1978 year-class in descending order. The Padre Island National
Seashore “imprint"-groups of the 1978 and 1980 year-classes grew
faster than the corresponding Rancho Nuevo "imprint"-groups. The
opposite was true for the two “imprint"-groups of the 1979 yearclass.
Detransformed growth curves for year-classes 1978-1980 are shown
in Figure 3. While these curves are not strictly comparable to those
of year-classes 1981-1983, due to differences in the time variable
used on the abscissa as well as different levels of sampling
variation, one can get an impression from Figure 3 of the differences
in growth among all of the year-classes. Year-class 1980 stands out

as the best-growing year-class, and 1983 as the poorest.

Biomass Increase Comparisons

The slope of the straight-line relationship represented by
equation 5 was an index of the rate of increase in biomass with age
for year-classes 1981-1983 (Table 10). In Figure 4, the indices for
each clutch within year-classes 1981-1983 are plotted along with hori-
zontal lines representing the “average” (common) biomass increase
indices for each year-class. Three features of these plots are worth
noting as compared to Fig. 2. First, the rank order of the two indi-
ces (weight increase and biomass increase) by year-class is the same.
Second, for each year-class, the common index (horizontal line) for
biomass increase (Fig. 4) was lower than that for the comparable
weight increase index (Fig. 2), indicating that the rate of increase
in individual weight was faster than the rate of increase in biomass.
Third, the common index for biomass increase varied more among year-
classes than the common index for growth in weight. In other words,
year-classes and clutches showed greater similarity in growth rate
than they did in rate of biomass increase, the difference reflecting
variability in survival among clutches and year-classes. Analysis of
covariance (Table 11) detected significant differences among the
slopes of the regressions (equation 5) applied to clutches within the
1981-1983 year-classes (Table 10), indicating significant differences

among biomass increase indices within year-classes.

16


Table 2. Number of times (m) that samples of weights and measure-
ments of Kemp's ridleys were taken, by yearclass, “imprint"-
—group, and clutch.

LAS SSATP tyr Pr re P-rich eve SP

No. of times

Year- "Imprint "= sampled,
class groupl/ Clutch m
1978 PINS Na2/ 4}
RN " 24
1979 PINS " 39
RN " 15
1980 PINS " 52
RN " 10

me NNN A a ae fr Pa eth ent pedajearemmmammmmenms

1981 PINS 1 11
2 10
3 10
4 il
5 1l
6 11
7 11
8 ll
9 10

10 11
11 10
12 1l
13 11
14 11
15 ll
16 ll
17 11
18 11
19 10
20 10
21 11
22 10
23 10

aT I SS Sch fv SS nary unin entnaspeenaeren


Conservation and Management, National Marine Fisheries Service and
Texas A&M University, Galveston, TX.

Marquez, Re 1972, Resultados preliminares sobre edad y crecimiento

de la tortuga lora, Lepidochelys kempi (Garman). Mem. IV Congreso
Nac. Oceangr. (Mexico), p. 419-427.

McVey, Je Per Je Ke Leong, R. S. Wheeler and R. M. Harris. MS. The
culture of young Kemp's ridley sea turtles (Lepidochelys kempi).

Unpublished manuscript, NMFS SEFC Galveston Laboratory, Galveston,
TX,

McVey, J. P. and T. Wibbels. 1984. The growth and movements of
captive-reared Kemp's ridley sea turtles, Lepidochelys kempi,
following their release in the Gulf of Mexico. NOAA Technical
Memorandum NMFS-SEFC~145, 25 p. plus 3 figures and 3 tables.

Mrosovsky, N. 1983. Conserving sea turtles. The British
Herpetolog. Soc. c/o the Zool. Soc. of London, 176 p.

Nuitja, I.N.S. and I. Uchida. 1982. Preliminary studies on the
growth and food consumption of the juvenile loggerhead turtle
(Caretta caretta L.) in captivity. Aquaculture 27:157-160.

Owens, D. W., M. Ae Grassman, and J. R. Hendrickson. 1982. The

imprinting hypothesis and sea turtle reproduction. Herpetologica
38(1):124-135,.

Pritchard, P. C. H. and R. Marquez M. 1973. Kemp's ridley turtle
or Atlantic ridley. Internat. Union for Conservat. of Nature and
Nat. Resources, Monograph No. 2, 30 p.

Rajagopalan, M. 1984, Studies on the growth of olive ridley

Lepidochelys olivacea in captivity. Central Mar. Fish. Res.
Inst. Bull. 35:49-54, Indian Council of Agricult. Res., Cochin,
India.

33


Table 6. Regtilinear regressions (equation 1) of, the natural logarithms of weights (1nW;
: fe)

gen ee uare sect Of ages (T'72; T in days Kemp's ridleys, by clutch
Coefficient of
Intercept, Slope, Variance of deviations determination,
Year—class Clutchl/ Ina b from regression, Siev. 2
1981 1 2e27 0.217 0.9070 0.932
2 2.18 0,254 0.046 0.964
3 2.32 0.229 0.059 0.948
4 2.44 0.228 0.055 0.949
5 2.21 0. 250 0,032 0.974
6 2.34 0. 240 0.025 0.978
7 2.41 0.237 0.030 0.975
8 2.38 0. 240 0.024 0.980
9 2.41 0. 237 0.028 0.977
10 2.27 0, 242 0.040 0.967
11 2.38 0.239 0.031 0.975
12 2.38 0.232 0.031 0.972
13 2.44 0.223 0.0338 0.961
14 2.36 0.243 0.032 0.974
15 2.46 0.230 0.034 0.968
16 2.35 0.247 0.022 0.983
17 2.30 0. 249 0.024 0.981
18 2.41 0.234 0.033 0.971
19 2.31 0.226 0.059 0.952
20 2.38 0.230 0.041 0.967
21 2243 0.216 0.064 0.940
22 2.35) 0.242 0.051 0.964
23 2.20 0,253 0.030 0.980
Clutches
combined 2.34 0.238 0.049 0.960
1982 1 2.33 0.216 0.017 0.860
2 2.35 0.255 0.061 0.944
3 2.28 0,267 0.053 0,967
4 2.56 0.250 0.045 0.969
5 2.55 0.249 0.031 0.978
6 2.49 0, 246 0.066 0.954
7 2.12 0.274 0.029 0.982
8 2216 0.271 0.092 0,942
9 2.32 0.264 0.023 0.985
10 2.33 0,231 0,015 0.886
11 2.41 0.247 0.011 0.921
12 2.51 0.257 0.051 0.966
13 2.20 0,267 0,062 0.959
14 2.22 0.264 0.039 0.975
15 2.20 0.260 0,041 0.974
16 2.16 0,259 0,041 0.974
17 2.33 0.254 0.047 0.970
18 2.35 0.261 0.022 0.986
19 2.22 0,257 0.042 0.974
20 2.21 0.267 0.059 0.965
chapehed 2.30 0.257 0.089 0.943

CO a a



medium-sized crabs, > of a SEATAB tablet, and two veterinary-grade
vitamin capsules (one containing 10,000 IU of vitamin A and 400 IU of
vitamin D, and the other containing 400 IU of vitamin £).

Health care for the turtles consisted of prophylactic and thera-
peutic measures associated with research in turtle pathology (Clary
and Leong 1984: Leong et al., MS).

Environmental Variables

During the rearing operations, salinity, pH and 24-hr maximum and
minimum water temperatures were monitored intermittently in selected
raceways, and served as general guides to environmental conditions
(Fontaine et al., 1985; McVey et al., MS). Temperature ranged from a
low of 20°C (with occasionally lower temperatures in September-
February) to 30°C (with occasionally higher temperatures in July-
September), on an annual cycle. During winter, despite the heating of
the air in the quonset huts with forced-air heaters and the incoming
seawater by immersion heaters, the temperature in the raceways
dropped. Levels of pH were slightly above 7.0 during most of the
year, except in late summer and fall when they increased to levels
near 7.5. Occasionally this range was extended by somewhat lower and
higher pH, respectively. For the most part, salinity was near 26 ppt,
tising above 30 ppt in July-September and dropping below 20 ppt in
May~June. A more precise assessment of environmental conditions was
not possible due to limitations on quantity and quality of the

available data.

Rectilinear Regression Analyses

Rectilinear regressions of the form Y = a + bX are used a number
of times in this paper to fit straight lines to various groups of
data. ‘Therefore, the dependent variable, "y", the independent
variable, "Xx", and parameters a and b represent different quantities

when representing different data sets.

Rationale for Logarithmic Transformation of Weights
The range in weight among individuals increased with age or time,
indicating that variance in weight was heterogeneous (Caillouet and
10


Weight Increase Index

8. 306

GB.275 4,
A A A
“ 4
4
ow 1982
8.258 4 4 @ A A o °?
© 5 26 ° ° 4 - °
o 6 A ° ° °
8.2254 8———* 19983 ° ©
|” °
8.208
8.175
8.152
rTT?T?Trirrirrili?rritrtririrtitrtittt
1 3 5 4 S 11 13 1S 17 19 2 | 23
Clutch Number
Figure 2. Weight increase indices for Kemp's ridley clutches of the

1981-1983 year-classes. These indices were calculated from
rectilinear regression equation 1 (see Table 6). The
horizontal lines represent the "average" weight increase

index for each year-class based on the common regression

for combined clutches of a year-class.


Table 12. Parameter estimates for Gompertz growth function fitted to
datal/ on weight (W, in kg) versus lapsed time (T', in days)
for 10 head started Kemp's ridleys of the 1978 year-class main-

tained at Sea-Arama Marine World, Galveston, Texas,

Uh a a a, a —

Estimated
Parameter2/ value
Wo 0.2513 kg
Woo 29.2 kg
G 4.756
g 0.001551

Re a le a

1/The number of paired observations of W and T!' was 436.

2A = WoeGU-e79TM" Dag

where,
W is the weight in kg at lapsed time T’ in days
Wo is the weight at T' = 0.
G is the instantaneous growth rate at T' = 0.
g describes the rate of decrease in G.

a is the residual or deviation from regression.

W = Woe?
where,

W, is the upper asymptotic weight in kg

The coefficient of determination, re, was 0.959, and the variance of
deviations from regression, 32, was 1.696.

See Ricker (1975, p. 232)


Percent Survival

1B

© rN
7
Oo , 27 &
Oo A
© @7
Oo °P A
oO A A 4
98 8 °
oO 8. 4
A
© o A A
© 4
©O
8a— 4
| 4
| a
78— 6
6 “
©
9
|
5@
8.210 8.2408 0.2/2
Weight Increase Index
Figure 6. Relationship between percent survival (at the end of the

head starting period) and the weight increase index for
clutches of the 1981 (circles), 1982 (triangles) and 1983
(squares) year-classes of Kemp's ridley.

8.306


Table 10. Continued

Coefficient of

Intercept, Slope, Variance of deviations determination,
Year—class Clutch Ina b from regression, Shov. r2
1983 1 -0.244 0, 202 0.016 0.989
2 —0.483 0. 237 0.021 0.989
3 -1.381 0.168 0.024 0.981
Clutches
combined —0.807 0.217 0.692 0.653

V/see Table 2 for number of paired observations of B and T taken over the head starting
period. It is the same as the number of times, m, the turtles were weighed over the
head start period.


of different clutches that hatched at different times. The
“imprinting” per se was not expected to have had any effect on growth.
The variability among individuals and the patterns of growth of aggre-
gates of turtles of the 1978 and 1979 year-classes could have been
influenced by the intermittent "cropping" of the largest animals.

