Anisakid Presence in the European Conger, Conger conger, from Spanish Mediterranean Waters

Abstract

The European conger, Conger conger, is a benthic marine fish species with a geographical distribution extending through the northeastern Atlantic and the Mediterranean. Despite being extensively distributed and widely appreciated by Spanish consumers, studies regarding parasite presence in this fish are scarce. In the present work, a hundred and eight specimens from the Mediterranean coast of northeastern Spain (Catalan waters) were surveyed for the presence of nematode parasites. Several species were morphologically identified: third-stage larvae of Anisakis type I (sensu Berland, 1961) (n = 131), third-stage larvae of Anisakis type II (sensu Berland, 1961) (n = 18), third- and fourth-stage larvae and adults of Hysterothylacium spp. (n = 48), adults of Cucullanus sp. (n = 391), and adults of Cristitectus congeri (n = 69). Moreover, some fish and decapode species were also observed as part of the host's diet, with the most detected preys being Micromesistius poutassou, Sardina pilchardus, Macropipus sp., and Goneplax rhomboides. This represents the first survey of nematode parasites infecting C. conger from the northeastern Spanish Mediterranean waters. Among the parasite species detected, the presence of Anisakis species should be highlighted as the ingestion of C. conger parasitized with these larvae could potentially lead to anisakiasis in consumers.

Keywords: Anisakis; Conger; Mediterranean; nematode; prey.

Figure 1

Microphotographs showing anterior, central, and posterior regions of the nematodes found in C. conger specimens: (a–c) anterior (a), central (b), and posterior (c) regions of L3 of Anisakis type I (sensu Berland, 1961); (d–f): anterior (d), central (e), and posterior (f) regions of L3 of Anisakis type II (sensu Berland, 1961) (g–i): anterior (g), central (h), and posterior (i) regions of an adult of Hysterothylacium spp.; (j–l): anterior (j), central (k), and posterior (l) regions of an adult male of Cucullanus sp.; (m–o): anterior (m), central (n), and posterior (o) regions of an adult female of Cucullanus sp.; (p–r): anterior (p), central (q), and posterior (r) regions of an adult of C. congeri. t: tooth, o: esophagus, v: ventricle, i: intestine, m: mucron, an: anus, l: labia, ic: intestinal caecum, vap: ventricular appendix, spi: spicules, bc: buccal capsule, d:deirids, nr: nerve ring; Scale bar 50 µm in all microphotographs with the exception of b, h and l (100 µm).