Fang, Anlandungen, Discard und Bestand der Nordsee-garnele (Crangon crangon L.)

Landings of brown shrimp (Crangon crangon) for human consumption are not the only part that is taken from the North Sea shrimp stocks. Small amounts of industrial shrimps taken in the second half of a year in Germany add as well to the total amount that is taken from the stocks as the moribund animals discarded all over the year during the first sieving process on board, as the cooked and discarded ones in the second sieving on board and as those from the third sieving process ashore normally being crushed and used for animal feed stuff. All these fractions of the total catch of brown shrimps give a total of approximately 74 000 tonnes that were taken from the North Sea in 2005. Nevertheless, due to low predator abundance and changing climate conditions Crangon stocks show no signs of overexploitation so far with increasing LPUE values in the north-eastern part of the German Bight and decreasing ones in the south-east and Channel. There is the need of further investigations of these changes in the life history and distribution of shrimp as well as in the fishing behaviour and effort of the shrimp fleets .

Fishery dynamics and present status of the yellowfin tuna population of the Eastern Pacific Ocean

ENGLISH: From morphometric data, tagging results and reaction of the stock to fishing, it is inferred that the yellowfin tuna of the Eastern Pacific form a distinct population which intermingles little, if at all, with populations to the westward. Excellent statistics of catch and effort, and records of total catch, available since 1934, during rapid growth of the fishery, have made possible application of a generalized mathematical predator-prey model to estimate the effect of fishing on the population, and the average abundance and yield corresponding to different amounts of fishing effort, and also to estimate the rate of fishing mortality per unit of effort. From serial samples of size composition of catches, and from tagging experiments, it has been possible to determine rates of growth and of total mortality. These kinds of information permit application of the catch-per-recruit model of Beverton and Holt. Combination of the results of application of the Beverton and Holt model and of the generalized predator-prey model, leads to inference of the relationship between stock size and recruitment. The form of the relationship is remarkably similar to the theoretical model developed by W. E. Ricker. These studies, based on the data of the near-surface fishery by baitboats and purse seiners, indicate clearly that the increased intensity of fishing has caused diminution of the stocks to the point where they are somewhat "overfished"-that is, incapable of supporting the maximum sustainable average harvest. SPANISH: De los datos morfométricos, de los resultados de las marcaciones y de la reacción del stock a la pesca, se infiere que el atún aleta amarilla del Pacífico oriental forma una población diferente que se mezcla poco, si es que llega a mezclarse, con las poblaciones del oeste. Las excelentes estadísticas de la captura y el esfuerzo y los registros de la pesca global disponibles desde 1934, durante el rápido crecimiento de la pesquería, han hecho posible la aplicación de un modelo matemático generalizado depredador-presa para estimar el efecto de la pesca en la población y el promedio de la abundancia y del rendimiento correspondientes a los diferentes valores del esfuerzo de pesca, y también para estimar la tasa de la mortalidad de pesca por unidad de esfuerzo. Gracias a las muestras en serie de la composición de tamaños de las capturas y a los experimentos de marcación, ha sido posible determinar las tasas del crecimiento y de la mortalidad total. Estos tipos de información permiten la aplicación del modelo de la captura-porrecluta de Beverton y Holt. La combinación de los resultados de la aplicación del modelo de Beverton y Holt y del modelo generalizado depredador-presa, conduce a la inferencia de la relación entre el tamaño del stock y el reclutamiento. La forma de la relación es notoriamente similar al modelo teórico desarrollado por W. E. Ricker. Estos estudios, basados en los datos de la pesquería cerca de la superficie efectuada por barcos de carnada y rederos, indican claramente que el aumento de la intensidad de la pesca ha causado la disminución de los stocks hasta el punto de dejarlos algo "superexplotados", o sea, incapacitados para mantener una producción máxima promedio. (PDF contains 50 pages.)

Welche Faktoren beeinflussen die Stärke der Dorsch-Jahresklassen?

In the previous years extensive investigations were carried out concerning the reproduction biology of cod in the Baltic Sea. The analyses showed that the year class strength of the eastern Baltic cod stock is decisively determined by the bad oxygen conditions during the spawning season in the summer and by sprat as predator of the cod eggs. In the western Baltic Sea these factors have no importance. The year classes are mainly determined by the strong variations of the portions of female cods, which participated in the spawning activities in the region. The individuals within the length range from 35 cm to 45 cm have a special importance at this time, caused by the actual age structure of the cod stock.

