Anchovy Engraulis Encrasicolus Research Articles

Evaluation of sustainable feeds for “caviar” production in the Mediterranean sea urchin Paracentrotus lividus (Lamarck, 1816)

To improve the sustainability of aquaculture practices, a step towards the use of alternative nutrient sources (such as food processing discards) may secure the future of aquaculture sector, namely for emergent species, such as sea urchins. In this context, adult females of the commercial sea urchin Paracentrotus lividus were reared using four feeds based on lettuce discards (72%) and enriched (8%) with an animal-source ingredient (fish Sardina pilchardus, Feed-S; krill Euphausia superba, Feed-K; mussel Mytilus galloprovincialis, Feed-M; anchovy Engraulis encrasicolus discards, Feed-AD). A fifth feed, used as control treatment, was composed of macroalgae (Laminaria sp. and Ulva sp., Feed-UL). Feed performance was evaluated employing a new productive protocol, the Raking method, which propose testing feed effects on sea urchin caviar (oocytes rather than gonads) production. Thus, ingestion rates and absorption efficiency were measured to evaluate feed palatability. Somatic growth and caviar production, expressed introducing the ovosomatic index (OI) instead of the traditional gonadosomantic index, were measured to assess feed productive performances. Caviar quality was assessed by nutritional content and color. Ingestion rate results showed that all feeds were palatable, while findings on absorption efficiency showed differences between the five proposed feeds, with Feed-M and Feed-AD presenting the worst results. Somatic growth was promoted regardless the provided feeds, while OI resulted higher with Feed-K and Feed-M than the other feeds. All produced caviar resulted suitable for human consumption with high protein and fatty acid content, but caviar produced by Feed-UL showed the poorest nutritional profile. Similarly, Feed-UL led to the production of caviar with the lowest quality color, while Feed-S showed the best orange color. Lettuce-based feeds were therefore effective for feeding P. lividus as they stimulated production of high quality caviar. Findings support the exploitation of food discards for the production of eco-friendly feeds for sea urchin aquaculture.

Variation in the levels of anisakid infection in the European anchovy Engraulis encrasicolus (Linnaeus) from the Bay of Biscay during the period 2000-2023 (ICES Subarea 8).

The European anchovy Engraulis encrasicolus is one of the most important commercial species in the Bay of Biscay (ICES Subarea 8), and our analysis focused on the analysis of the temporal mean abundance, prevalence, and intensity of Anisakis spp. larvae species in anchovies from ICES Subarea 8 in the years 2000, 2001, 2014-2016, and 2019-2023. Prevalence in adult individuals of anchovy was only 1% in 2000 but increased to 90% in 2014. Since 2015, the prevalence has decreased, and the number of individuals affected in 2023 accounted for 17.6%. The mean abundance showed a similar trend, with a peak of 3.79 nematodes/anchovy in 2014, falling to 0.21 in 2023. The species A. simplex sensu stricto and A. pegreffii were identified by PCR/SANGER sequencing and PCR/RLFP techniques in 2019 and 2020. Anisakis simplex (s.s.) was the most abundant species and, according to the results returned by these two techniques, it accounted for an average of 62.4% and 52.1% of total nematodes in 2019 and 2020, respectively. The results of studies monitoring infection levels in anchovies showed that the mean abundance and prevalence changed over the course of the study period and that the proportion of different species of Anisakis is also subject to variation from year to year.

Length-Weight and Length-Length Relationships of European anchovy Engraulis encrasicolus (Linnaeus, 1758) Population Distributed in İzmir Bay (Aegean Sea)

