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The population size structure and length–weight relationships (LWRs) are fundamental tools in fishery science, providing valuable insights into the health, dynamics, and management of fish populations and contributing to the sustainable use of aquatic resources. The data used in this study were estimates from the main small pelagic fishes exploited in the Gambia. They were collected using surface and bottom gillnets between November 2020 and October 2021 during scientific fishing operations. The main small pelagic fish size composition showed a modal class of 20 cm for Ethmalosa fimbriata, 21 cm for Sardinella aurita, 22 cm for Sardinella maderensis, and 30 cm for Trachurus trecae. The parameter b value of these fish species ranged from 1.6831 to 2.9461, and the correlation coefficient ranged from 0.81 to 0.95. Statistical LWRs for all species were very significant. Information obtained is essential in reviewing and establishing basic management measures for depleted shared pelagic stocks in the Gambian fisheries and the sub‐region. In the context of poor data fisheries, such results also encourage the Gambian government and intergovernmental subregional organizations to support data collection in the long term. [ABSTRACT FROM AUTHOR]

In Mexico, marine acoustics research still faces technical and scientific challenges. For the past decade, the country has made a sustained effort to implement acoustic techniques to generate time series of standardized information; however, these data have been underutilized. Marine acoustics research has been used mainly for small pelagic species and has contributed to improving fishery management and to advising stakeholders. The Mexican scientific community has perceived marine acoustic techniques as expensive tools that are only used for industrial fishing purposes. Marine acoustics can provide information on the variability and interactions between species, their physical environment, and other communities of species, but this approach has not yet been integrated into interdisciplinary research programs or ecosystem models. Additionally, acoustic data provide estimates of biomass and indices of relative abundance, and they have suitable statistical properties for use in integrated catch-at-age models. In summary, to consolidate marine acoustic techniques in Mexico, it is necessary, at a minimum, to maintain the current infrastructure for acoustic studies, to increase the budget for the development of monitoring programs that collect ecosystem indicator data, to promote the training of human resources, and to encourage peer review of the information generated and reported in gray literature. [ABSTRACT FROM AUTHOR]

Although fluctuations in the biomass of small pelagic fish are strong and rapid, they are largely investigated as individual events or generalized to what is common across several species and populations. The Barents Sea capelin population, which experienced four large decreases in biomass between 1980 and 2016, can be used to compare the similarity of causes and sequence of events leading up to large biomass decline in the same population. Here, we used an age-structured state-space model to investigate the possible contributions from somatic growth, food availability, temperature, predation by Atlantic cod, herring interactions, and/or fisheries on the capelin biomass declines. We recalculated total biomass while perturbing these effects and assessed the change in total biomass. We did not find a single, common cause for the dramatic biomass declines. Although median biomass increased in several of the scenarios, a large decline in total biomass was mostly retained. Atlantic cod predation and food availability influenced adult capelin biomass. Food availability mainly impacted the first period, while the importance of Atlantic cod predation increased from the first period to the third period. Reducing larval mortality from herring interactions or temperature did not suppress the biomass declines. Recruitment failures were maintained due to a combination of process errors and uncertainty in the effect of spawning biomass, and thus fisheries, on age 0 abundance. The impact of each perturbation depended on the specific ecosystem context at the time of the biomass decline. [ABSTRACT FROM AUTHOR]

The biology and dynamics of sardina pilchardus and sardinella aurita from the east coast of Algeria were studied to compensate the lack of data concerning the exploitation of their stocks in this area. The von Bertalanffy growth equations were as follows: Lt = 21.58 [1-e-0.39 (t +0.086)] for S. pilchardus and Lt = 26.68 [1-e-0.41 (t +0.085)] for S. aurita. The equations of the length - weight relationship were TW = 0.0039 TL3.236 for S. pilchardus and TW = 0.005 TL3.134 for S. aurita. The lengths at first maturity (Lm50) were 11.61 and 13.54cm for S. pilchardus and S. aurita, respectively. The natural mortalities (M) were 0.46 year-1 for both species, while those of fishing mortality coefficients (F) were 1.49 year-1 for S. pilchardus and 1.41 year-1 for S. aurita. The results of the virtual population analysis (VPA) showed the existence of an overfishing status for both species. To limit the risk of stock collapse, we recommended adjusting the Fcurrent fishing effort factor to F0.1, it should be reduced by 65% for S. pilchardus and 60% for S. aurita; this would allow for resources renewal. as well as increasing the exploitable biomass of both stocks. [ABSTRACT FROM AUTHOR]

