999) ont été menée en étroite collaboration avec l’Institut Français de Recherche et d’Exploitation de la Mer (IFREMER). Ces campagnes ont pour objectifs de préciser l'abondance relative des petits pélagiques et leur variabilité spatiaux-temporelles mais également de quantifier les potentiels exploitables des stocks des animaux aquatiques préalablement définis, et surtout de familiariser l’équipe des scientifiques tunisiens, aux méthodes numériques et informatiques utilisées en participant à la lecture des échogrammes et aux traitements des données des campagnes en mer en vue d'évaluer les stocks. Il est connu que les méthodes d'évaluation indirectes des stocks s'ajustent mal à des espèces telles que les petits pélagiques, raison pour laquelle on fait recours pour l'estimation de leur biomasse à la prospection acoustique en utilisant les techniques de l'écho-intégration. Les dites prospections ont révélé que pour toute la Tunisie et malgré les sources possibles d’erreur dans le calcul du potentiel exploitable et compte tenu du niveau d’exploitation qui tourne au mieux autour de 35.000 tonnes, nous pouvons affirmer la possibilité d’accroître les captures à un niveau raisonnable que nous le fixons empiriquement à 75% de la valeur calculée soit à un plafond de 60.000 tonnes. Mais il sera fortement recommandé plus de précision dans le calcul du taux minimum d’exploitation susceptible d’être supporté par le stock pélagique. Aussi un échantillonnage régulier des débarquements des professionnels dans les principaux ports permettrait l’estimation rigoureuse des différents paramètres dynamiques des principales espèces exploitées. في إطار تنفيذ البرنامج الوطني المتعلّق بتقييم الموارد السطحيّة والقاعيّة للمياه التونسيّة (1996-1999) قام المعهد الوطني لعلوم وتكنولوجيا البحار (INSTM) بالتعاون مع المعهد الفرنسي لاستغلال البحار (IFREMER) سنة 1998 بحملتين استكشافيتين بعرض السواحل التونسيّة. تصدّق هذين الحملتين أساسا تمكين فريق تونسي من تحديد الوفرة النسبيّة للأسماك الصغيرة العائمة وقراءة تغييراتها حسب الزمن والموقع وكذلك تقييم المخزون القابل للاستغلال. أظهرت استكشافات الأسماك الصغيرة بالصدى تواجد مخزون لا بأس به يسمح بالنهوض بالقطاع وتطوير الإنزالات إلى حدود 60.000 طنّ على الأقلّ مع العلم أنّ هذا لا يمثل سوى 75 % من الكميّة المقدّرة الّتي بالإمكان إنزالها بالمواني التونسيّة. Within the frame of the National Program (PNM), “Assessment of Marine Tunisian Resources” (1996-1999), two prospecting surveys on small pelagic fishes, have been led in narrow collaboration with French Institute IFREMER. Their objectives were to specify the relative fishes abundance, their spatial-temporal variability but also to quantify the maximum sustainable yield (MSY) of this resource. A third important goal was to familiarize a Tunisian scientist team, with numerical methods and data processing used during the cruises (reading of echograms, treatments of data, etc.) in stocks assessment. It is known that the indirect stocks assessment methods of small pelagic species is not reliable, reason for which we opted to apply echo - integration techniques. Those campaigns revealed that for all the Tunisian waters, and despite of possible sources of errors in the estimation of the MSY and considering the level of exploitation that turns to best around 35.000 tons, we assume the possibility of increasing captures to a reasonable level. That level was fixed empirically to 75% of the calculated value, to 60.000 Tons. But it will be recommended more accuracy in the calculation of the minimum rate of exploitation to be supported by small pelagic stocks. A regular sampling of professional landings in the main harbours would permit the available estimation of the different dynamic parameters of the main exploited species. Published petits pélagiques

