Parameters of the length–weight relationship of the form W=aLb are presented for 45 demersal fish species caught on the upper continental slope of the Caribbean Sea off Colombia. The b values varied between 2.13 and 4.97, with the mean b = 3.042 (95% CI, 2.887- 3.196)

Acero, A.

Diaz, L.S.

Garcia, C.B.

Navas, G.

Roa, A.

English

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23Naga, The ICLARM Quarterly (Vol. 23, No. 3) July-September 2000
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Length-Weight Relationships of Demersal
Fishes from the Upper Continental
Slope off Colombia
L.S. Diaz, A. Roa, C.B. Garcia, A. Acero, and G. Navas
Introduction
The medium depth (300-500 m)
demersal fish fauna of the
Colombian Caribbean is relatively
unknown (Gartner et al. 1997).
Due to this, a survey was conducted
in 1999 in order to initiate an inven-
tory of species from such depths. Al-
though primarily concerned with
taxonomy, we took advantage of the
materials collected to provide
estimates of the length-weight
relationship (LWR) parameters of 45
species (out of 140 species
identified) for which enough data
pairs were available.
An empirical relationship like
LWR is an important piece of infor-
mation in studying the natural
history of fishes. For instance, LWR
allows predictions of weight from
length in yield assessments (Pauly
1993) and can also be indicative of
the ‘condition factor’, i.e., the gen-
eral well-being of fish populations.
An interesting possibility, not yet
explored to our knowledge, is to
conduct comparisons of the
parameters a and b  in space (latitud-
inal and depth gradients) and time
(period/season of the year) for both
fish   assemblages and for individual
species. We believe there is some-
thing to be learned here in relation
to the general metabolism of species
and communities.
Materials
 and Methods
Sampling was done with a small
otter trawl (7.5 m headline, 9.5 m
footrope). About 80 stations were
visited in 1999, covering the latitud-
inal range of the Colombian
Caribbean (Fig. 1). Trawling lasted
an average of 10 minutes at each
station. Trawl hauls were conducted
along two transects on the upper
continental slopes, one at 300 m
depth and the other at 500 m depth.
Individuals were measured
(total length in all cases) to the
nearest mm and weighed to the near-
est hundredth gram in the laboratory.
The parameters a and b of the LWR
of the form:
W=a Lb
were estimated using the routines of
the computer program FISHPARM
(Prager et al. 1989) that implements
Marquadt’s algorithm for non-linear
least-squares parameter estimation.
Results
The results of the length-weight
analysis are given in Table 1. Fig. 2
shows the frequency distribution   of
the b values. With the exception of
one extreme value to the right, the
distribution tends to be symmetrical
and in line with the distributions of
b values found for shallower
demersal fish assemblages from the
Colombian Caribbean (Duarte et al.
1999). The b values varied  between
2.13 (Caelorinchus caelorincus) and
4.97 (Halosaurus ovenii) with mean
b equal to 3.042 (95% CI=2.887-
3.196).
Acknowledgements
COLCIENCIAS/BID Grant
2105-13-079-97 for the project
“Caractericion de la macrofauna Del
Caribe Colombiano. Fase I. Epi-
fauna de la franja superior del Talud
Continental (300 y 500 m)”, and the
Abstract
Parameters of the length–weight relationship of the form W=aLb are presented for 45 demersal fish species
caught on the upper continental slope of the Caribbean Sea off Colombia. The b values varied between 2.13 and 4.97,
with the mean b = 3.042 (95% CI, 2.887- 3.196).
24 Naga, The ICLARM Quarterly (Vol. 23, No. 3) July-September 2000
Table 1. LWR parameters for 45 demersal fish species from the upper continental slope (300 m and 500 m depth)
of the Colombian Caribbean.
Species n Weight range Length range a b
(g) (mm)
Antigonia capros        38 1.4 - 103.0 40 - 153 7.33 E -05 2.80
Antigonia combatia 63 1.3 - 102.1 35 - 155 5.60 E -06 3.31
Argentina striata 114 1.3 - 19.4 48 -  150     3.64 E -04 2.14
Bathyclupea argentea   11 15.0 - 150.0 146 - 256  2.24 E -07 3.66
Bathygadus macrops   61 2.6 - 225.0 87 - 414 8.44 E -05 2.85
Bathypterois dubius   16        5.5 - 20.3       121 - 75    8.28 E -07 3.29
Bembrops anatirostris   77 1.6 - 225.0 71 - 317 9.64 E -07 3.33
