Abstract
We studied the use of parasites as biological tags for discriminating fish stocks of Aphanopus carbo (Osteichthyes: Trichiuridae) from Portugal (Sesimbra on the mainland, Madeira and the Azores). Sixteen different metazoan parasites were found (14 from Madeira, 9 from Sesimbra and 7 from the Azores). Some parasites occurred only in fish from Madeira. The prevalence and mean intensity of the infection was recorded for each parasite and locality, and their values were statistically compared between the three sampling localities and related to host length classes. The differences between some of these parameters were statistically significant among the three localities or between two of them. It is suggested that 6 parasites (Tentacularia coryphaenae, Sphyriocephalus tergestinus, Campbelliella heteropoeciloacantha, Anisakis spp., Bolbosoma vasculosum and unidentified Acanthocephala larvae) can be used as biological tags to discriminate Portuguese stocks of Aphanopus carbo.
Highlights
Fish stock discrimination is important for economically valuable species
Table 2. – Fork length, total weight (g), and sex ratio of Aphanopus carbo, and statistical significance between the values recorded for the three sampling localities (Ses, Sesimbra; Mad, Madeira; Azo, Azores) assessed by Mann-Whitney’s U (MW) and chi-square (c2) tests (s.d.= standard deviation, min.= minimum, max.= maximum)
When the analysis addressed prevalence, significant differences were found for three parasite taxa: S. tergestinus, B. vasculosum larvae and the unidentified Acanthocephala larvae (Table 4)
Summary
Fish stock discrimination is important for economically valuable species. It may help to establish the fishing periods and catching efforts appropriate to a particular fishing ground, with a view to identifying measures to sustain or increase fisheries. The black scabbardfish, Aphanopus carbo Lowe, 1839 (Osteicthyes: Trichiuridae) is an economi-. Cally important deep-sea fish species that has been exploited in the eastern Atlantic, off the Madeira Islands, for several decades. About 30 years ago, this species was reported near Sesimbra, on the west coast of mainland Portugal, and off the Azores Islands. The Sesimbra population has undergone intense fishing, whereas at the Azores the captures have been much lower, and the fishery activity is irregular
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