The collection of wild breeders of the Indian white prawn Fenneropenaeus indicus from two semi-industrial trawlers fishing in Maputo Bay is assessed for the period between August and November 1993. The daily mean catch (12-21 prawns dayˉ¹) increased until October but monthly yields were not significantly different (P>0.05). The monthly mean mortality ranged between 8% and 20% and was similar for males and females. More than 70% of the catch comprised small (grade B1: 20-39 g) and medium size (grade B2: 40-59 g) prawns. While males were exclusively of grade B1 (99%), the females were predominantly of grades B2 and B3 (60-80 g). The collection of larger breeders (grade B4: >80 g) was low and represented only 1% of total catches and a maximum of 3% of females. The net profit of breeders collection increased with size (grade) of prawns, and represented a maximum yield of 114% for grade B3. The added value of live prawns exceeded 450% of the cost to the fisherman, but decreased with size of breeders. It is considered that the semi-industrial trawling fishery operating in Maputo Bay has potential for supplying wild breeders of the Indian white prawn for aquaculture. This activity can also contribute to value adding of part of the catch traditionally destined for human consumption.

This paper shows how a highly complex potato production system, like the Argentinian one, can be surveyed and analysed. A survey was complemented with the use of a Geographic Information System and a simulation model approach which improves the understanding of the possibilities for increasing future crop production by expanding the area cropped with potatoes and/or the yield. A yield gap analysis was also a useful and comprehensive tool to identify and rank yield defining, yield limiting and yield reducing factors for those agro-ecological zones where the potato is currently grown. With these procedures, the physiological age of seed tubers and virus diseases were identified as the most relevant factors limiting and reducing yield. Specific strategies can be developed to counteract their limiting and reducing effects upon seed quality and tuber yield. The approach of this work does not only apply for the specific situation of the potato crop in Argentina, but this framework could be successfully applied to other crops or production systems elsewhere.

This study was designed to calibrate and test an agrometeorological model over 18 growing seasons in three soybean production areas in Brazil: Passo Fundo (Rio Grande do Sul State), Londrina (Parana State), and Dourados (Mato Grosso do Sul State). The soybean potential yield (Yp) was determined by two methods: estimated using the FAO Agroecological Zone Model or based on the maximum yield published by the Brazilian Institute of Geography and Statistics (IBGE), increased by 10, 20 and 30%. The estimate of actual yield (Ya) was calculated by correcting Yp for the relative water deficit at different growth stages. The results showed that the best performance was obtained when the Yp was represented by the maximum yield increased by a certain percentage. The model showed satisfactory Ya estimates for the three locations, generating R 2 values of 0.64, 0.46 and 0.70, with mean absolute errors (MAE) of 303, 289 and 259 kg ha -1 for Passo Fundo, Londrina and Dourados, respectively. In a global analysis, the performance of the model was satisfactory, with an R 2 , agreement modified index (d 1 ), confidence index (C) and MAE of 0.64, 0.52, 0.71 and 300 kg ha -1 , respectively.

Potato is the most important horticultural crop in Argentina and at present 100,000 ha are grown in different regions and seasons. The four possible growing seasons are defined as early (June–October), medium-early (July–November), medium-late (October–March) and late (February–June) and have already been characterized by assessing weather, soil and crop type, yield level and yield determining, yield limiting and yield reducing factors. However, there is scarce or no information on the possibilities of expanding actual crop frontiers, either at regional or national level and on the potential yield of the crop in different agro-ecological zones. Hence, in this work, we (1) characterize agro-ecological zones for potato production, (2) establish potential duration of the crop cycle and potential growing seasons, (3) estimate the potential yield of the crop in these zones and seasons and (4) demonstrate how Geographic Information Systems (GIS) for land evaluation and simulation models that establish potential yield of the crop can be used together to assess possibilities for increasing crop production at regional or national scales. Seven potential growing seasons ranging from 3500°C day were identified for areas where one crop can be grown per year, whereas four areas were identified where there is a potential for a second crop of potatoes. In these areas and seasons, potential tuber yields ranged from 20 Mg ha−1 dry matter. The study identified suitable soils and ascertained the corresponding potential duration of the growing seasons and the potential yield for each of the suitable sites and seasons.

The findings are presented of an assessment made of the gillnet fishery in Kainji Lake, Nigeria from 1969 to the present, on the basis of data sets from commercial and experimental gillnet fishing, with the purpose to detect trends in some key fishery monitoring indicators. During this period, there has been an increase in the number of small meshed nets in the fishery resulting in a shift in the mode to lower mesh sizes; consequently, the average mesh size declined gradually in the fishery. This trend is found to be directly correlated with the decline in the CPUE and mean weight of the fish species. It is argued that the observed trend in CPUE and mean weight is forcing the fishermen to switch effort to gears such as traps which have very small meshes and can indescriminately take all sizes of the fish. It is shown that the catch composition by weight of Citharinus citharus, Lates niloticus and tilapias declined in the gillnet fishery in the late 70's and early 80's. Recent data, from 1994 to 1996, however indicates that C. citharus is recovering, but with declining mean weight. This suggests that the exploitation pattern is shifting to the smaller fish through the use of small meshed nets. In general, however, there has not been drastic changes in species bio-diversity in the Lake as a result of predatory effect and ecosystem overfishing as has happened in other great African Lakes. The species composition since lake formation continued to be dominated by fewer that 20 species. The potential yield for the lake has been estimated to be 32,166 tonnes (excluding clupeids) and the required optimum fishing effort to be 1,814 fishing canoes. In view of the relative stability of the species diversity in the lake and the current fish production level, it is proposed here that this MSY be adopted for all species. This would be achieved with the current effort level in the lake assuming that the efficiency of the fishermen and their gears do not improve. It should be reviewed after 10 or more years of catch and effort data collection. (PDF contains 65 pages) Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project Pag. 42 does not exist due to pagination error

This study includes an analysis of the trawl survey that was carried out by the Kainji Lake Fisheries Promotion Project in May, 1997. The objective of the survey was to assess the biomass and the potential yield of clupeids and the carrying capacity of the beach seine fishery in the entire Kainji Lake (Nigeria). The biomass of the beach seine by-catch was also estimated. The density (kg /km super(3)) of the clupeids was higher in the Bussa and Foge than in the other stations. The lowest density of clupeids was in the Anfani station followed by Jetty, both in the southern basin. These stations were the deepest parts of all the areas trawled, measuring between 37-120 m of depth. There was an inverse correlation between depth trawled and the catch rates of clupeids, though the correlation was poor. The average annual biomass of the clupeids was estimated at 36,769.85 Mt in the entire Lake with an MSY of 11,705.95 Mt. The smaller species, Sierrathrissa leonensis, made up about 97% of the total clupeid population in the lake and occurred at a shallower depth than the larger species Pellonula afzeliusi. From the clupeid production statistics in 1996, it is estimated that the MSY is already overshot by 34%. Therefore, about 698 beach seines instead of the present 810 would be sufficient for sustainable exploitation of the clupeid stocks. Because of the substantial by-catch in the beach seines, this fishing method was banned from Kainji Lake in 1997. An offshore open water seine net is recommended to replace the beach seines on the lake. The number of these nets should not exceed 500. The current ban on beach seine is supported by this study. Nevertheless, and since the ban may not be 100% effective, effort should concentrate on maintaining that the number of beach seines must be kept at most at the present level. Recommendation is made against the introduction of the pair trawling not only from an economic point of view but also for resource conservation, legal and social reasons. The development of this fishery could pose a serious danger to continuity of stocks. It is proposed that priority be given to the development of an open water seine which is at the same level of exploitation as the beach seine and requires similar cost to acquire. (PDF contains 39 pages) Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project