In the Mediterranean, one of the most prized small pelagic species is the European anchovy (Engraulis encrasicolus). This species has long been targeted by fishermen in the southern Alboran Sea and the Mediterranean Sea. The objective of this research was to identify any linkages that may exist between environmental changes in the southern Alboran Sea and the reported drop in anchovy landings between 1983 and 2020. The method of forward stepwise regression was used, taking into account environmental indicators, such as sea surface salinity (SSS), sea surface temperature (SST), surface chlorophyll a (Chl-a), U and V wind components, NAO index, and Atlantic jet velocity. To select the best prediction models, generalized linear models (GLMs) were created and organized based on their corrected akaike information criteria (AICc) values. Trended time data were used to create six top models, which explained 60 to 79% of the variation in anchovy landings. Temperature, salinity, and the U wind component all displayed a negative association with anchovy landings. On the other hand, the Atlantic jets' velocity as they traveled through the Strait of Gibraltar was positively correlated with anchovy landings. When the trend component was taken out; however, none of the environmental variables could explain the variations in anchovy landings. This may imply that while environmental influences have an effect over the long term, they have little effect on the inter-annual time scale. Hence, the decline in landings of this species may be due to factors other than environmental change. Overfishing may have played a substantial role in the long-term decline in landings since this species was the most targeted of the small pelagic species in the study area. [ABSTRACT FROM AUTHOR]

In Mexico, marine acoustics research still faces technical and scientific challenges. For the past decade, the country has made a sustained effort to implement acoustic techniques to generate time series of standardized information; however, these data have been underutilized. Marine acoustics research has been used mainly for small pelagic species and has contributed to improving fishery management and to advising stakeholders. The Mexican scientific community has perceived marine acoustic techniques as expensive tools that are only used for industrial fishing purposes. Marine acoustics can provide information on the variability and interactions between species, their physical environment, and other communities of species, but this approach has not yet been integrated into interdisciplinary research programs or ecosystem models. Additionally, acoustic data provide estimates of biomass and indices of relative abundance, and they have suitable statistical properties for use in integrated catch-at-age models. In summary, to consolidate marine acoustic techniques in Mexico, it is necessary, at a minimum, to maintain the current infrastructure for acoustic studies, to increase the budget for the development of monitoring programs that collect ecosystem indicator data, to promote the training of human resources, and to encourage peer review of the information generated and reported in gray literature.

Thread herrings (Opisthonema spp.) are economically important fish species in the Tropical Eastern Pacific. Knowledge of the parasitofauna of commercially exploited species is useful as it can increase our understanding of fish biology and ecology. However, our knowledge of the parasites of Opisthonema spp. is limited. During a fisheries exploration survey in April 2022, samples of Opisthonema bulleri and O. libertate were collected from three oceanographic stations in the Gulf of Tehuantepec in the Mexican Pacific. Parasitological analysis of these materials uncovered four parasite species: Myosaccium ecaude (Trematoda), Cribromazocraes sp. (Monogenea), Pseudoterranova sp. (Nematoda), and an unidentified crustacean of the family Pennellidae (Copepoda). All these species appeared rarely, except for M. ecaude, which reached a prevalence of 100%. The median intensity of M. ecaude infection was significantly higher in O. bulleri than in O. libertate. We analyzed the relationship between parasitic infection intensity and three host traits (fork length, body weight, and age). Only body weight showed a significant positive association with intensity. Future studies are required to analyze the possible effects of seasonality, locality, and host ontogeny on the occurrence of M. ecaude in thread herrings in the Tropical Eastern Pacific.

Understanding the dynamics of pelagic fish fluctuations is crucial to ecosystem well-being and sustainable fishery. Here, inter- and intra-annual landing dynamics of small and medium pelagic fish were delineated between 2000 and 2022 in the landlocked Sea of Marmara. Time series of environmental variables and fisheries landings were analyzed for their trends and inter-correlations. Results showed that variations in the landings of small and medium pelagic fish in the Sea of Marmara had strong seasonality and were very likely affected by fishing effort, and sea surface temperature regimes. During the study period, landings of anchovy, bonito and bluefish, and net primary production showed no significant trends. On the other hand, Mediterranean horse mackerel had a significant decreasing trend, while sardine landings and the sea surface temperature (0.05 ± 0.01 °C/y−1) had a significant increasing trend. Analysis of the duration of the fishing period in a given fishing season showed that reaching 90% of the landings (L90) for anchovy, sardine, and Mediterranean horse mackerel shifted almost one month earlier, and for bonito, L90 showed no change for larger ones, but extended almost one month for small individuals. The multiple linear regression models indicated that the landing dynamics of small and medium pelagic fish were also influenced by the prey-predator relations in the food web. Exploiting anchovy stocks would likely have consequences on the dynamics of bonito and bluefish stocks, and exploiting bonito and bluefish stocks would have a cascading trophic impact on small pelagic fish catches. This study highlights the necessity of adaptive management measures for fisheries under regional sea warming conditions, and a one-and-a-half-month delay in the opening time of the fishing season, thus shortening its duration is strictly recommended. [ABSTRACT FROM AUTHOR]

