Applied Ecophysiology: An Integrative Form to Know How Culture Environment Modulates the Performance of Aquatic Species from an Energetic Point of View - Aquaculture and the Environment: A Shared Destiny - page 166

With these equations it is possible to calculate how much of energy abalones needs per mg
of biomass, how much of energy could be obtained, as a scope for growth per joule of
ingested food (Table 2) and at the end the quantity of food that is needed to produce 1g of
living abalone.

joules
day -1 mg -1

H U R SFG

%

Physiological response %

Inge sti on rate I 457 100

4

14

Fece s H 62 14

45

Absorption rate Ab 395

Nitrogen excretion rate U 16 4

38

Re spi rati on rate R 172 38

Scope for growth SFG 207 45

Table 2. Energetic balance obtained on optimal culture conditions of H. fulgens . Values
obtained from equations derived from table 1. Circle indicates the proportion (%) of
ingested energy (100%) that is channeled to each physiological response.

To make the calculations it is necessary to consider that 1g living abalone have 0.13g of dry
weight biomass DBW (Table 1), that food have 18000 joules g -1 (Farias et al., 2003) and that
scope for growth obtained was around 207 joules day -1 mg -1 DBW (Table 2). Following the
next steps:

1. Joules day -1 needed to produce 1g living abalone =

( )

( )

− 1 − 1

130 mg DBW of abalone contained into 1g living weight x 207 joules day mg DBW

1 mg DBW
35, 100 joules day

−− 11

= g LW

2. If 1g of food have a content of 18,000 joules g -1 , but only 45% of it (8,100 joules g -1 ) are

really converted in biomass, then the quantity of food required to produce 1g of living
abalone will be:

Food to produce 1g of living abalone = 35.1 kjoules day -1 g -1 /8.1 kjoules g -1 = 4.3g or 4.3kg of
food for 1kg of abalone. With these models it is possible to help farmers to calculate not only
biomass production levels but cost of that biomass production.

In a more generalized application of energetic balance results it is possible estimate the
food needed to produce other abalone species as H. rufescens (Hernández et al . , 2009). In
that case formulated diet with 4.15 kjoules g -1 wet weight were compared with two macro
algae with 2.7( Porphyra columbiana ) and 0.92( Macrocystis pyrifera ) kjoules g -1 wet weight
energy contents, respectively. At the light of that energy contents and assuming the same
conversion efficiency of H. fulgens (45%) it is possible to observe that to produce 1kg of
abalone with macro algae will be necessary to use 4.15kg of formulated food, 28.9kg of P.
columbiana and 84 kg M. pyrifera , both given as a fresh food. Results of the H. rufescens
assay showed that abalones fed with macro algae grew 120% and 40% higher than
observed in animals fed formulated diet suggesting that macro algae could be used to
cultivate abalones instead of formulated diet. However natural production of macro algae