The local commonly used kreol name for Ranina ranina is krab ziraf. The krab ziraf fishery in Seychelles started functioning as a commercial fishery in 1986 when the resource was identified as potentially viable. Prior to this time these crab stocks were unexploited. In keeping with the Seychelles Fishing Authority (SFA) policy of monitoring catch and effort in new fisheries a research programme was implemented to assess the state of the Seychelles stock and determine the viability of the fishery as a whole. The objective of this report is to provide an indication of the state of the crab stock at the present fishing levels and give estimates of the standing stock biomass and the potential yield of the fishery. The biomass estimates give a range of between 2460 tonnes and 4486 tonnes for the Mahe plateau. For the calculations of the potential yield these figures were used to derive MSY estimates. The MSY estimates range between 381.36 tonnes and 695.44 tonnes taken as the most conservatively calculated estimates. Given that only an approximate 30 tonnes of krab ziraf are caught per annum the MSY estimates would suggest that the stocks has the potential to be more intensively exploited. Published

The mothership/dory fishing operation 'Pecheur Breton' spent 13 days fishing at the northwestern submarine promontory of Saya de Malha Bank between 24th February and 14th March 1993. The mothership fished using 12 dories which were equipped with echo-sounders and electric fishing reels. A total of 74.3 tonnes of fish was caught in the depth range of 55 to 130 m. of which the blue spotted jobfish (Pristipomoides filamentosus) represented 80%. The catch rates were observed to decreased with time and could not be attributed to changes in climatic conditions, fishing depth, fishing method or bait type. The initial biomass of Pristipomoides filamentosus at the northwestern submarine promontory of Saya de Malha Bank was estimated at 76.1 tonnes through application of the Leslie constant catchability model. Biomass densities of 2,478 kg/km² and 1,264 kg/km-1 were obtained by applying the initial biomass estimates to the surface area of the grounds fished. The quantity removed by the mothership/dory fishing operation was found to be more than 3 times the estimated maximum sustainable yield. Published

A compilation of 48 estimates of Caribbean and Pacific coral reef fish catches, ranging from 0.1 to 23.7 t km super(-2) year super(-1), obtained from coral reef areas ranging from 0.1 to nearly 4-10 super(5) km super(2), are used to show that observed catches, and hence potential yield estimates, depend strongly on the reference area. The implications for coral reef fisheries assessments are discussed.

Monthly catch data of bonito Sarda chiliensis from northern Chile, from 1976 to 1989, were used to obtain a series of estimates of the Z-G parameter (i.e., total mortality minus the growth coefficient in weight). This series was then used to estimate a maximum sustainable yield of 4,500 t/year through a modified version of the surplus production model of J. Csirke and J. Caddy. The status of the fishery is discussed.

A principal restrição para o emprego de modelos agrometeorológicos de previsão de safras é a falta de informação mais completa sobre a produtividade potencial dos cultivares de soja. Assim, adaptou-se um modelo agrometeorológico de estimativa da produtividade potencial baseado em modelo proposto pela FAO, onde se incorporou um fator referente à penalização para excedentes hídricos. Estimou-se experimentalmente a produtividade potencial em função da época de semeadura para os principais cultivares recomendados para o Estado de São Paulo, a partir de séries de cultivo efetuados na Estação Experimental de Ribeirão Preto (SP), do Instituto Agronômico, durante oito anos consecutivos. Os cultivares IAC-11, IAC-12, IAC-8 e IAC-10 apresentaram as maiores produtividades potenciais em semeaduras precoces (setembro-outubro). O 'IAC-11', a produtividade potencial mais elevada, até de 5.500kg/ha. Os cultivares Santa Rosa, IAC-13 e Paraná, as maiores nas semeaduras intermediárias (outubro-novembro).The lack of complete information on the yield potential for different soybean cultivars is the major limiting factor for the utilization of agrometeorological models to predict crop yield. A model proposed by FAO was modified including a factor refering to excess of rainfall. Estimates of potential yield was made, as a function of planting date of experiments conducted at Ribeirão Preto Experimental Station during eight consecutive years using the main soybean cultivars grown in the State of São Paulo. The cultivars IAC-8, IAC-10, IAC-11 and IAC-12 showed greater yield potential when sowed in September-October. The IAC-11 showed the yield potential of up to 5,500kg/ha. On the other hand the cultivars Santa Rosa, IAC-13 and Paraná showed higher yield potential when sowed in October-November.