Fishermen migration and Small Pelagic fishing in west Africa: dynamics and Issues. The objective of this article is to present the trends in the flows of migrant fishermen targeting small pelagic fish in West Africa from fishing locations to consumption areas. The methodology involved identifying the different migrant small pelagic fish supply chains in various West African countries. Subsequently, field research in collaboration with national research institutions and a synthesis of regional studies on migrant fishing were conducted. These efforts allowed for an analysis of developments in terms of actors involved, volumes and values of catches, and the forms of processing and marketing of products from migrant fishing supply chains during the period from 2008 to 2018. The quantities of pelagic fish caught by migrant fishermen are increasingly significant. The production of migrant fishing for small pelagic fish has nearly doubled over a decade, going from an average of 180,200 tonnes in the period from 2008 to 2012 to a current average production of nearly 324,500 tonnes. More than 48% of this production is sold on the market fresh or frozen. More than 74,800 tonnes (or 23%) and 94,000 tonnes (or 28%) are respectively destined for artisanal and industrial processing. Migrant fisheries thus supply the industrial processing sector more than they do the artisanal processing sector. Consequently, over the past decade, migrant supply chains have contributed to the emergence of fishmeal factories in West Africa, leading to an increase in food insecurity. Furthermore, their contribution to local economies is increasingly significant. However, despite their substantial growth in terms of volumes and values of catches, migrant fisheries still operate outside of legislative frameworks and are not explicitly accounted for in national statistics. Additionally, conflicts are on the rise due to current tensions and issues surrounding the exploitation of small pelagic fish in West Africa. © 2023 Lavoisier, Paris. Tous droits réservés [ABSTRACT FROM AUTHOR]

AbstractThe wellbeing of millions of Ghanaians hinges on food security. As the country strives to meet the United Nations Sustainable Development Goals Agenda 2030, fish consumption must be sustained. Predicting the future trends of fish consumption and supply is of significant importance to policy-makers and fisheries managers to better anticipate future demands, plan actions to effectively meet them and sustainably manage the fisheries. The present study seeks to quantify the future and historical fish consumption (consumption per capita and apparent consumption), production (captures, aquaculture, and commodities) and fish trade (imports) estimate and projections from 2017 to 2030. We obtained data from the Ministry of Fisheries and Aquaculture Development, Fisheries Scientific Survey Division, Ghana Statistical Services, United Nations International Trade Statistics Database, Organisation for Economic Co-operation and Development, World Bank, FishStatJ, Food and Agriculture Organization online query panels, and other online publications. Our analyses showed that fish consumption will continue to fluctuate with an expected highest peak of 905,400 tonnes by 2028 and drop to 889,096 by 2030. Overall consumption is expected to average 839,272 tonnes from 2019 to 2030, growing at an annual rate of 0.61% from 2017 to 2030. Per capita fish consumption is expected to decrease slightly, reaching 23.93 kg by 2030. Growth in capture fisheries will be very slow at 0.06%, while aquaculture is expected to grow at 6.58%. In terms of fish supply, capture fisheries, aquaculture, and imports are expected to contribute 45%, 9%, and 46%, respectively. Pelagic fish import is expected to be 392,450 tonnes, making up 96.4% of all fish imports by 2030. The need for Ghana to be self-sufficient in fish production and reduce imports by sustainably managing the small pelagic fishery should be paramount. To achieve sustainable fish production, supply, and consumption, the study suggests that there is a need to urgently accelerate aquaculture development, reduce unstainable harvest levels, and ensure general improvement in the fisheries management practices.

Morphometric indices of body condition are assumed to reflect an animal’s health and ultimately its fitness, but their physiological significance remains a matter of debate. These indices are indeed usually considered as proxies of energy reserves, ignoring other physiological processes involved in animal health such as nutritional, immune and hormonal states. Given the wide variety of ecological processes investigated through morphometric body condition indices in marine sciences, there is a clear need to determine whether morphometric indices reflect primarily individuals’ energy reserves or their broader integrated physiological status. To address this issue, we used morphometric and physiological data (cortisol level, oxidative stress, digestive enzymes activity, and both fatty acids percentage and total amount) collected in three stocks of the European sardine (Sardina pilchardus) presenting contrasted patterns of growth and body condition. We found that morphometric body condition indices are indeed mainly and consistently linked to a proxy of the amount of lipid reserves (i.e., fatty acids amount), but also significantly to quality of lipid reserves (i.e., fatty acids percentage) and fish chronic stress (scale cortisol levels). We found no significant relationship between morphometric indices of body condition and both oxidative stress proxies and variables measuring digestive enzymes activity. Our study confirmed that morphometric body condition indices primarily reflect the variance in individuals’ lipid reserves and to a lesser extent the actual composition of these reserves (linked to differences in fish diet) and scale cortisol levels (indicating fish metabolism and/or their chronic stress levels). Therefore, some non-energetic aspects should be considered when studying individuals’ responses to environmental changes and other key physiological processes (oxidative stress proxies, activity of digestive enzymes) should be investigated directly to support scientific-based decision-making in the context of climate change.

