- PRESS TRUST OF INDIA

New technique for easy collection of ‘Karimeen' fish eggs

NEW DELHI, SEPT. 26: The Indian Council of Agricultural Research (ICAR) scientists have developed a unique method for collection of the eggs laid by Pearlspot, also known as the “state fish of Kerala”, which is much more efficient than the earlier method employed.

Pearlspot (Etroplus suratensis) also known as "Karimeen" in Kerala, is an excellent table fish, fetching a good market price up to Rs 350 a kg.

“The fish has very complicated method of breeding and nesting. They bury their eggs in the bottom mud of the ponds, hence, the survival of juveniles is very less, which has been a major concern for fish farmers,” said Mr M. Natrajan, Project in-charge at the Central Institute of Brackishwater Aquaculture (CIBA), Chennai, an institute of the ICAR.

“We can obtain 1,200 juveniles from a pair of parent fishes. However, in traditional techniques, it is hardly 200 juveniles,” added Mr Natrajan.

Pearlspot can be reared in ponds and cages in both freshwater and salt water environments. It is a hardy fish, easy to propagate and culture on a large scale, depending upon the capacity of the entrepreneur and farmer.

Pearlspot can be farmed in homestead ponds in the backyard of houses, enabling poverty alleviation as well as high-value fish production in States such as Kerala.

The Central Institute of Brackishwater Aquaculture (CIBA), Chennai, has developed an innovative technology for easy propagation of the fish by breeding them under controlled conditions.

CAPTIVE BREEDING

At its Muttukadu Field Centre, CIBA has successfully developed a captive broodstock of Pearlspot fish in cages, drawing from a diverse genetic pool (from Pulicat and Muttukadu, in Tamil Nadu, and Kumarakam, in Kerala) to establish a simple and effective facility for consistent egg production by this fish species.

Under the ‘Matsya Keralam' scheme, the State Government is promoting farming of brackishwater fish on a large scale and due to this, the demand for quality Pearlspot fish juveniles has increased.

The CIBA, Chennai, has been approached by the Kerala Government to extend its know-how and expertise with regard to this technology to promote Pearlspot fish production in the State.

Efforts are also being made to promote Pearlspot fish culture in derelict inland saline wetlands of Karnataka.

É preciso apenas uma fêmea grávida de "guppy" para uma invasão alienígena

How reproductive ecology contributes to 

the spread of a globally invasive fish.

Deacon AE, IW Ramnarine and AE Magurran 

(Practical Fishkeeping - http://www.practicalfishkeeping.co.uk/content.php?sid=4324)

Copyright © Mich De May, Creative Commons

The well-known ability of female guppies (Poecilia reticulata) to store sperm for up to six months and give birth long after being inseminated is responsible for their runaway success as one of the world's worst invasive fish species.

In research published in a recent issue of the online journal PLoS ONE, Amy Deacon, Indar Ramnarine and Anne Magurran document the current global distribution of the guppy, producing the most complete picture of the current distribution of this invasive species to date, and show that it is contributing to the homogenisation of fish communities on a global scale. 

At the same time, they conducted experiments to test the prediction that a single pregnant female guppy is capable of routinely establishing viable populations when introduced to a new habitat.

Despite the small native range of the guppy, the authors found that its introduced range now spans every continent with the exception of Antarctica, as well as numerous oceanic islands. 

Their data show that the worldwide distribution of the guppy is considerably more extensive than previously described in the literature or in any database.

For the second part of their study, the authors carried out an experiment in which 30 plastic mesocosms were established and a single pregnant female wild-caught guppy was added. The experiment was allowed to run for two years, during which the fish were counted, measured and their performance (in activity and evasion) were recorded.

The authors found that the single female guppies were capable of establishing viable populations within the mesocosms during the study period in a large majority of the cases: 91% of mesocosm populations persisted at the end of the first year and 86% at the end of the second.

Furthermore, their studies showed that the behavioural performance of the offspring from such introductions was not impaired. Although inbreeding is very likely to take place as a result of using a single founder individual, the guppies may be employing a number of pre- and post-copulatory strategies to minimise inbreeding, surmise the authors.