Benthodesmus tenuis 11 0.8 - 49.6 160 - 551 4.84 E -10 4.02
Bregmaceros atlanticus 12 0.3 - 1.3 40 - 68 2.52 E -05 2.54
Caelorinchus caelorhincus 251 3.1 - 110.0 81 - 356 4.24 E -04 2.13
Cealorinchus carribaeus 390 1.9 - 61.5  75 - 262 4.85 E -06 2.90
Chaunax suttkus 119 0.5 - 250.0 7 - 232 7.40 E -05 2.77
Chlorophthalmus agassizi 108 0.7 - 24.3 50 - 170 1.21 E -05 2.82
Coloconger meadi 13 6.5 - 24.7 135 - 265 5.11 E -06 2.91
Cyttopsis roseus   30 8.9 - 8.9 8.9 - 185 8.10 E -06 3.08
Dibranchus atlanticus 128 0.5 - 0.5 37 - 172 9.89 E -06 3.04
Epigonus pandionis   14 2.8 - 125.0 34 - 220 9.18 E -07 3.49
Halosaurus ovenii 12 0.8 - 79.1 117 - 425 6.72 E -12 4.97
Hemanthias aureorubens 19 1.6 - 215.0 48 - 310 3.21 E -06 3.15
Hoplostethus occidentalis 33 2.1 - 47.9 52 - 142 6.80 E -06 3.17
Laemonema goodebeanorum 222 0.4 - 150.0 17 - 285 6.32 E -07 3.14
Lonchopisthus lemur 65 0.9 - 10.0 45 - 100 1.24 E -04 2.41
Malacocephalus occidentalis   37 0.64 - 300.0 58 - 424 8.09 E -09 4.02
Myxne mccoskeri 36 5.6 - 32.0 163 - 282 2.07 E -05 2.50
Neobythites gillii 83 1.3 - 20.1 61 - 156 1.18 E -05 2.81
Neobythites bimarginatus 46 1.4 - 27.0 70 - 185 1.98 E -06 3.14
Neoscopelus macrolepidotus 105 0.8 - 22.5 47 - 165 7.42 E -05 2.52
Neoscopelus microchir 16 1.0 - 38.7 48 - 177 2.19 E -05 2.78
Nezumia aequalis 183 0.5 - 35.5 61 - 224 1.78 E -05 2.68
Peristedion gracile 12 3.3 - 27.2 89 - 183 9.84 E -07 3.28
Peristedion greyae 15 18.5 - 59.0 165 - 223 8.26 E -06 2.92
Peristedion miniatum 17 4.1 - 93.5 88 - 260 2.06 E -04 2.36
Physiculus fulvus 14 0.44 - 35.0 5.23 - 82 7.70 E -07 3.54
Poecilopsetta inermis 257 0.9 - 20.0 57 - 145 4.65 E -06 3.04
Polymixia lowei 20 4.7 - 58.9 76 - 178 1.00 E -05 3.02
Polyipnus asteroides 98 0.6 - 9.4 21 - 87 9.80 E -05 2.55
Pontinus longispinis 81 0.3 - 375.0 26 - 300 9.15 E -06 3.08
Pontinus nematophthalmus 29 0.2 - 33.8 23 - 155 9.60 E -06 2.99
Setarches guentheri 19 1.5 - 105.8 55 - 194 2.73 E -06 3.31
Steindachneria argentea 27 5.3 - 225.0 129 - 405 1.28 E -07 3.52
Synagrops bellus 56 0.1 - 125.0 23 - 235 7.45 E -06 3.04
Synagrops microlepis 15 3.2 - 12.8 69 - 109 6.97 E -05 2.59
Synagrops spinosus 13 4.6 - 26.9 78 - 144 2.62 E -06 3.25
Xenomystax congriodes 13 2.3 - 24.3 84 - 430 2.41 E -07 3.04
Zenion hololepis 70 0.5 - 8.4 32 - 86 4.71 E -05 2.72
25Naga, The ICLARM Quarterly (Vol. 23, No. 3) July-September 2000
f
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Fig. 1. Location of the sampling stations off the Caribbean coast of Colombia.
Instituto de Investigaciones Marinas
y Costeras, INVEMAR. Sandra
Vilardy, Tania Yie and Adriana
Bermudez helped in the process of
measuring and weighing the
samples.
References
Duarte, L.O., C.B. Garcia, N. Sandoval, D.
von  Schiller,  G. Melo  and  P.  Navajas.
1999.  Length-weight  relationships  of
fishes  from  the  Gulf  of Salamanca,
Colombia.  Naga, TheICLARM  Q.
22(1): 34-36.
Gartner, J.V., R.T. Crabtree and K.J. Sulak.
1997.  Feeding  at  depth, p. 115-182. In
 D. J. Randall  and   A.P.  Farrell  (ecls).
Deep sea  fishes, Vol.16. Academic
Press, New York.
Pauly, D. 1993. Editorial. Fishbyte section.
Naga, The ICLARM  Q.  16(2-3): 26.
Prager, M.H.,  S.B. Saila  and  C.W
Recksieck. 1989. FISHPARM: a micro-
computer  program for parameter
estimation of non-linear  models  in
fishery  science. 2nd Old Dominion
University Tech. Rep. 87-10, 18 p.
Old Dominion University,
Norfolk,Virginia.
____________________
L.S. Diaz, A. Roa and G. Navas are
from the Instituto de Investigaciones
Marinas y Costeras, INVEMAR, A.
A. 1016, Santa Marta, Colombia.
C.B. Garcia is from the Departa-
mento de Biologia, Universidad
Nacional de Colombia, INVEMAR
and A. Acero is from the Instituto
de Ciencias Naturales, Universidad
Nacional, INVEMAR.
Fig. 2. Frequency distribution of b values for 45 species from the upper continental
slope of the Caribbean Sea off Colombia (mean b = 3.042; 95% CI,2.087-3.196).
Exponent of LWR (b)
Fr
eq
ue
nc
y
15
10
5
0
2 3 4 5
77° 76° 75° 74° 73° 72° 71°
Caribbean Sea
Colombia
Venezuela
8°
9°
10°
11°
12°
13°
50 100 150 Kilometers
La
tit
ud
e 
(N
)
Longitude (W)
50
100
200
300


Length-weight relationships of demersal fishes from the upper continental slope off Colombia

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