Thread herrings (Opisthonema spp.) are economically important fish species in the Tropical Eastern Pacific. Knowledge of the parasitofauna of commercially exploited species is useful as it can increase our understanding of fish biology and ecology. However, our knowledge of the parasites of Opisthonema spp. is limited. During a fisheries exploration survey in April 2022, samples of Opisthonema bulleri and O. libertate were collected from three oceanographic stations in the Gulf of Tehuantepec in the Mexican Pacific. Parasitological analysis of these materials uncovered four parasite species: Myosaccium ecaude (Trematoda), Cribromazocraes sp. (Monogenea), Pseudoterranova sp. (Nematoda), and an unidentified crustacean of the family Pennellidae (Copepoda). All these species appeared rarely, except for M. ecaude, which reached a prevalence of 100%. The median intensity of M. ecaude infection was significantly higher in O. bulleri than in O. libertate. We analyzed the relationship between parasitic infection intensity and three host traits (fork length, body weight, and age). Only body weight showed a significant positive association with intensity. Future studies are required to analyze the possible effects of seasonality, locality, and host ontogeny on the occurrence of M. ecaude in thread herrings in the Tropical Eastern Pacific. [ABSTRACT FROM AUTHOR]

The high fishing pressure may cause species evolutionary changes toward smaller maturation sizes. In this context, the fishing practices of mackerel scad, Decapterus macarellus (Cuvier, 1833), in tropical eastern Indonesia provide an excellent opportunity to examine this hypothesis. Two distinct fishing grounds, the Sulawesi Sea and Maluku Sea, were selected to explore this phenomenon. Samples of D. macarellus caught by purse seine fishers operating were sourced from the two fishing grounds. Analysing the total length and maturity stage of each D. macarellus specimen from the two stocks were made to estimate key parameters such as the length at first maturity (Lm) and total mortality (Z). The results revealed that total mortality, used as an indicator of fishing pressure, was higher in the Maluku Sea (5.3 year-1) than in the Sulawesi Sea (3.7 year-1) and other areas. Additionally, the Lm of D. macarellus in the Maluku Sea was remarkably lower (22.9 cm) than in the Sulawesi Sea (23.9 cm), which can be attributed to the higher fishing pressure. These findings support the fisheries-induced evolution hypothesis, particularly within Indonesian tropical fish stocks and their respective regions, adding new growing evidence that fishing pressure affects fish reproductive biology. The length at first maturity may serve as a valuable proxy for assessing the intensity of fishing pressure on fish stocks. [ABSTRACT FROM AUTHOR]

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By catch is a serious conservation challenge for the fisheries whose viability is increasingly under threat. To approach maximum by catch reduction with minimum loss of targeted catch, fisheries need to have information on the environmental and anthropogenic factors in multi species seas like the Mediterranean. In this study, we used generalized additive models (GAM) to by the catch ratio of purse seine fishery to determine the effects of environmental variables. The data were col-lected during each fishing trip in the 2018-2019 fishing season that covers the time period between September 1st and April 15th. There were 26 species (66.216 mt in total) recorded as by catch and the rates of by catch species in the total by catch amount varied between 0.001% and 23.1%. In terms of habitat of by catch species, the total ratios of benthopelagic, demersal and pelagic spe-cies were 52% , 28% and 20%, respectively. Significant interactions observed indicate that the fluc-tuations in by catch ratios differed by depth and sea surface temperature, whereas the quarters of year and the moon phases were not found to affect by catch ratios significantly.

Information on the biological parameters of exploited fish stocks facilitates the objective assessment and management of these living resources. The sardine (Sardina pilchardus) is considered as overexploited in northwest Africa. It is a key species of the Canaries current large marine ecosystem (CCLME) of the Atlantic Ocean due to its socioeconomic importance, as well as being a key intermediary species in marine food web. A massive decline in caught fish for Senegal over half a century is also reported (61,648 t in 1994 to 7486 t in 2017). Here, we analyzed the age and growth parameters of sardines in the Exclusive Economic Zone of northern Senegal. Maximum body size was 31 cm total length (TL). A growth performance index (φ′) and a growth rate coefficient (K) of 2.65 and 0.85, respectively, were determined, with this being the first record for this country. Sardines had higher asymptotic length (L∞, 30.5 cm TL) and age (6 years) in northern Senegal compared with Morocco (Atlantic Ocean) and the Mediterranean Sea. The asymptotic length found in Northern Senegal was also higher than in other part of the CCLME and Mediterranean Sea. This difference might be attributed to differences in the pelagic habitat, environmental factors, and/or fishing pressure. This study provides new insights towards establishing management measures, especially in data-poor fisheries and should act as an advocacy to increase sub-regional collaborations. [ABSTRACT FROM AUTHOR]

