Iglesias-Estévez, J. (José)

Moxica, C. (Covadonga)

Otero-Pinzas, J.J. (Juan José)

Sánchez-Conde, F.J. (Francisco Javier)

English

Repositorio Institucional Digital del IEO

:./,: .' .. ,-" . .,'-1 .,!=~.•,"~.:.:!~. l.~\:~~;~'_::~7~~:-:~.~~::!'~~~:-:,:1.'!,~.~--:"::7 ~'· ·''t·_·~·;.~,':··;..:'.-s ..·...; ;;'f> .,'-'j.r;!?:ñ~N¡i_F.'""':.. :O.~"" .AQUACULTURE ANO V.JATER:FISI-[ CULTURE, SIIELLFISH CULTURI~ ANDWATER USAGEL'AQUACULTURE ET L'EAU:.::12CICULTURE, CONCHYLICUL TURE ETUSAGE DE L'EAUAbsuacts of couuibutions prescntcd ti! thc lntemational ConfcreuceResumes des contributions présentées au Congres lnternationalAQUACULTURE EUROPE '98Bordcaux, Franco, Octobcr 7-10, 1998Cornpilcd by / COI11[1iléparH. GrizelP. Kcstcmont1.ayout and proccssingF. Luizi, L. Aspeslagh, and S. Van CraeynestEUROPEAN AQUACUL TURE SOCIETYSPECIAL PUBLlCATION NO. 26Oosrcnde, BclgiumAugust 1998"'--~.....• ".,;:' •• :;;, "•• 0",'.'¡~~~1~~,'~";:<." .. ;'./Aquaculture Europe 98. Bordeaux, October 7-10, 1998GROWTH OF OCTOPUS (OCTOPUS VULGAR/S) MALES ANDFEMALES UNDER CULTURE CONDITIONSF.l. Sánchez, 1. Iglesias, C. Moxica and 1.1.OteroInstituto Español de Oceanografía. Apdo. 1552.36280 Vigo. SpainIntroductionThe common octopus (Octopus vulgaris) is considered to be a promisingspecies for cultivation in Galicia (NW Spain): its great demand in localand international markets, the increasing market prices together with thehigh growth rates of these animal s support this affirmation. In recentexperiences of ongrowing in tanks (Iglesias et al. 1997) and in floatingcages (Rama- Villar et al. 1997), rates of growth as high as 0.5 to 1.0kgper month were registered. The goal of this study was: 1) to register therate of growth of males and females separately and 2) to improve theyield of ongrowing avoiding the process of spawning, loss of weight anddeath that occurs in fecundated females from lkg onwards.Materials and MethodsFifty seven wild octopus were separated by sex and transferred into tworectangular tanks of 8 m3 provided with an open circuit (1.2 rrr'h") wherethey were grown for five months. Temperature ranged between 12°C-19°C and salinity between 32%0 and 35°/00' Animals were weighedmonthly, and the specific growth rate (G = Ln Wf - Ln w, /t x 100) wasregistered. Separation according to sex was made by observing the tip ofthe 3rd right arm in the animals, which is rounded in the case of malesand pointed in females. Food consisted of frozen decapod crustaceans.Daily ration was calculated as a percentage of the tank biomass. Growthcurves for both sexes were statistically compared by a slope t-testcomparison method.ResultsInitial mean weights for males and females were 637.0g and 657.9grespectively, reaching final mean weights of 3624.0g and 2780.0grespectively after five months. Daily ration was higher at the beginning ofthe experimental period (7%), decreasing at the end (3.5%). The foodconversion index was 2.1 for males and 4.2 for females. Growth in weightadjusted to the following exponential equations:Males:Females:y = 544.11 e 0.3327 xy = 632.47 e 0.2704 x(r2 = 0.75)(r2 = 0.69)Slopes of both curves were significantly different (p< 0.05), malesshowing a higher growth rate than females (Fig 1).Method of sex separation showed an effectiveness of 100%.The monthlymortality rate during the first four months ranged between 0% - 4.0%(males) and 0% - 6.7% (females). In the fifth month, rate of mortalityincreased in both groups (see Table 1). At this time, most of the femaleshad developed big ovarian masses.WEIGHT(g)o!g malesa <)I? ;~o l' ~~ females~ ~ §1000 i=-==-=-=-=-- ~---- o oO+I------~--------~------~------~------_,o4000300020002 3 4 5MONTHSFigure l.- Growth ofmales (diamonds) and females (squares) of Octopusvulgaris in separate tanks.-o •TABLE 1: mean weight (MW), specific growth rate (G), and monthlymortality rate (MM) of males and females of octopus in separate sexcultures.Month O 1 2 3 4 5Sex cJ ~ cJ ~ cJ ~ cJ ~ cJ ~ cJ ~637.0 1250.8 1806.0 2341.4 2955.0 3624.0MW(g)657.9 1248.8 1812.4 2148.3 2483.0 2780.0- 2.11 1.08 0.93 0.83 0.66G(%)- 2.00 1.10 0.61 0.52 0.36- 3.7 3.8 4.0 O 13.0MM(%)- O 6.7 O O 10.7ConclusionsIn separate-sex cultures, Octopus males grow faster than females.Separation of males and females improves the process of ongrowingsince non fecundated females continue to grow until cornmercial size.Recornmended attainable weight in separate sex cultures is 3kg(males) and 2.5kg (females). Beyond this point, the increasing rate ofmortality decreases the yield ofthe ongrowing process.LiteratureIglesias J., F.J. Sánchez and J.J. Otero. 1997. Primeras experiencias sobreel cultivo integral del pulpo (Octopus vulgaris) en el Instituto Español deOceanografia. p. 221-226. In: Actas del VI Congo Nac.de Acuicultura.Cartagena, Junio 1997.Rama-Villar A., V. Faya-Angueira, C. Moxica and M. Rey-Méndez.1997. Engorde de pulpo (Octopus vulgaris) en batea. p. 245-250. In:Actas del VI Congo Nac.de Acuicultura. Cartagena, Junio 1997.

Growth of octopus (Octopus vulgaris) males and females under culture conditions

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