İzmir Körfezi’nde dağılım gösteren Hamsi popülasyonunun boy- ağırlık ve boy-boy ilişkisinin mevsimlere ve eşeylere göre çalışıldığı bu araştırmada Eylül 2020-Ağustos 2021 periyodunda körfezde avlanan ticari balıkçılardan toplam 905 adet birey elde edilmiştir. Eşeyi belirlenen 843 adet bireyin %35’i erkek %65’i dişi olarak saptanmıştır. Popülasyonun ortalama total boy ve ağırlık değerleri sırasıyla; 11.42±0.048 cm, 9.19±0.163 g’dır. Türün dişi, erkek ve tüm bireylerinde boy-ağırlık ilişkisi denklemi sırası ile: W=0.0027*TL3.321 (r2=0.933); W=0.0042*TL3.132 (r2=0.925); W=0.0030*TL3.272 (r2=0.931) olarak hesaplanmıştır. Sonuç olarak, popülasyonun dişi, erkek ve tüm bireylerinde pozitif allometrik büyüme belirlenmiştir. Ayrıca tüm bireyler için hesaplanan boy-boy ilişkisi parametrelerinin yüksek düzeyde ilişkili olduğu saptanmıştır (r²>0.959, P

Post-mortem ‘soft flesh’ in three commercial fish species from off Atlantic Morocco associated with the myxosporean parasites Kudoa thyrsites and K. encrasicoli (Myxozoa)

Small pelagic fishes represent one of the most important food resources off the Northwest coast of Africa. Despite their economic significance, little is known about the infections with flesh invading myxosporean parasites of genus Kudoa (Cnidaria, Myxozoa). Heavy infections in the flesh may be associated with post-mortem myoliquefaction, commonly known as ‘soft flesh’. This condition may reduce the quality and marketability of the fish fillet, resulting in both economic losses to the fishing industry and loss of consumer confidence. In this study, we investigated Kudoa-induced ‘soft flesh’ occurrence in European anchovy Engraulis encrasicolus, European pilchard Sardina pilchardus, and Atlantic chub mackerel Scomber colias caught in 2019 off the Moroccan Atlantic coast. Five hundred specimens of each fish species were examined for ‘soft flesh’ by texture testing and visual inspection 48 h post-catch. ‘Soft flesh’ occurred in 0.2 % of the European anchovies, 1.4 % of the European pilchard, and in 4.4 % of the Atlantic chub mackerel. Microscopic examination of muscle samples revealed that ‘soft flesh’-affected fish were infected with myxospores of K. thyrsites-like morphotype. Analysis of the kudoid SSU rDNA sequence obtained from European pilchard and the Atlantic chub mackerel identified these as K. thyrsites (100 % identity), whereas analysis of the sequence from European anchovy identified the presence of K. encrasicoli (100 % identity). Even if there are no known human health consequences associated with the ingestion of these Kudoa species, the unsightly appearance of some infected fillets is a food quality issue, that can eventually lead to reduced marketability and value.

Low hypoxia tolerance in larvae of the sardine Sardinops sagax and anchovy Engraulis encrasicolus may limit their stock recovery in the northern Benguela upwelling system

Physiological traits of five key fish species (Cape hake Merluccius spp., pelagic goby Sufflogobius bibarbatus, Cape horse mackerel Trachurus capensis, European anchovy Engraulis encrasicolus and sardine Sardinops sagax) from the northern Benguela upwelling system (NBUS) were compared during their larval stage by measurements of enzymatic activities of key metabolic enzymes (citrate synthase [CS] and pyruvate kinase [PK]). Two distinct age classes (early larvae: 8‒14 days old; late larvae: 22‒29 days old) for each species and from two areas were compared: Terrace Bay (20° S), the main spawning ground of Cape horse mackerel and anchovy, and Kunene (17° S), near the Angola–Benguela frontal zone, where warm and hypoxic water masses intrude into the NBUS. The results revealed significantly higher CS activity in both larval age classes in Cape horse mackerel, anchovy and sardine compared with Cape hake and pelagic goby. Pelagic goby and Cape horse mackerel had significantly higher PK activity compared with Cape hake, anchovy and sardine, apparent in both larval age classes and both areas. Results for anaerobic metabolism indicate higher capacity for pelagic goby and Cape horse mackerel to recover from oxygen debt built up in prey capture and predator escape behaviour and a higher potential for hypoxia tolerance when compared with Cape hake, anchovy and sardine. These results suggest higher survival probability for pelagic goby and Cape horse mackerel compared with the other species under conditions of a shoaling oxygen minimum zone and may explain their current dominance in the NBUS.