The authors conclude, "Our results demonstrate how introductions consisting of a few animals, or even a single individual, can lead to thriving populations of invasive species. A highly specialised reproductive system, coupled with a remarkable adaptability is likely to have led to the phenomenal success of the guppy outside of its native range. These findings reinforce the need for caution when releasing exotic species, and show that seemingly innocuous or beneficial activities such as a child freeing a few pet fish or a concerned householder using guppies to control mosquitoes can result in a thriving population of invasive poeciliids that may then go on to compete with the indigenous freshwater fauna. They also illustrate how many small actions replicated across the globe, in the form of the accidental or deliberate release of a few fish, combined with natural adaptations in these fish for life in ephemeral habitats, can contribute to the reduction of diversity in freshwater fish assemblages worldwide."
Deacon AE, IW Ramnarine and AE Magurran (2011). How reproductive ecology contributes to the spread of a globally invasive fish. PLoS ONE 6, e24416. doi:10.1371/journal.pone.0024416

Sistema de Transposição de Peixes

          MEIO AMBIENTE

Época de piracema: Santo Antônio Energia monitora 

migração de peixes do rio Madeira

De: Santo Antônio Energia 

09 de Setembro de 2011

Imagem - Divulgação

Entre agosto e novembro, a equipe do Programa de Conservação da Ictiofauna marcará 4 mil peixes que serão monitorados em um estudo sobre as rotas migratórias no período de reprodução das espécies. O objetivo é verificar se os animais estão utilizando o Sistema de Transposição de Peixes (STP), estrutura construída para ajudá-los a ultrapassar a barragem da Usina na época de piracema.

Equipamentos de telemetria para obtenção e transmissão de dados a longa distância foram instalados em parte dos animais e o monitoramento será feito por antenas instaladas nas margens e em barcos ao longo do rio Madeira. A outra parte dos peixes receberá uma marcação chamada LEA, um tubo com um número que é fixado na barbatana para identificá-lo quando ele for pescado.

Cuidado Parental!!!! Fantástico momento!!!!

Jawfish Eggs about to Hatch

Photo and caption by Suzan Meldonian

A male Banded Jawfish (Opistognathus macrognathus), incubates it's eggs in it's mouth, assuring survival of at least this stage of their lives. Held in by it's father's teeth at some point the overgrown siblings become cumbersome, yet the devotion of survival mode is so strong that the jawfish will only poof them out for a second or two to quickly catch a morsel of food in the water column, then quickly sucking the eggs back into it's mouth. This process is also called aerating the eggs... so it serves more than one purpose... sort of like rotating the eggs in a hatchery.

http://ngm.nationalgeographic.com/ngm/photo-contest/2011/entries/72526/view/?source=link_tw20110907ngm-pc

Oportunistas: Ciclídeos seguem raias na busca por alimento

Cichlids follow stingrays to food

Published: Dr Heok Hee Ng 

http://www.practicalfishkeeping.co.uk

Copyright © Steven Johnson, Creative Commons

Brazilian scientists have discovered that some cichlids follow potamotrygonid stingrays to opportunistically feed on the invertebrates flushed out by the foraging activity of the rays.

Publishing the results of their study in a recent issue of the Journal Neotropical Ichthyology, Domingos Garrone-Neto and Ivan Sazima record this association while making in situ observations of the fishes at two sites in the upper Paraná river drainage. 

The authors found that the foraging activities of the stingrays Potamotrygon falkneri and P. motoro, attract four cichlid species (Crenicichla britskii, Satanoperca pappaterra, Cichla kelberi, and Geophagus proximus) to follow them. 

The authors describe the association as “…a ray stirring the unconsolidated (loose) substrate to uncover small invertebrates such as insect larvae, crabs, and snails.

Food clouds

This activity stirs the substrate particles and discrete sediment clouds are formed near the foraging ray. These clouds apparently catch the attention of nearby cichlids that approach the ray and feed on small preys and other food types exposed this way.” 

