Thanks for your patience in waiting for an answer on this one!
We spoke to our contact at Dawul Wuru and he said it is a difficult question to answer, as when planting mangroves it’s not usually a case of needing to walk along a length of shoreline and plant the mangroves in a straight line, rather they typically replant in pockets of areas (for example a bend in a river). As such, they’re not covering a distance per se, but rather working within a specific patch to replant the mangroves, so the actual distance covered is hard to calculate.
Some approximate information that was shared is that it can take around half a day to plant 50 mangroves, and they are usually planted about 500mm apart from one another.
As such, you can imagine that an average walking speed is difficult to calculate, but you can assume that it is slower than average due to the thick muddy conditions and difficult terrain, as they also need to drag about 50-60kg of equipment with them.
Please let me know if you have any other questions, and good luck with your project!