O estudo foi baseado em dados fenológicos obtidos de experimentos conduzidos pela Seção de Leguminosas do Instituto Agronômico, em Campinas, Ribeirão Preto e Pindamonhangaba, durante os anos agrícolas de 1977/78, 1978/79 e 1979/80 para os cultivares de soja UFV - 1, Viçoja, Santa Rosa e Paraná. A partir desses dados, desenvolveu-se um modelo agrometeorológico de estimativa de produção de grãos, baseado na penalização de produtividade potencial de cada cultivar de soja, em função das condições meteorológicas reinantes durante o desenvolvimento da cultura. O modelo proposto foi o seguinte: YEst = (YPot) x (FTer) x (FDef) x (FExc), onde: YEst = produtividade estimada em grãos (kg/ha); YPot = produtividade potencial do cultivar em cada localidade (kg/ha); FTer = fator térmico indicativo do grau de desenvolvimento relativo da cultura; FDef = fator referente à penalização para déficit hídrico e FExc = fator correspondente à penalização para excedente hídrico. As estimativas da produtividade da soja por esse modelo mostraram-se bastante satisfatórias. Os coeficientes de determinação, entre dados observados e estimados, variaram de 0,76 a 0,87 para os quatro cultivares estudados.The study was performed using phenological observation of field experiments carried out during three years (1977/78, 1978/79 and 1979/80), for four soybean cultivars in three localities. The proposed model to estimate crop yield was based on the reduction of the potential productivity when soil water content decreases below a critical value or when the surplus was above the potential evapotranspiration for a given period, in a manner that: YEst = (YPOT) x (FThe) x (FDef) x (FSur), where: YEst = estimated yield; YPot = potential yield for a defined locality, being a function of the cultivar and technology; FThe = thermal factor, to express the degree of crop development (accumulated degree days); FDef = effect of water deficit in the soil on crop yield; FSur = effect of water surplus on crop yield. A comparison between the observed and estimated yield was highly satisfactory with determination coefficient (R²) ranging from 0.76 to 0.87 for all cultivars.

Size compositions and total landings of skipjack tuna caught in the southeastern Brazilian waters by bait-boats are used as the basis of the assessment of the population for 1980-1983 period, employing the length cohort analysis and virtual population analysis. From monthly size frequency data it is suggested that there is constant immigration and emigration of different modal groups in the fishing area with an interval of two to three months. The exploitation rate was very low for length class between 35-45 cm FL, then increased gradually. The weighted mean exploitation rates were 0.060 and 0.448, respectively for length classes smaller and larger than 55 cmFL. The estimate of the average number of fish attaining a size of 43 cm FL (recruit) was 11.0 x 10(6) fish for assumed values of M - 0.7 and K = 0.307. Increasing the fishing mortality rate by 30% and 50%, an estimated increment in yield is 8% and 12%, respectively. From virtual population analysis, we obtained the biomass estimate of skipjack population older than two years-old to be 70.3 thousand tonnes for assumed value of M = 0.7 and the estimated MSY was 24.6 thousand tonnes.

A principal restrição para o emprego de modelos agrometeorológicos de previsão de safras é a falta de informação mais completa sobre a produtividade potencial dos cultivares de soja. Assim, adaptou-se um modelo agrometeorológico de estimativa da produtividade potencial baseado em modelo proposto pela FAO, onde se incorporou um fator referente à penalização para excedentes hídricos. Estimou-se experimentalmente a produtividade potencial em função da época de semeadura para os principais cultivares recomendados para o Estado de São Paulo, a partir de séries de cultivo efetuados na Estação Experimental de Ribeirão Preto (SP), do Instituto Agronômico, durante oito anos consecutivos. Os cultivares IAC-11, IAC-12, IAC-8 e IAC-10 apresentaram as maiores produtividades potenciais em semeaduras precoces (setembro-outubro). O 'IAC-11', a produtividade potencial mais elevada, até de 5.500kg/ha. Os cultivares Santa Rosa, IAC-13 e Paraná, as maiores nas semeaduras intermediárias (outubro-novembro). The lack of complete information on the yield potential for different soybean cultivars is the major limiting factor for the utilization of agrometeorological models to predict crop yield. A model proposed by FAO was modified including a factor refering to excess of rainfall. Estimates of potential yield was made, as a function of planting date of experiments conducted at Ribeirão Preto Experimental Station during eight consecutive years using the main soybean cultivars grown in the State of São Paulo. The cultivars IAC-8, IAC-10, IAC-11 and IAC-12 showed greater yield potential when sowed in September-October. The IAC-11 showed the yield potential of up to 5,500kg/ha. On the other hand the cultivars Santa Rosa, IAC-13 and Paraná showed higher yield potential when sowed in October-November.

