Ecology and host relationships of the whale-louse Isocyamus delphini (Amphipoda: Cyamidae) parasitizing long-finned pilot whales (Globicephala melas) off the Faroe Islands (Northeast Atlantic)

Abstract

In cooperation with an international research program concerning the biology of the long-finned pilot whale (Globicephala melas) in the Northeast Atlantic, 152 pilot whales taken in the Faroese drive fishery were examined for ectoparasites. The whale-louse Isocyamus delphini was detected on 45(29.61%) of the whales. Four whale groups were established, according to sex and sexual status: immature or pubertal males, mature males, immature females, and mature females. Whale-lice showed over-dispersed distributions on these four whale groups. Prevalence, abundance, and spatial distribution of I. delphini on sexually mature males were significantly different from those on the other whale classes. Heavy infections were only observed on mature males. Behavioral differences between males and females and between adults and juveniles could account for these results. The genital slit was by far the site most preferred by I. delphini. This location seems to be one of the few that offers appropriate shelter for this cyamid.

Frequency distributions of fish parasites in the perch Perca fluviatilis L. from Lake Constance

“…2). This sort of statistical distribution of parasites has been observed very often by several authors (Bliss and Fisher 1953;Crofton 1971;Pennycuick 1971;Anderson 1974;Henricson 1977;Kennedy and Burrough 1977;Robert et al 1990;Balbuena and Raga 1991). The percentage of uninfected fish was very high (Fig.…”

Living in a harsh habitat: epidemiology of the whale louse, Syncyamus aequus (Cyamidae), infecting striped dolphins in the Western Mediterranean

“…This social behaviour contrasts with that reported in other delphinids. For instance, adult males of long‐finned pilot whale Globicephala melas have been observed to have unhealed wounds because they engage in frequent agonistic contacts to access mature females (Balbuena & Raga, ). Interestingly, adult males also have a significantly larger prevalence and abundance of the cyamid Isocyamus delphinii as they provide more opportunities for whale louse exchange, and a higher amount of suitable microhabitat for feeding and sheltering, such as in wounds.…”

“…Arguably, the genital–anal slits would also be potentially suitable microhabitats (see, e.g. Balbuena & Raga, ; Fransen & Smeenk, ; Haney et al ., ) but surprisingly they were not used by S. aequus . It is unclear why this might be so.…”

“…The ectoparasites of cetaceans have not been studied widely because these organisms often go unnoticed, the access to their hosts is difficult and experimental work can hardly be carried out (Rowntree, ). However, the available studies have shown that the ectoparasites of cetaceans are useful indicators of the evolutionary and natural history of their hosts (Balbuena & Raga, ; Kaliszewska et al ., ) and of disease (Aznar, Balbuena & Raga, ; Aznar et al ., ; Vecchione & Aznar, ).…”

“…described so far (Margolis, McDonald & Bousfiel, ). Whale lice usually aggregate on skin areas with reduced water flow, which provide shelter and food, such as skin folds, eyes, blowhole, or wounds (Leung, ; Balbuena & Raga, ). The life cycle of cyamids lacks actively swimming stages, thus transmission between hosts is assumed to occur through direct contact (Pfeiffer, ).…”