European Pilchard Sardina Pilchardus Research Articles

Detection of different Betanodavirus genotypes in wild fish from Spanish Atlantic coastal waters (Galicia, northwestern Spain).

The nervous necrosis virus (NNV; genus Betanodavirus) is an aquatic pathogen that is responsible for a neurological disease affecting marine fish. Despite its almost worldwide distribution, global warming could favor the spread of NNV to new areas, highlighting the importance of conducting epidemiological surveys on both wild and farmed marine fish species. In this study, we assessed NNV prevalence in wild fish caught along the Galician Atlantic coast. In total, 1277 fish were analyzed by reverse transcription real-time polymerase chain reaction. Twenty two (1.72%) of those fish tested positive for NNV, including two species in which the pathogen had not yet been reported. The reassortant RGNNV/SJNNV (red-spotted grouper NNV/striped jack NNV) was detected in 55% of NNV-positive individuals, while the remaining 45% harbored the SJNNV-type genome. Moreover, from European Pilchard Sardina pilchardus and Atlantic Mackerel Scomber scombrus, we isolated four reassortant strains that carried amino acid mutations at key sites related to NNV-host interaction.

Number Dynamics of Mass Ichthyoplankton Species in the Waters of Morocco

Data on the number dynamics of the mass fish species at early developmental stages in the northern and southern regions of Morocco during 2003–2016 have been analyzed. The values of number index and absolute number of eggs and larvae of the mass fish species have been calculated. As a rule, the values of absolute number of ichthyoplankton are 1.3–2.9 times higher than of the number index values. In general, the trends of interannual fluctuations of these values are similar. The study revealed that the patterns of fluctuations of the subtropical fish species at early developmental stages (European pilchard Sardina pilchardus, Atlantic horse mackerel Trachurus trachurus, and mackerel Scomber japonicus colias) are similar over the whole study area within the Morocco economic zone (32°–21° N). The fluctuations in the number of the tropical fish eggs and larvae (round sardinella Sardinella aurita and Cunene horse mackerel T. trecae) are not identical in the northern and southern parts of Morocco. No clear correlation between these fluctuations in the bordering regions is revealed.

Effect of Bait Type and Bait Size on Catch Efficiency in the European Hake Merluccius merluccius Longline Fishery

AbstractWe investigated the effect of bait type and bait size on the catch efficiency of a demersal longline fishery targeting European Hake Merluccius merluccius in the North Sea. Automation of the labor‐intensive processes onboard fishing vessels requires finding alternatives to the traditional bait used in the fishery (i.e., whole European Pilchard Sardina pilchardus). Of the six alternative baits investigated, four resulted in significant reductions in catch efficiency ranging from 32% to 90%. Only chopped Atlantic Herring Clupea harengus was a reasonable alternative bait, with an estimated non‐significant loss of only 2.12% in European Hake catch efficiency. Our results demonstrated that choice of bait type and size can affect the catch efficiency of different sizes of European Hake. Thus, the choice of bait may also affect the size distribution of the catch. The latter highlights the importance of considering fish size when inferring the effect of bait choice on the catch efficiency of longline fisheries.

Ontogenetic and seasonal changes in the feeding habits and trophic levels of two small pelagic fish species

ABSTRACT: We investigated ontogenetic and seasonal changes in the feeding ecology of 2 smallpelagic fish species, the European anchovy Engraulis encrasicolus and the European pilchardSardina pilchardus in the Gulf of Lions (NW Mediterranean). By analysing the stable isotopes δ 13 Cand δ 15 N, we determined the seasonal variation in the food sources and in the trophic level ofthese species, and we examined dietary shifts during development. The results of these investiga-tions provided estimates of the diets of both species. We compared the values observed duringdifferent seasons (summer, autumn and winter) and at different developmental stages (late -larvae, juveniles and adults) for both species, together with the values of potential groups of prey(microplankton, cladocerans, copepods and appendicularians). Late-larvae preferred to feed onmicroplankton, although differences in the diet appeared after metamorphosis. Cladocerans wereusually the preferred prey when available (summer), and appendicularians were the preferredprey in autumn. During the winter, the diets seemed to be more heterogeneous. Different feedingbehaviours between the late-larvae of the 2 species were the most likely reason for the slightlydifferent trophic levels found in the present study. This research demonstrates that studies withstable isotopes can furnish an alternative and/or complementary method for determining the dietof small pelagic fishes over extended periods and provides comprehensive knowledge of the func-tioning of the pelagic ecosystem. KEY WORDS: