The influence of environment and spawning distribution on the survival of anchovy (Engraulis encrasicolus) larvae in the Bay of Biscay (NE Atlantic) investigated by biophysical simulations

A growth and survival model of the early life stages was run along virtual drift trajectories tracked in a hydrodynamic model to simulate the annual recruitment process of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). These biophysical simulations concerning three different years were analysed in order to investigate the influence of environment and spawning dynamics on the survival of larvae and juveniles. The location of space–time survival windows suggested major environmental mechanisms involved in simulated recruitment variability at the different scales – retention of larvae and juveniles in favourable habitats over the shelf margins and turbulence effects. These small‐scale and meso‐scale mechanisms were related to the variations in wind direction and intensity during spring and summer. Survival was also variable according to the origin of the drift trajectories, that is spawning distribution in space and time. The observed spawning distribution (according to field surveys) was compared with the spawning distribution that would maximize survival (according to the biophysical model) on a seasonal scale, which revealed factors not considered in the biophysical model (e.g. spawning behaviour of the different age classes). The variation of simulated survival according to spawning distribution was examined on a multi‐annual scale and showed a coherent pattern with past and present stock structures. The interaction processes between the population (influence on spawning) and its environment (influence on survival) and its implications on recruitment and stock dynamics are discussed.     

Variation in the condition factors of California pelagic fishes and associated environmental factors

Time series of condition factors for mackerel, Scomber japonicus , jack mackerel, Truchurus symmetricus , and northern anchovy, Engraulis mordax , stocks in the Southern California region were compared with time series of oceanographic indices to develop hypotheses concerning physical environmental forcing of the population dynamics and energetics of small pelagic fishes. Mackerel and jack mackerel condition factor time series showed decade-scale variation, whereas those of anchovy showed coherent fluctuations for 1 to 2 years. Mackerel, and to a lesser extent jack mackerel, condition factors were correlated with proxy indices of alongshore advection (sea level), offshore advection (Ekman transport), ambient temperature (shore station temperature), and ambient salinity (shore station salinity). The condition factor of anchovy was much less correlated with environmental variables. Multiple regression analyses which included sea level, upwelling and salinity proxies explained 80% (33%) of the variance in the annual (monthly) condition factor of mackerel. The first-order variation in condition factors of mackerel and jack mackerel suggests that they are responding to very large-scale perturbations of the California Current system which are at least partially described by variations in sea level. The population size of mackerel is apparently also responding to these large-scale perturbations, making it difficult to isolate environmental dependence of condition factors from density dependence. The second-order variation is more regional in nature and unexpectedly it appears to be associated with upwelling in the Baja California region.     

Distribution and settling of Japanese anchovy (Engraulis japonicus eggs at the spawning ground off Changjiang River in the East China Sea

Spatial patterns in the distribution and abundance of Japanese anchovy, Engraulis japonicus, eggs were studied from net surveys in the East China Sea in May 1991. Egg abundance was> 5 × 10³ eggs (100 m³)^?1 in the area off Changjiang River, where a large spawning ground was developed. The vertical distribution of living eggs showed a maximum concentration at the surface (40700 eggs (100 m³)^?1) and rapidly decreased to ～5000 eggs (100 m³)^?1 at 14 m. Newly spawned eggs (stage I) were found throughout the water column but were most abundant near surface. Some eggs were morphologically identified as dead owing to their abnormal development and physical damage. In contrast to living eggs, no dead eggs were found at the surface and the concentrations were low to 21 m depth (40–64 eggs (100 m³)^?1). The concentration increased markedly with increasing depth, reaching a maximum of 634 eggs (100 m³)^?1 near the bottom (35 m). Dead eggs accounted for less than 0.3% of the total caught within 7 m of the surface and increased exponentially to 12% near the bottom. The settling loss of dead anchovy eggs also was studied by employing sediment traps at the spawning ground. The downward flux of settling eggs was low (304–405 eggs m^?2 day^?1) at 15 and 20 m depths, but rapidly increased with increasing depth, reaching a maximum of 1622 eggs m^?2 day^?1 at 35 m (5 m above bottom). By comparing the egg flux at 20 m with the living eggs abundance in the upper 20 m, the settling loss of eggs was calculated as about 0.098 day^?1. This probably represents the natural mortality of anchovy eggs caused by genetic abnormalities and incomplete fertilization.     