Although small pelagic fishing in Tanzania is rising, lack of information on population structure has been a significant concern in its management. This study aimed to determine the species composition, length-weight relationship and length at first maturity of Amblygaster sirm, Encrasicholina heteroloba, Encrasicholina punctifer, Stolephorus commersonii, and Spratelloides gracilis landed at Kilwa Kivinje, Kipumbwi and Shangani along the Tanzanian coast. These landing sites were chosen because of their locations and importance in the small pelagic fishery. Sampling was done monthly from October 2018 to June 2020. The catch composition was site specific such that E. heteroloba dominated at Kilwa Kivinje and Shangani, while E. punctifer dominated at the Kipumbwi site. Further analysis shows allometric coefficient to be greater than 3 for A. sirm and E. punctifer, indicating positive allometric growth, while for S. commersonii and S. gracilis, the allometric coefficient was less than 3, indicating negative allometric growth. Our findings showed that length at first maturity (L50) differed, implying that these species start spawning at different sizes, an essential biological reference for sustainable small pelagic fish exploitation. We recommend seasonal closure of the fishery to maintain reproductive seasons since many species are multiple spawners. [ABSTRACT FROM AUTHOR]

Several studies have shown the effect of climatic oscillations on fisheries. Small pelagic fish are of special global economic importance and very sensitive to fluctuations in the physical environment in which they live. The main goal of this study was to explore the relationship between the North Atlantic Oscillation (NAO), the East Atlantic pattern (EA), and the Arctic Oscillation (AO) on the landings and first sale prices of the most representative small pelagic commercial species of the purse-seine fisheries in the Gulf of Cadiz (North East Atlantic), the European anchovy Engraulis encrasicolus and the European sardine Sardine pilchardus. Generalised linear models (GLMs) with different data transformations and distribution errors were generated to analyse these relationships. The best results of the models were obtained by applying a moving average of order 3 to the dataset with a double weighted median. Our results demonstrate relationships between NAO, AO, and EA and European anchovy and sardine landings. These cause an indirect effect on the first sale price in markets through catch variations, which affect the price according to the law of supply and demand. The limitations of this study and management implications are discussed. [ABSTRACT FROM AUTHOR]

By catch is a serious conservation challenge for the fisheries whose viability is increasingly under threat. To approach maximum by catch reduction with minimum loss of targeted catch, fisheries need to have information on the environmental and anthropogenic factors in multi species seas like the Mediterranean. In this study, we used generalized additive models (GAM) to by the catch ratio of purse seine fishery to determine the effects of environmental variables. The data were collected during each fishing trip in the 2018-2019 fishing season that covers the time period between September 1st and April 15th. There were 26 species (66.216 mt in total) recorded as by catch and the rates of by catch species in the total by catch amount varied between 0.001% and 23.1%. In terms of habitat of by catch species, the total ratios of benthopelagic, demersal and pelagic species were 52%, 28% and 20%, respectively. Significant interactions observed indicate that the fluctuations in by catch ratios differed by depth and sea surface temperature, whereas the quarters of year and the moon phases were not found to affect by catch ratios significantly. [ABSTRACT FROM AUTHOR]

Information on the biological parameters of exploited fish stocks facilitates the objective assessment and management of these living resources. The sardine (Sardina pilchardus) is considered as overexploited in northwest Africa. It is a key species of the Canaries current large marine ecosystem (CCLME) of the Atlantic Ocean due to its socioeconomic importance, as well as being a key intermediary species in marine food web. A massive decline in caught fish for Senegal over half a century is also reported (61,648 t in 1994 to 7486 t in 2017). Here, we analyzed the age and growth parameters of sardines in the Exclusive Economic Zone of northern Senegal. Maximum body size was 31 cm total length (TL). A growth performance index (φ′) and a growth rate coefficient (K) of 2.65 and 0.85, respectively, were determined, with this being the first record for this country. Sardines had higher asymptotic length (L∞, 30.5 cm TL) and age (6 years) in northern Senegal compared with Morocco (Atlantic Ocean) and the Mediterranean Sea. The asymptotic length found in Northern Senegal was also higher than in other part of the CCLME and Mediterranean Sea. This difference might be attributed to differences in the pelagic habitat, environmental factors, and/or fishing pressure. This study provides new insights towards establishing management measures, especially in data-poor fisheries and should act as an advocacy to increase sub-regional collaborations.

