Assessment of captive rearing conditions on loggerhead hatchlings: Effect of handling frequency and stocking density

Growth trials were conducted using hatchery produced spat of Pinctada imbricata fucata (Gould, 1850) having average dorso-ventral measurement (DVM) of 3.99 mm, hinge length (HL) 3.94 mm, thickness (THK) 1.25 mm and weight (WGT) 0.008 g. The first experiment was a comparative growth assessment of spat grown in one ton FRP tanks in the hatchery and with that of spat reared in micron meshed cages under open sea conditions for a period of three months. During the third month, spats grown in micron meshed cages showed growth increments of 7.83 mm (DVM), 4.86 mm (HL), 1.61 mm (THK) and 0.192 g (WGT) whereas those grown in FRP tanks grew only by 0.95 mm (DVM), 0.5 mm (HL), 0.46 mm (THK) and 0.004 g (WGT) indicating faster growth in open sea conditions. Second experiment was conducted to elucidate the effect of stocking density on the growth and survival of juveniles reared in plastic baskets at different stocking densities viz., 200 (0.03 nos. cm-3) 300 (0.049 nos. cm-3), 400 (0.065 nos. cm-3), 500 (0.08 nos. cm-3), 600 (0.098 nos. cm-3), 700 (0.11 nos. cm-3), 800 (0.13 nos. cm-3), 900 (0.14 nos. cm-3) and 1000 (0.16 nos. cm-3) numbers per basket. Results indicated that P. imbricata fucata juveniles can be grown at stocking densities of up to 400 per basket for a period of five months with 90% survival without much reduction in growth. Third experiment was conducted on the growth of P. imbricata fucata subadults in box cages at different stocking densities viz., 200 (0.006 nos. cm-3), 300 (0.01 nos. cm-3), 400 (0.013 nos. cm-3), 500 (0.016 nos. cm-3), 600 (0.02 nos. cm-3), 700 (0.023 nos. cm-3), 800 (0.026 nos. cm-3), 900 (0.03 nos. cm-3) and 1000 (nos. cm-3) numbers per cage. Survival rates ranged from 98.5 to 98.6% at stocking densities up to 400 per cage during the fifth month without any significant variation in the DVM, HL and THK of oysters.

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Feeding, Growth, and Survival of Atlantic Cod (Gadus morhua) Larvae Reared in Replicate Plastic Enclosures

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-105 ◽

1993 ◽

Vol 50 (5) ◽

pp. 913-924 ◽

Cited By ~ 12

Author(s):

Håkon Otterå

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Brachionus Plicatilis ◽

Larval Mortality ◽

Larval Density ◽

Larval Growth ◽

Stocking Density ◽

Gut Content ◽

Growth And Survival ◽

Rearing Conditions

Feeding, growth, and survival of Atlantic cod (Gadus morhua) larvae were examined during their first 2 mo of life. The experiment was carried out in eight plastic enclosures of 10 m3 volume each. Larval cod, at an initial stocking density of 10 larvae/L, were fed rotifers (Brachionus plicatilis) and natural zooplankton collected from the sea. The enclosures replicated well with regard to hydrography, feeding conditions, and larval growth and survival. Larval mortality was low during the first month, with a mean mortality rate (Z) of 0.02/d. Growth, however, was very slow and mortality increased significantly after about 4 wk, possibly due to starvation. Brachionus plicatilis dominated the gut content during the first 3–4 wk. The zooplankton concentration averaged 15–80 rotifers/L during the first 2 wk, which seemed to be insufficient under the present rearing conditions. Most of the larvae were distributed in the upper parts of the rearing enclosures, while rotifers were distributed deeper. This, together with the high larval density, inadequate rotifer enrichment, and low temperature probably amplified the unfavourable feeding conditions.

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Effect of different weaning time on the growth and survival ofCommon carp (Cyprinus carpio L.) larvae

Acta Agraria Debreceniensis ◽

10.34101/actaagrar/75/1646 ◽

2018 ◽

pp. 55-59

Author(s):

Dániel Minya ◽

László Kovács ◽

Dávid Homoki ◽

Milán Fehér ◽

Péter Bársony ◽

...

Keyword(s):

Survival Rate ◽

Survival Rates ◽

Stocking Density ◽

Artemia Salina ◽

Live Food ◽

Biomass Growth ◽

Growth And Survival ◽

Production Parameters ◽

Rearing Conditions ◽

The Individual

Within our experiment, we studied the combined effect of live food application and feed training on the production parameters of carp larvae. In addition, we examined whether there is a difference in the growth rate and survival rate of the specimens of Szeged mirror landrace reared in similar stocking density but with different treatments. Specimens of Szeged mirror landrace from induced propagation were placed into 12 pieces of 40-liter aquaria. For the 4 different treatments, (K, A3, A6, A9), live food (Artemia salina) was fed, as well as feed training was applied. We also sought to find an answer as to how our feeding and rearing conditions can affect the production parameters of common carp fries and what impact these conditions may have on their survival rates. At the end of the 2-week experiment we determined the individual weight gain of the carp fries, their survival rate and the biomass growth. The purpose of the study is to examine the optimum timing of shifting from live food to feed for carp larvae.

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