The distribution of clutches among rearing containers was not ran-
dom. Therefore, any differences in growth among clutches or between
"imprint"-groups of turtles were confounded with locational or
microenvironmental effects. Because clutches were received and
distributed among the rearing containers over time, the clutch and
"“imprint"-group effects are, in part, sequential effects reflecting
the different ages of the clutches as well as the order in which they
were received and distributed. Also, clutches within year-classes did
not all hatch at the same time, so they were not all reared over pre-
cisely the same time interval within each head starting year.
Therefore, the survival and growth of different clutches could have
been affected differently by seasonal effects, depending on the time-
phasing of the rearing and sampling within the year, and this could
have contributed to the observed variability among year-classes.
Clutches were not distinguished in the 1978-1980 year-classes, so no
information is available on clutch effects for these year-classes.
Even though differences in patterns of survival, variability and
growth among clutches, "imprint"-groups and year-classes can be
depicted (Caillouet and Koi, 1985), the causes of these differences
remain obscure.

Because the food and feeding regimen was more or less the same for
most of the year-classes, the large differences in growth rate among
year~-classes suggest some other cause (perhaps temperature differences
among years). Based on nationwide temperature data in Kerr (1985),
the average winter (December, January, February) temperatures for the
years of head starting can be ranked by year, from highest to lowest,
in the following order: 1982-1983, 1980-1981, 1979-1980, 1981-1982,

1983-1984, and 1978-1979. The rank order of growth rates from highest
to lowest did not correspond exactly with the rank order of average

20


Table 2, continued

No. of times

Year- "Imprint"- sampled,
class group!/ Clutch TMm

1982 PINS 1 1i

2 il

3 11

4 11

5 11

6 11.

7 11

8 1l

9 ll

10 ll

11 11

12 11

13 11

14 11

15 11

16 11

17 11

18 11

19 ll

20 11

1983 Pins3/ 1 6

2
3
1/prIns = Padre Island National Seashore;
RN = Rancho Nuevo.
2/NA = Not applicable: clutch identity was not maintained for the
first three year-classes.
3/pINS-"imprinted" clutches 5, 6, 9, 12, 14 and 17 and the
RN-"imprinted" turtles of the 1983 year-class were excluded from
all analyses due to low numbers of turtles in these clutches (see
Table 1).


BACKGROUND

The only known nesting colony of Kemp's ridley sea turtle,
Lepidochelys kempi, estimated to contain more than 40,000 nesters in
1947 (Hildebrand, 1963), has dwindled to fewer than 600 (Jack Woody,
U.S. Fish and Wildlife Service, Albuquerque, NM, personal com
munication, June 1986). The nesting beach is located near the village
of Rancho Nuevo, Tamaulipas State, on Mexico's upper coast bordering
the Gulf of Mexico (Carr, 1963; Casas-Andreu, 1978: Chavez et al.,
1968; Hildebrand, 1963; Pritchard and Marquez, 1973). The most likely
cause of the pronounced decline in nesters is excessive exploitation
of the turtles and eggs by man, but predation and other natural causes
have not been eliminated as contributing factors (Caillovet, 1984).

In 1966, the Mexican government initiated biological investiga-
tions and beach patrols to prevent Kemp's ridley, the most endangered
of the sea turtle species, from becoming extinct (Chavez et al.,
1968). In 1978, the U.S. Fish and Wildlife Service (PWS), the
National Park Service (NPS), the National Marine Fisheries Service
(NMFS), and the Texas Parks and Wildlife Department (TPWD) joined with
Mexico's Instituto Nacional de la Pesca (INP) in a cooperative program
directed toward enhancement of the Kemp's ridley population (Klima and
McVey, 1981). The program's objectives now include: (1) prohibitions
on the possession and sale of the eggs, turtles and various turtle
products for which the demand is substantial: (2) protection of the
nesting turtles, their nests and eggs by Mexican military personnel
and international teams of biologists through beach patrols during the
nesting and hatching season from April through August; (3) transloca-
tion of clutches of eggs to protected corrals at Rancho Nuevo: (4)
promotion of the use of specialized gear (turtle excluder device or
trawling efficiency device) to allow escapement of turtles caught
incidentally in shrimp trawls; (5) “head starting" Kemp's ridley with
a view toward establishment of a new nesting colony at the Padre
Island National Seashore near Corpus Christi, Texas, and (6) captive

propagation.
Head starting involves the incubation and hatching of eggs and


Carr, A. 1967. So excellent a fishe: a natural history of sea

turtles. The Amer. Museum of Nat. Hist. Press, Garden City, N. Y.
248 Pp.

Carr, A. 1980. Some problems of sea turtles ecology. Amer. Zool.
20: 489-498,

Casas-Andreu, G. 1978. Analisis de al anidacion de las tortugas

marinas del genero Lepidochelys en Mexico. An. Centro Cienc. del
Mar y Limnol. (Univ. Nal. Auton. Mexico) 5(1):141-158.

Chavez, H., M. Contreras G., and T. P. F. Herndandez D. 1968. On
the coast of Tamaulipas. Internat. Turtle & Tortoise Soc. J,
2(4):20-29, 37 and 2(5):16-19, 27-34.

Clary, J. C. IIT and J. K. Leong. 1984, Disease studies aid Kemp's

ridley sea turtle head start research. Herpetolog. Rev.
15(3):69-70,

Ehrenfeld, D. W. 1974. Conserving the edible sea turtle: Can
mariculture help? Amer. Sci. 62:23-31.

Fontaine, C. T., K. T. Marvin, T. D. Williams, W. J. Browning, R. M.
Harris, K. L. W. Indelicato, G. A. Shattuck and R. A. Sadler.
1985. The husbandry of hatchling to yearling Kemp's ridley sea
turtles, Lepidochelys kempi. NOAA Technical Memorandum NMFS-SEFC-
158, iii plus 34 p., 10 tables, 22 figures and 2 appendices.

Fontaine, C. T. and C. W. Caillovet, Jr. 1985. The Kemp's ridley
sea turtle head start research project: an annual report for
fiscal year 1984. NOAA Technical Memorandum NMFS-SEFC-152, ii
plus 13 p. and 3 tables.

Frazer, N. B. and. F. J. Schwartz. 1984. Growth curves for captive
loggerhead turtles, Caretta caretta, in North Carolina, U.S.A.
Bull. Mar. Sci. 34(3):485-489.

2)


Biomass Increase Index, Weight Increase Index, and Survival

Figure 5 shows the relationship between the biomass increase index
and weight increase index for clutches of the 1981-1983 year-classes.
A curved trend (concave downward) is evident with only one apparent
outlier represented by clutch 3 of the 1983 year-class. Clutch 3 was
sampled the fewest times of all clutches during head starting (Table
2), so it is not surprising that it was aberrant. Though 46 different
clutches representing three different year-classes were represented,
most of the points followed a rather tight pattern. Also, the two
indices converged (became more alike) as they increased.

Within the 1978-1980 year-classes, highest survival (95%) was
exhibited by year-class 1980, intermediate (83%) by year-class 1979,
and lowest (68%) by year-class 1978. Slowest growth was associated
with lowest survival and vice versa. Survival rates for the 1978-1980
year-classes treated as survivors not only the healthy turtles tagged
and released after the head start period, but also those transferred
to the Cayman Turtle Farm (year-class 1979) and marine aquaria
(year-classes 1978 and 1979), those tagged and released before the end
of the head start period (year-class 1978), and those that were abnor-—
mal, sick or permanently handicapped by injuries at the end of the
head start period and therefore were not tagged and released,

Survival in 39 of the 46 clutches of the 1981-1983 year-—classes
was above 80%. Among the clutches exhibiting less than 80% survival
over the head start period were 1, 13, and 21 of the 1981 year-class,
1 and 5 of the 1982 year-class, and 1 and 3 of the 1983 year-class.
Survival rates for the 1981-1983 year-classes included not only the
healthy turtles tagged and released after head starting, but also
those transferred to marine aquaria (year-class 1982), and those that
were abnormal, sick or handicapped at the end of the head start period
and therefore were not tagged and released.

A scatter plot of final survival (in %) against the weight
increase index (Fig. 6) for clutches of the 1981-1983 year-classes
showed wider variability than the plot in Figure 5. Survival and

growth rate increased concommitantly up to a point, then survival
appeared to decline with further increase in growth rate.

17


captivity. Fast growth in captivity may lead to early maturity,
assuming that the egg layings of 5-year-old and 7-year-old head started
Kemp's ridleys at the Cayman Turtle Farm represent earlier maturation
than would occur in the wild. If rapid growth in captivity leads to
early maturation, then the growth of head started turtles may slow
down (after maturity) at an earlier age as compared to wild turtles of
similar size that do not reach maturity as quickly (David W. Owens,
Department of Biology, Texas A&M University, College Station, TX, per-
sonal communication, November 1984). If true, captive rearing might
produce smaller adults with lower egg-laying capacity than turtles
that spend their entire lives in the wild. The 5-year-old Kemp's
ridleys that nested at the Cayman farm had a weight near 20 kg (Wood
and Wood, 1984), which is below the asymptotic weight of 29.2 kg esti-
mated from the Gompertz equation describing growth in the head started
Kemp's ridley at Sea-Arama Marineworld. Both of these weights are
well below those (39-49 kg) of adult female Kemp's ridleys nesting at
Rancho Nuevo (Chavez et al., 1968).

Our working hypothesis has been that larger yearlings have a
better chance of surviving in the wild than smaller ones. So far,
head starting of Kemp's ridleys has been directed toward maximizing
their survival and growth so as to provide as large a number of large,
healthy yearlings as possible for tagging and release. In this
respect, the methods used have been successful. Through control of
water temperature, the amount of food, and the frequency of feeding,
growth rate of captive-reared Kemp's ridleys probably can be manipu-
lated. Modifying the seawater management methods, stocking density,
size of containers, amount of food, and frequency of feeding might
increase survival and optimize growth while improving fitness of the
turtles for survival and maturation in the wild and in captive
breeding colonies. Achieving rapid growth in captivity, provided it
does not reduce the general health, fitness, survival or reproductive
efficiency of the turtles, may well be a good strategy for head
starting. However, the optimum growth rate for Kemp's ridleys to be
tagged and released or added to a captive brood stock remains to be
determined. There is much left to be learned about the relationships

among growth, survival and maturity in this species.

