Life history of Chrysichthys catfish in Volta Lake, Ghana

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.

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APA

Vanderpuye, C (2021). Life history of Chrysichthys catfish in Volta Lake, Ghana. Afribary. Retrieved from https://afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana

MLA 8th

Vanderpuye, Chief "Life history of Chrysichthys catfish in Volta Lake, Ghana" Afribary. Afribary, 19 Apr. 2021, https://afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana. Accessed 21 Jun. 2024.

MLA7

Vanderpuye, Chief . "Life history of Chrysichthys catfish in Volta Lake, Ghana". Afribary, Afribary, 19 Apr. 2021. Web. 21 Jun. 2024. < https://afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana >.

Chicago

Vanderpuye, Chief . "Life history of Chrysichthys catfish in Volta Lake, Ghana" Afribary (2021). Accessed June 21, 2024. https://afribary.com/works/life-history-of-chrysichthys-catfish-in-volta-lake-ghana