The creation and delimitation of marine protected areas has generally been carried out without considering the three-dimensional and open nature of the marine environament, neither planktonic dispersion or the hydrodynamics, which determine the composition, structure, distribution and dynamics of the communities. The Maritime-Land National Park of the Cabrera Archipelago (MLNPCA) was not an exception. Nowadays, accurate information on its hydrographic environment, pelagic communities, and even on the processes of export and larval retention inside the MLNPCA, is crucial for the correct management. This chapter describes the current state of knowledge of the pelagic communities in the MLNPCA environment, previously explaining the sampling strategies of the main programs and research projects carried out in the last 25 years. The main results and conclusions of the studies on the communities that inhabit the water column, from bacteria to large pelagic fish, are summarized, paying special attention to the processes that affect the spatio-temporal dynamics of meroplankton (eggs and larvae of marine organisms). It is worth highlighting the great biodiversity observed in many taxonomic groups, similar to subtropical areas. An annual cycle is given in the composition of the different communities, with two well diferentiated periods: one of a mixture water column, more productive, and another with a strong stratification (thermocline) that limits the vertical moviments. However, there is a great variability in the pelagic communities, associated with surface water bodies, wether those of Atlantic origin or Mediterranean residents. As regards the processes of export and larval retention in the MLNPCA, they depend mostly on a combination of ephemeral retention processes (dependent on the wind and topography), and on the initial distribution and evolution of the behavior of larvae along the ontogeny. The fish populations of MLNPCA are mantained self-sufficiently because of self-recruitment. [ABSTRACT FROM AUTHOR]

Small pelagic fish species, such as anchovy (Engraulis ringens) and Pacific sardine (Sardinops sagax), play a crucial role in marine ecosystems worldwide as they serve as an important food source for higher-order predators, such as seabirds, marine mammals, and larger fish species; also from their high productivity in terms of fishery landings, they help with maintaining food security. However, small pelagic populations are known for their variability, with fluctuations in their distribution and abundance influenced by interactions with environmental and human-related factors in different spatio-temporal scales. This study aims to investigate the variability in anchovy and sardine populations in northern Chile and their potential environmental drivers by using a class of models that address the changes in variability (i.e. variance) over time, namely Generalized autoregressive conditional heteroskedasticity (GARCH) models. In particular, this work considers a GARCH model that includes an additional term in the variance, that could help to better model the variability fluctuations of both anchovy and sardine, explained by environmental factors. Since there is no estimation procedures for those type of models, we propose a hybrid Approximate Bayesian Computation (ABC) procedure that involves the use of Deep Learning structures for estimating the parameters of the model and obtain posterior distributions. The results are two-fold: First, the proposal of a new time series model that better explain conditional variance with exogenous variables and a novel estimation procedure, and second, a novel approach for establishing explicit models that address the variability of small pelagic fisheries and their interaction with the environment. • Anchovy and sardine landings variability is studied by considering its conditional variance over time. • A GARCH-X model that considers an observable exogenous variable is proposed for this analysis. • A set of local and global environmental variables are analyzed and two environmental indexes are presented based on the results from a principal components analysis. • The parameter estimation for the GARCH-X model is performed by a proposed hybrid ABC-CNN estimation procedure. • The good performance of the proposed models is compared with other GARCH-type models. [ABSTRACT FROM AUTHOR]

We examined growth rates and reproductive characteristics of Sardinella aurita off Senegal and other coastal areas over a 20 year period (1995–2014) to determine how they relate to variations in environmental characteristics of coastal waters. Based on fish length‐frequency data and a coastal upwelling index, we found that S. aurita recruitment tends to occur during the periods of most intensive upwelling (March–April off Senegal). Peak reproduction corresponds to periods of low sea‐surface temperature (in February or March). The sex ratio was remarkably consistent during the 30 year study period and so was not affected by environmental changes. We hypothesise that S. aurita takes advantage of the higher zooplankton productivity that occurs in coastal waters when upwelling brings nutrient‐rich water to the surface (i.e., it increases its growth rate and accumulates energy reserves for spawning). Growth performance appears to be strongly dependent on environmental conditions. The timing of spawning seems to occur when food (zooplankton) is most available for supplying the energy requirements needed by adults for spawning and early development of larvae. Environmental changes seem to have a significant effect on S. aurita growth and reproduction, which endorses their high phenotypic plasticity. [ABSTRACT FROM AUTHOR]

The annual alteration of gonad morphology in anchovy, Engraulis encrasicolus (Linnaeus,1758), caught in the period from July 2006 to June 2007 using beach seines in the region of Boka Kotorska Bay (Montenegro, southern Adriatic) was studied. Samples were taken each month. Total length of individuals ranged from 6.6 to 12.2 cm, while weight ranged from 1.58 to 11.27 g, Their ovaries were extracted and weighed, and a piece of female gonad tissue was sampled for histological analysis. The length-weight relationship of all anchovy specimens was described by the equation: W = 0.0032 LT3.2537; (r2 = 0.9528). The lowest GSI values were found in November and remained at low levels until April, which corresponded to the gonad rest stage. The GSI increased gradually during April and May, which coincides with the begining of spawning period. Although primary oocytes (stage I) were present during all months, their percentage increased from October and was the highest during the winter months (November-March 100%). Mature cells, stage IV, were present during April - October period, with highest value in May when they comprised 12.3% of total oocyte number. An increase in the percentage of oocytes in the yolk vesicle (II) and yolk (III) stages occurred in April, remaining almost unchanged until October. Smallest average oocyte size was noticed in period November - February with an average of 59.69 μm, while greatest size was recorded in April 2007, 185.84 μm. [ABSTRACT FROM AUTHOR]

