PHILIPP AGRIC SCIENTIST
Vol. 95 No. 4, 378–385
December 2012
ISSN 0031-7454
Skip Feeding as an Alternative Strategy in the Production of Nile
Tilapia Oreochromis niloticus (Linn.) in Cages in Selected Lakes in the
Philippines
Maria Lourdes Cuvin-Aralar1,*, Philip Gibbs2, Adelaida Palma3, Aida Andayog4 and Lydia
Noblefranca4
1
Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC/AQD), Binangonan Freshwater
Station, Binangonan, 1940 Rizal, Philippines
2
Industry and Investment NSW Division of Primary Industries (Fisheries), 202 Nicholson Parade, Cronulla, New South
Wales, Australia 2035
3
National Inland Fisheries Technology Center, Bureau of Fisheries and Aquatic Resources, Km 53 Manila East Road,
Tanay, Rizal, Philippines
4
Bureau of Fisheries and Aquatic Resources, Region V, Pili, Camarines Sur, Philippines
*
Author for correspondence; e-mail: [email protected]; Phone: +63-9178615992
Many inland water bodies in the Philippines are currently used for fish cage culture. Inappropriate
practices including feed management in aquaculture results not only in the degradation of water
quality but also in economic losses for the fish farmers. The effect of two feeding management
schemes on the production of cage-cultured Nile tilapia Oreochromis niloticus (Linn.) in Lakes Bato
and Buhi in Camarines Sur Province and Laguna de Bay in Rizal Province were studied. Daily
(DAILY) and skip-feeding (SKIP) schemes using the same daily ration based on standing biomass
were used. Mean final weight and daily growth rate were 18% higher in DAILY compared with SKIP
in Lake Bato. No significant differences in both parameters were observed in tilapia reared in the
two feeding treatments in Lakes Buhi and Laguna de Bay. Condition factor, survival and final yield
did not show any significant differences in both treatments in all three lakes. Significant differences
in feed conversion ratios (FCR) were observed between the two treatments with SKIP having 36%
lower feed conversion ratio (FCR) in Lake Bato and 41% lower FCR in Lake Buhi and Laguna de Bay
compared with the DAILY treatment. The results suggest that skip feeding is an economically and
ecologically viable alternative to the cage culture of Nile tilapia in cages.
Key Words: cage culture, feeding management, Nila tilapia, skip feeding, sustainable aquaculture
Abbreviations: ACIAR – Australian Centre for International Agricultural Research, BFAR – Bureau of Fisheries and
Aquatic Resources, CS – cooperator site, DGR – daily growth rate, FCR – feed conversion ratio, FM – feeding
management, SEAFDEC/AQD – Southeast Asian Fisheries Development Center, Aquaculture Department
INTRODUCTION
The cage culture of tilapia (mainly Oreochromis
niloticus) is a major contributor to the livelihood of rural
communities in many parts of the Philippines. Inland
water bodies such as lakes and reservoirs have been used
for tilapia culture. As is typical in inland bodies of water
used for aquaculture, among the problems identified is
environmental degradation, brought about by excessive
stocking and improper feeding practices. Lakes Bato,
Buhi and Laguna de Bay are among the largest lakes in
the Philippines widely used for tilapia cage culture
(Bagarinao 2001; Guerrero 2001; Richter et al. 1999).
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Lake Bato is a eutrophic lake in the province of
Camarines Sur, Philippines. It ranks 7th in terms of size
among the inland bodies of water in the Philippines
(Guerrero 2001). It has an area of 3,800 ha and is widely
used for aquaculture and open water fisheries. Tilapia
cage culture in the lake started in the late 1970s. Nile
tilapia and their hybrids are the primary species of culture
in fixed net cages. There are an estimated 247 registered
fish cage operators in the lake and the total number of
fish cages is close to 14,000 based on 2005 data (Pili,
Municipal Agriculturist of Bato, pers. comm).
Lake Buhi, on the other hand, has an area of 1,800
ha, and is also used for aquaculture and fisheries. It is
also located in the Province of Camarines Sur. This lake
The Philippine Agricultural Scientist Vol. 95 No. 4 (December 2012)
Skip-feeding in Cage-cultured Nile Tilapia
was adjudged as the “Cleanest Lake in the Philippines” in
1996 (SCPW 2012). However, because of the widespread
activities in the watershed (agriculture and forestry) as
well as in the lake itself (aquaculture), the lake’s water
quality has since deteriorated. The lake is surrounded by
10 coastal villages engaged in fish farming. Forty to 80%
of the population is engaged in fishing or fish farming
(Binoya and Gerpacio 2008). Eighty percent of the fish
produced in Lake Buhi is tilapia, mainly from cage
culture operations.