Fischbestände der Ostsee, ihre Entwicklung seit 1970 und Schlussfolgerungen für ihre fischereiliche Nutzung - Teil 3: Sprotte

The sprat of the Baltic Sea is not as short-lived as inother Seas probably because fish predator species arerestricted mainly on cod and salmon. Sea bird popula-tions are much smaller and marine mammals are rare inthe Baltic Sea. The sprat stock biomass is fluctuatingstrongly. The fluctuation is mainly influenced by thestock recruitment and is also dependent on the strengthof the cod stock. After a strong decrease during the1980ies sprat catches increased again from 1992 onwardsand reached a peak with over half a million tonnes in 1997. At about the same time the character of the BalticSea sprat fishery changed from catches mainly for hu-man consumption to catches mainly for industrial pur-poses initiated by the fishery of Sweden. The recentrecord high catches of sprat have been possible only dueto the low level of the cod stock of the main Baltic SeaBasins over some years. A sprat fishery on such a highcatch level might cause conflicts with a recovering codstock in future.

Preliminary observations on the feeding, habits and reproduction biology of Gymnarchus niloticus from Lake Chad

The preliminary results obtained from the study of stomach contents of specimens of Gymnarchus niloticus of a size ranging from 56 cm (66 grams) to 152 cm (12.0 kg.) from August to December, 1982 indicate for these sizes an exclusively piscivorous diet. The predominant prey species in Lake Chad are Tilapia/Sarotherodon , and Clarias . The prey is often cut in two parts before it is swallowed. Small prey may be swallowed whole. The implication of this prey capture method on prey-predator relationship and therefore the impact of the predator is discussed. The breeding season of Gymnarchus niloticus in Lake Chad has been deduced from observation of changes in gonad maturity stages and the results indicate that breeding takes place between August and November. Data are also presented on the fecundity, size of ripe eggs and probable size at maturity

The cast net fishery, Kainji Lake, Nigeria 1970-1997

This study was carried out to establish trends in the cast net fishery of Kainji Lake, Nigeria. The cast net fishery was second in importance to the gillnet fishery in the early years after impoundment of the lake and still continues to be an important component of the fishery. Some of the economically important species such as Citharinus spp, Tilapia spp, Labeo spp, Alestes spp and Synodontis spp are exploited by cast nets. The study has not revealed any drastic perturbation in the species diversity, catch composition, and any real ecosystem overfishing. On the other hand, both the catfish, Auchenoglanis spp and the predator Hydrocynus spp appear to have increased in the catch in recent years. Never-the-less there is a decline in the mean weight of the major exploited fish species due to the capture of under sized fishes without allowing them to grow to 'legally' marketable sizes. The use of small meshed cast net and also fishing in the shallow waters of the lake can give rise to this situation. Thus, there are signs of growth overfishing in the fish stocks. It must also be acknowledged that the situation is complicated by the fact that in a multi-gear fishery as on Kainji Lake, the cast net fishery could not be managed in isolation without due regard to the other competing gears. The catch per unit of effort (CPUE) has declined in the cast net fishery possibly due to the increase in effort by the major fishing gears over the years. The ongoing extension campaigns by the KLFPP appears to be having the desired effect, as there was reduction in the number of the major fishing gears on the Lake in 1997. It can be anticipated that if this trend continues, the CPUE will recover in the long run. Yields observed from the mesh selectivity study revealed that for major species in the cast net fishery, both by number and weight, were maximal at 2.5 inch mesh, which contrasts with the fact that current minimum allowable mesh in the Fisheries Edict for the Lake is 2.0 inch. The adoption of 2.5 inch as the minimum allowable mesh in the cast net fishery is recommended to be included in future revision of existing regulations. It is also recommended that for this control to have a desired effect, the casting of the net from the shore should be prohibited so as to reduce the incidence of juvenile mortality in the nursery areas. (PDF contains 28 pages)