This is yet another case of a nuclear-follower association, which has been reported for a number of South American freshwater fishes.

The nuclear-follower association is an interspecific interaction defined by the presence of a nuclear species that promotes a disturbance during foraging and a follower species that feeds on the items exposed or flushed out by the former.

For more information, see the paper: Garrone-Neto, D and I Sazima (2009) The more stirring the better: cichlid fishes associate with foraging potamotrygonid rays. Neotropical Ichthyology 7, pp. 499–501.

Fenômeno da Bioluminescência por tornar o Tubarão-Lanterna invisível contra predadores.

Glow-in-the-dark shark can become invisibleAbility to 'disappear' may save it from predators, but researchers find it amazing
By Jennifer Viegas (© 2011 Discovery Channel)

Bioluminescence most likely facilitates the rare splendid 

lantern shark in mating, schooling and other behaviors.

(Jerome Mallefet)

The first detailed study of the rare splendid lantern shark reveals that not only does it glow in the dark, but the light effects create a "cloak of invisibility" that helps shield it from predators.

The study, accepted for publication in the Journal of Experimental Marine Biology and Ecology, is also the first to document the cylindrical-shaped shark's presence in waters around the Okinawa Islands of Japan. Previously, the shark was confirmed to exist only in the East China Sea, off Taiwan, and in the waters around southern Japan.

Its natural light show, produced by light-emitting organs called photophores, serves many functions. The cloak of invisibility is perhaps one of the most beneficial, since it helps to protect the small, shark from upward-looking predators. The lantern shark is a member of the small dogfish sharks.

"The photophores replace the down-welling light from the sun, which is absorbed by the shark's body," lead author Julien Claes explained to Discovery News. "The silhouette of the shark therefore disappears when seen from below."

Claes, a postdoctoral researcher in the Catholic University of Louvain’s Marine Biology Lab, and colleagues Keiichi Sato and Jerome Mallefet collected, and maintained in captivity, three specimens of the splendid lantern shark.

Analysis of the sharks revealed that each had nine distinct luminous zones where light was emitted. Some of these zones, such as one on the belly, contribute to the "cloak of invisibility" effect. Other, even brighter, zones are present on the shark's sexual organs, flanks, tail and pectoral fins. The researchers suspect these are probably used during schooling and sexual communication.

"Sharks use internal fertilization, so the presence of photophores on the sexual organs may facilitate mating," Claes said. "Moreover, it might also be a way for the sharks to signal that they are ready to mate or that they are a better candidate for reproduction in a light-induced sexual selection system."

The scientists believe nerves and hormones primarily control the light, with pigments also moving in cells as part of the process.

The luminescence likely evolved when lantern sharks colonized the deep sea probably during the end of the Cretaceous, 65 to 75 million years ago. The splendid lantern shark to this day lives 656 to 3,281 feet below the water's surface, an area with extremely low light levels.

Claes and his colleagues previously studied another member of this shark family, the velvet belly lantern shark. Both this and the splendid lantern shark share similar luminous zones and other features. It's therefore probable that their ability to glow evolved long before their clades split up at least 31.55 million years ago.

It's even possible that many other prehistoric marine animals could glow in the dark.

"Unfortunately bioluminescence is a soft-tissue phenomenon that leaves no, or extremely few, fossil tracks," Claes said. "It is therefore very difficult to establish if a lot of prehistoric animals were luminous, but it is probably the case at least in the deep sea, since bioluminescence is currently widespread in this environment."

Nicolas Straube, a researcher at the Bavarian State Collection of Zoology, told Discovery News that he "fully agrees" with the new paper's conclusions.

Straube explained that this latest study supports previous theories about lantern shark evolution and luminescence, given both the similarities and differences between the two best-documented species: the velvet belly lantern shark and now the splendid lantern shark.

At least 33 species exist in this diverse shark family, however, so much remains to be discovered about these dwellers of the ocean depths.

Quais são as técnicas mais adequadas e de baixo custo para engordar peixes em tanques escavados e em tanques circulares?