鳀鱼落网抗风浪装置的试验和应用_

鳀鱼落网抗风浪装置的试验和应用孙泰昌，尹彦水，李守刚，邓炳悦，杨家波（山东省海洋水产研究所，烟台２６４０００）（山东省牟平县渔业技术推广站，２６４１００）关键词　鱼落网，抗风浪装置ＴＥＳＴＡＮＤＡＰＰＬＩＣＡＴＩＯＮＯＦＳＴＯＲＭＰＲＯＯＦＥＱＵＩＰ...     

Climate change and interspecific interactions drive species alternations between anchovy and sardine in the western North Pacific: Detection of causality by convergent cross mapping

The abundance and recruitment of anchovy Engraulis spp. and sardine Sardinops spp. alternate in a synchronized way across the Pacific. Convergent cross mapping (CCM) indicated that climate change drives the alternation of the two species in the California Current System. However, climate indices patterns in the western North Pacific contrast with those in the eastern North Pacific, despite synchronous species alternations occurring. Therefore, it is of great interest to clarify whether climate change, or any other factors, affects the population dynamics of Japanese anchovy and Japanese sardine in the western North Pacific. Using CCM, we tested whether climate change and interspecific interactions affect the population dynamics of these two species. We found that climate change affected recruitment, and we clarified the spatiotemporal pattern of this effect. This result supports the existing hypotheses that population dynamics are regulated by climate change in the western North Pacific. The present study also detected interspecific interactions between sardine and anchovy, which might promote the alternation of the two species, and has not been reported in other regions.     

The Effects of Natural Antioxidant Extract Isolated from Giant Red Shrimp (Aristaeomorpha foliacea) Shells on Fatty Acid Profiles of Anchovy (Engraulis encrasicolus) During Refrigerated Storage

The aim of the present study was to determine the effects of natural antioxidant extract isolated from the shells of giant red shrimp (Aristaeomorpha foliacea) on the changes in fatty acid profile of anchovy (Engraulis encrasicolus) during refrigerated storage (2.7°C). Total antioxidant activity of shell extract was determined as 45.84%, total phenolic compound as 17.87 mg/100 g shell, and total carotenoid content in shell as 20.31 mg/100 g shell. Total saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA) contents in the control group and the group with 0.1% shell extract addition were found to be affected by the duration of storage (p < 0.05). A percentage increase was determined in MUFA content, while decreases were observed in PUFA content. No statistically significant change was detected in SFA, MUFA, and PUFA contents of groups with added butylated hydroxytoluene (BHT) and 0.5% of shell extract (p > 0.05). It was concluded that the extract isolated from shrimp shells could be used during the cold storage of fish fillets instead of synthetic antioxidants.     

Impacts of climate change on the complex life cycles of fish

To anticipate the response of fish populations to climate change, we developed a framework that integrates requirements in all life stages to assess impacts across the entire life cycle. The framework was applied on plaice (Pleuronectes platessa) and Atlantic herring (Clupea harengus) in the North Sea, Atlantic cod (Gadus morhua) in the Norwegian/Barents Seas and European anchovy (Engraulis encrasicolus) in the Bay of Biscay. In each case study, we reviewed habitats required by each life stage, habitat availability, and connectivity between habitats. We then explored how these could be altered by climate change. We documented environmental processes impacting habitat availability and connectivity, providing an integrated view at the population level and in a spatial context of potential climate impacts. A key result was that climate‐driven changes in larval dispersion seem to be the major unknown. Our summary suggested that species with specific habitat requirements for spawning (herring) or nursery grounds (plaice) display bottlenecks in their life cycle. Among the species examined, anchovy could cope best with environmental variability. Plaice was considered to be least resilient to climate‐driven changes due to its strict connectivity between spawning and nursery grounds. For plaice in the North Sea, habitat availability was expected to reduce with climate change. For North Sea herring, Norwegian cod and Biscay anchovy, climate‐driven changes were expected to have contrasting impacts depending on the life stage. Our review highlights the need to integrate physiological and behavioural processes across the life cycle to project the response of specific populations to climate change.     

