Parasitism, condition and reproduction of the European hake (Merluccius merluccius) in the northwestern Mediterranean Sea

Abstract

It is well known that parameters relating to physical condition and reproduction of fish provide essential data for estimating the productivity of exploited populations, as is the case with the European hake (Merluccius merluccius) in the northwestern Mediterranean Sea. Although parasitism might affect these parameters, research in this area is very scarce (and in the case of the Mediterranean almost non-existent). This study evaluates for the first time the potential link between parasitism, condition and reproduction of the European hake. Indicators of fish energy reserves (total lipid content in liver and gonads) and reproductive capacity (fecundity, egg quality and atresia) were evaluated, as were the prevalence and intensity of infection by metazoan parasites. The results indicate that the impact of anisakid nematodes is mostly negative and occurs mainly when hake are allocating their energy reserves to gonadal development. Although the results reveal a link between parasitism, condition and reproduction, we concluded that the northwestern Mediterranean hake population is in equilibrium with its metazoan parasites, which are not causing severe impairment to their physical condition or reproductive capacity.

Trade‐offs between life‐history traits in a coldwater fish in the Mediterranean Sea: the case of blue whiting Micromesistius poutassou

“…Two different MFTs belonging to the Anisakis genus were identified; i.e ., Anisakis Type I (AT1) and Anisakis Type II (AT2). A molecular analysis on fish from the same region performed previously by our laboratory (Ferrer‐Maza et al, ) revealed that AT1 belongs to Anisakis pegreffi and AT2 to Anisakis physeteris . The most dominant MFTs were AT1, Hysterothylacium aduncum (HA) third stage larvae (L3) and AT2 and the most intense infections were caused by NI1, AT1 and HA‐L3 (Table ).…”

Temporal and spatial patterns of reproductive indices of European hake ( Merluccius merluccius ) in the northern North Sea and Norwegian coastal areas

“…Spawning biology of European hake has been extensively studied in other areas of its distribution, such as the Mediterranean (Olivar et al, 2003;Al-Absawy, 2010;Ferrer-Maza et al, 2014), around the Iberian Peninsula (Pérez and Pereiro, 1981;Piñeiro and Saínza, 2003;Costa, 2013), the Bay of Biscay (Martin, 1991;Alvarez et al, 2004; and in the Celtic Sea (Hickling, 1930;Alvarez et al, 2004). Similar information for the North Sea is limited to investigations from the early 20th century (Schmidt, 1909), although monitoring of the biomass and distribution is included in ICES data collection programmes and more recently in annual Norwegian research surveys.…”

Health and reproduction of red mullet, Mullus barbatus, in the western Mediterranean Sea

“…However, it should be noted that some authors have pointed out that the boundaries between capital/income breeding and determinate/indeterminate fecundity are not as clear as had previously been assumed Ganias, 2013). For example, Domínguez-Petit et al (2010) argued that for the European hake, Merluccius merluccius, in the northeastern Atlantic, gonadal development was at the expense of food intake, whereas Ferrer-Maza et al (2014) has shown that, in the northwestern Mediterranean, this species is a capital breeder most of the year except in summer, when the abundance of its prey is at its peak in the Mediterranean. Thus, spawning strategies may be flexible within species and may depend on the availability of food.…”

“…did not experience a depletion in the total lipid content, but there was an increase in the free fatty acids in their viscera. Finally, Ferrer-Maza et al (2014) have recently revealed that the anisakid nematodes, especially Anisakis pegreffi Campana-Rouget & Biocca 1955, negatively affect the condition of the European hake, Merluccius merluccius, mainly when these fish are allocating their energy reserves to gonadal development, while infections by other parasites do not affect them significantly.…”