Regional Differences in the Infection of the European Anchovy Engraulis encrasicolus with the Nematode Hysterothylacium aduncum in the Winter Period off the Coasts of Crimea and the Caucasus

Regional Differences in the Infection of the European Anchovy Engraulis encrasicolus with the Nematode Hysterothylacium aduncum in the Winter Period off the Coasts of Crimea and the Caucasus

Regional Differences in the Infection of the European Anchoy <i>Engraulis encrasicolus</i> with the Nematode <i>Hysterothylacium aduncum</i> in the Winter Period of the Crimea and the Caucasus Coasts

The main indicators of infestation of European anchovy Engraulis encrasicolus (L.) with larvae of the nematode Hysterothylacium aduncum (Rudolphi, 1802) in winter were studied in two areas of the Black Sea: off the coast of Crimea and the Caucasus. Regional differences in the indicators of invasion intensity and abundance index in two-year-old and three-year-olds were revealed. When analyzing the values of the extensiveness of invasion, no significant differences were found. Three main factors that determine regional differences in anchovy infestation in the studied areas are analyzed.

Age Determination of the Azov Anchovy Engraulis encrasicolus maeoticus (Engraulidae) Based on the Otolith Image Analysis

To specify the age determination of the Azov anchovy Engraulis encrasicolus maeoticus, the length of otoliths of the age 0+ fish and the radii of annual rings in the otoliths of individuals of different age groups have been analysed. The otoliths of 380 fish caught in the Sea of Azov in October–November 2018 and off the northwestern coast of the Caucasus in February 2019 have been analyzed. The ImageJ software has been used for measuring the maximum otolith length and plotting the reflected light intensity profiles along the length of the otolith transect. In the fingerlings (0+) with an average total length of 70.9 ± 6.7 mm, in October–November, the otolith radius averaged 0.95 ± 0.08 mm, while in February, with an average 66.6 ± 10.6 mm, it was 0.86 ± 0.15 mm. In the smallest fish (48–55 mm), the distance from the core of the otolith to the edge of the white opaque zone varied from 0.54 to 0.72 mm (on average, 0.63 ± 0.04 mm). According to the averaged data, the radii to the center of the dark hyaline zone of otoliths for different age groups of anchovy are: R1, 0.94 ± 0.09; R2, 1.23 ± 0.08; and R3, 1.40 ± 0.07 mm. The present study is aimed at developing automatic methods for determining the age of fish from light intensity profile peaks on otolith images.

First Report of <i>Aphanurus stossichii</i> (Digenea: Hemiuridae) from <i>Engraulis encrasicolus</i> on the Turkish Coast of the Black Sea, with Light and Scanning Electron Microscopic Observations

The aim of this study is to investigate in detail the morphological features of the digenean parasite Aphanurus stossichii isolated from the European anchovy Engraulis encrasicolus using light and scanning electron microscopy (SEM). The specimens of A. stossichii were obtained from the pharynx and stomach of the European E. encrasicolus caught by commercial fishing vessels in the Black Sea. Parasites were killed in a hot normal saline solution, preserved in to 70% ethanol for light microscopic (LM) studies, and in 2.5% glutaraldehyde for SEM. The morphological diagnostic features of A. stossichii were studied in detail under both LM and SEM. The morphological characteristics of the examined adult A. stossichii specimens were found to be similar to the original descriptions describing the basic characteristics of forebody and hindbody shape, the position and shape of the vitellarium, ovary, and and testes, and the shapes of oral and ventral sucker. The measurement data for all morphological diagnostics were provided; photomicrographs of each part of the parasite were presented. Infection prevalence, mean intensity and mean abundance values were 8.89%, 4.5 and 0.4, respectively. All available records of A. stossichii morphology are based on light microscope, this is the first study to identification the morphological features of the parasite with SEM. This research is the first on A. stossichii presence in E. encrasicolus on the Turkish Black Sea coast.

