South Pacific Studies Vol.29, No.1, 2008

Morphometric Relationship and Condition Factor ofSiganus stellatus, S. canaliculatus and S. sutor (Pisces:
Siganidae) from the Western Indian Ocean Waters
Nina WAMBIJI1, Jun OHTOMI2, *, Bernerd FULANDA1, 2, Edward KIMANI1,
Nicholas KULUNDU1 and Md. Yeamin HOSSAIN2

1:Kenya Marine & Fisheries Research Institute, Marine & Coastal,P. O. Box 81651, Mombasa-80100, Kenya
2:Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima 8900056, Japan

Abstract
The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. Some
biological attributes including morphometric relationships (length-length, length-weight) and condition
factors of three siganids of the Western Indian Ocean were estimated over peak April-August monsoon
season in Southcoast Kenya. Specimens were caught using basket traps "malema", one of the main gears
in the traditional fishery. A total of 64, 260 and 736 specimens of Siganus stellatus, S. canaliculatus andS. sutor were recorded, with mean±standard error for total length (TL) as 16.0±0.6cm, 22.5±0.3cm and26.5±0.2cm with corresponding wet body weights (BWs) of 71.28±8.53g, 158.58±6.45g and 258.80±4.30g
respectively. TL-BW relationships were best expressed by log10BW=2.597log10TL-1.356 for S. stellatus,
log10BW=2.800log10TL-1.635 for S. canaliculatus and log10BW=2.716log10TL-1.484 for S. sutor withrelative condition factors expressed by Kn = BW/ [(4.41x10-2) (TL2.597)], Kn = BW/ [(2.32x10-2) (TL2.800)]
and Kn = BW/ [(3.28x10-2) (TL2.716)] for the three species respectively. TL and BW were significantly
correlated with Kn and K. To the best knowledge of the authors, this study provides the first L-W
relationship and Kn data for S. stellatus within the species geographical distribution. The overall results andequations provide useful simple tools for in-situ gauging of overall health of wild siganid populations inSouthcoast Kenya for fisheries management and assessment of potential aquaculture species.
Key words: condition factor, morphometric relationship, Siganidae, Southcoast Kenya, Western Indian
Ocean,

Introduction
Morphometric relationships including length-length (L-L) and length-weight(L-W) relationships and relative Kn and Fulton's K condition factors are importantbiological parameters for fishes, from which the condition of stocks health of fish
populations can be deduced (BAGENAL and TESCH 1978). These parameters are also
invaluable in the selection of species for aquaculture.
The family siganidae, comprised of rabbit fishes and spinefoots inhabit tropical*Tel: +81-99-286-4152, Fax: +81-99-286-4133.
Email: ohtomi@fish.kagoshima-u.ac.jp
Received: 6 December 2007
Accepted: 12 March 2008

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South Pacific Studies Vol.29, No.1, 2008

and subtropical Indo-Pacific regions mainly within sea grass beds at <15m water
depths (JONES 1981). The members are almost all marine except Siganus vermiculatus
which is brackish, and are widely distributed in the tropical Indo-Pacific and eastern
Mediterranean (WOODLAND 1990). Ecologically, these diurnal herbivores are importantin keeping filamentous and leafy algae from smothering corals (JOHNSON and GILL
1998) and form key target species for the artisanal fisheries of the East African coasts(GUARD 1999). Together with lethrinids, siganids constituted ~31% of the total reef fish
landings along the Kenya coast over the last five years in the 1990’s (FAO 1998).
The Kenya coast, part of the wider Western Indian Ocean (WIO) marine ecoregion extends from Vanga (Tanzania border, at 4.663oS and 39.215oE) to Kiunga(Somalia border, at 1.663oS and 41.557oE), supporting an estimated coastal populationof 2.49 million people ((HORRIL and KAMAU 2001). Five siganid fishes; Siganus
stellatus (FORSSKÅL 1775), S. luridus (RUPELL 1928), S. canaliculatus (PARK 1797), S.
argenteus (QUOY and GAIMARD 1885) and S. sutor (VALENCIENNES 1835) are common
in the inshore waters with S. sutor (‘tafi’) being by far the most abundant in theartisanal catch (NTIBA Unpubl.).
The siganids of the WIO region are fairly well studied (GEORGE 1972, BRYAN etal. 1975, GUNDERMANN et al. 1983). Localized studies show two spawning seasons inJanuary/February and May/June off the Kenyan and Tanzania waters respectively (DeSOUZA 1988, NTIBA and JACCARINI 1990, KAMUKURU 2006). However, species-specificmorphometric analysis (L-L and L-W relationships) and condition factor (relative
Kn and Fulton’s K) studies for these siganids of the WIO waters have received little
attention. Consequently, such information gaps have led to lack of clearly defined stock
management strategies. Further, lack of significant sexual differences in siganids also
makes interpretation of body condition factors difficult (THRESHER 1984). However,relative condition Kn remains a practical tool that biologists and managers can use togauge the overall health of fish stocks regardless of the underlying assumptions andlimitations, providing an alternative to the expensive in-vitro proximate analyses oftissues (SUTTON et al. 2000). The present paper provides information on L-L and L-W
relationship parameters and body condition factors of three common species; Siganus
stellatus, S. canaliculatus and S. sutor from the artisanal fisheries of the WIO waters of
Kenya, sampled during peak southeast monsoon (SEM) season, April through August,
2007.

