In a great many species, females exhibit preferences for larger males – including that world-dominating species Homo sapiens (though a recent PLoS ONE study reveals the effect is only modest in actual couples). Certainly in the marine environment, choices such as this correspond to greater fitness in a species, with larger individuals being more fertile than smaller ones. Fishing can disrupt mating systems by altering population size structure – that is, causing a shift to smaller individuals. This is a particular problem when populations are fragmented (due to patchy habitats), as there are already limits on partner choice. Lobsters populations are often fragmented and with this in mind, Drs Denice Robertson and Mark Butler have investigated the size preferences of the spotted spiny lobster (Panulirus guttatus).