The classical Mitscherlich equation is based on Liebig's Law of the Minimum and describes the yield response of a crop to an increase in the main factor that is limiting growth. The maximum, or potential, yield is an important parameter in the Mitscherlich equation and is assumed to be constant, that is, not affected by other factors that limit actual yields under field conditions. The assumption that potential yield is a constant does not apply to rainfed agriculture in semi-arid regions because under such conditions potential yields vary with crop-available moisture. A theoretical framework for the application of the Mitscherlich equation to rainfed crop production is presented. Water-limited potential yield is assumed to be a linearly increasing function of available moisture. Similarly, the quantity of nutrients required by a crop to achieve water-limited potential yield is assumed to be a linearly increasing function of seasonal rainfall. Finally, nutrient availability is also thought to depend on available moisture. The general form of the modified Mitscherlich equation for response to nutrients is simplified, by expressing all moisture dependent parameters as functions of annual rainfall.

The statistics provided by the Argentinean Fishing Vessel and the biological data collected by scientist in the last eleven years, allow us to estimate different aspects of the population dynamics of the common hake (Merluccius hubbsi). This work deals with the relative abundance and the maximal sustainable yield of this species, considering the bonaerense stock of the Southewest Atlantic. Analyzing the effective fishing density, concluding remarks can be made. The high catches of 1967 (more than 600.000 tons.)made by the Russian Fleet, affected the fishing density in 1968. Since 1969, the resource recovered the high density level as a consequence of a decrease in the catches and in the fishing effort, but vulnerability of the stock is shown. Publisher permission Published Gadiformes, Merlucciidae, Merluccius hubbsi, producción potencial, captura/esfuerzo

Observations (76 nos) on height-length and whole weight-meat weight relations of mussels (Perna viridis), both wild and cultured were made. From the length of mussel the height can be worked out by the equations (logarithmic scale), 1. y = 0.360+0.988 x for wild; 2. y = 0.334+1.011 x for cultured, where x is the length (cm) and y is the height (cms). So also to any height the corresponding meat weight can be obtained by the regression equation. log w=-0.8178+1.9769 log H for wild variety (1) log w=-1.3049+2.8385 log H for culture-variety (2) where w is the meat weight (g) and H is the height (cm) of the mussel. Fourteen observations on size weight measurements of dams were made. The yield varied from 8.9 to 13%. The length-height relationship worked out for clams (Villorita sp) is y=0.485+1.005 x for length x and height y. Pt. 1: Crab (Scylla serrata) Forskal. Fishery Technology, 23(2), pp. 196-198.

Sixty one observations on length-breadth and whole weight-meat weight relations of India crab (Scylla serrata) were made. From the length of crab (cm) the whole weight (gm) can be computed by the equation: log W=-0.1708+2.3341 log L. Similarly for any given length (cm) the meat weight (gm) can be found by the relation, log w=-1.5745+3.0148 log L. Pt. 2: Mussel (Perna viridis) and clam (villorita cyprinoides). Fishery Technology, 23(2), pp. 178-182.

