172
Majority of the studies was published in international refereed journals, some in workshopconference proceedings and a few in grey literatures. The use of the words grey literature implies reports e.g., consultancy
and research reports that are not published, and not in a retrievable form, thus not easily accessible. Postgraduate dissertations and theses are accessible only through the University Library and the authors themselves. An
analysis of the various categories for the 85 references on Mgayas list is presented in Table 1.
Table 6.1. Distribution of publications in the area of othe marine living resources.
Category Number of items
International refereed journals 44
Published conference proceedings 8
Unpublished conference proceedings 2
Books or book chapters 4
Unpublished reports 17
Ph.D. theses 2
M.Sc. theses 8
Total 85
6.5 Age of information
A few studies were carried out a long time ago e.g. Anderson, 1952; Verdourt, 1954; Spry, 1961; 1964. There were quite a few studies conducted in 1990s. Out of 84 references on Mgayas list, 2 appeared in 1950s, 3 in
1960s, 21 in 1970s, 12 in 1980s and 47 appeared in 1990s. The trend in these studies has been a gradual shift from baseline studies which dominated in 1960s through 1980s to applied studies. For example, majority of the
studies conducted in 1990s is applied in nature, as witnessed in seaweed farming research. However, baseline studies still featured in 1990s, as seen in studies on marine mammals and non-conventional resources like sea
cucumbers and molluscs.
Reference can still be made to old studies, for example, in tracing changes e.g. species distribution, abundance, etc. over time. Generally speaking, some of the old studies, particularly those on seaweeds by Professor K.E.
Mshigeni and Professor A.K. Semesi formed the basis for seaweed farming. Work by Dr. J. Frazier on sea turtles, for example, raised the awareness on the species and the information was useful in designing management
strategies for the species.
6.7 Main findingsobservations 6.7.1
Types of resource use
There are various resource use types depending on the species in question. For example, Seaweeds of the genus Eucheuma
are exploited for phycocolloid carrageenans production and turtles are consumed by fishermen whenever they are caught, but they are not targeted. Fishermen in Mtwara were reported to kill dolphins for use as
bait in the longline fishery, targeting tiger sharks Galeocerdo cuvieri Chande et al., 1994. Dugongs are killed for their meat and oil, while turtles are slaughtered for their meat, eggs and tortoise shell Howell, 1988b. Sea
cucumbers are harvested and prepared as beche-de-mer which is usually exported Mgaya et al., 1999a. Besides the foregoing consumptive uses, there are non-consumptive uses with some of the resources. For example,
mollusc shells are collected for the curio trade Newton et al., 1993, a certain type of seaweed is being harvested in Bagamoyo for use as a bait for rabbitfish Semesi et al., 1998.
6.7.2 Condition of the resource goodoveruseddepleteddegradedpristine
173
Studies leading to determination of the status of the resource are rare. Various authors give statements that point to resource depletion as a result of uncontrolled exploitation. Some examples are given hereunder. In their review
paper, Stensland et al. 1998 express an urgent need for the status assessment of marine mammals. Newton et al. 1993 note that gastropods e.g. cowries which have commercialvalue because of the shell trade are over-
exploited. The cetaceans are apparently not commercially exploited in Tanzanian coastal waters, but populations of both dugongs and marine turtles are exploited and these animals are regarded as endangered Howell, 1988b.
Based on interviews conducted in Bagamoyo, Mgaya et al. 1999a reported that sea cucumber stocks are declining and that collectors are now employing SCUBA equipment, thus depleting the resources further.
6.7.3 Human impacts
There is some information of qualitative nature on human impacts on resources and habitats. Bryceson 1981 reviewed some anthropogenic impacts e.g. sand mining, dynamite fishing on marine habitats and resources and
builds a rationale for their conservation. Howell 1988a discusses human impacts, particularly habitat destruction e.g. deforestation and dynamite fishing and pollution e.g. oil spills on coastal seabirds. Chemical pollutants
such as petroleum products in the water may interfere with olfaction in marine turtles, which may be used in navigation and orientation. Turtles are especially vulnerable to pollutants because many feed on invertebrates,
which concentrate various pollutants Howell, 1988b.
Stensland et al. 1998 present an argument for the need toprotect marine mammals from destruction emanating from human activities particularly fishing and marine pollution. Khatib 1998 lists several anthropogenic impacts
on sea turtles around Unguja Island.
Generally, seaweed farming is considered to have mild environmental impacts, but Johnstone and Ólafsson 1995 reported that the activity has a clear effect on both benthic microbial processes and meiofauna populations. For
example, they showed that attached algae vibrated in the current thus brushing against the benthos, consequently preventing consolidation of any micro-algal mats. Ólafsson et al. 1995 suggested that seaweed farming had a
negative effect on the abundance of meiobenthos, mainly through increased predation by benthic feeding fish and the mechanical disturbance of the sediments. Mtolera et al. 1992 noted that unselective farm clearance
weeding through removal of sedentary animals, seagrasses and other seaweeds is likely to affect the benthic communities.
6.7.4 Natural impacts