This study investigates the feeding intensity and the morphology of the feeding apparatus (gill rakers) of the European sardine Sardina pilchardus (Walbaum, 1792) in two hydro-dynamical contrasting areas of the eastern boundary upwelling system off Morocco. North, one area is characterized by a summer upwelling while South, the other area is more productive with a strong and almost permanent upwelling. Fish from both areas differ in their feeding intensity, fish condition and gill raker number but no difference is found in the length of the first lower branchial arch. Fish from the southern fishing area are characterized by higher gill raker number and higher feeding intensity mainly from January to May, while specimens from the other area have a significantly lower gill raker number and higher feeding activity from July to November. The high values of fullness index during summer-autumn and the lower value of gill raker number suppose that S. pilchardus from the latter area feed more intensively on larger preys, taking advantage from the trophic conditions prevailing during these seasons. In the southern area, S. pilchardus develop more many gill rakers which might allow to filter the smaller and more abundant preys. These results show that seasonal differences in environment conditions, i.e. permanent versus seasonal upwelling that induce differences in the available resources, may have shaped differently the feeding apparatus, the feeding activity and the condition of S. pilchardus. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Niño Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance of sardinella is determined by a strong seasonal pattern and inter-annual fluctuations. The abundance of S. aurita peaked in spring and in autumn, whereas that of S. maderensis peaked in the warm season (July-September). The trend of the sardinella abundance was significantly correlated with the CUI, especially in autumn and spring. Interannual fluctuations of S. maderensis and S. aurita abundance are, respectively, driven by the precocity and the duration of the upwelling season that is attributed to distinct migration patterns. Both sardinella species also respond with a delay of around 4 years to the winter NAO index and the autumn CUI, and the AMO index, respectively, both related to migration patterns. The wide variations in sardinella biomass are caused by variations in environmental conditions, which should be considered in the implementation of an ecosystem-based approach in sardinella stocks management. [ABSTRACT FROM AUTHOR]

Fishery management is a complicated task that often results in overfishing, overcapacity, and low profits for the industry. The management of shared fish stocks is particularly problematic, especially if national authorities pursue different objectives. Multi-species fisheries add further complexity to the problem. It is no accident that management tools frequently used in Northern Europe, such as total allowable catches and individual quotas, are not applied in the Mediterranean Sea, where more target species are caught simultaneously. However, the European Commission intends to introduce a market-based driver for a strong, profitable fishing industry by phasing in transferable fishing concessions. This management approach is new for the Mediterranean, and it requires in-depth examination at institutional, legal, and economic levels. In this paper, after a review of the institutional setting, the economic perspective was analyzed by estimating the production function for the Italian small pelagic fishery in the Adriatic Sea. With the addition of Croatia to the European Union, the Adriatic Sea can become a Mediterranean communal exclusive fishing area. The results indicate that output measures such as total allowable catches and individual quotas should not cause serious discarding problems for this multi-species fishery.