Ancylidae (Mollusca, Heterobranchia, Pulmonata, Basommatophora) do Estado do Rio de Janeiro, Brasil: morfologia, sistemática e distribuição geográfica

Os moluscos pateliformes de água doce da região Neotropical são comumente atribuídos a família Ancylidae sensu latum, abrangendo sete gêneros com pelo menos 13 espécies válidas e sete com identificação duvidosa. Os ancilídeos possuem pequenas dimensões, alcançam no máximo 15 mm de comprimento. Sua concha é frágil, composta por duas regiões, a protoconcha e a teleoconcha, as quais apresentam caracteres relevantes para a sistemática. Na parte mole as impressões musculares, a pigmentação do manto, o sistema reprodutor e a rádula são importantes para o estudo da família. Apesar de existirem vários registros de ocorrência para ancílideos no Estado do Rio de Janeiro (ERJ), existem poucos dados morfológicos. O principal objetivo deste estudo foi fornecer e ampliar as informações sobre a morfologia e distribuição geográfica das espécies de Ancylidae encontradas no ERJ. Os materiais utilizados foram procedentes de coletas próprias, material depositado em Coleções Científicas e dados de revisão bibliográfica. O estudo da morfologia comparada das conchas foi realizado com o auxílio de imagens de microscópio óptico e de varredura. Para a comparação das partes moles, os espécimes foram corados e dissecados sob lupa. Através da conquiliometria analisamos as diferenças inter e intrapopulacionais. Com este trabalho, a riqueza conhecida para Ancylidae no ERJ, aumentou de cinco para sete espécies: Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828),G. ticaga (Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata e U. concentricus constituem novos registros para o ERJ, e G. radiata para a Região Sudeste. As três espécies com o maior número de registros de ocorrência no ERJ foram: G. ticaga (66%), Ferrissia sp. (37%) e Gundlachia sp. (18%). A ampla distribuição de G. ticaga pode ser devido à capacidade de suportar ambientes impactados. Em relação à morfologia, Burnupia sp. difere de Burnupia ingae Lanzer, 1991, única espécie deste gênero descrita para o Brasil, por apresentar diferenças na microescultura da concha e também na forma das impressões musculares. Ferrissia sp. difere de F. gentilis Lanzer, 1991, devido a diferenças na microescultura apical e número de cúspides no dente central da rádula. Gundlachia sp. é diferente de G. ticaga e G. radiata, por apresentar a abertura da concha mais arredondada, ápice mais recurvado, ultrapassando a borda da concha, pontuações irregulares em toda a protoconcha e forma dos músculos adutores anterior direito e posterior mais elíptica. A morfologia interna também mostra diferenças entre Gundlachia sp. e G. ticaga, como o apêndice terminal do útero e o número de folículos do ovoteste. Através das análises conquiliométricas, constatamos para os gêneros Burnupia, Ferrrissia e Gundlachia, que os índices morfométricos se mostraram melhores que as medidas lineares para a discriminação das espécies, provavelmente porque esses índices diminuem o efeito da amplitude de tamanho das conchas, que são fortemente influenciadas pelas variações ecofenotípicas. Contudo, os caracteres diagnósticos das conchas e das partes moles (impressões musculares) são indispensáveis para a identificação dos gêneros e espécies de Ancylidae. Palavras-chave: Mollusca. Moluscos de água doce. Morfologia. Distribuição geográfica. Estado do Rio de Janeiro.uscos.

Predation and selection in copepod populations of Alpine waters [Translation from: Bollettino di Zoologia 21 541-545, 1954]

Zooplankton was studied in four alpine lakes in Switzerland, France and Italy. The presence the presence of the invertebrate predator Heterocope in three lakes was stated. It is then discussed why in three of these four lakes, the copepod Arctodiaptomus denticornis is present in the absence of Arctodiaptomus bacillifer, and vice versa respectively in the second and first parts of the lacustrine summer.