Materials and Methods
Study sites
Three study sites; Diani, Msambweni and Shimoni were selected for thisstudy on the Diani-Vanga coastal stretch (Fig. 1) based on annual fish landings withpreference for fishing villages under the beach management program of the Fisheries
Department, Kenya. The Diani site straddling at 4.296oS and 39.590oE had six fish

WAMBIJI N et. al: Morphometric Relationship of Three Siganids

3

designated landing beaches; Congo beach, Southern palms, Trade winds, Mwaepe,
Mvuleni, and Mwanyaza. Sampling was conducted on the last three landing beaches.
The Msambweni site, straddling at 4.472oS and 39.473oE with two designated landing
beaches; Mwaembe and Mkunguni borders Diani site to the south. The site has afringing reef 0.5-1.5 km offshore with shallow lagoons, and a reef flat that exposedin some places during low tide, sloping down to about 30m at 2km offshore. The lastsite, Shimoni, at 4.648oS and 39.380oE lies within the Funzi bay complex bordering
Msambweni to the north and Vanga to the south. Four landing beaches were sampled inthis stretch; Kibaoni, Kijiweni, Nyuli and Kibuyuni making a total of 9 landing beaches
sampled along the Southcoast Kenya during the present study.

Fig. 1. A map of Diani, Msambweni and Shimoni sites of the Western Indian Ocean waters of Kenya in thepresent study of Siganus stellatus, S. canaliculatus and S. sutor (Pisces: Siganidae), April throughAugust, 2007.

Sampling procedures and data analyses
Fish sampling was conducted using 10 baited traditional basket traps, “malema”
common in the traditional artisanal fishery (Fig. 2). The traps, hexagonal in shapemeasuring 1.5m diagonally, 20cm height and 10cm at mouth opening, are fabricatedout of sticks and reeds. The traps were baited with seaweeds before setting daily, for 5

4South Pacific Studies Vol.29, No.1, 2008

Fig. 2. Traditional basket valve traps “malema” of the traditional fishery used in the present study of Siganus
stellatus, S. canaliculatus, and S. sutor (Pisces: Siganidae) in Diani, Msambweni and Shimoni sitesof the Western Indian Ocean waters of Kenya in the present study, April through August, 2007.
The traps measure 150cm diagonally, 20cm height and 10-15cm mouth diameter and are anchoredby a single stone on each side.

days every month over a period of five months from April though August, 2007. The
fish samples were sorted to family level and all siganids specimens selected and further
identified to species level for morphometric measurements. Total length (TL), from tipof snout to tip of caudal fin and standard length (SL), from tip of snout to posterior endof last vertebra were measured to the nearest 0.1cm using a graduated measuring-board
while wet body weight (BW) was measured to the nearest 0.01g using an electronicbalance (VIBRA AJ4200CE, Gemini, BV).
In order to examine the morphometric changes occurring with increases in bodysize, the relationships between TL and SL were calculated using the linear relationshipequation SL = a + bTL. A plot of log10TL against log10BW for each species by studysite was used to determine the intercept and slope parameters a, and b (HAYES et al.
1995) of the equation. The relative condition factor Kn for each individual (based on
sample size n) was calculated according to Le CREN (1951) equation Kn = BW/aTLb,
where BW and TL are the wet body weight and total length respectively. Fulton’s
condition factor K was calculated using the equation K = 100 x (BW/TL3). Pearson’s
correlation coefficients (as coefficient of determination, r2) were determined foranalyses of the relationship between the morphometric indices (Kn and K) with TL andBW.

