Philosophiae Doctor - PhD / Growth rates of three commercial eucheumoids: brown Eucheuma denticulatum and green and brown Kappaphycus alvarezii were studied at three sites (Gazi Bay, Kibuyuni and Mkwiro) in southern Kenya. The study was conducted using the fixed off-bottom rope technique over a 15 month period from August 2001 to October 2002, in 4 plots (5 m x 1.5 m) set up at each site. The brown E. denticulatum had the highest mean growth rate over the entire period of 4.7% day-I compared to the green and brown K. alvarezii which were 4.3% day l and 4.2% dayl, respectively. Mean relative growth rates were highest at Gazi (5.6% dayl), and lowest in Kibuyuni (3.2% day-I) with intermediate values of 4.8% dail at Mkwiro. Increased water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The 'ice-ice' syndrome affected both brown E. denticulatum and brown K. alvarezii but not green K. alvarezii. Mean growth was higher during the southeast monsoon (4.7% day+) than during the northeast monsoon (4.0% dayl).The carrageenan characteristics of the three morphotypes were measured for 12 months. The highest carrageenan yield was obtained for green K. alvarezii (59.1% dry wt), whereas the average carrageenan yield for brown K. alvarezii was 56.5% dry wt and 56.6% dry wt for brown E. denticulatum. The plants at Gazi (58.0% dry wt) had a slightly, though significantly, higher carrageenan yield than both those at Kibuyuni (57.1 % dry wt) and Mkwiro (57.3% dry wt). However, from a commercial point of view the differences in carrageenan yields were not meaningful. Highest gel strengths were obtained in carrageenans from green K. alvarezii (1042.1 g cm") and brown K. alvarezii (1053.7 g ern"), whereas low values of 100.8 g ern" were obtained for brown E. denticulatum. The brown E. denticulatum had carrageenan with higher viscosity (81.7 mPa.s) and sulphate content (29.1% dry wt) than both green and brown K. alvarezii. The gel viscosities of all the morphotypes were higher during the southeast monsoon (67.3 mPa.s) than during the northeast monsoon (46.3 mPa.s) and were positively correlated with gel strengths.A survey was conducted among households in the three villages, from April to September 2001 to assess their socio-economic characteristics. There were 182 household heads interviewed; about 20% were women. Fishing was the main source of livelihood for about 48% of the household members. In 2001, the average monthly income for the surveyed households was Kshs. 9904 (1 US$=75 Kshs.), with about 67% having less than Kshs. 10 000. The average prevalence of poverty among the households surveyed was 45.1% with 38.8%,54.8% and 46.7% of households in Gazi, Kibuyuni and Mkwiro villages, respectively, living below the poverty line of Kshs. 1239 per month per adult person. An economic feasibility study for growing brown E. denticulatum and brown K. alvarezii in pilot farms of 0.1 ha was conducted at Gazi and Kibuyuni. A higher yield of 793 kg dry wt was obtained for plants grown at Gazi than those at Kibuyuni (793 kg dry wt). The net income derived from E. denticulatum was estimated at Kshs. 7549 annually in a 0.1 ha seaweed farm. A higher annual income of Kshs. 49 126 was generated from K. alvarezii. The rate of return on investment in farming E. denticulatum ranged from 15 to 63%, while 122 to 380% for K. alvarezii. The pay back period was shorter for the latter (0.3 to 0.7 years) than the former (1.2 to 2.7 years).A cross-sectoral policy analysis regarding legislation and policy relevant to the introduction and development of eucheumoid cultivation in Kenya, with particular reference to Kenyan legislation was conducted. The analysis showed that there is no system of promoting or regulating mariculture, though there are fragmented regulations that are scattered among the policies, Acts and regulations of various institutions. Such regulations were not designed specifically for mariculture and as a result they do not fully address the needs of mariculture. The establishment of a national mariculture development programme in Kenya is proposed as a means to develop and manage the farming of marine resources, including seaweeds.