23


biomass. There was no randomization of clutches among the rearing
containers nor allocation of clutches according to an experimental
design for the purpose of segregating possible clutch (i.e., genetic)
effects from locational (among rearing containers) or microenvironmen-
tal effects. Rather, the data for this paper were fortuitous
outgrowths of higher-priority husbandry. The data came from
“mensurative experiments" which are experiments that involve the
taking of measurements at one or more points in space or time
(Hurlbert, 1984), As a result, it cannot be determined whether the
observed differences in growth rates among clutches, "imprint"-groups,
and year-classes reflect genetic effects, sex ratio differences, cli-
matic effects, locational or microenvironmental effects, or other
influences, because such effects were confounded. Evaluators of the
results presented herein should consider that the methods of collec-
ting the data reflected secondary and lower-priority purposes as com
pared to that of head starting the turtles,

If there are differences between male and female Kemp's ridley in
growth and survival, they could have contributed to the observed dif-
ferences in variability within aggregates of turtles in our analyses.
As far as we know, Kemp's ridley does not exhibit secondary sexual
characteristics during its first year of life. Because this species
is seriously endangered, sacrificing healthy animals to determine
their sex is prohibited. The gonads of most of the turtles that died
during head starting were excised and preserved for sex determination
by histological methods (Leong et al., MS). They were transferred to
Robert King, NPS, Corpus Christi, TX, and thence to David Owens, Texas
A&M University, College Station, TX, for sex determination. Wibbels
et al. (1986) have determined that there was a male bias in the sex
ratios of captive-reared Kemp's ridleys of year-classes 1981-1983.

Variability among clutches within the two "imprint"-groups of the
1978-1980 year-classes could have contributed to variation between
these two groups. Any differences observed between the two

"imprint"-groups could have occurred because the groups were made up

19


Grassman, M. A., D. W. Owens, J. P. McVey and R. Marquez M. 1984.
Olfactory-based orientation in artificially imprinted sea
turtles. Science 224:83-84,

Hildebrand, H. H. 1963. Hallazgo del area de anidacion de la

tortuga marina "lora", Lepidochelys kempi (Garman), en la costa
occidental del Golfo de Mexico. Ciencia (Mexico) 22(4):105-112.

Hirth, H. Fe. 1982. Weight and length relationships of some adult
marine turtles. Bull. Mar. Sci. 32(1):336-341.

Holden, C. 1984, Zoos forging new role in science: the day is

coming when zoos will be the preserver of endangered species.
Science 225(4658):147.

Hurlbert, S. H. 1984. Pseudoreplication and the design of ecological
field experiments. Ecol. Monogr. 54(2):187-211.

Kerr, Re Ae 1985. Wild string of winters confirmed. Science 227:506.

Klima, EF. F., and J. P. McVey. 1981. Headstarting the Kemp's ridley
turtle, Lepidochelys kempi, p. 481-487. In: Bjorndal, Karen A.
(ed.), Biology and Conservation of Sea Turtles, Proceedings of the
World Conference of Sea Turtle Conservation, Smithsonian
Inst. Press, Wash., D.C., 583 p.

LeBrun, Ge 1975. Elevage a la reunion de juveniles de la tortue
verte Chelonia mydas (Linnaeus) 1758. Science et Peche, Bull.
Inst. Peches marit. no. 248, 25 p.

Leong, J. Ke, De Le Smith, D. B. Revera, J. C. Clary III, D. H. Lewis,
J. Le Scott and A. R. DiNuzzo. MS. Health care and diseases of
captive-reared loggerhead and Kemp's ridley sea turtles.
Manuscript submitted for publication in the Proceedings of the
First International Symposium on Kemp's Ridley Sea Turtle Biology,

32


Samples taken from aggregates of turtles made up of more than one
clutch, as was the case for “imorint"-groups of the 1978-1980 year-
classes, contained possible clutch differences that would be expected
to inflate the variability in weight among individuals. Therefore,

a sample size larger than 25 would be required to detect mean dif-
ferences between samples containing mixed clutches. We would recom
mend against lumping clutches in samples, because it is easy enough
to keep track of clutch identities during head starting. Also, for
turtles kept in a captive breeding stock, the measurement of their
growth, as related to their parentage, may be an important criterion

in selective breeding.
RESULTS

Weight-Length and Width-Length Relationships

Relationships between weight and carapace length and between cara-
pace width and carapace length were calculated for each “imprint"—
group of the 1978-1980 year-classes and for each clutch of the
1981-1983 year-classes. The differences among the groups and clutches
appeared negligible, so the relationships were determined for data
lumped by year-classes (Tables 4 and 5). The exponent of the exponen-
tial weight-length relationship was near 3 (Table 4) as expected from
the "cube law" of growth in weight with length. The carapace of
Kemp's ridley is almost as wide as it is long (Carr, 1967), as con-
firmed by the observed slopes, slightly less than 1, for the rec-
tilinear width-length relationships (Table 5).

Growth Pattern and Variability in Weight

The range in weight increased as the animals grew larger and
there was a slowing of growth about the middle of the growth period
(Caillouet and Koi, 1985). As expected, variability in weight among
individuals at any given time during head starting was greater in the
1978-1980 year-classes than in the 1981-1983 year-classes (ibid.).
The two different forms of sampling, by “imprint"-group within the

1978-1980 year-classes (which included variation among clutches) and
14


end of each rearing period and had to be transferred to basins for a
short time before release.

Rearing containers were drained, flushed by hosing, and refilled
with clean seawater about thrice each week, except in rearing the 1978
year-class during which these were daily practices (Fontaine et al.,
1985; McVey et al., MS). Once each week, all containers were scrubbed
with brushes to remove attached algae and waste materials.

The 10 Kemp's ridleys {all "imprinted" at the Padre Island National
Seashore) transferred to Sea-Arama Marineworld were maintained there
in a concrete tank holding about 1,760 liter of seawater and parti-
tioned into 10 compartments (each 120 cm x 106 cm x 68 cm deep) by
plywood dividers, with one turtle per compartment. Seawater was
exchanged by flow-through at a rate approximating 23 liter per min.

Sampling for Weight, Length and Width

Weights, carapace lengths (total carapace length as defined by
Bjorndal and Balazs, 1983) and carapace widths were taken on all
hatchlings, then on random samples of turtles at approximately monthly
intervals during head starting (McVey et al., MS; Fontaine et al.,
1985). Wet weighings were made to the nearest 0.1 9 on an O'haus
triple-beam balance. The balance pan was dried and the balance re-
zeroed after consecutive weighings of three turtles. Length and width
measurements were made to the nearest 0.1 cm by the straight-line
method. Until the turtles were 4-5 months old, lengths and widths
were taken with a ruler. Thereafter, calipers were used.

For year-classes 1978-1980, McVey et al. (MS) recorded the weights
and measurements only by "imprint"-group within year-class (Table 1);
one group "imprinted" at the Padre Island National Seashore and the
other at Rancho Nuevo. Clutch identity was neither kept track of nor
recorded. At approximately monthly intervals, it took two or more
consecutive days to weigh and measure the large samples of sea turtles
which were then considered to be representative of the two “imprint”
groups. In analyzing the data recorded by McVey et al. (MS), we
treated each day's weights and measurements as coming from independent
samples from the particular "“imprint"-group sampled. Because these
samples represented aggregates of clutches, they included turtles of

6


Society, North Harris County College, Houston, TX, and the members of
HEART deserve especial recognition for their efforts in increasing
public awareness and support of the Kemp's ridley head start research
project and of the need for sea turtle conservation in general. For
their efforts, we are especially grateful.

29


died. It lost 0.3 kg in weight during the interim, from the 1.4 kg it
weighed upon capture. Caldwell suggested that its survival under such
a long period of starvation was an example of the survival potential
for the species.

Rajagopalan (1984) examined growth in the closely related olive
ridley, L. olivacea, reared in captivity for 47 months following
emergence as hatchlings. He fed the turtles a diet of clams and fish.
The 1980 year-class (15 animals) weighed an average of 0.5, 4.4, 13.4
and 19.0 kg at the end of 12, 24, 36 and 44 months, respectively. At
47 months, 11 survivors averaged 19.5 kg. The 1981 year-class (19
animals) weighed an average of 1.1, 9.9 and 14.5 kg at the end of 12,
24 and 32 months, respectively. At 35 months, 17 survivors averaged
15.8 kg. Such growth in captive olive ridleys was approximately com-
parable to that of Kemp's ridleys reared for extended periods in cap-
tivity (Fig. 7: Marquez, 1972; Pritchard and Marquez, 1973).

The head starting of Kemp's ridley at the Galveston Laboratory has
been successful in terms of good survival and growth. It has produced
10,792 healthy animals tagged and released into the Gulf of Mexico,
plus 264 for distribution among a turtle farm and marine aquaria for
extended head starting and captive propagation (Caillouet et al., MS).
Preliminary results from 481 reported recoveries (as of September
1986) indicate good growth and survival as well as wide dispersal in
the tagged animals in the wild (Fontaine and Caillouet, 1985; Fontaine
et al., 1985: Sharon Manzella, NMFS SEFC Galveston Laboratory,
Galveston, TX, personal communication, September 1986).

Adding to the success of head starting are the egg layings and
successful hatches of Kemp's ridley at Cayman Turtle Farm (Wood and
Wood, 1984; James Wood, Cayman Turtle Farm, Grand Cayman, BWI, per-
sonal communication, September 1986), events which may lead to suc-
cessful captive propagation within a much shorter time than was
previously believed possible. Our results point out the need and
opportunity for examining the relationships among survival, growth and
maturation of Kemp's ridley in captivity and in the wild, as adjuncts
to head starting and captive propagation. Through NOAA Sea Grant pro-
jects, David Owens and his students at Texas A&M University, College

26


alive. A few head started turtles that exhibited abnormalities or
were incurably sick or permanently handicapped by injuries were either
transferred to other investigators or disposed of humanely (Fontaine
et al., 1985).

In May 1984, two 5-year-old female Kemp's ridleys that had been
veared from hatchlings at Galveston then transferred to the Cayman
Turtle Farm in February 1980 laid eggs at the farm (Wood and Wood,
1984). Three of the eggs hatched, indicating that they had been fer-
tilized by the captive-reared males, but the hatchlings did not sur-
vive. There was no reported reproductive activity in this captive
stock in 1985. In spring 1986, several nestings occurred and viable
hatchlings were produced. These events represent major breakthroughs
by documenting the earliest age for copulation and nesting in the spe-
cies as well as proving feasibility of captive propagation as a
"safety net" for the species (Caillouet, 1984),

Growth of captive-reared sea turtles other than Kemp's ridley has
been examined by a number of investigators (Bacon et al., 1983: Frazer
and Schwartz, 1982; Hirth, 1982; LeBrun, 1975: Nuitja and Uchida,
1982; Rajagopalan, 1984; Stickney et al., 1973; Uchida, 1967: Witham
and Futch, 1977; Witzell, 1980; Wood and Wood, 1981). Growth of
Kemp's ridley in captivity has been depicted by Caillouet and Koi
(1985), Caldwell (1962), Fontaine et al. (1985), Klima and McVey
(1981), Marquez (1972), McVey and Wibbels (1984), McVey et al. (MS),
and Pritchard and Marquez (1973).

