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15
Sectior IV: Actual Croc Data, l,todela aud Aptrlication
1. The data. We used actual grorirth records taken
a population-of
fron
Cfocodvlus aeurus ln southern Florida.
ctaEa
The
\{ere.collected by paul l4oler (Florida Gane and Fresh
Fish.
Water
cornnission) specific gror,rth . In this paper of Arnerican hre are crocodiles concerned not but lrith rather the
performance
-lne
of various growth models in fitiinq
with ''i"'Gllectua1
the
Therefore,
aata.
in order not to poach pi"i;
property, we hawe been carefui (1) newer "" to " rit any qrowth
curves to his entire data set and 1i) never to rnaie putfic
specific paraheter
any
values for
fit to =,,!="ta'Jf pa,_,f ,"
data. The subset of data r^re used "rrrv". included aUoui s!o-"aprur"_
ewents for 34O knolrn_age anlmals.
2. Curve fitting and testinq ptan.
a. We used a random nu-rnber generator -ca-r,-f-ei;rroN
data set into tv/o approxinately equal parti, to chop u
the
SET and
oafa
a TEST DATA sET.
t'. We flt the folloving 12 ,rmodels,r to
calibration
the
data set:
REGRESSTON
LINE ALL: fength as a function of age, all caplures;
LINE LASI: length as a function of age, last capEures
only for each animal.
OUAD ALL: length as i function of age and age squareat,
all captures;
QUAD LAST: length as a function of age and age squared,
last captures only;
CUBE ALL: length as a function of age, age squared, and
age cubed, all captures;
CUBE I"AST: Iength as a cubic function of age, last
captures only;
FOUR
-ALL: length-as a function of age, age squared, ag,e
cubed, and age to the fourth polrer;
FOUR tAST: length as a quartlc function of age, Iast
captures oitfy.
VON BERTAI,ANFI'Y
VONB INl' ALL: Von Bertalanffy model fit (by a nonlinear
progran using the euasi-Newton nethod of variance
mrnlnrzatlon; SYSTAT) to all inter_capture intervals for
all anihals;
VONB INT IONG: Von Bertalanffy model fit (as above) to
only the tongest inter-captur; interval fii.=i
co Iast capture) for each anihat,
"""t"i"
VONB FD ALL: Von Bertatanffy nodet fit by a finite
difference nethod (using linear regression to estinate
asympEotlc Iength and the gror.rth rate pararneter; see
Andrews, 1982, p. 287) to a1t inter_capiure in*..r;t;
for all anirnals;
VONB FD LONG: Von Bertalanffy nethod fit by a finite
dj-fference nethod (as above) to only the tong-est intercapture
interval for each aninal.