WAMBIJI N et. al: Morphometric Relationship of Three Siganids

5

Results
Species composition
In the present study, a total of 1060 siganids ranging from 11.2 to 44.8cm TL
were caught using set traditional basket traps “malema” in the artisanal fisheries ofthe Western Indian waters of the Diani, Msambweni and Shimoni, Southcoast Kenya.
Three species, Siganus stellatus, S. canaliculatus and S. sutor were encountered in
the samples, accounting for 64, 260 and 736 of the fish caught respectively. Siganus
stellatus recorded the lowest catch representing only 6% of the total siganid catch. No
specimens were recorded from the Diani site. S. canaliculatus was the most widelydistributed, recording specimens from all the study sites. There was unexplained
absence of S. sutor specimens from Msambweni although this site lies centrally
sandwiched between the other two sites. Moreover, the species accounted for >69% of
the total catch, distributed in both Diani and Shimoni at 45.7% and 54.3% respectively.
Length-frequency distribution
The results of the morphometric measurements for the three species are shownin Table 1. In S. stellatus, 64 specimens pooled from Msambweni and Shimoni
samples recorded 16.0±0.6cm TL. All the recorded specimens were mainly below the
18.0cm length class (Fig. 3). The Shimoni sites recorded 16.2±0.7cm TL compared
to 14.0±0.4cm in Msambweni but the differences were statistically insignificant (P =0.739, U-test).
In S. canaliculatus, a total of 260 specimens were recorded from all the three sites

Fig. 3. Total length frequency distribution for Siganus stellatus in Msambweni and Shimoni sites of theWestern Indian Ocean waters of Kenya in the present study, April through August, 2007. n =samples size.

6South Pacific Studies Vol.29, No.1, 2008

Fig. 4. Total length frequency distribution for Siganus canaliculatus in Diani, Msambweni and Shimoni
sites of the Western Indian Ocean waters of Kenya in the present study, April through August, 2007.
n = samples size.

Fig. 5. Total length frequency distribution for Siganus sutor in Diani and Shimoni sites of the Western
Indian Ocean waters of Kenya in the present study, April through August, 2007. (n = samples size).

with mean 22.5±0.3cm TL. A clear unimodal distribution was noted in S. canaliculatus
at Shimoni site although the 34cm-35.9cm and 34cm– 37.9cm size classes wereabsent in both Diani and Shimoni (Fig. 4). Similarly, the 28.0cm+ TL size class was

260

736

Siganus canaliculatus

Siganus sutor

Kn= BW/[(4.41x10 -2)(TL 2.597)

Kn= BW/[(2.32x10 -2)(TL 2.800)

K n= BW/[(3.28x10-2)(TL2.716)

BW = (2.32 x 10-2)(TL2.800)(r2 = 0.973)

BW = (3.28 x 10-2)(TL2.716)(r 2 = 0.909)

SL = 0.849 TL -1.121(r 2 = 0.982)

SL = 0.824 TL -0.220(r 2 = 0.943)

Kn

BW = (4.41 x 10-2)(TL2.597)(r 2 = 0.989)

TL-BW relationship

SL = 0.867 TL -1.544(r 2 = 0.988)

SL-TL relationship* shows significance (P 0.01), n = samples size

64nSiganus stellatus

Species0.009* 0.141* 0.097* 0.001*

0.130* 0.205* 0.167* 0.069*

0.349* 0.345* 0.667* 0.648*

K n-TL K n-BW K -TL K -BW

r 2, for correlation between

Table 2. Overall length-length (SL-TL) and length-weight (TL-BW) relationships and relative condition factor (Kn) equations, and coefficient of determination (r2) for Kn
and K with total length (TL, cm) and wet body weight (BW, g) for Siganus stellatus, S. canaliculatus and S. sutor (Pisces: Siganidae) in Diani, Msambweni and
Shimoni on the Western Indian Ocean waters of Kenya in the present study, April through August, 2007

WAMBIJI N et. al: Morphometric Relationship of Three Siganids
7

8South Pacific Studies Vol.29, No.1, 2008

Fig. 6. Relationship between logarithm of body weight (g) (log10BW) and logarithm of total length (cm)(log10TL) for Siganus stellatus (a), S. canaliculatus (b) and S. sutor (c) (Pisces: Siganidae) in Diani,
Msambweni and Shimoni of the Western Indian Ocean waters of Kenya in the present study, April
through August, 2007.