The Maximum Sustainable Yields of all fish species for 9 man-made reservoirs in Sri Lanka were calculated by the simplified version of Schaefer Model. The relationship between the Maximum Sustainable Yield (MSY) and Morpho-edaphic Index, (MEI) for Sri Lankan reservoirs was found to be: Log sub(e) MSY = 0.9005 log sub(e) MEI + 1.9220. MSY for these reservoirs were estimated using this relationship. The number of Tilapia) juveniles needed to be recruited to the fisheries of some reservoirs in addition to the present recruitment to increase the fish production to the level estimated by MEI relationship were calculated mathematically. National Aquatic Resources Agency now incorporated in: National Aquatic Resources Research and Development Agency, Sri Lanka

O estudo foi baseado em dados fenológicos obtidos de experimentos conduzidos pela Seção de Leguminosas do Instituto Agronômico, em Campinas, Ribeirão Preto e Pindamonhangaba, durante os anos agrícolas de 1977/78, 1978/79 e 1979/80 para os cultivares de soja UFV - 1, Viçoja, Santa Rosa e Paraná. A partir desses dados, desenvolveu-se um modelo agrometeorológico de estimativa de produção de grãos, baseado na penalização de produtividade potencial de cada cultivar de soja, em função das condições meteorológicas reinantes durante o desenvolvimento da cultura. O modelo proposto foi o seguinte: YEst = (YPot) x (FTer) x (FDef) x (FExc), onde: YEst = produtividade estimada em grãos (kg/ha); YPot = produtividade potencial do cultivar em cada localidade (kg/ha); FTer = fator térmico indicativo do grau de desenvolvimento relativo da cultura; FDef = fator referente à penalização para déficit hídrico e FExc = fator correspondente à penalização para excedente hídrico. As estimativas da produtividade da soja por esse modelo mostraram-se bastante satisfatórias. Os coeficientes de determinação, entre dados observados e estimados, variaram de 0,76 a 0,87 para os quatro cultivares estudados. The study was performed using phenological observation of field experiments carried out during three years (1977/78, 1978/79 and 1979/80), for four soybean cultivars in three localities. The proposed model to estimate crop yield was based on the reduction of the potential productivity when soil water content decreases below a critical value or when the surplus was above the potential evapotranspiration for a given period, in a manner that: YEst = (YPOT) x (FThe) x (FDef) x (FSur), where: YEst = estimated yield; YPot = potential yield for a defined locality, being a function of the cultivar and technology; FThe = thermal factor, to express the degree of crop development (accumulated degree days); FDef = effect of water deficit in the soil on crop yield; FSur = effect of water surplus on crop yield. A comparison between the observed and estimated yield was highly satisfactory with determination coefficient (R²) ranging from 0.76 to 0.87 for all cultivars.

Seminario Curso de Oceanografía Biológica (INIDEP, Mar del Plata) Unpublished Serranidae, Acanthistius brasilianus, mero, estructura poblacional, producción potencial, biomasa, distribución por tamaño

The coastal zone along the west coast of India is very productive with a mean secondary production rate of 5.89 mg C/m super(3)/day. Statewise, maximum zooplankton standing stock was observed off Maharashtra. The existing yield of fishery from the surveyed region has been compared with the estimated sustainable fishery potential.

Abundance and biomass of an unexploited ormer population in the vicinity of Saint-Malo (northern Brittany) are estimated using a stratified sampling technique. Examinations are made be diving at 200 sites. The mean biomass of the population is about 400 tons but the stock is not evenly distributed over the studied area: the greatest densities are observed on schist substrate. Size and weight frequency distribution reveal a "top-heave" structure due to an accumulation of old individuals with low production., Un échantillonnage stratifié, portant sur 200 stations prospectées en plongée, a été mis en oeuvre dans la région de Saint-Malo (Bretagne nord) pour estimer les caractéristiques de la population d'ormeaux. La biomasse moyenne de celle-ci a été évaluée à 400 tonnes environ mais elle est répartie de manière hétérogène sur la zone étudiée, les fonds de nature schisteuse apparaissant les plus favorables à l'espèce. L'examen des distributions de fréquence de taille et de poids révèle globalement une forte proportion d'individus âgés constituant une biomasse accumulée peu productive.