OBJECTIVES

The main objective of this paper is to examine and summarize data
on growth, increase in biomass and survival of the first six year-
classes, 1978-1983, of Kemp's ridleys head started by the Galveston
Laboratory. We describe first-year exponential growth in weight per
individual and increase in biomass of aggregates of Kemp's ridley, as
well as their survival in captivity from the time the hatchlings were
received to their release as "yearlings" into the Gulf of Mexico, or
their transfer to other organizations. A second objective is to
describe the growth in weight of ten Kemp's ridleys (eight remained

alive in December 1986) that were transferred to Sea-Arama Marineworld

—~


the rearing of hatchlings in captivity so as to enhance their survival
(Mrosovsky, 1983). In the wild, the eggs and hatchlings of Kemp's
ridley are vulnerable to a variety of natural predators (Hildebrand,
1963), and little is known about the turtles during their first year
at sea (Carr, 1980).

At the NMFS Southeast Fisheries Center's (SEFC) Galveston
Laboratory in Texas, eight year-classes, 1978-1985, of Kemp's ridley
have been head started by rearing them in captivity for one year or
less. Out of 15,260 hatchlings received alive, 10,792 (71%) have been
reared, tagged and released into the Gulf of Mexico in hopes that some
will mature and return to nest on the beaches at Padre Island or
Rancho Nuevo to which they were exposed as hatchlings (Caillouet et
al., MS: Fontaine and Caillouet, 1985; Klima and McVey, 1981; Owens et
al., 1982).

An additional 264 captive-reared Kemp's ridleys were tagged and
distributed among Bass Pro Shops (Springfield, MO; 5 turtles of the
1984 year-class), the Cayman Turtle Farm (Grand Cayman Island, British
West Indies: 96 turtles of the 1979 year-class; 5 turtles of the 1982
year-class; 15 turtles of the 1984 year-class), Clearwater Marine
Science Center (Clearwater, FL: 5 turtles of the 1982 year class),
Dallas Aquarium (Dallas, TX; 5 turtles of the 1984 year-class),
Gulfarium (Fort Walton Beach, FL; 5 turtles of the 1982 year-class),
Marineland, Inc. (St. Augustine, FL; 5 turtles of the 1984
year—class), Marine Life Park, Inc. (Gulfport, MS; 5 turtles of the
1982 year-class), Miami Seaquarium (Miami, FL; 29 turtles of the 1978
year-class: 50 turtles of the 1979 year-class), New England Aquarium
(Boston, MA: 4 turtles of the 1984 year-class), North Carolina Marine
Resources Center (Kure Beach, NC; 3 turtles of the 1984 year-class),
Pan American University (South Padre Island, TX; 2 turtles of the 1984
year-class), Sea-Arama Marineworld (Galveston, TX; 10 turtles of the
1978 year-class; 3 turtles of the 1984 year-class), Sea World of
FLorida (Orlando, FL: 5 turtles of the 1984 year-class), and Theater
of the Sea (Islamorado, FL: 5 turtles of the 1982 year-class), for
extended head starting or captive propagation. In September 1986, 111

(42%) of these, ranging in age from 2 1/4 to 8 1/4 years, remained


by clutch within the 1981-1983 year-classes, contributed to the dif-
ferences in levels of variability among year-classes. In the 1978 and
1979 year-classes, another source of variation in size of individuals
was the intermittent "cropping" of the largest of the turtles for
tagging and release or transfer to marine aquaria (McVey et al., MS).
These removals no doubt affected the ranges and average sizes of sub-

sequent samples from those two year-classes,

Growth Comparisons

Table 6 gives the slopes and other statistics for the rectilinear
regressions (equation 1) of transformed weight on transformed age of
Kemp's ridleys by clutch for year-classes 1981-1983. These Slopes are
indices of the rate of growth in weight of the turtles, and we refer
to them as weight increase indices or growth rate indices. Analysis
of covariance (Table 7) detected significant (used here and henceforth

in this paper to refer to the 5% level of significance) differences
| among these indices. Figure 2 is a plot of the indices (slopes) for
each clutch of the 1981-1983 year-classes, along with three horizontal
lines representing the "average" indices, one for each year-class,
derived as the common regression for all clutches combined within a
year-class (Table 6). Clearly, the 1982 year-class exhibited the most
rapid rate of growth in weight, followed by the 1981 year-class and
‘the 1983 year-class, in descending order (Fig. 2). Detransformed
growth curves for year-classes 1981-1983 are shown in Figure 3,

Table 8 gives the slopes and other statistics for the rectilinear
regressions (equation 3) of transformed weight on transformed lapsed
time for Kemp's ridleys by "imprint"-group for year-classes 1978-1980.
These slopes are indices of growth in weight with lapsed time, and we
refer to them as weight increase indices or growth rate indices.
However, they are not strictly comparable to those for the 1981-1983
year-classes. Analysis of covariance (Table 9) detected significant
differences among the slopes for "imprint"-groups. Also, the
"average" (common) weight increase indices for each of the three year-

classes were different (Table 8). The 1980 year-class clearly showed
the most rapid growth rate, followed by the 1979 year-class and the

15


As the hatchlings emerged (either at the Padre Island National
Seashore or at Rancho Nuevo) they were taken to the beach and allowed
to crawl into the surf where they were scooped up in nets (Caillouet,
1984; Fontaine and Caillonet, 1985; Fontaine et al., 1985: Klima and
McVey, 1981; McVey et al.; MS). The "imprinted" hatchlings (Table 1)
were placed in boxes and transported by aircraft to the Galveston
Laboratory where they were reared in captivity. It is hoped that
exposure to beach sand and seawater imprinted the hatchlings (Grassman
et al., 1984) so that some of those reared in captivity then tagged
and released into the Gulf of Mexico will mature and return to nest at

the beach to which they were exposed (Owens et al., 1982).

Rearing Containers

The containers used to rear the 1978-1983 year-classes of Kemp's
ridley have been described by Fontaine et al. (1985) and McVey et al.
(MS). They included fiberglass raceways, concrete tanks, and
fiberglass basins. However, the primary rearing containers were 15
rectangular raceways, each filled with approximately 3,140 liter of
Seawater. The raceways were housed within two metal-framed quonset
huts covered with white polyethylene sheathing which allowed penetra-
tion of sunlight. The 2 x 8 m raceways were placed side by side (with
a walk-space between them) in an east-west row inside the quonset
huts. As clutches were received, they were distributed more or less
sequentially among the rearing containers: i.e., no attempt was made
at randomization.

Rearing of the 1978 year-class began by intermingling the hatch-
lings within the containers, but the turtles bit and injured each
other which led to mortality (Klima and McVey 1981; McVey et al., MS).
Therefore, beginning in January 1979, the turtles were reared in iso-
lation. Most were placed as individuals in separate plastic buckets
containing about 10 liter of seawater when suspended within the
raceways. The raceways each held 108 buckets (6 columns x 18 rows)
perforated by holes (2.5 cm in diameter) in their bottoms to allow
circulation of seawater and liberation of turtle excrement and uneaten

food (Fontaine et al., 1985). The fiberglass basins, of 26—-liter

capacity, also were used intermittently as rearing containers for
individual turtles. Also some turtles outgrew their buckets near the

5


winter temperatures, but the three year-classes (1979, 1980 and 1982)
with the most rapid growth (Fig. 3) were associated with the years of
highest average winter temperature, and those (1978, 1981 and 1983)
with the slowest growth were associated with the lowest average winter
temperatures. |

Regardless of the causes of the observed differences in growth,
biomass increase and survival within and among year-classes, it is
obvious that our regression equations 1 and 5 provide sensitive tools
for detecting differences among clutches and year-classes., With care-
fully designed and executed experiments, it should be possible to
segregate clutch and year-class effects from treatment effects.
Segregating sex effects, if any, from other influences on growth will
require a simple, rapid and non-sacrificial method of determining the
sex of juvenile turtles.

The observed relationship between growth rate and survival would
be expected if growth were not density-dependent. According to
Patrick Burchfield (Gladys Porter Z00, Brownsville, TX, personal com
munication, October 1984), healthy and robust hatchlings of reptiles
are characteristically predisposed to good survival and growth, and
sickly or small hatchlings usually perform poorly. However, the size
of hatchlings from the various year—classes (Tables 4 and 5) gave no
clue as to causes of differences in the growth among the year-classes
(Fig. 3). Only in the case of year-class 1983, which exhibited the
slowest growth, does it seem clear that the hatchlings were pre-
disposed to poor performance. We received only 250 hatchlings from
the 1983 year~class. This was the year-class with the poorest hatch
of the six (Table 1).

The observations that the biomass increase index became larger as
the weight increase index became larger, and that the two indices con-
verged as they increased (Fig. 5), are of significance. Such results
would be expected if carrying capacity of the raceways for turtle
biomass were a limiting factor and the turtles exhibited compensatory
mortality as they grew larger. Variability in the rate of increase in
biomass seems to have been influenced more by differences in survival
than by differences in growth rate among clutches (Figs. 5 and 6).

21)


G pro me”,

4 4,

NOAA Technical Memorandum
NMFS-SEFC- 186

oo NATIONAL

fy
Ra
%, Ce

a CS
A TMENT OF cow

"3,

Growth and Survival of Kemp’s
Ridley Sea Turtle, Lepidochelys
kempi, in captivity

By

Charles Wax Caillouet, Jr., Dennis Brian Koi,
Clark Timothy Fontaine, Theodore David Williams,
William John Browning, and Richard Monte Harris

U. S. DEPARTMENT OF COMMERCE
Malcolm Baldrige, Secretary

National Oceanic and Atmospheric Administration
Anthony J. Calio, Administrator

National Marine Fisheries Service
William E. Evans , Assistant Administrator for Fisheries

DECEMBER 1986

This Technical Memorandum series is used for documentation
and timely communication of preliminary results, interim
reports, or similar special-purpose information. Although
the memoranda are not subject to complete formal review,

editorial control, or detailed editing, they are expected
to reflect sound professional work.


Table 7. Analyses of covariance (test of slopes) based on rectilinear
regression (equation 1) of transformed weight on transformed
age for Kemp's ridley clutches in year-classes 1981-1983 (see
Table 6).

1981 Year-class

Source of Degrees of Sum of Mean

variation freedom squares square F
Among clutches 22 17.371 0.790 — 20.79
Within clutches 8,182 313.903 0.038

1982 Year~class

Source of Degrees of Sum of Mean
variation freedom squares square F
Among clutches 19 24.149 1.271 21.18

Within clutches 6,146 371.681 0.060

1983 Year-class

Source of Degrees of Sum of Mean
variation freedom squares square F
Among clutches 2. 22471 1,236 24.24

Within clutches 806 41.251 0.051



Island on 18 August 1983. ‘The number of times in which a given com-
bination was sampled during head starting was designated m (Table 2).
This number varied somewhat depending on how long the turtles were
held in captivity and upon variation in the interval between _
samplings. In the 1978-1980 year-classes, m was inflated by the
sampling procedure which spread the monthly sampling of turtles within
"imprint"-groups over a number of consecutive days. In these cases,
each day was considered to provide a separate sample for our analyses.
For the 1981-1983 year-classes, fewer turtles were weighed and
measured on any given occasion, and m was the number of samples taken
from a given clutch over the period of head starting.

The 10 Kemo's ridley transferred to Sea~Arama Marineworld were
weighed and measured approximately monthly during the first few years,
then less frequently thereafter.

Survival

For year-classes 1981-1983, the number of survivors in each year-
class-clutch combination was determined each time samples were taken
for weighing and measuring, and at the end of the head starting period
(Fontaine et al., 1985). For year-classes 1978-1980, only final sur-

vival was determined by year-class (ibid.; McVey et al., MS).