Comparative Morphometric Analysis of the Azov Anchovy (<i>Engraulis encrasicolus maeoticus</i> Pusanov, 1926) and the Black Sea Anchovy (<i>E. encrasicolus ponticus</i> Alexandrov, 1927) Based on the Body Shape

A comparative analysis of body shape was performed on 841 specimens of anchovy collected from 21 catches from the Sea of Azov, the Kerch Strait, and the Black Sea off the Crimea and the northeastern coast of the Caucasus in 2006–2007 and 2016–2017. Twenty-three measurements between 12 homologous landmarks of the body of each specimen according to the “Truss Network System” served as characters for analysis. Fifteen characters showed significant differences between the Azov anchovy Engraulis encrasicolus maeoticus Pusa-nov, 1926 and the Black Sea anchovy E. encrasicolus ponticus Alexandrov, 1927. Specimens of the Azov subspecies had larger relative values for all characters of the head region, the height of the trunk region, the re-lative length of the bases of the dorsal and anal fins, and the height of the base of the caudal fin. Specimens of the Black Sea subspecies had a greater postdorsal length and a larger distance from the end of the dorsal fin base to the end of the anal fin base. A multivariate principal component analysis revealed the highest variabi-lity of characters of body height, which depends on the fatness of the fish and demonstrates seasonal dyna-mics. The second group combines characters that do not have a seasonal component (dimensions of the head region, lengths of the bases of the dorsal and anal fins, and postdorsal distance) and can be used for distinguishing the shape of the Azov and Black Sea anchovies. The success rate of classification of Azov and Black Sea anchovies according to the body shape measurement characters using the discriminant analysis was 83.4%.

ТРОФИЧЕСКИЕ ОСНОВЫ ФОРМИРОВАНИЯ ЗАПАСОВ ХАМСЫ В АЗОВСКОМ МОРЕ

Formation of the European anchovy Engraulis encrasicolus (Linnaeus, 1758) stocks in the Azov Sea depends on the development of zooplankton, which is the main food source for this fish species. Under the conditions of the natural flow regime of the rivers (1937-1951) and the 10.6 ‰ salinity of the sea, native zooplankton species ensured a high food supply for the anchovy, which resulted in relatively large anchovy stocks. During the Azov Sea salinization up to 12.8 ‰ that occurred in the late 60-70s of the last century, the zooplankton species composition changed. Predatory scyphoid jellyfish species - Aurelia aurita and Rhizostoma pulmo - underwent drastic increase in abundance, which led to the reduction in the summer biomass of the zooplankton almost by half. During that period, large stocks of the European anchovy developed less often. In the late 1980s, as a result of the introduction of a predatory ctenophore Mnemiopsis leidyi in the Azov Sea, the summer biomass of the zooplankton decreased further by 2-3 orders of magnitude. During the feeding season of the European anchovy, the areas with high zooplankton productivity disappeared, which resulted in the recurring low stocks of this fish species. At the end of the 1990s, a ctenophore Beroe ovata , feeding on the mnemiopsis, appeared in the Azov Sea. Its invasion led the delayed entry of the mnemiopsis into the sea, which, in turn, ensured the development of a sufficient food supply for the anchovy during its pre-spawning period. However, the main feeding season of the anchovy, just as before the arrival of B. ovata , took place under a shortage of the food supply. In the last few years, another increase in salinity to 15.0 ‰ is observed in the Azov Sea. The Black Sea jellyfishes A. aurita and R. pulmo are actively developing once again and, along with M. leidyi , provide even stronger food competition for the anchovy. During these years, only low-productive generations and low stocks of this fish species have been observed.

Climate and fishing simultaneously impact small pelagic fish in the oceans around the southernmost tip of Africa

Climate and fisheries interact, often synergistically, and may challenge marine ecosystem functioning and, ultimately, seafood provision and human wellbeing that depend on them. Holistic and integrative approaches aiming at evaluating the spatial overlap between these major stressors are crucial for identifying marine regions and key fish species that require conservation priority to prevent possible future collapses. Based on highly resolved information on environmental conditions and fishing pressure from the Southern Benguela and the Agulhas Bank ecosystems off South Africa, we identified the main areas where small pelagic fish species (European anchovy Engraulis encrasicolus, Pacific sardine Sardinops sagax, and West Coast round herring Etrumeus whiteheadi) have been highly impacted in terms of unfavourable environmental conditions and fishing pressure over the period 1993-2018. We termed these areas cumulative “hotspots” of climate change and fishing impact. We also identified fishing grounds where environmental conditions are now more favourable for these pelagic fish species, terming these “bright spots” of climate change. Environmental conditions and fishing intensity show contrasting patterns between the Southern Benguela and the Agulhas Bank ecosystems, with the Southern Benguela region accumulating most of the cumulative hotspots and showing the most negative trends in CPUE (a proxy for local fish abundance). Contrastingly, bright spots, identified on the south coast but also south of Cape Town, showed more positive trends in CPUE, suggesting that they may support sustainable growth of the small pelagic fishery in the medium term. Focussing future fishing effort on these bright spots may serve to alleviate pressure on the doubly and highly impacted cumulative hotspots from the western side of the southernmost tip of Africa.

Length Based Assessments for European Pilchard Sardina pilchardus and European Anchovy Engraulis encrasicolus, in the İzmir Bay, Aegean Sea

In the Mediterranean Sea, European pilchard Sardina pilchardus and European anchovy Engraulis encrasicolus are the most important small pelagic fish regarding their ecological role, and revenue. Here, we perform a comprehensive assessment of length-based methods for those small pelagics from İzmir Bay, Aegean Sea. Therefore, the Length-based Bayesian Estimator and Length-based Spawning Potential Ratio were used to evaluate the stock structure and status of two important small pelagic fish. The length range for Sardina pilchardus was from 7.1 cm to 17.3 cm in TL. The ratios Lmean/Lopt and Lc/Lc_opt were over 1, suggesting truncated length structure and fishing of not too small individuals. The proportion of mature individuals in the catch was far less than half (36%) suggesting that in these fisheries catch consists mostly of immature individuals. The length range for Engraulis encrasicolus was from 5 cm to 15 cm in TL. The ratios Lmean/Lopt and Lc/Lc_opt were over 1 (1.2 and 1.3, respectively), suggesting truncated length structure and fishing of large individuals. The proportion of mature individuals in the catch was over half (52%) suggesting that in these fisheries catch consists of adults. The estimated sizes at median 50% selectivity (SL50) for S. pilchardus (11.1 cm) was ∼0.6 cm shorter than its lengths at 50% maturity (L50) of 11.7 cm, which indicates that a large proportion of the catch was immature. The median estimate of the spawning potential ratio was ∼0.19 for S. pilchardus and ∼0.48 for E. encrasicolus.

Diet and trophic interactions of Mediterranean planktivorous fishes

Diet and trophic interactions of seven species of planktivorous fishes: European anchovy Engraulis encrasicolus, European sardine Sardina pilchardus, round sardinella Sardinella aurita, European sprat Sprattus sprattus, red bandfish Cepola macrophthalma, damselfish Chromis chromis and bogue Boops boops were studied in the Bay of Marseille (North-Western Mediterranean Sea) from March to September 2017. Taxonomic composition and size distribution of prey were studied using stomach content analysis, and compared to prey availability determined by continuous zooplankton sampling at a fixed point. Frequently consumed items included copepods, decapod larvae and fish eggs. Comparatively, E. encrasicolus consumed more calanoid copepods (i.e. Centropages spp.), S. pilchardus, S. aurita and S. sprattus consumed more harpacticoid copepods (i.e. Microsetella/Macrosetella spp.), C. macrophthalma consumed more decapod larvae, C. chromis consumed more pteropods and B. boops consumed more benthic polychaetes. Sardina pilchardus consumed the widest diversity of prey. Prey size distribution and average prey size significantly differed among species. The prey–predator size ratio (PPSR) was highest for B. boops and lowest for S. aurita. Carbon and nitrogen stable isotope composition of species overlapped, probably due to the ingestion of particulate organic matter from the same sources at the base of the planktonic food web in the Bay of Marseille. Furthermore, trophic niche overlap supported the hypothesis of potential trophic competition between Engraulidae and Clupeidae.

