Rearing of <i>Octopus vulgaris</i> paralarvae: present status, bottlenecks and trends

Due to the high mortality rates and poor growth generally observed in Octopus vulgaris paralarval rearing experiments, it was decided to organize a working group in order to formulate recommendations to tackle this problem. Over a dozen scientists representing the most active current research groups related to this subject attended the meeting in Vigo, Spain, in November 2005. The aim of this working group was to determine the bottlenecks that prevent success in paralarval rearing, define the most appropriate rearing conditions, and identify required future research.This paper describes rearing techniques for the O. vulgaris paralarvae used by the different research participant teams, with regard to tank systems, feeding environment, and diets (Artemia, crustacean zoeae, sandeel flakes, copepods, etc.). Additionally, it includes other related themes such as the culture of Artemia and copepods, organisms that are commonly used in paralarval rearing.When embarking on O. vulgaris rearing it is advised to use prey rich in DHA (docosaenoic acid, 22:6n-3) and EPA (eicosapentaenoic acid, 20:5n-3), and with high DHA/EPA ratio. Such prey could be enriched Artemia, accompanied or not by crustacean zoeae or any microdiet. It is also recommended that, in future studies, values of growth and survival rates are recorded at the beginning of the benthic phase, in order to compare them to successful previous studies. Dry weight and DHA/EPA ratio of paralarvae may also be good criteria to define paralarval viability and evaluate success of the rearing system.It is further concluded that the nutritional aspect is the most important factor influencing larval mortality. Certain lipids (phospholipids, cholesterol, and polyunsaturated fatty acids), amino acids (lysine, leucine and arginine), and essential elements (e.g. copper) play a relevant role in the larval nutrition. It is believed that the PUFA content, especially DHA and EPA, constitutes one of the basic nutritional requirements.Regarding new research lines, no standardized system for paralarval rearing exists, and it is essential to make progress on this issue. Research on nutritional requirements is considered an area of highest priority, especially the development of a specific enrichment for Artemia, the search for alternative live preys, and the development of suitable formulated diets

Rearing of Octopus vulgaris paralarvae: Present status, bottlenecks and trends

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Ingestão de ração e comportamento de larvas de pacu em resposta a estímulos químicos e visuais Diet ingestion rate and pacu larvae behavior in response to chemical and visual stimuli

Este estudo foi realizado com o objetivo de comparar a influência dos estímulos visual e/ou químico de náuplios de Artemia e de dieta microencapsulada sobre a taxa de ingestão da dieta microencapusulada por larvas de pacu Piaractus mesopotamicus. Utilizou-se um esquema fatorial 7 x 4 (estímulos e idades) com duas repetições. Verificou-se efeito da idade das larvas e dos estímulos, mas não houve efeito para a interação idade <FONT FACE=Symbol>&acute;</FONT> estímulos. O estímulo químico da Artemia e ambos os estímulos da Artemia resultaram em maior taxa de ingestão de dieta inerte. Resultado intermediário foi obtido com o estímulo visual da dieta microencapsulada. O estímulo químico, em comparação ao estímulo visual da Artemia, resultou em maiores taxas de ingestão da dieta. Com o aumento da idade, houve incremento na taxa de ingestão. Os estímulos visual e químico dos náuplios e o estímulo visual da ração aumentaram a ingestão de dieta inerte por larvas de pacu. Náuplios de Artemia devem ser oferecidos antes do fornecimento da dieta inerte, pois podem auxiliar no processo de transição alimentar. Os resultados deste trabalho apontaram novas possibilidades de estudos com larvas de peixes neotropicais visando a substituição precoce do alimento vivo para o inerte.<br>The effect of visual, chemical and the combination of both stimuli from Artemia nauplii and from microencapsulated diet on dry diet ingestion by pacu Piaractus mesopotamicus larvae was evaluated in this research. The experiment was analyzed as a 7 x 4 factorial arrangement (seven stimuli and four ages) with two replicates. It was observed effect of larvae age and stimuli, but no interaction (age <FONT FACE=Symbol>&acute;</FONT> stimuli) was observed. The chemical effect from Artemia and both effects from Artemia resulted in higher ingestion rates. An intermediary result was obtained with visual effect from microencapsulated diet. The chemical stimulus from Artemia resulted in higher ingestion rates than that obtained with Artemia visual stimulus. Ingestion rate increased as age increased. Chemical and visual stimuli from nauplii and visual stimuli from diet increased microencapsulated diet ingestion by pacu larvae. Artemia nauplii offered before the artificial diet may assist weaning. These results opens new study possibilities with Neotropical fish larvae precocious weaning