Included as survivors were any animals that were "cropped" for tagging
and release or for transfer to the Cayman Turtle Farm or to marine
aquaria before the head starting period was complete, and any abnor-
mal, sick or handicapped (by injuries) turtles still alive at the time

of the last weighing and measuring.

Foods, Feeding and Health Care

The foods and feeding methods used in head starting Kemp's ridley
have been elaborated in detail (Fontaine et al., 1985; McVey et al.,
MS). The primary food was a dry, floating, pelleted diet (Table 3)
manufactured by Central Soya and Subsidiaries, Fort Wayne, Indiana
Feeding methods evolved both through small-scale experimentation and
by trial-and-error. The 1978 year-class was fed three times per day,
and the 1979-1983 year-classes two times per day.


ages differing by days or weeks. Clutches were received from NPS
shortly after they hatched (Table 1), but all clutches did not hatch
simultaneously, because they came from nestings over a period of time.
Also, all hatchlings from a given clutch did not emerge on the same
day, some taking longer than others to hatch. Therefore, individuals
in the same clutch could have varied in age by a few days, and
clutches could have varied in age by several weeks. About one month
from the end of each head starting period, all healthy survivors to
be tagged and released were weighed and measured.

For year-classes 1981-1983, most of the hatchlings were
"imprinted" at the Padre Island National Seashore (Table 1), and
observations on these were taken and recorded by clutch (Fontaine et
ale, 1985). For year-classes 1981 and 1983, random samples of not
more than 25 turtles from each clutch (some clutches contained fewer
than 25 turtles) were weighed and measured at approximately monthly
intervals. Exceptions were that all hatchlings of a year-class were
weighed and measured before head starting, and all healthy survivors
in each clutch were weighed and measured at the time they were tagged,
about one month before their release. Thus the first and last samples
contained more than 25 turtles, if the clutch initially contained more
than 25 hatchlings or subsequently contained more than 25 survivors.
Tf the clutch contained fewer than 25 hatchlings or survivors, all
were weighed and measured each time samples were taken. For the 1982
year-class, monthly random sample size was not more than 30 per clutch
with comparable exceptions concerning the first and final samples of
weights and measurements. Though weights and measurements were taken
on turtles from all clutches of the 1983 year-classes (Table 1), only
clutches 1-3 were included in our analyses for that year-class because
the other clutches contained too few turtles.

Each combination of year-class and "imprint"group, or year-class
and clutch, provided at least one sample of turtle weights, carapace
lengths and carapace widths at approximately monthly intervals
(Fontaine et al., 1985; McVey et al., MS). An exception was the 1983
year-class for which sampling intervals were wider due to the disrup-

tion and damage caused by hurricane Alicia which crossed Galveston


1978 YEAR-CLASS

38

28

12

Figure 7.

161 S26 S92 1257 1622 1987
C1979) C198@> C19S8i2 C1982) C1983) ¢1984)

days Cyears)

Growth in weight (kg) of 10 head started Kemp's ridleys of
the 1978 year-class maintained at Sea-Arama Marineworld,
Galveston, Texas. The solid line represents the fitted
Gompertz growth function (see Table 12).


Table 4, Rectilinear regressions of the natural logarithms of weights (1nW: W in g) on
the natural logarithms of carapace lengths (1nCL: CL in cm) of Kemp's ridleys,

by year-class,

{ni = Ina + bincL Range
Coeff. of

Year- No. of paired Intercept, Slope, determination,

class observationsl/ ina b r2 Wr g CL, cm
1978 8,114 -1.44 2.88 0.984 12.6-2,392 1.3-25.5
1979 8,050 -1.43 2.87 0.985 10.0-1,844 0.8-22.9
1980 5,984 -1.67 2.98 0.995 12.6-1,920 4,.1-22.2
1981 8,228 -1.63 _ 2.98 0.990 11.2-1,110 3.8-18.6
1982 6,186 ~1.48 2.91 0.993 12.3-1,482  3.6-20.7
19832/ 812 -1.33 2.85 0.995 13.0-664 3.6-15.8

l/yumber of paired observations of W and CL taken over the entire head starting period.
This is a combination of the number of turtles weighed and measured each time samples
were taken and the number of times that turtles were sampled over the head start period
(see Table 2). It is possible that individual turtles could have been drawn more than
once through random sampling.

2/tncludes only clutches 1, 2 and 3 (see Tables 1 and 2).


ACKNOWLEDGMENTS

Special thanks are due Rene Marquez Millan (INP; Mexico), Jack
Woody and David Bowman (FWS, Albuquerque, NM), Milford Fletcher (NPS,
Santa Fe, NM), Patrick Burchfield (Gladys Porter Zoo; Brownsville,
TX}, and Robert King (NPS, Corpus Christi, TX), their staffs and their
predecessors, for their respective roles in providing Kemp's ridley
hatchlings for head starting.

Head starting of the 1978-1983 year-classes of Kemp's ridley was
conducted under consecutive INP permits no. ABC-IV-0751/8676,
ABC=IV—1258/4287, 242~0180-3794, 242,.2-2610, 242. 2~-00026/1147 and
CG-115-900 (and Mexican Diplomatic Note no. 316502), respectively,
under FWS Endangered and Threatened Species Permits no. PRT 2-1770,
PRT 2~4481 and PRT-676379, and under scientific permits issued by TPWD
and FDNR. |

The authors are grateful to Edward F. Klima, James P. McVey and
Ray S. Wheeler who initiated sea turtle head starting at the Galveston
Laboratory. McVey and Wheeler managed Kemp's ridley head starting for
year-classes 1978-1980, and initiated rearing of the 1981 year-class.
Under the direction of Charles W. Caillouet, Jr., Clark T. Fontaine
managed the completion of head starting of the 1981 year-class and the
head starting of year-classes 1982 and 1983. The efforts of their
staffs also are appreciated. Jorge Leong provided health care advice
during the rearing of all the year~classes, and along with his staff
provided preventive and therapeutic health care for the 1978-1981
year-classes.

We thank John Kerivan and his staff at Sea-Arama Marineworld in
Galveston, Texas, for maintaining captive-reared Kemp's ridleys and
for providing data for our analyses.

Dickie Revera and Marcel Duronslet assisted in checking, verifying
and validating some of the data used in our analysis. Bea Richardson
typed the manuscript through its many revisions.

carole Allen, Chairperson of HEART (Help Endangered Animals -
Ridley Turtles), a special committee of the Piney Woods Wildlife

28


Table 8. Rectilinear regressions (equation 3) of the natural logarithms of weights (Inw;

Win g) on the square roots of lapsed timel/ (t'Y2: 7! Gin days) for Kemp's

tidleys, by “imprint"-group in year-classes 1978~19802/.

a

Coefficient of

"Imprint "— Intercept, Slope, Variance of deviations determination,
Year-class group3/ Ina’ b! from regression, Stev, v2
er
1978 PINS 1.97 0. 268 0.211 0.865
RN 1.33 0.296 | 0.169 0.872
Groups
combined 1.87 0.269 0.219 0.853
1979 PINS 2.02 0.273 0.104 0.943
RN 2.51 O. 246 0.063 0,959
Groups
combined 2.08 0.270 0.105 0.942
1980 PINS 1,64 0. 300 0.104 0.947
RN 1.48 0.318 0,060 0.964
Groups
combined 1.63 0.301 0.100 0.948

1/trom the date that measurements were first taken on a clutch of the year-class.
These dates were 6 July 1978, 7 July 1979, and 24 June 1980, for the 1978, 1979

and 1980 year-classes, respectively.

2/see Table 4 for the number of paired observations of W and T' taken over the head

starting period. It is the same as the number of paired observations of W and CL.

3/pINs = Padre Island National Seashore: RN = Rancho Nuevo.


Station, TX, are studying the reproductive physiology and behavior of
Kemp's ridley in collaboration with INP, FWS, NPS, NMFS, Cayman Turtle
Farm, and various marine aquaria. Andre Landry and his students at
Texas A&M University in Galveston, TX, are conducting morphometric
studies of Kemp's ridley in hopes of distinguishing the sexes of juve-
niles reared in captivity and segregating new recruits from previous
nesters at Rancho Nuevo. Ron Malone and his students at Louisiana
State University in Baton Rouge, LA, are developing and testing
recycled seawater systems for use in rearing Kemp's ridley.

There are many issues and questions that must be considered in
captive rearing and propagation of an endangered species (Carr, 1980;
Ehrenfeld, 1974; Holden, 1984; Soule and Wilcox, 1980). Nevertheless,
head starting not only has provided a large number of Kemp's ridleys
for release into the wild and retention in captivity, but also has led

to the first indications that captive propagation is feasible.

27


after having been reared from hatchlings at the laboratory.

New empirical relationships (equations) were developed to describe
the exponential phases of increase in weight per individual and
increase in biomass of aggregates of Kemp's ridley with age or lapsed
time {when age was unknown) during their first year of life. The
equations were derived by fitting rectilinear regressions of the
natural logarithm of weight (g) or the natural logarithm of biomass
(kg) on the square root of age (days) or the square root of lapsed
time (days) when age was unknown. The slopes of the rectilinear
regression equations are indices of rates of increase in weight and in
biomass with age or lapsed time, and they were used to compare year-
classes and subdivisions (e.g., “imorint"-groups and clutches) within
year-classes. Variability in weight among individuals, clutches, and
larger aggregates of turtles was examined, and the sample size
required for detecting differences between means of logarithmically—
transformed weights, both between and within clutches, was determined.
Weight-length and width-length relationships were derived.

MATERIALS AND METHODS

Source of Hatchlings

Fach spring, beginning in 1978, INP and FWS personnel and colla-
borators collected clutches of Kemp's ridley eggs as they were being
laid at the beach near Rancho Nuevo (Caillouet, 1984; Fontaine and
Caillouet, 1985; Fontaine et al., 1985; Klima and McVey, 1981; McVey
et al., MS). Most of the eggs were collected in plastic bags to pre-
vent their contact with and possible imprinting on Rancho Nuevo beach
sand (Table 1). At Rancho Nuevo, the eggs were placed in polystyrene
fceam boxes containing beach sand from the Padre Island National
Seashore, and the boxes were transported by aircraft to the Padre
Island National Seashore where they were tended by NPS personnel
during incubation. Within the first three year-classes (1978-1980), a
few clutches were incubated in Rancho Nuevo beach sand (Table 1).

Within the second three year-classes (1981-1983), so few eggs were
incubated in Rancho Nuevo sand that the turtles that hatched were

excluded from our analyses.