Selective plankton feeding by the coregonid ”bondella” (Coregonus sp.) of Lake Maggiore [Translation from: Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 31 181-203, 1974]

In recent times, some specialists have begun to study the subject of food selection of fish in an organized way, thus highlighting its importance. In the present work, the author intends to evaluate the impact of predation on the eupelagic zooplanktonic biocenosis of Lake Maggiore, producing, in this way, as far as possible, a basis for a better understanding of the population dynamics of the species of zooplankton directly involved. Another aspect which has been studied is that related to the mechanism of selective capture set in action by the predator. To this end the study tries to bear in mind that the subject should be interpreted as a function of numerous factors acting contemporaneously, that is as the interaction of characters peculiar to the predator and to the prey. The species studied, locally called ”bondella”, belongs to the family Salmonidae, subfamily Coregoninae and was introduced into Lake Maggiore in 1950.

Diet and condition of American Alligators (Alligator mississippiensis)in three central Florida lakes

Understanding the diet of crocodilians is important because diet affects condition, behavior, growth, and reproduction. By examining the diet of crocodilians, valuable knowledge is gained about predator-prey interactions and prey utilization among habitats. In this study, I examined the diet and condition of adult American alligators (Alligator mississippiensis) in three central Florida lakes, Griffin, Apopka, and Woodruff. Two hundred adult alligators were captured and lavaged from March through October 2001, from April through October 2002, and from April through August 2003. Alligators ate a variety of vertebrate and invertebrate prey, but vertebrates were more abundant and fish dominated alligator diets in the lakes. Species composition of fish varied among the lakes. The majority of the diet of alligators from Lakes Apopka and Woodruff was fish, 90% and 84% respectively. Lake Apopka alligators consumed a significantly (P = 0.006) higher proportion of fish in their diet. Fish were 54% of the diet of Lake Griffin alligators and the infrequent occurrence of reptiles, mammals, birds, and amphibians often resulted in a large biomass. Differences in alligator diets among lakes may be due to differences in sample size (higher numbers of samples from Lake Griffin), prey availability, habitat, prey vulnerability, or prey size. Alligator condition (Fulton’s Condition Factor, K) was significantly (P < 0.001) different among the lakes. Alligators from Lake Apopka had the highest condition, followed by those from Lake Griffin, and alligators from Lake Woodruff had the lowest condition. Composition of fish along with diversity and equitability of fish in alligator diets may have contributed to differences in condition among lakes. Condition was probably also due to factors other than diet such as alligator hunting behavior, alligator density, or year-round optimal temperature that prolongs feeding. The observed diet and condition differences probably reflect both habitat differences and prey availability in these three lakes.

The unsteady forces on slender delta wing hydrofoils oscillating in heave

The investigations described herein are both experimental and theoretical. An experimental technique is described by which the models tested could be oscillated sinusoidally in heave. The apparatus used to gather the unsteady lift, drag and pitching moment data is also described.

The models tested were two flat delta wings with apex angles of 15° and 30° and they had sharp leading edges to insure flow separation. The models were fabricated from 0.25 inch aluminum plate and were approximately one foot in length.

Three distinct types of flow were investigated: 1) fully wetted, 2) ventilated and 3) planing. The experimental data are compared with existing theories for steady motions in the case of fully wetted delta wings. Ventilation measurements, made only for the 30° model at 20° angle of attack, of lift and drag are presented.

A correction of the theory proposed by M.P. Tulin for high speed planing of slender bodies is presented and it is extended to unsteady motions. This is compared to the experimental measurements made at 6° and 12° angle of attack for the two models previously described.

This is the first extensive measurement of unsteady drag for any shape wing, the first measurement of unsteady planing forces, the first quantitative documentation of unstable oscillations near a free surface, and the first measurements of the unsteady forces on ventilated delta wings. The results of these investigations, both theoretical and experimental, are discussed and further investigations suggested.

