serikali ya mapinduzi zanzibar care tanzania and department

Movement and migration is a common phenomenon for animals including fishes.
Movements could be for feeding purposes, escaping predation, or escaping unsuitable
conditions.
The migrations like other characteristics of the species have some adaptive
significance, ensuring favourable conditions for the existence and reproduction of the
species. The cycles of migrations usually consist of:
1. Spawning migration: movement of fishes from the feeding grounds to the
spawning grounds
2. Feeding migrations: movement away from the spawning grounds to the
feeding grounds
Most marine species are migrants. Migration between marine and estuarine
ecosystems has ecological and commercial significance. In Ngezi fishermen report
large numbers of fish migrating from deep-water areas into the shallow seagrass beds
when the sea is rough and turbulent. These fish return to deep water when the sea is
calm.
Feeding migration
Feeding migration is normally accompanied by the changes of the tidal regime at
Ngezi. When water recedes to a low tide the juvenile and mature fishes tend to
migrate to deeper waters. When tide in the bay reaches high water mark the fishes
especially the detritivorous, omnivorous and herbivorores also migrate to the feeding
grounds in shallow waters.
In general carnivorous species constitute 50-70 % of the fish. Godman and Talbot
(1976) reported that many of the carnivorous fish appear not to be highly specialized
to a given food type but instead are opportunistic feeders, taking whatever is available
to them.
Herbivores and coral grazers make up the next largest groups of fishes and account
for 15% of the species. Of these, Scaridae and Acanthuridae are most important. The
remaining fishes are considered to be omnivores and include all families of fishes on
the reef (i.e. Pomacentridae, Chaetodontidae, Pomacanthidae, Monacanthidae,
Ostraciidae, Tetraodontidae). A few groups, mainly small schooling fishes in the
families Pomacentridae, Clupeidae and Atherinidae, are zooplankton feeders.
4.2.12.4 Fish habitats and spawning areas
Fishes and mangroves
Mangroves are one of the most productive ecosystems. They harbour a diversity of
fish species due to the presence of organic matter (dissolved or particulate), detritus
from plant litter and their associated organisms (bacteria, fungi, micro, macro and
meio fauna). Between 80% and 90% of the inshore landing in East Africa comes from
artisanal fishers who operate within 22 km limits to territorial waters (Anon, 1979).
The presence of mangroves in Ngezi makes the area a potentially important habitat for
fish and fishing.
Large predators enter the mangroves with incoming tide (Sasekumar et al., 1984;
Blaber et al, 1985). The lack of important piscivorous fish reported in some
mangroves (Blaber 1980; Bell et al., 1984) seems to relate to high turbidity and very
low depth where predators become less effective. Most of the fish species breeding in
mangrove areas completes all their lifecycle there (Thallot, 1992). This situation is
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