Growth of Kemp's Ridleys at Sea~Arama Marineworld

The weight of the 10 turtles (9 remained alive after 9 June and 8
after 11 June 1984) maintained at Sea-Arama Marineworld followed an
asymmetric sigmoid trend, so a Gompertz growth function (Ricker, 1975,
p. 232) was fitted to the data (Table 12; Fig. 7). Hatchlings in the
Padre Island National Seashore "imprint-group" of the 1978 year-class
were received from 6 July to 3 August 1978 (Table 1). The date 23
July was chosen as day zero for lapsed time T' on the abscissa. The
data for first-year's growth of the 1978 year-class (Fig. 3) were not
included in the fit for two reasons: (1) the animals chosen for
transfer to Sea-Arama Marineworld had been among the largest available
from the year~class, and therefore were not representative of the
year-class as a whole, and (2) variability in weight of individual
turtles was heterogeneous among the samples within the first year of
life (Caillouet and Koi, 1985), but appeared to be homogeneous from
sample to sample thereafter (Fig. 7). The upper and lower asymptotes
of the fitted Gompertz growth curve were 29.2 kg and 0.25 kg, respec-
tively. The sigmoid curve was fitted without forcing it through the
origin. The lower asymptote, 0.25 kg, of the fitted growth curve was
15-17 times higher than the average weight of hatchlings (15-17 g), in
part probably an artifact of curve fitting and selection of large ani-

mals from the 1978 year-class for transfer to Sea-Arama Marineworld.
DISCUSSION

While the head starting activities produced the data upon which
the statistical analyses in this paper are based, they did so inciden-
tal to the primary objective of culturing the animals for tagging and
release into the wild. The rearing methods used were chosen to assure
adequate safety, health, survival and growth of the turtles, as well
as for convenience, within the constraints of available resources
(Fontaine et al., 1985; McVey et al., MS). No attempts were made by
McVey et al. (MS) or Fontaine et al. (1985) to conduct large-scale,

carefully planned and executed experiments; e.g., to test effects of
different foods, feeding rates or feeding frequency on growth and

18


Biomass Increase Index

0.302

8.27 A 4s

A a aA
°
af
2.242 — oe
°
5 0 8
© °
08,0
8.218 ©
Og
0.186 £9
res
0.158 _ _
PT | |
08.210 0.2402 G.270 0.300

Weight Increase Index

Figure 5. Relationship between the biomass increase index and the
weight increase index for clutches of the 1981 (circles),
1982 (triangles) and 1983 (squares) year-classes of

Kemp's ridley. The straight line is drawn to represent
1:1 correspondence.


Table 1, Dates and numbers of Kemp's ridley hatchlings received alive for head starting at the SEFC Galveston Laboratory.

LR Re Pe re Pei sg gp np cette

Year-class
1978 1979 1980 198 1982 1983
Clutch Imprint- Dat No. Date No. Date No. Date No. Date No. Date No.
no. 1/ group2/ From To From To From To From To From To From To
1 PINS 6/24 63 7/24 54 «7/6 94 7/8 7/13 97
2 7/4 86 8/1 72 7/19 9 7/8 87
3 7/9 7/10 98 8/8 8/11 37. 7/16 108 = 7/27 22
4 7/9 7/10 82 8/7 53 7/16 7/19 101
5 7/9 7/10 111 8/7 70 7/19 1067/27 10
6 7/12 82 8/7 59 7/19 80 7/27 1
7 7/9 7/10 88 8/6 8/7 105 = =7/26 7/28 72
8 " 7/26 63 7/9 7/10 91 8/6 8/7 78 7/28 8/2 59
9 " 7/26 107 7/9 7/10 = 73 8/7 90 7/26 94 8/8 2
10 7/12 95 8/6 8/7 104 7/26 7/28 71
11 7/14 88 8/7 86 7/28 8/2 63
12 7/17 AO 8/6 87 7/26 118 = 8/8 2
13 7/12 74 8/6 8/7 77 ~=—8/2 36
14 " 7/26 129 7/14 60 8/6 89 8/10 8/13 56 8/8 3
15 PINS 7/26 93 7/14 73 8/6 8/7 85 8/13 56

16 " 7/26 63 7/14 7/17 87 8/6 8/7 117. 8/13 74


Table 1. continued

er rp LE

Year-class

1978 1979 1981 1982 )

Clutch Imprint- Dates’ No. Date No. Date No. Date No, Date No. Date No.
no.!/ _group2/___sFrom__To From To From To From To From To From To

17 " 7/26 63 7/14 7/15 58 8/6 111 8/13 8/16 67 8/12 6
18 7/14 89 8/6 105 8/13 69

19 W/17 84 8/11 61 8/10 114

20 7/14 67. B/17_—i«; 53 8/13 8/16 77

21 8/19 102

22 8/22 84

23 8/22 85

24

25

24/ " 1/6 8/3 1,266 7/7 7/23 1,656 ? 195/

? RN 7/6 G8/1L 1,226 6/26 187 7/26 207 | 7/8 20
Combined 7/6 8/11 3,080 6/26 7/23 1,843 6/24 7/17 1,815 7/24 8/22 1,864 7/6 8/13 1,524 7/8 8/12 250

cece a ep Pp A SS SS

1/algo used by National Park Service (NPS) at Padre Island National Seashore.

2/PINS = Padre Island National Seashore; RN = Rancho Nuevo.

3/month/Day.

4/> indicates that clutch numbers on other information were not known, and the data represent composites of clutches.

5/unaccounted for: these probably died before being distributed among raceways.


D

Observed Mean Difference,

Figure 1.

Sample Size, n

Relationships between the mean difference (5) and sample
size, n, for the natural logarithms of weights (1nw, W in
g) of random samples from Kemp's ridley clutches. 5 repre—
sents the minimum detectable (or critical level) real dif-
ference between means (1nW') of random samples of
transformed weights of turtles from the same clutch at two
different times, or from two different clutches at the same
time. The three curves represent relationships at the 80%,
90% and 95% probabilities of detecting real differences
(power of the test) of magnitude D at the 5% level of

significance.


Our statistical analyses are more detailed and involve more ani-
mals than did previously published accounts of growth in Kemp's
ridley. Pritchard and Marquez (1973) presented graphs of monthly
increments in weight, carapace length and carapace width, based on
investigations by Marquez (1972) of captive hatchlings and tagged
adults. Their graphs indicated that the increment in weight during
the first year was less than 0.5 kg. Extrapolation of our results
(Tables 6 and 8; Fig. 3) to 365 days gave annual average increments of
0.6 kg for the slowest growing year-class (1983) and 1.6 kq for the
fastest growing year-class (1980).

Klima and McVey (1981) presented a plot of the arithmetic average
weight, over a 9=-month period, for Kemp's ridleys of the 1978 year-
class head started at the Galveston Laboratory. The plot compared two
groups, one hatched and "imprinted" at Rancho Nuevo and the other at
the Padre Island National Seashore. Klima and McVey (1981) concluded
that there was no difference in average growth rate between groups
"imorinted" at Rancho Nuevo and at the Padre Island National Seashore.
Our results for the 1978-1980 year-classes suggest that those
"imprinted" at the Padre Island National Seashore grew at signifi-
cantly different rates from those “imprinted” at Rancho Nuevo. For
the 1978 and 1979 year-classes, the difference between "imprint"-
groups might have been even greater had the Padre Island "imprint"-
group not been "cropped" by removal of larger animals. Our detection
of significant differences as compared to the results of Klima and
McVey (1981) reflects a difference in statistical treatment of the
data, and emphasizes the sensitivity of our growth analyses (equation
3) in detecting differences. We do not believe that the differences
between "imprint"-groups had anything to do with the "imprinting" per
se, but to the choice of clutches and the timing of hatching of the
eggs for the two “imprint"-groups, as well as other possible factors.

Mcevey et al. (MS) presented plots of arithmetic means and ranges
in weight and carapace length versus months for the 1979 and 1980
year-classes of Kemp's ridleys head started for 10 months at the
Galveston Laboratory. Their plots clearly exemplified the kind of

heterogeneity of variance in weight discussed herein as well as

24


Biomass Inerease Index

8.300

Q.275 s
A A
A n a 4 ; , A
as A 4 , “_ 1982
@.250 5 a,
res IN OS oO °
°
a ; o 5 ° 5
° °
g.225-| ___, __- 2
5 6) ; ° 5 re)
©
. 1983 °
8.208
Q.175 an °

8.1Se— TTTTTTITITITT?tttttrrirrittiitityil
13 1S 17 19

I 3 > 7 g 11 2 i 23

Clutch Number

Figure 4, Biomass increase indices for Kemp's ridley clutches of the
1981-1983 year-classes. These indices were calculated from
rectilinear regression equation 5 (see Table 10). The
horizontal lines represent the "average" biomass increase
index for each year-class based on the common regression

for combined clutches of a year-class.


A minimum sample size of 25 turtles per clutch is adequate for
detecting differences between means of logarithmically-transformed
weights, either for comparisons among different clutches at the same
time or for comparisons within the same clutch at different times.
Growth in weight with carapace length followed the "cube law."
Carapace width and length were linearly related, with the former being
only slightly shorter than the latter.

Growth in weight of ten turtles from the 1978 year-class, held in
captivity for 5 years at Sea-Arama Marineworld in Galveston after
having been reared at the Galveston Laboratory, followed a sigmoid
pattern described by a fitted Gompertz growth function. The upper
asymptotic weight was 29.2 kg, much smaller than the size (39-49 kg)

recorded for nesting adults.

fe
fete
js


Table 6. continued

SL A Sc A ey eS SSS SS nel vr ch se lst PEP en

Coefficient of

Intercept, Slope, Variance of deviations determination,
Year-class Clutchl/ na b from regression, Sday, x2
1983 1 1.99 0,225 0.066 0.956
2 1.93 0. 246 0.034 0.980
3 2.20 0.226 0.058 0.968
Clutches
combined 1.99 0. 234 0.064 0.961

1/see Table 4 for the number of paired observations of W and T taken over the head

starting period. It is the same as the number of paired observations of W and CL.


Table 5, Rectilinear regressions of carapace widths (CW; in cm) on carapace

lengths (CL; in cm) of Kemp's ridleys, by year-class.1/

ee

mTM
CWe=a i =~+ bCL
a ea

Coeff. of
Intercept, Slope, determination, Range in CW,
Year~—Class a b r2 cm
Se — a =. See

1978 ~0. 241 0.937 0.989 3.4-24.6
1979 -0.012 0.893 0.986 2.4-20.0
1980 -0.313 0.931 0.993 3.1-21.0
1981 -0.381 0.936 0.991 3.0-16.8
1982 ~0. 226 0.923 0.993 3.1-19.5
19832/ ~0.163 0.908 0.980 5.7-14.6

1/see Table 4 for the number of paired observations of CW and CL, and for
ranges of CL. CW measurements were not taken on hatchlings of the 1983
year-class, This is the reason for the higher CW at the lower end of the
range in CW in year—class 1983, as compared to other year-classes. The
number of paired observations used to regress CW on CL for year-class 1983
was 605.

2/tncludes only clutches 1, 2 and 3 (see Table 1).


Koi, 1985). The method of Taylor (1961), based on the relationship
between sample variances and arithmetic means, was used to determine
the type of transformation of the weight data required for fitting
growth curves and for comparing means. The variances (s2) and arith-
metic means (W) of weight (W, in g) were calculated for each of the 52
time-series (Table 2) of samples of turtles (by "imprint"-group and
clutch). The slopes of rectilinear regressions of 1ns2 on 1nW (for
each time-series) ranged from 1.88 to 3.66. We considered them to be
close enough to 2 to justify logarithmic transformation of all sample
weights. The logarithmic transformation reduced the heterogeneity of
variance substantially, and had the added practicality of helping
transform the exponential phase of growth in the turtles into a
straight line.

