3.0 THE SEAWEED PRODUCTION CYCLE
In both the off-bottom and the floating line methods of farming cottonii, there are eight production cycles per year but die-offs are estimated to occur in at least one cycle per year in the
off-bottom method. The die-off typically occurs in a cycle following the heavy, rainy season March to May and is likely due to water salinity, sedimentation from run-off andor
temperature differentials during this period Mmochi et al. 2005. To account for the die-offs associated with the off-bottom method, this economic analysis bases its calculations for the off-
bottom plot on eight effective growing seasons but on only seven harvests per annum. Note that when annual labour costs are calculated for the off-bottom method, this means that those costs
associated with seed preparation, planting and farm management are incurred eight times per year and that those costs associated with harvesting and post-harvesting activities are incurred
only seven times per year. The calculations for the floating line plot are based on eight effective growing seasons and eight harvests per year.
Either a senior female household member or a male household member manages each seaweed farm, and it is estimated that on the average two persons per family are involved in seaweed
farming. Many farmers have more than one farm ranging between 1-5 farms. Most off-bottom plots owned by men tend to be larger than those owned by women. A large, man owned off-
bottom plot consists of 30 lines that are 20 meters each in length and a woman owned off-bottom plot consists of 30 lines that are 10 meters each in length. Seaweed seedlings are planted once
every six weeks. The seaweed grows for six weeks and is harvested and re-planted in the same tidal cycle. After each harvest, the seaweed is dried and stored by the farmers until buyers
purchase it. The buyers then export the seaweed to international carrageenan processors. Carrageenan uses are related to their ability to form thick solutions or gels. Cottonii contains
kappa carrageenan, a stronger gel that has a higher commercial value than the weaker gel, iota carrageenan, contained in spinosum. The main application for both types of carrageenan is in the
food industry McHugh 2003.
4.0 COSTS OF SEAWEED FARMING
4.1 Initial Investment Costs
4.1.1 Off-Bottom Plots
Each woman owned off-bottom plot has 20-40 lines of 10 meters m each, resulting in an average of 30 lines per plot. Rope costs 28 Tsh. per meter; therefore, the 300 m of rope required
for lines on a woman owned off-bottom plot costs 8,334 Tsh. Each larger, man owned off- bottom plot has 30 lines of 20 m each; therefore, a man owned off-bottom plot requires 600 m of
rope, which costs 16,668 Tsh. One roll of tie-tie is required for every three lines of 10 m rope. Each roll of tie-tie costs
between 250 and 300 Tsh. per roll, averaging 275 Tsh. per roll. The 30 lines on a woman owned off-bottom plot require 10 rolls of tie-tie, which costs 2,750 Tsh. when the average cost per roll
of tie-tie is used. For a man owned off-bottom plot, the lines are two times the length of the
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lines used on a woman owned off-bottom plot; therefore, the cost for tie-tie on a man owned off- bottom plot is double the cost as on a woman owned off-bottom plot.
A woman owned off-bottom plot requires two floaters per line, while a man owned off-bottom plot requires four floaters per line. This is equivalent to 60 and 120 floaters for a woman and
man owned off-bottom plot, respectively. This reveals that both types of plots use approximately one floater per 5 m length of line. The floaters are usually empty recycled plastic mineral water
bottles. Each bottle costs between 10 and 50 Tsh., resulting in an average cost of 30 Tsh. per bottle.
On both a man and a woman owned off-bottom plot, each line requires two stakes that are mostly taken from mangrove trees. Two stakes per line is equivalent to 60 stakes for both a woman and
a man owned off-bottom plot. One stake costs 25 Tsh.; therefore, 60 stakes cost 1,500 Tsh. Since a man owned off-bottom plot has longer lines than a woman owned off-bottom plot, the
unit input cost of stakes per unit output is smaller for a man owned plot than for a woman owned plot.
4.1.2 Floating Line Plots
Each floating line plot has 27 lines of 12 m each. A floating line plot frame requires one roll each of 12 mm 18,500 Tsh., 10 mm 14,000 Tsh., and 8 mm 8,000 Tsh. rope.
A floating line plot requires three rolls of 4 mm rope 2,500 Tsh. per roll for the seaweed lines, and one roll of tie-tie is required for every three 10 m lengths of line. The 27 lines are 12 m each
in length; therefore, a floating line plot requires 15 rolls of tie-tie, which costs 4,125 Tsh. when we use the average cost per roll of tie-tie. A floating line plot requires 25 floaters, with an
average cost of 30 Tsh. per bottle. Sixteen anchors are also required to secure the floating line plot. Anchors are typically stones that cost approximately 200 Tsh. each.
The total cost of constructing a floating line plot is 63,775 Tsh. This includes the cost of ropes 52,500 Tsh., tie-ties 4,125 Tsh., anchors 3,200 Tsh., floaters 750 Tsh. and an estimate of
the amount that would be paid for the labour to construct the floating line frame and to attach the initial seaweed lines and tie-ties 3,200 Tsh..
4.1.3 Initial Investment Costs Applicable to Both the Off-Bottom and Floating Line Methods