Resistência à infiltração de glicose de quatro cimentos reparadores

O presente estudo teve como objetivo comparar a qualidade do selamento promovido por 3 cimentos reparadores endodônticos: Ceramicrete, iRoot-BP Plus e BioAggregate, com o ProRoot MTA branco, utilizando o modelo de infiltração de glicose sob pressão. 64 incisivos centrais superiores, recém-extraídos e sem tratamento endodôntico foram selecionados. A instrumentação do canal radicular foi realizada em todos os dentes com brocas Gates-Glidden e limas K-Flexofile (Dentsply Maillefer, Ballaigues Suíça), 1mm aquém do ápice. A patência foraminal foi confirmada a cada instrumento usado. Os dentes tiveram suas coroas removidas padronizando-os em 15mm de comprimento. Foi realizada apicetomia a 3mm do ápice e o preparo da cavidade retrógrada com o auxílio do ultrassom Various 350 (NSKNakanishi Inc., Tóquio, Japão) e da ponta E32D (NSKNakanishi Inc., Tóquio, Japão). As raízes foram distribuídas, randomicamente, em quatro grupos experimentais (n=15): G1Ceramicrete, G2iRoot BP Plus, G3BioAggregate e G4ProRoot MTA branco. Como controle negativo (n=2) foram utilizados dentes hígidos, e como controle positivo (n=2), dentes acessados e com patência confirmada. Os cimentos reparadores foram manipulados seguindo as recomendações do fabricante e inseridos na cavidade retrógrada utilizando a mesma ponta ultrassônica usada no preparo. As amostras foram mantidas na presença de umidade por 72h para o completo endurecimento dos materiais. As raízes foram montadas em um dispositivo de dupla-câmara selada para a infiltração da glicose. Foram utilizados 0,75ml de solução de glicose a 1Mol/L na câmara superior e 0,75ml de água destilada na câmara inferior. Os dispositivos foram conectados a um sistema de distribuição de pressão, que permitiu a infiltração de 32 amostras em uma mesma etapa. A solução de glicose foi forçada apicalmente sob uma pressão de 15psi durante 1 hora. Uma alíquota de 10l foi coletada da câmara inferior para quantificar a glicose infiltrada. A concentração de glicose foi determinada com o auxílio do Kit GlucoseHK (Megazyme, Wicklow, Irlanda) e de um espectrofotômetro de luz visível (Campsec M330, Cambridge, Reino Unido) em um comprimento de onda de 340nm. O teste não-paramétrico Kruskal-Wallis e o teste Dunns foram utilizados na análise estatística. Os resultados encontrados demonstraram que houve diferença significativa entre os grupos experimentais (p=0,0036). O BioAggregate apresentou a maior concentração de glicose-1,85(g/L), seguido do ProRoot MTA-1,2; IRoot BP-0,85 e Ceramicrete-0,75. Não houve diferença entre os três novos cimentos reparadores e o material padrão-ouro (p>0,05). Não houve diferença entre Ceramicrete e iRoot BP Plus (p>0,05), porém estes foram estatisticamente diferentes do BioAggregate (p<0,05). Diante dos resultados obtidos, pode-se concluir que: nenhum dos cimentos testados foi capaz de promover selamento hermético; os três novos cimentos testados não revelaram o mesmo padrão de selamento; os três novos cimentos testados revelaram um padrão de selamento semelhante a do ProRoot MTA branco; e o Ceramicrete e o iRoot BP Plus apresentaram padrão de selamento superior em comparação com o BioAggregate.

Erretinako distrofia heredagarrien mutazioetarako etekin handiko baheketa, Axiom Exome genotipatze mikrotxipetan oinarrituta

