Keywordsbeen reported in many species of vertebrates and invertebrates (e.g. Bianchi et al. 2000;Branch and Odendaal 2003;Roy et al. 2003;Harvey et al. 2006).In a wide range of taxa, body size is one of the key determinants of fitness in both males and females (Andersson 1994). For example, body size is positively correlated with reproductive fitness (e.g. mating success and fecundity). Mostly, larger males are stronger competitors for females (e.g. Hoefler 2007) or can provide more ejaculated sperm (e.g. Jivoff 1997), or better care for the offspring (e.g. Kolm 2002). In females, body size positively correlates with egg size (e.g. Einum and Fleming 1999), number of spawning (e.g. Claramunt et al. 2007), number of eggs spawned (e.g. Evans et al. 2008), or quality of larvae (e.g. Berkeley et al. 2004). Therefore, mate choice is non-random in the majority of animal species (Real 1990), and males and females prefer larger mates mutually (e.g. Sandvik et al. 2000;Herdman et al. 2004; Aquiloni and Gherardi
AbstractTo signal a need for caution for present large male-selective harvesting practices, negative impacts of the large male-selective harvesting on reproductive output in large decapod crustacean resources are introduced with emphasis on my own work with spiny king crab Paralithodes brevipes, coconut crab Birgus latro, and the stone crab Hapalogaster dentata. The large male-selective harvestings for several large decapod crustaceans have changed their population demographic structure by decreasing mean male size and skewing sex ratio towards females. By several field and laboratory experiments, the change of population demographic structure was anticipated to decrease female reproductive success in the resources (i.e. reproductive output of the harvested populations) through a decrease in sperm availability for females because of male size-dependent reproductive potentials and slow sperm recovery rate. Furthermore, reproductive output and stability of the large male-selective harvested resources were also anticipated to decline by a decrease in mate availability for females, attributing to combination of female mate choice for larger males with negative effects of female delayed mating and/or maternal influences. To establish the optimal management practices, the details of the mating system and reproductive ecology of each targeted species should be investigated.