not encountered in Msambweni samples. Site analyses showed highly significant
differences observed in S. canaliculatus (P < 0.001, Kruskal-Wallis test) with Diani
recording larger specimens at 25.1±0.6cm TL compared to 18.2±0.6cm in Msambweni

WAMBIJI N et. al: Morphometric Relationship of Three Siganids

9and 22.7±0.4cm in Shimoni (P < 0.01 for all pairs, Steel-Dwass test).
In S. sutor, a total of 736 specimens caught in Diani and Shimoni recorded
26.5±0.2cm TL with near-normal distributions in both sites (Fig. 5). There was notableabsence of S. sutor specimens in Msambweni site and like in S. canaliculatus, theDiani site recorded significantly larger specimens compared to Shimoni, at 27.2±0.2cm
and 26.1±0.2cm TL respectively (P < 0.001, U-test).
The L-L changes occurring with growth in the three siganids of Southcoast Kenya
were best described by equations SL = 0.867TL-1.544 for S. stellatus, SL = 0.849TL1.121 for S. canaliculatus and SL = 0.824TL-0.220 for S. sutor (Table 2).
Length-weight relationships and condition factors
Wet BWs ranged from 25.27 to 289.20g in S. stellatus, 16.33 to 650.27g in S.
canaliculatus and 30.10-1009.07g in S. sutor with mean±SE calculated as 71.28±8.53g,
158.58±6.45g and 258.80±4.30g for the three species respectively (Table 1).
Taking into account potential morphometric differences by species,
L-W relationships for the three species were best expressed by the equations
log10BW = 2.597log 10TL-1.356, log 10 BW = 2.800log 10TL–1.635 and log 10BW =2.716log10TL-1.484 for S. stellatus, S. canaliculatus and S. sutor respectively (Fig.
6). Using the slope b and intercept a from the power function of BL-TL relationship,
the relative condition factor for each species was best expressed by the equations Kn=BW/ [(4.41x10-2) (TL2.597)] for S. stellatus, Kn =BW/ [(2.32x10-2) (TL2.800)] for S.
canaliculatus and Kn =BW/ [(3.28x10-2) (TL2.716)] for S. sutor (Table 2).
Siganus stellatus recorded similar fish conditions in both Msambweni and
Shimoni, (P = 0.620 for Kn and 0.659 for K, U-test). However, significantly better fishcondition was recorded in Diani for S. canaliculatus and S. sutor (P < 0.001, U-test).
In overall, S. stellatus and S. sutor recorded similar but significantly better relative
condition factor Kn than S. canaliculatus. In contrast, Fulton’s condition factor K
showed significant variation among all the three species, with best performance by
S. stellatus, S. sutor and S. canaliculatus in that order, calculated as 1.471±0.021,
1.317±0.008 and 1.259±0.010 respectively (P < 0.001, Kruskal-Wallis test; P < 0.01
for all pairs, Steel-Dwass test) (Table 1). There was a positive correlation for Kn and K
with TL and BW for all the three species (P < 0.01 for all groups, Pearson’s correlationtest) (Table 2).

Discussion
The siganid fishes of the WIO waters of Diani, Msambweni and Shimoni fisheries
in Southcoast Kenya were in the same range of morphometric parameters and body
condition factors reported for fisheries within similar latitude ranges. In the present
study, the largest S. stellatus specimen encountered at 30.5cm TL in Shimoni wasnear the upper end of growth ranges (40cm TL) reported for this species (WOODLAND

