Exploitation and Conservation of Brown Mussel Stocks by Coastal People of Transkei

Abstract

The Brown Mussel (Perna perna) is an important fooditem for coastal people in the Republic of Transkei, providing some 16% of their annual protein requirements in 1978, though the energy benefit associated with the consumption of Mussels is relatively low. Uncontrolled heavy exploitation of the stocks of these Mussels resulted in reductions in both their density and size between 1978 and 1984. The reduced availability of Mussels to collectors led to increased exploitation-pressure on other, longer-lived, intertidal species: the proportion of limpets in the take of collectors rose from 7% in 1978 to 37% in 1984, while the proportion of Brown Mussels decreased from 92% to 57%.

Humans as predators on rocky reefs in New South Wales, Australia

“…Hockey et al (1988) found that 37 % of ethnic Africans on the shore in Transkei (South Africa) collected intertidal organisms. Intertidal animals are an important source of protein for these people (Siegfried et al 1985). In that study, only 4 % of the ethnic Europeans on the shore collected intertidal organisms.…”

“…Although some echinoids and gastropods were used as food, most were used as bait for fishing. This contrasts with studies in other parts of the world, where intertidal organisms are primarily utilised as food, for example in South America (Moreno et al 1984, Castilla & Bustamante 1989 and South Africa (Siegfried et al 1985, Hockey & Bosman 1986. Although there are anecdotal accounts of some ethnic groups being primarily responsible for taking intertidal organisms for food in NSW, race was not considered in this survey.…”

“…1984, Duran & Castilla 1989, Siegfried et al 1985. Little attention has been given to the design of surveys which assess the effects of people on the shore.…”

“…The frequency of rotation would vary according to the demography of organisms on the shore. Siegfried et al (1985), for example, advised a 14 mo rotational cropping basis for mussels due to the fast productivity of the animals. Decisions on timing of rotation are more difficult where a number of species is exploited.…”

Short-term effects of experimental trampling on polychaetes of a rocky intertidal substratum (Asinara Island MPA, NW Mediterranean)

“…Several studies have documented that these impacts affect the intertidal target species by inducing changes in abundance, decreasing species richness and shifting community composition (Siegfried et al, 1985, Keough et al, 1993, Dye et al, 1997Fernandez and Castilla, 1997;Lasiak, 1998).…”