Rectilinear Regression of Transformed Weight on Transformed Age or
Lapsed Time |

The time unit T (days), used to assess growth in clutches from
the 1981-1983 year-classes, was actual age (within a day or two). The
age from the day of hatching was known for each clutch, and all obser-
vations for each random sample of turtles from a given clutch usually
were taken within the same day. Rarely did this extend to three con-
secutive days. When measurements of a clutch spanned more than 1 day,

a weighted, arithmetic average age of the lumped samples was calcu-
lated.

Using the procedure of Box and Tidwell (1962), we determined that
a square root transformation of the time scale (abscissa) also was
necessary to obtain a straight line relationship. The straight line
relationship was obtained by fitting a rectilinear regression to the
data representing natural logarithm of weight and the square root of
age for clutches within year-classes 1981-1983:

“~~
lnW = Ina + bT2 + Ina (1)

where W is weight in g, T is age in days, 1na is the intercept, b is

the slope and an index of growth rate, and ind is the deviation or

11


<g

Q.

4)

5

.Q

Figure 3.

1979.

1980

1982

1981

1983

—T TOIT 7 rr | I
38 18 2/2

Days

Fitted growth curves for Kemp's ridley year-classes
1978-1983, These curves represent the exponential form
(i.e., equation 2) of rectilinear regression equation 1
applied to combined clutches of year-classes 1981-1983
(Table 6) and the exponential form (i.e., equation 4) of
rectilinear regression equation 3 applied to combined

“imprint"-groups of year-classes 1978-1980 (Table 8).

TM
368

[978


where W' is the sample geometric mean weight, Wy is the weight (in kg)
of the ith turtle in the sample, n is the number of turtles in the

sample, and i is 1, 2, ..., n. The relationship between biomass and

age was transformed to the straight-line relationship:

——,
InB = Ina + bTY2 + Ina (5)

where B is the biomass in kg, T is the age in days, Ina is the inter-
cept, b is the slope, and 1nd is the deviation or residual from

regression. Expressed in exponential form, the relationship is as
follows:

B= (aebT¥2)4 (6)

It was not possible to calculate biomass at intervals during rearing
of the 1978-1980 year-classes, because survival was not recorded by

McVey et al. (MS) at intervals during head starting.

Sample Size

Until our analyses were completed, it was not known what sample
size would be adequate for detecting differences in average weight
between groups of Kemp's ridleys reared in captivity, or in assessing
their growth in weight. A pooled variance (x3 = 0.0403) of the
logarithmically transformed weights of turtles from clutches of the
1981-1983 year-classes was used to determine sample size (n) required
to detect differences (D) between sample means of logarithmically
transformed weights of turtles. This sample size applies to samples
taken at different times from a given clutch or to samples from dif-
ferent clutches taken at the same time. In comparing two such
samples, designated 1 and 2 for example, the mean difference, D, is
(1nw')) - (1nW')>. Figure 1 shows relationships between the critical
level of D and n for the 80%, 90% and 95% probabilities of detecting
real differences (i.e., the power of the test) of magnitude D at the
5% level of significance (i.e., probability of type I error - reject—
ing the null hypothesis of no difference when it is true). It is
clear that a minimum sample size of 25 is adequate, because the criti-
cal level of D increases rapidly as sample size decreases below 25,

13


ABSTRACT

Six year-classes (1978-1983) of Kemp's ridley sea turtle,

Lepidochelys kempi, were reared at the National Marine Fisheries

Service, Southeast Fisheries Center, Galveston Laboratory in
Galveston, Texas. This paper describes the growth in weight per indi-
vidual, the increase in biomass, and the survival of aggregates of
turtles during their first year of life in captivity. It also lays a
statistical foundation for future experiments on factors affecting
growth and survival of Kemp's ridley in captivity.

The exponential phases of first-year growth in weight per indivi-
dual (for all year-classes, 1978-1983) and increase in biomass (only
for year-classes 1981-1983) of aggregates of turtles were transformed
to straight-line relationships represented by the rectilinear regres-
sions of the natural logarithm of weight or biomass on the square root
of age or square root of lapsed time (when age was unknown). The
slopes of the straight lines, as indices of the rates of increase in
weight (growth rate) and biomass, were used to detect differences
among year-classes or sub-divisions (e.g., "imprint-groups" and
clutches) within year-classes. The most rapid growth was exhibited by
the 1980 year-class and the slowest growth by the 1983 year-class.

Within the 1981-1983 year-classes, there were significant dif-
ferences among clutches in growth rate and rate of increase in
biomass, but these differences were confounded with other sources of
variation. There was greater similarity in growth rates than in rates
of biomass increase among year-classes and among clutches within year-
classes. There was a curved relationship (concave downward) between
the indices of biomass increase and of growth. At lower levels of
both indices, the growth rate index exceeded the index of biomass
increase. The two indices converged (became more alike) as they
increased. Survival and growth rate index increased up to point, then
survival declined with further increase in the growth rate index.

Such results suggest that carrying capacity of the raceways for turtle
biomass is a limiting factor and that compensatory mortality occurs as

the size of the turtles increases.

ii


Ricker, W. E. 1975. Computation and interpretation of biological
statistics of fish populations. Fish. Res. Bd. Canada Bull. 191,
382 Pp.

Stickney, Re. Re, D. Be White and D. Perlmutter. 1973. Growth of
green and loggerhead sea turtles in Georgia on natural and artifi-
cial diets. Bull. Georgia Acad. Sci. 31:37-44.

Soule, M. Ee, and B. A. Wilcox (eds.). 1980. Conservation biology:
an evolutionary-ecological perspective. Sinauer Assoc., Inc.
Publ., Sunderland, Mass., 395 p.

Taylor, L. Re 1961. Aggregation, variance and the mean. Nature
189( 4766) :732-735,.

Uchida, I. 1967. On the growth of the loggerhead turtle, Caretta
caretta, under rearing conditions. Bull. Japanese Soc. Sci.
Fish. 33(6):497-507.

Wibbels, T., D. Owens, G. Dienberg and J. Noell. 1986.
Determination of sex ratios produced in the Kemp's ridley head
start program. Final Report to the National Park Service,
Contract No. PX7490-5-0100, Department of Biology, Texas A&M
University, College Station, TX, 14 p.

Witham, R. and Cc. R. Futch. 1977. Early growth and oceanic survival
of pen-reared sea turtles. Herpetologica 33(4):404-409.

Witzell, W. Ne. 1980. Growth of captive hawksbill turtles,
Eretmochelys imbricata, in Western Samoa. Bull. Mar. Sci.
30(4) :909-912.

Wood, J. R. and F, BE. Wood. 1981. Growth and digestibility for the
green turtle (Chelonia mydas) fed diets containing varying protein

levels. Aquaculture 25:269-274.

34


In other words, growth under the particular conditions of head
starting did not appear to be density~dependent, but survival may have
been density-—dependent. This lends support to the idea that the
carrying capacity of the rearing containers for turtle biomass was a
limiting factor. In the absence of specific tests of effects of
stocking density on survival and growth of head started Kemp's ridley,
such interpretations should be considered speculation.

The turtles were not stocked at high densities. For example, ini-
tial stocking density in raceways was not more than 108 hatchlings per
raceway, or roughly 1 per 28 liter. On the other hand, if carrying
capacity of the raceways for biomass of turtles were a limiting fac-
tor, such limitation would be approached as the turtles grew larger.
The total amounts of turtle excrement and uneaten food increased as
the turtles grew larger. This, coupled with only thrice-weekly re-
placement of seawater, probably led to a greater buildup of poten-
tially harmful by-products of decomposition of wastes in the rearing
containers when they contained larger turtles than when they contained
smaller turtles. Compensatory mortality probably was the result. For
example, ammonia was one by-product of decomposition that accumulated
rapidly over the 1 to 2 days between seawater replacements (Fontaine
et al., 1985).

As the turtles grew larger, the space available to them within the
buckets decreased, and this probably limited their scope of activity,
thereby enhancing their growth. Near the end of the head starting
period, individuals that outgrew their buckets had to be transferred
to larger quarters (¢.g., hemispherical basins) for a short time
before tagging and release. Fast growth under confinement may make
the turtles physically less fit than their wild counterparts.

Transfer of larger turtles to the basins allows them greater latitude
for exercise (swimming), and may alleviate this problem. A study of
fitness and stamina in Kemp's ridley as related to head starting
methods is currently underway in this regard.

Further experiments will be required to determine and evaluate the

relationships among growth, survival and maturity of Kemp's ridley in

22


NOTICE

The National Marine Fisheries Service (NMFS) does not approve, recommend or
endorse any proprietary product or proprietary material mentioned in this
publication. No reference shall be made to NMFS, nor to this publication
furnished by NMFS, in any advertising or sales promotion which would indi-
cate or imply that NMFS approves, recommends or endorses any proprietary
product or proprietary material mentioned herein, or which has as its pur-
pose an intent to cause directly or indirectly the advertised product to

be used or purchased because of this NMFS publication.

This report should be cited as follows:

Caillouet, Charles Wax, Jr., Dennis Brian Koi, Clark Timothy Fontaine,
Theodore David Williams, William John Browning, and Richard Monte
Harris. 1986. Growth and survival of Kemp's ridley sea turtle,
Lepidochelys kempi, in captivity. NOAA Technical Memorandum
NMFS-SEFC-186, iii plus 34 pp., 12 Tables, and 7 Figures.

Copies can be purchased from the National Technical Information Service,
5258 Port Royal Road, Springfield, VA 22161.


Table 9. Analyses of covariance (test of slopes) based on rectilinear
regression (equation 3) of transformed weight on transformed
time lapse for Kemp's ridley "imprint"-groups in year-classes
1978-1980 (see Table 8).

1978 Year-class

Source of Degrees of Sum of Mean

variation freedom squares square | F
Among groups 1 2.84) 2.841 28.7
Within groups 5 980 593.036 0.099

1979 Year—-class

Source of Degrees of Sum of Mean

variation freedom squares square F
Among groups 1 11,951 11.951 119.5
Within groups 8,046 808.742 0.100

1980 Year-class

Source of Degrees of Sum of Mean

variation freedom squares square F
Among groups 1 19.187 19.187 96.9

Within groups 8,110 1,604,530 0.198


LITERATURE CITED

Bacon, Pe, Fe Berry, K. Bjorndal, H. Hirth, L. Ogren, and M. Weber
(eds.). 1983. Symposium on sea turtle research of the western
Atlantic (populations and socioeconomics). Proceedings of the
western Atlantic turtle symposium, 17-22 July 1983, San Jose,

Costa Rica, Center for Environmental Education, Washington, D.C.

In three volumes.

Bjorndal, K. A. and G. H. Balazs (eds.). 1983. Manual of sea turtle
research and conservation techniques. Second Edition. Center for

Environmental Education, Washington, D.C. 126 p.

Box, G. FE. Pe, and P. W. Tidwell, 1962. ‘Transformation of the
independent variables. Technometrics 4(4):531-550.

