Abstract
Eastern boundary upwelling provides the conditions for high marine productivity in the Canary Current System off NW-Africa. Despite its considerable importance to fisheries, knowledge on this marine ecosystem is only limited. Here, parasites were used as indicators to gain insight into the host ecology and food web of two pelagic fish species, the commercially important species Trichiurus lepturus Linnaeus, 1758, and Nealotus tripes Johnson, 1865. Fish specimens of T. lepturus (n = 104) and N. tripes (n = 91), sampled from the Canary Current System off the Senegalese coast and Cape Verde Islands, were examined, collecting data on their biometrics, diet and parasitisation. In this study, the first parasitological data on N. tripes are presented. T. lepturus mainly preyed on small pelagic Crustacea and the diet of N. tripes was dominated by small mesopelagic Teleostei. Both host species were infested by mostly generalist parasites. The parasite fauna of T. lepturus consisted of at least nine different species belonging to six taxonomic groups, with a less diverse fauna of ectoparasites and cestodes in comparison to studies in other coastal ecosystems (Brazil Current and Kuriosho Current). The zoonotic nematode Anisakis pegreffii occurred in 23% of the samples and could pose a risk regarding food safety. The parasite fauna of N. tripes was composed of at least thirteen species from seven different taxonomic groups. Its most common parasites were digenean ovigerous metacercariae, larval cestodes and a monogenean species (Diclidophoridae). The observed patterns of parasitisation in both host species indicate their trophic relationships and are typical for mesopredators from the subtropical epi- and mesopelagic. The parasite fauna, containing few dominant species with a high abundance, represents the typical species composition of an eastern boundary upwelling ecosystem.
Highlights
Marine productivity is high off the West African coast due to strong seasonal upwelling processes (Van Camp et al, 1991; Mbaye et al, 2015)
This eastern boundary upwelling ecosystem (EBUE) is an important resource for fisheries (FAO fishing area 34, Eastern Central Atlantic), with 2.5% of annual catches worldwide originating from this region (FAO, 2012)
A fish species frequently encountered in the north-eastern Atlantic tropical upwelling region is the cutlassfish Trichiurus lepturus Linnaeus, 1758 (Trichiuridae)
Summary
Marine productivity is high off the West African coast due to strong seasonal upwelling processes (Van Camp et al, 1991; Mbaye et al, 2015). This eastern boundary upwelling ecosystem (EBUE) is an important resource for fisheries (FAO fishing area 34, Eastern Central Atlantic), with 2.5% of annual catches worldwide originating from this region (FAO, 2012). A fish species frequently encountered in the north-eastern Atlantic tropical upwelling region is the cutlassfish Trichiurus lepturus Linnaeus, 1758 (Trichiuridae). Cutlassfish is a highly relevant commercial fishery resource with stable annual captures of 1.3 million tons since 2008 (Nakamura & Parin, 1993; FAO, 2014). As one of the ten most important species targeted by marine fisheries worldwide, its annual take is similar to other commercially important species, e.g., yellowfin tuna (Thunnus albacares) and Atlantic cod (Gadus morhua) (FAO, 2014). Cutlassfish is a popular food fish especially in Asia and usually cooked or served raw as sashimi (Nakamura & Parin, 1993)
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