Tanques para piscicultura

Fabiano Henrique W. Ribas

Barra do Chapéu - SP

http://revistagloborural.globo.com

O cultivo de peixes para consumo ou para ornamentação (utilizados em aquários, por exemplo) tem se popularizado no Brasil. As boas condições climáticas do país e a grande variedade de espécies nativas contribuem para o desenvolvimento da atividade. Com dedicação e empenho, produtores podem conseguir bons resultados e contar com a criação como fonte de renda principal de sua propriedade. 

Antes de escolher os peixes que mais se adaptem à região de cultivo e dar início ao novo empreendimento, entretanto, é necessário montar uma estrutura apropriada no local. De acordo com o orçamento disponível, pode-se decidir por vários materiais encontrados no mercado e por diferentes sistemas de criação (confira a tabela na página ao lado). 

O tanque de cultivo pode ser apenas escavado na terra ou, após a terraplenagem, ser construído em alvenaria e impermeabilizado com lona, fibra de vidro ou chapa galvanizada. Para o sistema de abastecimento de água, utilize blocos de concreto ou algum tipo de vala, com conexões de tubo de PVC para condução da água até o tanque. A vazão da água pode ser regulada com a instalação de um monge de alvenaria ou um cotovelo articulado, por meio do qual ocorre o escoamento da sujeira acumulada no fundo do tanque. 

De forma geral, é recomendável que os viveiros não sejam muito grandes, para evitar dificuldades no manejo, como nos momentos de alimentação, transferência de peixes e despesca. Uma boa medida recomendada é de 40 por 50 metros, com 1,60 metro de profundidade. O formato retangular é o mais indicado para a criação de várias espécies de peixes, pois facilita a renovação da água. O circular, que exige mais aparatos para a movimentação da água e filtros para a remoção de resíduos, é mais frequentemente usado na criação de trutas, embora também possa ser usado no cultivo de lambari, tilápia e pirarucu, entre outros. 

Piscicultores de algumas localidades do país têm optado por fertilizar a água dos viveiros com resíduos originários da suinocultura, promovendo a proliferação de micro-organismos que servirão de alimento para os peixes. Com produção que chega a 2 mil quilos de pescado por hectare por ano, o sistema é considerado uma opção para baratear os custos.

Muitos criadores brasileiros, no entanto, adotam viveiro com fertilização acrescida de alimentação suplementar. São aproveitadas sobras de hortaliças e/ou fornecidas rações de boa qualidade para a engorda dos peixes. A produção oriunda desses sistemas pode atingir 5 mil quilos por hectare por ano.

Para conseguir uma atividade mais produtiva e com custo baixo, os piscicultores também aproveitam para praticar o policultivo: várias espécies de peixes ocupam o mesmo viveiro, sendo que cada uma aproveita um espaço (mais no fundo, mais junto à superfície, etc.) e um tipo de alimento. Um exemplo de boa convivência é juntar em um único tanque tilápia com variedades de carpa. 

Podem dividir o mesmo ambiente a carpa comum, que, assim como a tilápia, come de tudo (onívora); a carpa capim, que consome plantas (herbívora); a carpa cabeçuda, que se alimenta de minúsculos animais (zooplanctófaga); e a carpa prateada, que gosta de algas (fitoplanctófaga). 

Uma recomendação importante para os iniciantes na criação de peixes é consultar a legislação ambiental. A orientação de um técnico competente pode assegurar o dimensionamento de um projeto econômico e produtivo. Um consultor em piscicultura também tem capacidade para avaliar as condições do local para a atividade, sugerir o melhor sistema a ser adotado, recomendar as espécies para cultivo e sugerir opções para baratear os custos. 

CONSULTOR: Jorge Meneses (consultor na área de piscicultura)

MAIS INFORMAÇÕES: Instituto de Pesca de São Paulo, instituto@pesca.sp.gov.br, www.pesca.sp.gov.br; Centro de Aquicultura de Jaboticabal (Caunesp), http://caunesp.unesp.br