400
736

Pooled0

ShimoniMsambweni

336

260

PooledDiani

146

Shimoni

54

64

PooledMsambweni

60

Shimoni60

4Msambweni

Diani

0

n

Diani

Study site――27.2±0.2a*

22.1±0.2a*

26.5±0.2c

22.5±0.3b

17.8±0.3b

21.7±0.1c

22.7±0.4c*

18.2±0.3c*

26.1±0.2b*

18.2±0.6b*

14.3±0.5b*

21.3±0.2b*

25.1±0.6a*

20.3±0.5a*―

16.0±0.6a

12.4±0.5a―

16.2±0.7

14.0±0.4

TL (cm)12.5±0.6

11.3±0.4

SL (cm)―258.80±4.30c

230.46±5.38b*―292.55±6.45a*

158.58±6.45b

163.22±8.36c*

86.83±7.57b*

211.85±14.11a*

71.28±8.53a

73.23±9.04

42.25±4.01

BW (g)―

1.112±0.006a

1.047±0.0082b*―

1.191±0.009a*

0.988±0.007b

0.997±0.008a*

0.909±0.018b*

1.038±0.016a*

1.095±0.112a

1.0933±.012

1.120±0.414

Relative K n―

1.317±0.008c

1.249±0.010b*―

1.397±0.012 a*

1.259±0.010b

1.261±0.012

1.251±0.022

1.259±0.023

1.471±0.021a

1.468±0.022

1.530±0.053

Fulton’s K

a, b, c indicate significant differences between species and a*, b*, c* study sites (P 0.01); same letters after mean denote lack of significant differences between sites
within species or between species (pooled). n = sample size.

Siganus sutor

Siganus canaliculatus

Siganus stellatus

Species

Mean ± standard error (SE)

Table 1. Morphometric measurements (standard length, SL; total length, TL; body weight, BW) and, relative (Kn) and Fulton’s (K) condition factors for Siganus stellatus, S.
canaliculatus and S. sutor (Pisces: Siganidae) in Diani, Msambweni and Shimoni, on the Western Indian Ocean waters of Kenya in the present study, April throughAugust, 2007

10
South Pacific Studies Vol.29, No.1, 2008

WAMBIJI N et. al: Morphometric Relationship of Three Siganids

111986) and the TL size classes of 12.0-15.0cm comprising small individuals recorded in
Shimoni suggest a continuous recruitment on this site. For S. canaliculatus, the largest
recorded specimen was 38.0cm TL in Diani compared to 33cm TL reported in India(JEYASEELAN 1988), 23.0cm TL from the west coast of Malaysia (AHMAD et al. 2003)
and 25.2cm TL in the Southern Negros islands of Philippines (PAULY 1978). Theseobservations probably suggest a low fishing pressure on S. canaliculatus populations
on this site owed to removal of modern gears such as beach seines and spear gun
fishing under the fisheries beach management program. The species however was lessabundant in catches compared to S. stellatus and S. sutor, attributed to its wider habitat
preference, tolerating more turbid waters, invasion of river mouths especially aroundsea grass beds and reduced schooling in adults (Woodland 1990). On the Diani site, S.
sutor recorded 44.8cm TL, comparable to 36.2cm SL reported from Gazi bay on thesame coast (NTIBA and JACCARINI 1988), 25cm TL in the near-shore fisheries off Daressalaam coast, Tanzania (BENNO Unpubl.), 49.9cm TL in Mauritius (JEHANGEER 1988)
and 52.1cm FL in Seychelles (GRANDCOURT 2002).
The L-L relationship parameters calculated for the three siganid species (slope b= 0.867, 0.849 and 0.824 for S. stellatus, S. canaliculatus and S. sutor respectively)
were consistent with those reported in other populations, deviating little fromWOODLAND (1990) (slope b = 0.784 for S. stellatus), WASSEF and ABDUL (1997) andWOODLAND (1990) (slope b = 0.704, 0.796, and 0.845 for S. canaliculatus in Arabiangulf) and WOODLAND (1990) (slope = 0.810-0.846 for S. sutor). Similarly, for the L-W
relationship, the parameters (slope b = 0.0441, 0.0232 and 0.0328 for S. stellatus, S.
canaliculatus and S. sutor respectively) were consistent, though slightly deviating fromthose reported elsewhere; YANAGAWA (1994) (slope b = 0.0120 for S. canaliculatus ofRayong gulf, Thailand) and, SAMBOO and MAUREE (1988) (slope b = 0.0596 / 0.0597
for male/female S. sutor from Mauritius).
In the present study, L-W relationships for the three siganids indicated negative
allometric growth for pooled samples of each species (Table 2). MURPHY et al. (1991)
noted for L-W relationships, the main controlling factors for Kn and K are mainly
age, spawning season, sex, food availability, stomach fullness and general fatness.
The calculated Kn ranged from 0.909±0.018 for S. canaliculatus in Msambweni to1.191±0.009 for S. sutor in Diani. Fulton’s condition K was lowest for S. sutor in
Shimoni (1.249±0.010) and highest for S. stellatus in Diani (1.530±0.053). These
results indicate better health in the Diani stocks compared Shimoni and Msambweni.
However, literature on comparative studies on body condition from other siganid
populations are lacking, making it difficult to gauge the health of the siganids of the
WIO waters of Southcoast Kenya relative to other populations. Notwithstanding, thepresent results may be suggestive of better food availability in the Diani site owing
to banning of destructive gears. Fewer records of 18cm-27.9cm TL size classes for S.
stellatus in Msambweni may also point to higher fishing pressure on larger specimens,
comparable to the absence of 26.0cm+ TL size-classes for S. canaliculatus, thus
creating possible gaps in recruitment for these species.