Laguna de Bay is the largest inland body of water in
the Philippines with a surface area of 90,000 ha (LLDA
2012). The lake is shallow with a mean depth of 2.8 m; it
is eutrophic and widely used for cage and pen culture.
Recent production figures for Nile tilapia in the lake
averaged 10,472 metric tons between 1996 and 2006
(Israel et al. 2008) with an annual growth rate of 9.85%
for the same period.
Traditionally fish cages started out in these three
lakes, relying mainly on the lake’s natural productivity.
The decline in production resulted in a change in culture
practices to intensive feeding particularly a few months
prior to harvest. All three lakes are now overpopulated
with fish cages and the natural production in these lakes
can no longer sustain the growth of the cultured fish
species without feeding. Unsound feeding practices have
resulted in massive fish kills attributed to deterioration of
water quality in these lakes (Cuvin-Aralar et al. 2001;
Arguelles et al. 2010).
Various feeding management options have been
suggested to decrease feed inputs as well as to address
issues of eutrophication from aquaculture activities.
Mixed feeding and restricted feeding regimes in various
approaches have been used for a number of fish species
such as barramundi Lates calcarifer (Tian and Qin 2003,
2004), gilthead sea bream Sparus aurata (Eroldoğan et
al. 2008), red sea bream Pagrus major (Oh et al. 2007),
channel catfish Ictalurus punctatus (Chatakondi and Yant
2001), Nile tilapia (Barretto et al. 2003; Wang et al.
2009) and hybrid tilapia Oreochromis mossambicus x O.
niloticus (Wang et al. 2004, 2005). These strategies use
fixed periods of no feeding and re-feeding, with the fish
fed usually to satiation during the re-feeding phase. This
type of feeding management hopes to take advantage of
the capacity of the species for compensatory growth,
which restores the original growth trajectory during
recovery from total or partial feed deprivation (Ali et al.
2003).
Instead of prolonged periods of starvation and refeeding cyle, Bolivar et al. (2006) used the alternate day
feeding strategy for Nile tilapia cultured in ponds and
showed that fish remained healthy and robust in this type
of feeding management with no significant difference in
production performance variables, with yield comparable
to those fed daily. In another study, hybrid tilapia given a
The Philippine Agricultural Scientist Vol. 95 No. 4 (December 2012)
Maria Lourdes Cuvin-Aralar et al.
restricted diet of 3% of total body weight rationed 1, 2
and 3 d a week with subsequent daily feeding showed
compensatory growth only for those fish with the 1- and
2-d feed restriction weekly (Abdel-Hakim et al. 2009).
Previous studies on alternate-day feeding in Nile
tilapia culture were conducted in pond systems (Bolivar
et al. 2006) but none thus far has been conducted in cages
in open waters. This study was conducted from 2008 to
2010 as part of a project funded by the Australian Centre
for International Agricultural Research (ACIAR) to
determine the production response of cage-cultured Nile
tilapia to a skip-feeding or an alternate day feeding
regimen initially in Lakes Bato and Buhi. A subsequent
run in Laguna de Bay was also conducted to determine if
the results obtained in the previous trial would also be
applicable to other lakes used for tilapia cage culture.
MATERIALS AND METHODS
Feeding Management
Two feeding management schemes were tested in the
cage culture of Nile tilapia in three different lakes. The
feeding scheme used is shown in Table 1. One treatment
(DAILY) received feed twice daily at 0800 h and 1600 h.
The other treatment received the same feed ration at the
same schedule but only on Mondays, Wednesdays,
Fridays and Saturdays (SKIP). No feed was dispensed the
rest of the week. Twice daily feeding schedule was
adapted because this frequency did not show any
disadvantage compared with more frequent (e.g., four
times daily) feeding in terms of fish growth and feed
utilization. Moreover, it has the added advantage of
reducing labor costs (Schmittou 2006). The commercial
feeds dispensed in each of the lakes were selected based
on the type of feed commonly used by the fish farmers in
each lake. The feeding rates were adjusted based on the
estimated total weight of fish in each cage. Feed ration
was adjusted mid-way between sampling based on
estimates of growth rate obtained from the most recent
fish sampling. No feed was dispensed on the sampling
days.
Lake Bato
Two sites for the cage culture trial were identified for
Lakes Bato. One site was licensed to Mr. Alejandro Pili
(PIL) and the other to Mr. Pascual San Buena (BUE). In
each site, six cages with dimensions of 5 m x 5 m x 2 m
were set up. The depth of the cages used in each of the
lakes was typical of that used by fish farmers in these
lakes. Nile tilapia fingerlings with average size of 2.7 +
0.9 g were stocked in each of the cages at a stocking
density of 10 fish per m3 (500 fingerlings per cage). The
stocking density was based on the results of a previous
stocking density experiment conducted in the same lake
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