As the least organized kayak angler I know, I use lanyards, aka tethers, to help keep my fishing tools, such as pliers and scissors, handy and prevent them from sliding under my chair or out of the yak. Some folks put longer tethers on fishing rods, landing nets and fish-measuring devices. I personally am more concerned about getting tangled in lanyards upon capsizing than I am of booting any of those things into the drink.
To make your own coiled lanyards inexpensively, use round trimmer line (both the .080- and .095-inch sizes work). Just wrap it around 1/2- or 3/8-inch dowel rods and cook it. Cable clamps that fit snugly on the line create loops to accept small carabiners or chain-link connectors. One end attaches to the yak; the other end holds the tool.