serikali ya mapinduzi zanzibar care tanzania and department

also expected to occur in shallow water in Ngezi area. The lack of many potential
predators in the area provides a suitable environment for the juvenile fish grow to
maturity.
The first order consumers have been noted to determine estuarine fish communities
(Blaber 1980). First order consumers including Gerreidae, Atherinidae, Clupeidae,
Teraponidae, Acropomatidae, Apogonidae and Gobiidae (Blaber 1980) were found to
dominate in Gazi fishing community (Kimani et al, 1996). Short term feeding
migration of reef fishes into the creek may represent a connectivity and energy
transfer between the two ecosystems.
Fishes and seagrass
Fishes are abundant in seagrass beds and many of them feed within the bed removing
considerable biomass. Ogden (1980) reported that herbivore fishes are not resident in
seagrass beds, but migrate during the night from surrounding reefs. Larger fish e.g.
rays and sharks are important in structuring seagrass communities through
carnivorous species preying on fish, which graze on seagrasses so reducing grazing
pressure. Seagrasses provide an important nursery habitat for the juveniles of many
fishes such as Tarwhine (Rhabdosargus sarba), Eastern Blue Grouper (Achoerodus
viridis) and Yellow-finned Leatherjacket (Meuschenia trachylepis). The young fish
feed on small animals living among seagrass leaves and use the seagrasses to hide
from larger predators. Most of these fish will leave the seagrass meadows and migrate
to other habitats, such as kelp beds and rocky reefs, as they get older.
For many other fishes such as Pipefishes, White's Seahorse (Hippocampus whitei),
Southern Pygmy Leatherjacket (Brachaluteres jacksonianus), Leaf Fish (Ablabys
taenionotus) and Blue-spot Goby (Pseudogobius sp.) seagrasses provide lifelong
habitat. Sea grass meadows are ecologically important habitats in marine
environments as they are:
• places of great attraction of larger marine organisms, especially fishes in
search of good feeding areas
• good nursery grounds for juvenile stages of commercially important
shrimps, crabs, lobsters and fishes
• important feeding sites for adult fishes and birds.
In Ngezi fishermen reported that mangroves and seagrass meadows were important
fish habitat and spawning areas. Mangroves were particularly important for prawn
breeding; it was reported that most prawns breed in the mangroves.
4.2.12.5 Threatened species of fish (IUCN threat categories)
There are several factors, which may lead to fish species to become threatened. The
causative agents of the threat are usually humans and human activities. It is
commonly known that some species of sharks, swordfish, Billfishes are threatened
(Table 4.19). Many of these fish occur in deep water sea or are the local people do not
easily see benthic species. These fish are also not usually caught by artisanal
fishermen hence are not locally reported, although distribution maps show that they
occur on Zanzibar (FAO, 1984a, 1984b, 1984c, 1984d; Smith and Heemstra, 1991).
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