WorldFish Center Quarterly
No. 1 (January March 2003)
preliminary study on the feasibility of using
brushparks for fish production in Lake Chilwa,
D.M. Jamu, K. Chaula and H.
A study to
investigate the feasibility of using fenced brushparks
for fish ranching in Lake Chilwa was conducted
for five months at the Kachulu Harbor. In a water
depth of 1.4 m enclosures constructed from bamboo
sticks embedded in the sediment and surrounded
by a 13 mm seine net, were filled with three different
subrates (Typha, bamboo, and Sesbania
branches) and a no substrate enclosure served
as a control. Netting materials contributed 57
per cent towards the total cost (US$ 0.24-0.30/m2)
of brushpark contruction. Fish productivity was
highest in the Typha, bamboo and control
treatments and lowest in the Sesbania treatments.
The decomposition of substrates did not affect
water quality. The results indicate that enclosed
brushparks may be a feasible technology for enhancing
fish yields and providing alternative income sources
to fisherfolk in small lakes and water bodies.
Article (PDF 157 KB)
relationship of fishes from coral reefs along
the coastline of Jordan (Gulf of Aqaba)
The parameters a and b of the length-weight
relationship of the form W = a.Lb
were estimated for 15 fish species caught along
the coastline of Jordan in the Gulf of Aqaba.
The sampling was carried out between July 1999
and January 2001. Data from 1 000 fish individuals
(identified to eight families and 15 species)
were used for this purpose.
Article (PDF 102 KB)
disease management using bioactive marine secondary
metabolites: an eco-friendly approach
J. Selvin and A.P.
Vibriosis caused by opportunistic and secondary
bacterial pathogens is still a serious disease
problem in aquaculture of the black tiger shrimp
Panaeus monodon. Attempts were made for
controlling shrimp bacterial disease using Marine
Secondary Metabolites (MSMs). Findings indicated
that the MSMs of seaweed Ulva fasciata
and Dendrilla nigra are effective for controlling
shrimp bacterial pathogens.
Article (PDF 112 KB)
relationships of coral reef fishes from the Alacran
Reef, Yucatan, Mexico
E. Pérez-Díaz, L. Santos-Rodríguez
and J. E. Arias-González
Length-weight relationships were computed for
42 species of coral reef fishes from 14 families
from the Alacran Reef (Yucatan, Mexico). A total
of 1 892 individuals was used for this purpose.
The fish species were caught by different fishing
techniques such as fishhooks, harpoons, gill and
trawl nets. The sampling period was from March
1998 to January 2000.
Article (PDF 140 KB)
approach to estimate the natural mortality rate
in fish stocks
Luis A. Cubillos
* Please refer to the full text article in the
View Article (PDF 88 KB)
Genetic improvement of the herbivorous blunt snout
bream (Megalobrama amblycephala)
Li and W.Q. Cai
Selection experiments with the herbivorous blunt
snout bream or Wuchang bream (Megalobrama amblycephala)
were started in 1985. Mass selection for size
and length/depth ratio resulted in a significant
increase in growth and better shape, while inbreeding
led to a significant decrease in growth. The total
selection ratio from fry to mature brooders was
about 0.03 per cent per generation. In the grow
out stage, the average daily body weight gains
of two lines of fifth generation (F5)
fish were 29 per cent and 20 per cent respectively
more than the control group, with an average of
5.8 per cent and 4 per cent improvements per generation,
respectively. The body was 4 per cent deeper in
ratio of standard length/body depth. The effects
of inbreeding were examined by crossing full-sibs,
the offspring of which were kept without selection.
The third generation inbred fish showed 17 per
cent lower growth as compared to the control group,
with an average of 7.5 per cent per generation.
The results demonstrate that selection is a powerful
tool to improve the economic traits of the blunt
snout bream, but inbreeding can rapidly lead to
a reduction in performance. In 2000, the 6th generation
of selected bream was certified by the Chinese
Ministry of Agriculture as a good breed for aquaculture.
Article (PDF 127 KB)