Spawning site selection by European anchovy (Engraulis encrasicolus) in relation to oceanographic conditions in the Strait of Sicily

European anchovy egg occurrence and density data from summer surveys (1998–2007) and oceanographic data were examined to study the mechanisms that control the spatial distribution of anchovy spawning habitat in the Strait of Sicily. Quotient analysis indicated habitat preference for temperature (18–19°C), bottom depth (50–100 m), water column stability (13–14 cycle h^?1), fluorescence (0.10–0.15 μg m^?3 Chl a), salinity (37.5–37.6 PSU), current speed (0.20–0.25 m s^?1) and density (26.7–26.8 kg m^?3, σ_t). Canonical discriminant analysis identified temperature, column stability and fluorescence as major drivers of anchovy spawning habitat. Three of the 4 years which had lower egg abundance were warmer years, with low values of primary productivity. A geostrophic current flowing through the Strait (the Atlantic Ionic Stream, AIS) was confirmed as the main source of environmental variability in structuring the anchovy spawning ground by its influence on both the oceanography and distribution of anchovy eggs. This 10‐yr data series demonstrates recurrent but also variable patterns of oceanographic flows and egg distribution. A lack of freshwater flow in this area appears to depress productivity in the region, but certain and variable combinations of environmental conditions can elevate production in some sub‐areas in most years or other sub‐areas in fewer years. These temporal and spatial patterns are consistent with an ocean triad theory postulating that processes of oceanographic enrichment, concentration, and retention may help predict fishery yields.     

Proximate Composition and Nutritional Profile of the Black Sea Anchovy (Engraulis encrasicholus) Whole Fish,Fillets, and By-Products

ABSTRACT

In this study, the proximate composition and nutritional profile of the Black Sea anchovy and its by-products were investigated. The total yield of by-products from anchovy was about 32% of the whole fish based on wet weight. The protein and fat contents of anchovy by-products were 13.39 and 10.02% for head, 16.47 and 15.50% for frame, and 12.05 and 23.90% for viscera, respectively. Significant differences were detected among the pH and color properties of anchovy whole fish, fillet, and by-products. Profiles of amino acids, fatty acids, and minerals of anchovy by-products showed they are rich sources of lysine (6–7% of total amino acids), leucine (5–6% of total amino acids), and a number of essential amino acid, polyunsaturated fatty acids (about 32–40% of total fatty acids), n-3 fatty acids (about 27–34% of total fatty acids), eicosapentaenoic acid + docosahexaenoic acid (about 26–32% of total fatty acids), and various minerals (P, Fe, Ni, Ca, Mn, Na, and Zn). These results revealed that anchovy by-products can be utilized for the production of value-added products such as protein powder, protein hydrolyzates, fish oils, and mineral supplements.     

Simulation of the impact of climate change on the egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island,the western coast of Japan

In order to investigate the impact of climate change on egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island western Japan, we conducted particle‐tracking simulations on transport success/failure to fishing grounds from 1960 to 2007. The modeled transport success since the mid‐1990s increased and decreased in the offshore and coastal zones, respectively, compared with the 1960s and 1970s. The estimated northward shift of the spawning ground and weakened Tsushima Warm Current contributed to increase in modeled transport success to the offshore zone. Conversely, the weakening trend of the modeled onshore current in the Goto‐Nada Sea combined with the northward shift of the spawning ground resulted in unsuccessful larval transport. These results suggest that fluctuations in juvenile and subadult anchovy catches in this area may be attributable to changes in the physical environment. The present study showed that changes in transport success induced by oceanographic fluctuations related to climate change, have the potential to affect anchovy recruitment off the western coast of Japan.