Trophic ecology of northern gannets Morus bassanus highlights the extent of isotopic niche overlap with other apex predators within the Bay of Biscay

Understanding the linkages within complex and evolving marine food webs is essential to comprehend marine ecosystem structure and dynamics. Carbon (δ13C) and nitrogen (δ15N) stable isotope signatures are recognized to be powerful descriptors of the trophic ecology and trophic relationships within marine communities. Apex predators such as seabirds can influence the structure of communities by predating in lower trophic levels. They also convey information both over a range of spatial and temporal scales due to their high mobility and longevity, respectively. For this reason, here, we studied the trophic ecology of northern gannets and the extent of niche overlap with other apex predators within the Bay of Biscay (North-East Atlantic), a key feeding area for numerous predatory species. Mixing models indicated that northern gannets fed primarily on European anchovy Engraulis encrasicolus and on a mixed group composed of European sardine Sardina pilchardus, European sprat Sprattus sprattus, juvenile hake Merluccius merluccius, Atlantic mackerel Scomber scombrus and Atlantic horse mackerel Trachurus trachurus. Within the apex predator community, the northern gannets trophic niche overlapped the most with common guillemots Uria aalge (15.58%, based on Stable Isotope Bayesian Ellipses (SIBER)) and overlapped to a lesser extent with cetacean species occupying shelf habitats (i.e., the harbour porpoise Phocoena phocoena (9.99%) and the short-beaked common dolphin Delphinus delphis (10.37%)). Overall, the overlap found was moderate indicating trophic similarities and dissimilarities between these species. Information on trophic interactions between co-existing species is necessary for holistic environmental management, particularly in areas where several megafauna species share their foraging grounds with fisheries activity.

Important marine areas for endangered African penguins before and after the crucial stage of moulting.

The population of the Endangered African penguin Spheniscus demersus has decreased by > 65% in the last 20 years. A major driver of this decrease has been the reduced availability of their principal prey, sardine Sardinops sagax and anchovy Engraulis encrasicolus. To date, conservation efforts to improve prey availability have focused on spatial management strategies to reduce resource competition with purse-seine fisheries during the breeding season. However, penguins also undergo an annual catastrophic moult when they are unable to feed for several weeks. Before moulting they must accumulate sufficient energy stores to survive this critical life-history stage. Using GPS tracking data collected between 2012 and 2019, we identify important foraging areas for pre- and post-moult African penguins at three of their major colonies in South Africa: Dassen Island and Stony Point (Western Cape) and Bird Island (Eastern Cape). The foraging ranges of pre- and post-moult adult African penguins (c. 600 km from colony) was far greater than that previously observed for breeding penguins (c. 50 km from colony) and varied considerably between sites, years and pre- and post-moult stages. Despite their more extensive range during the non-breeding season, waters within 20 and 50 km of their breeding colonies were used intensively and represent important foraging areas to pre- and post-moult penguins. Furthermore, penguins in the Western Cape travelled significantly further than those in the Eastern Cape which is likely a reflection of the poor prey availability along the west coast of South Africa. Our findings identify important marine areas for pre- and post-moult African penguins and support for the expansion of fisheries-related spatio-temporal management strategies to help conserve African penguins outside the breeding season.

Ingestion of microplastics by commercial fish species from the southern Black Sea coast

Microplastic (MP) contamination is a serious threat to today's marine life. Therefore, this study investigates MP ingestion in three commercial fish species (European anchovy Engraulis encrasicolus, whiting Merlangius merlangus, and red mullet Mullus barbatus) from the Turkish coast of the Black Sea. Ninety-five MPs were detected in all examined fish (371). Fiber forms were detected in the majority of cases based on the MP morphology. Polyethylene and polypropylene were the most dominant polymer type. The mean of ingested MPs was found as 0.15 ± 0.04, 0.28 ± 0.06, 0.40 ± 0.07 in anchovy, whiting and red mullet, respectively. The size of the MPs ranged from 118 μm and 4854 μm. The MP waste was detected in each species, and the highest MP amount was determined in the red mullet, which was significantly higher than European anchovy. The present study's data might be a baseline on the ecological risk assessment of MPs in the fish and future experimental studies on the fish species living in the Black Sea.

