ABSTRACT
This study, undertaken during 1974 to 1977 in Volta Lake, investigated
the identification, abundance and distribution, reproductive biology
and weight-length relationships of four Chrysichthys species (C . a u ratus,
C. walkeri, C. velifer and C. furcatus). The species were separated on
basis of position of the dorsal fin, color of the barbels and the body
and shape of the caudal fin and its lobes. Gill rakers also proved of
some value.
The Volta Lake, on the Volta River in Ghana, is the largest manmade
lake (area: 8,700 km^). It was dammed in 1964 and reached the m a x i mum
controllable level in 1968. The northern narrower arms are of riverine
character and the southern section, lacustrine. Water temperatures range
between 26.5 to 30.5°C throughout the year. Except in periods of overturn
(usually between December to March and June to August), dissolved oxygen
is considerably reduced below 10 m. Ampem station, established on one of
the main arms of the lake, was sampled monthly (except 9 out of 29 months)
with gill nets of graded mesh size, a beach seine, traps (hoop nets) and
rotenone. Other stations, in the various sections of the lake, were also
sampled occasionally.
ln 196 5 Chrysichthys were relatively abundant near the dam at
Akosombo. Sampling in 1970 showed a decline and a more even lakewide
Life history of Chrysichthys catfish in Volta Lake, Ghana
distribution with indications of higher abundance in the southern (more
lacustrine) areas. Thereafter, abundance fluctuated seasonally with
more fish being caught in the rainy season. Chrysichthys were seldom
found deeper than 10 m, probably because of low dissolved oxygen concentrations.
Chrysichthys also were seldom found in higher currents.
Length frequency data did not indicate different year classes or
spawning periods but were characterized by single modes which remained
fairly constant over a 6 -month period.
Spawning C. walkeri and C. auratus were taken in traps fabricated
from bamboo stems. Spawning was in a sheltered bay at depths of 1.0-1.5 m
over a firm substrate and egg masses were placed in darkened interior of
the bamboo traps. The smallest (standard lengths) spawning males, and
females were respectively 76 m m and 82 mm (C. auratus) and 82 m m and 72
m m (C. walkeri). Males were larger than their mates in 42 of the 43 pairs
collected in the bamboo traps.
The number of eggs per female increased linearly with weight for
C. walkeri and with weight and length for C. velifer and linearly with
the log lengths of C. walkeri and C. auratus.
The slopes for functional regressions of log weight on log length
did not differ significantly from 3.0 for C. walkeri and C. velifer but
was less than 3.0 for C. auratus and C. furcatus.
Vanderpuye, C (2021). Life history of Chrysichthys catfish in Volta Lake, Ghana. Afribary. Retrieved from https://track.afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana
Vanderpuye, Chief "Life history of Chrysichthys catfish in Volta Lake, Ghana" Afribary. Afribary, 19 Apr. 2021, https://track.afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana. Accessed 06 Nov. 2024.
Vanderpuye, Chief . "Life history of Chrysichthys catfish in Volta Lake, Ghana". Afribary, Afribary, 19 Apr. 2021. Web. 06 Nov. 2024. < https://track.afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana >.
Vanderpuye, Chief . "Life history of Chrysichthys catfish in Volta Lake, Ghana" Afribary (2021). Accessed November 06, 2024. https://track.afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana