424
The Biology of Sea Turtles, Vol. II
body weight as determined by a formula developed by the NMFS STF for Kemp’s
ridleys. The formula is also used for loggerheads. The food is scooped from a bucket
by hand, with the feeder being the unit of measurement. Each turtle is given one
scoop, twice per day. The NMFS STF feeding formula is
Y = 0.12515 + [(11.502x)/1000]
where x = turtle weight in grams and Y = amount of feed per turtle per day in grams.
Each turtle is individually fed, ensuring that all turtles get approximately the
same amount of food.
16.6.3 HATCHLINGS
NMFS STF hatchlings are not fed until they are 10 days of age. Often, hatchlings are
physically excavated from the nest, thus, they have not expended any energy emerging,
crawling, or swimming. At rearing facilities, hatchlings are housed in relatively confined containers where swimming motion and energy expenditure are minimal; a longer
time period is required for them to completely absorb the internal yolk sac. A delay
in feeding gives the hatchlings an opportunity to partially absorb the internal yolk
before they take in external nutrition. Feeding hatchlings prior to yolk sac absorption
can result in constipation, lethargy, dehydration, and sudden death (Leong et al., 1989;
Fontaine and Williams, 1997). Necropsy results on hatchlings fed prior to yolk sac
absorption show compaction of food in the gut caused by the yolk sac displacement
of internal organs (Leong et al., 1989; Fontaine and Williams, 1997).
16.6.4 POST-HATCHLINGS
Turtles are fed twice per day, at the beginning and end of the normal business day,
at 7:30 a.m. and 4:00 p.m. The turtles are allowed 15–30 min to consume the morning
feeding before the tanks are drained and cleaned. Hatchlings typically take longer
to consume their food than the larger turtles, and are given a minimum of 30 min
to consume food presented. On average, a healthy sea turtle will consume 100% of
food offered within 15 min.
16.6.5 GROWTH AND SURVIVAL
Sea turtle growth is directly related to food consumed and is exponential (Caillouet
et al., 1989; 1997; Fontaine, unpublished data) (Figure 16.4). Survival rates are
variable among different species and facilities and are a function of genetics and
husbandry practices (i.e., water quality, feed, disease prevention and treatment). Most
mortality occurs at the hatchling stage, and mortality levels off by month 6. Facilities
with steep and rapid growth curves also have lower survival; this may be a function
of water quality related to feeding. Much of the published data are from large-scale
captive rearing operations, and the same growth–survival trend may not be present
in smaller facilities such as zoos and aquaria. Sea turtle growth can be accelerated
or maintained by varying the amount of food offered.
1123_C16 Page 424 Tuesday, November 12, 2002 8:28 AM
The Biology of Sea Turtles, Vol. II
body weight as determined by a formula developed by the NMFS STF for Kemp’s
ridleys. The formula is also used for loggerheads. The food is scooped from a bucket
by hand, with the feeder being the unit of measurement. Each turtle is given one
scoop, twice per day. The NMFS STF feeding formula is
Y = 0.12515 + [(11.502x)/1000]
where x = turtle weight in grams and Y = amount of feed per turtle per day in grams.
Each turtle is individually fed, ensuring that all turtles get approximately the
same amount of food.
16.6.3 HATCHLINGS
NMFS STF hatchlings are not fed until they are 10 days of age. Often, hatchlings are
physically excavated from the nest, thus, they have not expended any energy emerging,
crawling, or swimming. At rearing facilities, hatchlings are housed in relatively confined containers where swimming motion and energy expenditure are minimal; a longer
time period is required for them to completely absorb the internal yolk sac. A delay
in feeding gives the hatchlings an opportunity to partially absorb the internal yolk
before they take in external nutrition. Feeding hatchlings prior to yolk sac absorption
can result in constipation, lethargy, dehydration, and sudden death (Leong et al., 1989;
Fontaine and Williams, 1997). Necropsy results on hatchlings fed prior to yolk sac
absorption show compaction of food in the gut caused by the yolk sac displacement
of internal organs (Leong et al., 1989; Fontaine and Williams, 1997).
16.6.4 POST-HATCHLINGS
Turtles are fed twice per day, at the beginning and end of the normal business day,
at 7:30 a.m. and 4:00 p.m. The turtles are allowed 15–30 min to consume the morning
feeding before the tanks are drained and cleaned. Hatchlings typically take longer
to consume their food than the larger turtles, and are given a minimum of 30 min
to consume food presented. On average, a healthy sea turtle will consume 100% of
food offered within 15 min.
16.6.5 GROWTH AND SURVIVAL
Sea turtle growth is directly related to food consumed and is exponential (Caillouet
et al., 1989; 1997; Fontaine, unpublished data) (Figure 16.4). Survival rates are
variable among different species and facilities and are a function of genetics and
husbandry practices (i.e., water quality, feed, disease prevention and treatment). Most
mortality occurs at the hatchling stage, and mortality levels off by month 6. Facilities
with steep and rapid growth curves also have lower survival; this may be a function
of water quality related to feeding. Much of the published data are from large-scale
captive rearing operations, and the same growth–survival trend may not be present
in smaller facilities such as zoos and aquaria. Sea turtle growth can be accelerated
or maintained by varying the amount of food offered.
1123_C16 Page 424 Tuesday, November 12, 2002 8:28 AM