Fatty acid composition and parasitism of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) populations in the northern Catalan Sea in the context of changing environmental conditions

Abstract

The status of sardine and anchovy populations in the northern Mediterranean Sea has been declining in recent decades. In this study, fatty acids and parasitism at different reproductive and feeding stages in these two species were assessed using specimens caught along the northern Catalan coast, in order to assess the links between lipid dynamics, reproduction and feeding in these two species and to contribute towards an explanation of the potential causes of the current poor situation of the stocks. The results support the use of fatty acid levels as indicators of the body condition of sardine and anchovy at different reproductive and feeding stages, as well as that of the pelagic environmental conditions. In particular, the relatively low n-3 polyunsaturated fatty acid levels found in spawning sardines compared to spawning anchovies indicate a poorer reproductive health status of sardine. By comparing the current total lipid content values with those recorded in other Mediterranean and North Atlantic areas, and others from more than 10 years ago, in the adjacent area of the Gulf of Lion, our study reveals the persistent poor condition of sardine and anchovy in the northern Catalan Sea. Furthermore, the low levels of diatom fatty acid markers observed throughout the spawning and non-spawning seasons in both sardine and anchovy indicate a diet poor in diatoms. Moreover, the results indicate that it is very unlikely that parasitism is a significant factor in the decline in condition of sardine and anchovy in the northern Catalan Sea. In fact, the results, which we believe provide useful insights for the management of small pelagic fisheries in the Mediterranean, suggest that the current poor condition of sardine and anchovy in the northern Catalan Sea has probably been exacerbated by a decrease in plankton productivity and/or a shift in the taxonomic composition of phytoplankton communities, adding to the ongoing effects of overfishing.

Ascaridoid parasites in European sardine throughout the annual cycle: Variability in parasitic load according to host stock features

“…In this line, no Anisakis spp. were characterised in sardines from the Northern Spanish Coast ( 6), supported by previous studies in the area ( Rello et al, 2008 ; Gutiérrez-Galindo et al, 2010 ; Frigola-Tepe et al, 2022 ), and contradicting analyses based on morphological identification ( Biton-Porsmoguer et al, 2020 ). Nevertheless, H. aduncum was observed throughout the whole year, except in winter in this location, and with much lower total prevalence and mean intensity than the 25.21% and the 2.10 obtained by Rello et al (2008) .…”

A study of trophic structure, physiological condition and mercury biomagnification in swordfish (Xiphias gladius): Evidence of unfavourable conditions for the swordfish population in the Western Mediterranean

“…Environmental changes, such as sea warming, are occurring and having an impact on the phytoplankton and zooplankton (Marbà et al, 2015) at the basis of marine food webs , providing evidence that sustains the hypothesis of a bottom-up mechanism affecting planktivorous species (Diaz et al, 2019). In the NW Mediterranean, the decrease in mean size and condition of small pelagic fish is probably related to changes in the quantity and/or quality of zooplankton (Chen et al, 2019;Biton-Porsmoguer et al, 2020) and this may impact the condition of their predators. Cephalopods (squids), the main prey of swordfish in the Mediterranean, present better adaptive trophic capacities than other groups and are generally proliferating (Doubleday et al, 2016).…”

How human health and well-being depends on healthy marine habitats in the Mediterranean: A review

“…Importantly, the amount of omega-3 fatty acids found in Mediterranean pelagic fish, such as sardine and anchovy [ 30 ] and benthic species, such as red mullet [ 29 ], depends on the characteristics of the habitats and, more specifically, on the quantity and quality of prey inhabiting these habitats, which consists of plankton for small pelagic species, and infauna for many benthic species. This is because omega-3 fatty acids are produced by phytoplankton and marine plants (algae and seagrass meadows), consumed by primary consumers in benthic habitats and then passed up through the food chain [ 31 ].…”