Axiom Exome DNA Genotipatze mikrotxipetan oinarriturik, etekin handiko baheketa (screening) genetikoa garatu da Excel bidez eginiko filtraketez baliatuta. Modu honetan, erretinako distrofia heredagarriak (EDH) modu eraginkorrean diagnostikatzea lortu nahi da. Ikerketa honetan, 55 familia ezberdinetakoak diren 80 EDHdun gaixok eta hauen 108 senitarteko osasuntsuk hartu dute parte. Guztira 188 norbanakoen odol periferikoa bildu eta hauen DNA laginak aztertu dira bi Axiom Exome Genotipatze Mikrotxip erabilita. Mikrotxip honen bidez, erretinako distrofietan zuzeneko eragina duten 181 generi dagozkien 5.044 aldaera aztertu dira. Hauetatik 82 genek Erretinosi Pigmentarioa (EP) izeneko gaixotasuna eragiten dute (sindromikoa edo ez-sindromikoa). Excelen oinarrituriko baheketa estrategia garatuz, gure populazioan EDHak eragiten dituzten aldaerak aurkitzea izan da xedea. Ondoren, aurkikuntza horretan lorturiko aldaera genetikoak, zuzeneko Sanger sekuentziazio bidez egiaztatu dira. Ikerketa honetan lorturiko emaitza nagusia, gaixotasunen eragile diren aldaera genetikoak identifikatzea izan da. Guztira 8 aldaera genetiko aurkitu dira, erretinako gaixotasuna eragiten duten 8 geneetan. 12 familiatako 15 gaixo eta 12 eramailetan aurkitu dira aldaera genetiko hauek. Ondorio modura, DNA genotipatze mikrotxip hauetatik lortzen den datu pila guztitik, biologikoki garrantzitsua den informazioa soilik eskuratu eta identifikatzeko aukera dagoela ikusi da, ikerketa honi esker garatu den Excel bidezko baheketa estrategia erabilita. Beraz, garaturiko Excel bidezko baheketa estrategiak aukera ematen du, EDH heterogeneo hauen karakterizazio molekularra modu eraginkorrean gauzatzeko. Erretinarako berariazkoak diren APEX mikrotxipen kostuarekin alderatuta eginiko analisien kostua 1/5 izatera jaisten da. Honek klinikoki garrantzia handia du, izan ere, ahalik eta gaixo gehien diagnostikatzeko aukera ematen du.

The control of indirect effects of biomanipulation

Results from long-term investigations on biomanipulation show that indirect effects are at least as important as direct effects are for the stability of biomanipulation. Three types of indirect effects can be distinguished: (1) a change in quantity or quality of the resource base, (2) behavioural change of the prey, and (3) development of anti-predator traits. Although indirect effects of type (2), (e.g. a change in the pattern of vertical migration of zooplankton), and type (3), (e.g. development of helmets and neck teeth in Daphnia), are important mechanisms, the most essential indirect effects regarding biomanipulation belong to type (1). An example of the latter will be demonstrated: the complex of indirect effects of enhanced grazing by large herbivores on the phosphorus metabolism of the lake. It is concluded that control of the indirect effects is absolutely necessary to stabilize biomanipulation measures, but this is much more difficult than the control of direct effects and needs deeper insights into the structuring mechanisms of food webs. Proper management of fish stocks, in combination with the control of phosphorus load and/or the physical conditions, seems to be the most promising way of controlling the indirect effects of biomanipulation.

Behavior ecology of the Humboldt squid, Dosidicus gigas: insights from an animal-borne video and data logging system

Dosidicus gigas is a large pelagic cephalopod of the eastern Pacific that has recently undergone an unexpected, significant range expansion up the coast of North America. The impact that such a range expansion is expected to have on local fisheries and marine ecosystems has motivated a thorough study of this top predator, a squid whose lifestyle has been quite mysterious until recently. Unfortunately, Dosidicus spends daylight hours at depths prohibitive to making observations without significant artificial interference. Observations of this squid‟s natural behaviors have thus far been considerably limited by the bright illumination and loud noises of remotely-operated-vehicles, or else the presence of humans from boats or with SCUBA. However, recent technological innovations have allowed for observations to take place in the absence of humans, or significant human intrusion, through the use of animal-borne devices such as National Geographic‟s CRITTERCAM. Utilizing the advanced video recording and data logging technology of this device, this study seeks to characterize unknown components of Dosidicus gigas behavior at depth. Data from two successful CRITTERCAM deployments reveal an assortment of new observations concerning Dosidicus lifestyle. Tri-axial accelerometers enable a confident description of Dosidicus orientation during ascents, descents, and depth maintenance behavior - previously not possible with simple depth tags. Video documentation of intraspecific interactions between Dosidicus permits the identification of ten chromatic components, a previously undescribed basal chromatic behavior, and multiple distinct body postures. And finally, based on visualizations of spermatophore release by D. gigas and repetitive behavior patterns between squid pairs, this thesis proposes the existence of a new mating behavior in Dosidicus. This study intends to provide the first glimpse into the natural behavior of Dosidicus, establishing the groundwork for a comprehensive ethogram to be supported with data from future CRITTERCAM deployments. Cataloguing these behaviors will be useful in accounting for Dosidicus‟ current range expansion in the northeast Pacific, as well as to inform public interest in the impacts this expansion will have on local fisheries and marine ecosystems.