12South Pacific Studies Vol.29, No.1, 2008

Population age significantly influences L-L and L-W relationships andconsequently the Kn and K condition factors. The observed SL-TL and TL-BW
relationships in the present study show that siganid populations of the WIO watersof Southcoast Kenya are still young. Sexes were not determined conclusively in thepresent study but literature indicates differential growth in sexes, though differences
may not be observable until the females have matured and reproduced several times(J OHNSON and G ILL 1998, N ELSON and W ILKINS 1993). Further, morphologicaldifferences exist between juveniles and adults, with early maturity in males throughout the family (NELSON 1994, THRESHER 1984, WHEELER 1975). However, lack ofobservable differences between sexes (KUITER 1993, THRESHER 1984) made external
sex determination difficult except hence this was only done by dissecting for gonads
in a few specimens. Consequently, the L-L and L-W relationships and Kn equations
presented herein may be used to conclusively distinguish sexes in the siganids of WIO
waters. Therefore, caution should be exercised when assessing sex differences by useof growth and condition factor equations except where sexes have been determined,refining the present equations into sex-specific SL-TL and TL-BW relationships andKn and K values. Notwithstanding, the broad spectrum of gonadal maturity stages
for these species with all year-round spawning and with visible peaks only in springand early summer, and a prominent lunar rhythm (THRESHER 1984) calls for caution
when assessing the populations. Further, intermittent spawning with non uniform
sexual activity and spawning within the adult population during any particularseason also calls for caution THRESHER (1984). Moreover, ovarian and testiculardevelopment studies show that many species gain water weight during food scarcity
therefore masking the effect of nutrition on body condition (B EAMISH et al. 1996).
Independent variation between water weight and fat weight thus makes interpretationof body condition as a measure of nutritional reserves difficult (SUTTON et al. 2000).
Notwithstanding, the equations developed from the present study for the SL-TL and
TL-BW relationship, and conditions factors Kn and K for the siganids of the WIO
waters provide a useful in-vitro tool for assessing the individual species and general
health of the siganids stocks.
Conclusion
The present study determined the SL-TL, TL-BW relationship for S. stellatus,
S. canaliculatus and S. sutor of the WIO waters caught during the peak SEM AprilAugust season and the TL-BW relationships were used to develop condition factor
equations for the three species. The SL-TL and TL-BW relationships and condition
Kn and K factor values obtained were comparable with siganid populations within thesame geographical range. The Diani site recorded higher Kn and K values comparedto the other two sites, probably indicative of better food resources, signaling residual
effects of the beach management program in supporting a relatively healthy population.
The SL-TL and TL-BW relationships and Kn and K equations developed are importantin assessing population health within the fisheries of the WIO waters. Caution should

WAMBIJI N et. al: Morphometric Relationship of Three Siganids

13

however be exercised when interpreting and comparing results of body condition data
for stock health assessment of individuals as shown by the wide distribution of S.
stellatus, though with fewer samples compared to S. canaliculatus and S. sutor. To thebest knowledge of the authors, this study provides the initial data on L-W relationshipand Kn for S. stellatus within the species geographical distribution. The results ofthe present study and equations developed herein provide useful simple tools for insitu gauging of overall health of wild siganid populations in the WIO eco-region forsustainable fisheries. The equations would also provide useful comparisons between
wild and cultured populations of the three siganid fishes.
Acknowledgements
The authors would like to thank the Director, Kenya Marine and Fisheries
Research Institute for financial and logistical support in the research initiative for theSouthcoast fisheries within the Western Indian Ocean; to fellow researchers for support
in scheduling and structuring the methodology and, to the fishers of Southcoast Kenya
for their patience with the traps and sampling period. It is our hope that the results ofthe present study go along way in helping sustain the siganid fisheries of the WIO ecoregion and improve fisher livelihoods.

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