Caillovet, C. We, Jr. 1984. Essai de prevention de 1'extinction
de la tortue de Kemp. Les Carnets de Zool. 44(2):28-34.

Caillovet, C. We, Jv., C. T. Fontaine, T. D. Williams, S. A. Manzella,
Ke. Le We Indelicato, M. J. Duronslet, D., B. Revera, Andre M.
Landry, Jr. and P. J. Howes. MS. The Kemp's ridley sea turtle

head start research project: an annual report for fiscal year
1986.

Caillovet, C. We, Jv. and D. B. Koi. 1985. Patterns and variability
in first-year growth in weight of captive-reared Kemp's ridley sea
turtle: a graphical analysis. NOAA Technical Memorandum
NMFS-SEFC-164, i plus 4 p. and 52 figures.

Caldwell, D. K. 1962. Growth measurements of young captive
Atlantic sea turtles in temperate waters. Los Angeles County

Museum, Contrib. in Sci. No. 50, 8 p.

Carr, A. F. 1963. Panspecific reproductive convergence in
Lepidochelys kempi. Ergebn. der Biol. 26:298-303.
30


Table 3. Compositionl/ of floating, pelleted diet used for head-
starting Kemp's ridley.

a

Proximate composition (%)

Crude protein (minimum) 45

Crude fat (minimum)

Crude fiber (maximum) 3

Other (undefined) 47 |

Ingredients

Plant protein products Animal protein products
Grain products Processed grain by-products
Roughage products Lecithin

Vitamin A supplement Vitamin E supplement
Vitamin B,]> supplement Choline chloride

Niacin supplement . Calcium pantothenate

Folic acid Riboflavin supplement
Menadione sodium bisulfite complex D-activated animal sterol

(source of vitamin D3)

Ascorbic acid Biotin

Pyridoxine hydrochloride Thiamine hydrochloride
Inositol Methionine supplement
Ground limestone Calcium phosphate

Salt and traces of magnesium oxide Magnesium oxide
Ferrous sulfate Calcium iodate

Ferrous carbonate Cobalt carbonate
Copper oxide Copper sulfate

Zinc oxide
re SS Ss i rs i a Sy FS ss i cf nN

l/provided by Central Soya and Subsidiaries, Fort Wayne, IN.


depicted graphically for the 1978-1983 year-classes by Caillouet and
Koi (1985). McVey et al. (MS) also presented a relationship between
weight (W, in grams) and carapace length (CL, in centimeters) for
5,064 Kemp's ridleys, from hatchlings to 20 kg in size (W =

0. 2301C1,2-382) |

McVey and Wibbels (1984) plotted the weights of Kemp's ridleys
against age, comparing groups maintained at Miami Seaguarium and
Sea-Arama Marineworld with animals recaptured after being tagged and
released, Growth was fastest at Miami Seaquarium, intermediate at
Sea-Arama Marineworld and slowest in the wild. Fontaine et al. (1985)
plotted the arithmetic mean weights of Kemp's ridley of the 1978-1983
year-classes over time, but no interpretation was given.

In our study we reanalyzed the same data upon which the graphs of
Fontaine et al. (1985), Klima and McVey (1981), McVey et al. (MS), and
McVey and Wibbels (1984) were based, but in much greater statistical
detail. Caillouet and Koi (1985) graphed and we analyzed additional
data collected since the previous studies were completed. Our sta-
tistical analyses of increase in weight (equations 1 and 3) and of
increase in biomass (equation 5) provide sensitive methods for
detecting differences among groups of turtles, whether the differences
are genetically induced, related to sex, or related to the particular
conditions of incubation, hatching and rearing,

Caldwell (1962) examined growth in two Kemp's ridleys in captivity,
one 3.2 kg and the other 2.8 kg upon capture at Fort Walton Beach, FL.
Such sizes were larger than those reached during the typical head
starting period at Galveston, so the animals were probably more than a
year old when collected. The larger of the two specimens grew to 4.8
kg in 316 days on a diet of “cut-fish," and the smaller to 4.2 kg in

330 days on the same diet (ibid.). In an additional year, the smaller

turtle grew to 6.0 kg. Such sizes were reached at two years of age in
the head started Kemp's ridleys maintained at Sea-Arama Marineworld.
Caldwell (1962) also measured growth in one smaller Kemo's ridley
caught in the surf near Fort Walton Beach and maintained at Gulfarium.
Though it appeared normal and was an active swimmer, it did not feed
regularly during the five months it was held in captivity before it

25


McVey et al. (MS) offered the turtles of the 1978-1980 year-
classes daily amounts of food that were slightly more than the amount
eaten (Fontaine et al., 1985). Starting with the 1981 year-class, we
fed the hatchlings at a rate roughly 5% of average body weight per
day, with the amount of food divided into two portions for two
feedings, one in the morning and the other in the afternoon. As the
turtles grew larger, the daily ration was gradually changed to reach
roughly 1.5% of average body weight per day by the end of the head
starting period. The total quantity of food for each day was based on
the biomass of all the turtles (estimated by multiplying the grand
arithmetic average weight of turtles from the most recently weighed
samples by the total number of survivors held in captivity). Once the
total amount of food was calculated, the food was distributed among
the turtles in each raceway by hand, with the larger turtles given
move than the smaller ones. This feeding technique, while admittedly
highly subjective, was used to assure adequate feeding while avoiding
excessive waste of food. However, if during the interval between
weighings, the turtles appeared to require more food than the calcu-
lated amount, additional food was provided. If the turtles showed
signs of bloating or if water quality deteriorated too rapidly from
decomposition of uneaten food, either the amount of food was decreased
or the feeding stopped until conditions improved.

Foods and feeding were not controlled in such a manner that their
effects could be evaluated statistically, but they provided acceptable
levels of survival and growth. However, the faster-growing turtles
received more food than their slower-growing counterparts under the
feeding regimen used, and the differences in amounts of food may have
further enhanced the differences in growth among turtles of different
sizes,

The Kemp's ridleys maintained at Sea-Arama Marineworld were fed a
diet of smelt (Osmeridae), mackerel (Scombridae), squid (Cephalopoda)
and live blue crabs (Callinectidae), supplemented by encapsulated
vitamins A, D and E and a vitamin-mineral tablet (SEATAB, Pacific
Research Laboratory, Inc., El Cajon, CA). They were fed three times
per week and received, at each feeding, 0.45 kg of fish or squid, 3


Table 10. Rectilinear regressions (equation 5) of the natural logarithms of biomass (1nB;

B in kg) on the square roots of ages (r¥2; T in days) of Kemp's ridleys, by
clutch in year-classes 1981-19831/,

ee

Coefficient of

Intercept, Slope, Variance of deviations determination,
Year-class Clutch Ina b from regression, Sdev. v2
1981 1 ~-0.379 0.178 0.023 0.971

2 -0,402 0.248 0.011 0.993
3 -0.939 0.219 0.012 0.990
4 -0.475 0.223 0,008 0.993
5 ~0,.439 0. 244 0.012 0.991
6 -0.475 0, 237 0.007 0,994
7 0,227 0.228 0.008 0.993
8 -0.118 0. 230 0.010 0.992
9 0.092 0,222 0.010 0.992
10 0.057 0.235 0.008 0.994
11 -0.030 0. 233 0.015 0.989
12 ~0.017 0.220 0,007 0.994
13 -0.141 0.203 0.008 0.991
14 -0,008 0.234 0.004 0.996
15 0,057 0.219 0.008 0.992
16 0,220 0. 245 0.006 0.996
17 0.151 0, 243 0.007 0.994
18 0.214 0.227 0.010 0.992
19 -0.351 0. 209 0.016 0.987
20 ~0.552 0.222 0.009 0.993
21 0.260 0.174 0,009 0.988
22 -0.068 0. 231 0.011 0.993
23 ~-0. 207 0. 243 0.013 0.992
Clutches .
combined -0.134 0.224 0.153 0.866
1982 1 0. 206 0.179 0,009 0.989
2 ~2,586 0.267 0.049 0.973
3 -0.004 0. 269 0.019 0.989
4 0,217 0.254 0.019 0.988
5 0,309 0.248 0.039 0.975
6 -0,044 0.246 0.011 0.993
7 -0.595 0.270 0.006 0.997
8 -0.660 0.264 0,018 0.989
9 ~0,118 0,272 0.016 0.991
10 ~0.223 0.216 0.009 0.992
11 -0.383 0.243 0.014 0.990
12 0,295 0. 265 | 0.029 0.983
13 -1,147 0. 267 0.007 0.996
14 -0.719 0. 260 0.005 0.997
15 —0.657 0.257 0.005 0.997
16 -0.444 0.257 0.007 0.996
17 -0.370 0.254 0.010 0.994
18 -0.363 0. 263 0.017 0.991
19 0.046 0.258 0,011 0.994
20 -0,397 0.265 0.013 0.993
Clutches

combined -0,378 0.253 0.384 0.775



Table 11. Analyses of covariance (test of slopes) based on rectilinear
regression (equation 5) of transformed biomass on transformed

age for Kemp's ridley clutches in year-classes 1981-1983 (see

TL LL LT A FA ee SPs SS rt et Pr a te a,

1981 Year—class
al ett at

Source of Degrees of Sum of Mean

variation freedom squares square F
Among clutches 22 1.727 0.078 728
Within clutches 199 1.993 0.010

SS Se rr Ss SSS reff Psu rs i io ss so yes suey:

1982 Year-class
rege

Source of Degrees of Sum of Mean

variation freedom Squares square F
Among clutches 19 1.991 0.105 6.5
Within clutches _ 180 2.798 0.016

1983 Year—-class |
ce rere nn te epee ean ene

Source of Degrees of Sum of Mean

variation freedom squares square F
Among clutches 2 0. 324 0.162 8.1
Within clutches 11 0.222 0.020

SSS LT LS SS SS rr a yp fl ep SE


residual from regression. This represents the following exponential

relationship between weight and age for a given clutch:
W = (gebT ¥2)q (2)

For the 1978-1980 year classes, extraneous variation in size
resulting from the sampling procedure and differences in age among the
turtles made it necessary to use the time unit T' (days) to assess
growth. T' represented the time lapsed from the earliest date on
which weights and measurements were taken on hatchlings of a given
year-class. For the growth analysis applied to data from the two
“imprint"~groups in each of the 1978-1980 year-classes, lapsed time
was substituted for age (which was not known) as follows:

an,
InW = Ina’ + bt’ + Inat (3)

where T' is the time lapse in days following the earliest weighings of
hatchlings from a given year-class. Parameters Ina' and b' and resi-
dual Ind’ are not strictly comparable to corresponding parameters in
equation (1). Equation 3 can be expressed in exponential form
relating weight to lapsed time for a given "“imprint"-group within a

year-class as follows:

@ = (ateb'T! ¥2yqq (4)

Rectilinear Regression of Transformed Biomass on Transformed Age
For each clutch of the 1981-1983 year-classes, size and survival
data were available upon which to calculate biomass at a given age.

Biomass was determined by multiplying the geometric mean weight (w')

of each random sample of turtles from each clutch by the number of

surviving turtles within the clutch. The geometric mean weight was
calculated as:

n
W' = Antilog E( 2 Inwy)/n)
LL

12