Asynchronized spawning responses of small pelagic fishes to a short-term environmental change

We provide substantial evidence on how short-term changes in environmental conditions activate and deactivate spawning activities in small pelagic fishes. An ichthyoplankton survey was conducted along the southernmost part of the Canary Current upwelling ecosystem in May 2013, covering the area twice within 20 d. This period coincided with a strong environmental change from a cold productive upwelling regime to a warmer and less productive upwelling relaxation event. This change triggered a shift in spawning activity from European anchovy Engraulis encrasicolus to round/flat sardinella Sardinella spp. We used zero-altered negative binomial regression models with a generalized additive structure based on integrated nested Laplace approximations to link early larval distribution patterns to the 2 different regimes. The models confirmed 2 species-specific temperature spawning windows, suggesting a spawning pause of anchovy during upwelling relaxation while simultaneously activating spawning in sardinella. Observing immediate spawning responses to the 2 environmental regimes underlines the assumption that windows of spawning opportunity are the main drivers of small pelagic fish fluctuations in upwelling regions. The duration of a specific environmental condition can, therefore, increase or decrease the chances for reproductive success. The observations of this study may explain why certain small pelagic fish species can dominate over others during a particular period and might also apply to other upwelling regions of the world oceans where upwelling and relaxation events alternate.

Trophic importance of small pelagic fish to marine predators of the Mediterranean Sea

Small pelagic fish (SPF) species such as European sardine Sardina pilchardus, European anchovy Engraulis encrasicolus, round sardinella Sardinella aurita and European sprat Sprattus sprattus play important ecological roles in the Mediterranean Sea marine ecosystem. However, changes in SPF abundance and biomass have recently been observed in the basin. Therefore, uncovering the trophic importance of SPF to their predators is key to unravelling potential ecological causes and consequences of SPF population changes related to predator dynamics. Here, we reviewed 101 published studies reporting the presence of the SPF species named above in the diet of marine predators inhabiting the Mediterranean Sea. We found that the number of species preying on SPF was highest for teleost fish species, followed by elasmobranchs, seabirds, marine mammals, cephalopods and sea turtles. These predators were both commercial and non-commercial taxa, and vulnerability ranged from medium to very high. From a conservation point of view, most predator species were considered Least Concern by the IUCN, with few exceptions such as the Balearic shearwater Puffinus mauretanicus, a Critically Endangered species. Geographic information showed that the European sardine was more important in the diet of predators from the western Mediterranean basin, while European anchovy consumption was higher on the eastern side. Round sardinella was consumed in high amounts in the Tyrrhenian Sea, and European sprat was anecdotally consumed. The importance of SPF in the diet of Mediterranean predators may indicate bottom-up control of the marine ecosystem; however, limited temporal information precluded the evaluation of temporal changes, highlighting the need to develop new studies in this area.

Are Cape Cormorants Phalacrocorax capensis losing the competition? Dietary overlap with commercial fisheries

Cape Cormorants Phalacrocorax capensis breed in southern Africa’s Benguela upwelling system and in 2013 were listed as Endangered by the IUCN following a population decrease of >50% over their three most recent generations. This decrease was associated with reduced prey availability, particularly of the pelagic shoaling fishes Cape anchovy Engraulis encrasicolus and sardine Sardinops sagax. The diet of Cape Cormorants was examined from 929 regurgitated prey samples collected at 11 localities off west South Africa from 1988 to 2007. By number, anchovy was the most important prey in all years, except 2007, in which the geographical distribution of samples was limited. Overall anchovy contributed 85% of all prey items eaten and sardine 6%. However, from 1988 to 1997, sardine formed 93% of the diet by mass in the southwest. The proportional contribution of anchovy to the diet increased between 1988–1997 and 1998–2007, whereas that of sardine decreased. Anchovy eaten in the northwest were smaller than those caught in the central west and southwest were. Small, immature sardine were eaten in all regions, but mature sardine only in the southwest, the spawning ground of the western sardine stock. Anchovy and sardine are targeted by South Africa’s purse-seine fishery. Most anchovy and sardine eaten by Cape Cormorants had caudal lengths of 5–9 cm and 15–21 cm, respectively, and showed considerable overlap with sizes harvested by the fishery. This highlights the potential for competition between Cape Cormorants and the fishery for anchovy and sardine.