La presente investigación se realizó con el fin de buscar una alternativa para el aprovechamiento, para consumo humano directo, de dos especies denominadas pequeños pelágicos propias del pacífico colombiano: la carduma (Cetengraulis mysticetus) y la plumuda (Opisthonema spp.). Se desarrolló una tecnología para la elaboración de tres productos: salchichas, salchichones y hamburguesas, basada en la elaboración previa de una pasta de pescado denominada surimi. Se determinó el contenido de humedad, proteína, grasas, cenizas y carbohidratos, así como también se hizo una valoración nutricional de las dos especies y de los productos finales. Se determinó, igualmente, el porcentaje de aprovechamiento de los recursos hidrobiológicos materia prima. Los productos se realizaron utilizando una mezcla 50/50 de surimi de cada una de las dos especies. Mediante análisis estadísticos se evaluó la aceptación de los productos propuestos aplicando pruebas afectivas de grado de satisfacción en jueces evaluadores no entrenados. Para esto se determinó evaluar los parámetros sensoriales: olor, color, sabor, apariencia y textura utilizando una escala hedónica de siete puntos, la cual abarcó desde "me gusta muchísimo" hasta "me disgusta muchísimo". El proceso se complementó con los análisis microbiológicos de los productos finales. Los resultados de la prueba de satisfacción indicaron que los tres productos fueron de gran agrado y buena aceptación por parte de los jueces consumidores utilizados para el desarrollo de la investigación. Los resultados mostraron una aceptación del 84,8% para las salchichas, del 86,1% para los salchichones y del 92,5% para las hamburguesas.Esta pesquisa foi realizada com o objetivo de buscar uma alternativa para o aproveitamento, para consumo humano direto, das duas espécies denominadas pequenas pelágicas próprias do litoral pacífico colombiano, a Carduma (Cetengraulis mysticetus) e a Plumuda (Opisthonema spp.). Foi desenvolvida uma tecnologia para a elaboração de três produtos: salsichas, salsichões e carne de hambúrguer com base na preparação previam de uma pasta de peixe denominada surimi. Foi determinado, igualmente, a percentagem de aproveitamento dos recursos hidrobiológicos (matéria prima). Os produtos processados foram elaborados utilizando uma mistura 50/50 de surimi de cada uma das duas espécies de peixe. Através da análise estatística foi avaliada a aceitação dos produtos processados aplicando os testes afetivos de nível de satisfação dos juízes avaliadores não treinados. Foram avallados os parâmetros sensoriais: aroma, cor, sabor, aparência y textura, utilizando uma escala hedônica de sete pontos, a qual abrangeu desde "gosto muitíssimo" até "não gosto muitíssimo". Também foram realizadas analises microbiológicas dos produtos processados. Os resultados indicaram que os três produtos processados tiveram boa aceitação. Os dados obtidos foram uma aceitação de 84,8% para salsichas, 86,1% para salsichões y 92,5% para carne de hambúrguer.This research was conducted to find an alternative use for direct human consumption of two small pelagic species known as the Colombian Pacific own carduma (Cetengraulis mysticetus) and plumuda (Opisthonema spp.). We developed a technology to produce three products: hot dogs, sausages and burgers, based on the prior preparation of a fish paste called surimi. We determined the moisture content, protein, fat, ash and carbohydrates, as well as a nutritional assessment were made of two species and final products. We determined also the percentage of utilization of aquatic resources feedstock. The products were made using a 50/50 mixture of surimi from each of the two species. Through statistical analysis evaluated the proposed product acceptance test application affective satisfaction in non-trained judges evaluators. To this was determined to assess the sensory parameters: odor, color, flavor, appearance and texture using a seven-point hedonic scale, which ranged from "I like very much" to "dislike me so much". The process was supplemented by microbiological testing of finished products. The test results showed a 84,8% acceptance for hot dogs, 86,1% acceptance for sausages and 92,5% acceptance for burgers.

Utilising histological preparations of ovaries from Engraulis ringens females collected in two contrasting spawning habitats along the Chilean coast, we assess the variability in oocyte size and batch fecundity during the peak spawning seasons in three years. The effects of female size (length and weight), batch fecundity and mean sea surface temperature on oocyte size were also examined. Results showed larger oocytes and lower batch fecundity in females from the southern area. Oocyte volume differences persisted inter-annually and were not explained by differences in female sizes. Since ovary weight was similar between areas, the cost of producing larger oocytes in the south population seems to be a fecundity reduction. The latitudinal variations in oocyte number and size seem to be determined by the predominant environmental conditions in each habitat. Hence, female E. ringens seem to adapt their reproductive tactics by producing eggs sizes and quantities that favour survival of their offspring under the environmental conditions in which they are to develop.

Se implementa dos modelos de evaluación de stock indirecta para analizar los cambios de abundancia en sardina común. Un modelo utiliza una asignación año calendario (enero-diciembre del año t), y el segundo un año biológico (julio del año t a junio del año siguiente, t + 1). El modelo se contrasta con datos de captura en número a la talla, capturas totales en peso, captura por unidad de esfuerzo en el periodo 1990-2002, y biomasa acústica evaluada en enero de 2000 al 2002 en la zona centro-sur de Chile. El modelo de dinámica poblacional aplicado, se diferencia estructuralmente sólo en el tratamiento de los datos para reflejar cambios anuales, tanto bajo el enfoque año calendario como biológico. Los cambios observados en el stock de sardina común, según año calendario o biológico, indican tendencias similares a los que han sido reportadas en evaluaciones previas. Sin embargo, se observan diferencias en los estimados de ambas evaluaciones, donde la estructura año biológico, presenta índices de abundancia de menor magnitud y estrechamente ligados al reclutamiento, esto considerando la real composición en magnitud que posee la clase anual. En contraste, la evaluación año calendario incorpora la presencia de clases anuales remanentes, generando de esta manera un escenario erróneo en la fuerza de la clase anual. Ambos modelos se contrastan con un indicador que utiliza la composición de la verosimilitud, encontrándose a la evaluación año biológico el mejor modelo basado en un mayor ajuste frente a los datos y mayor grado de explicación.Two indirect stock assessment models are implemented in order to analyze changes in the common sardine abundance. One model uses a calendar-year configuration (January-December year t) and the other a biological-year configuration (July year t - June year t+1). Each model is contrasted with catch-at-length data, total catch in weight, catch per unit effort from 1990 to 2002, and biomass from acoustic surveys done every January from 2000 to 2002 off central-southern Chile. The two applied population dynamics models (calendar and biological year approaches) differ structurally only in the treatment of the data that reveal the annual changes. The changes observed in the common sardine abundance, per calendar or biological year, indícate similar trends as those reported in earlier studies. Nevertheless, differences were registered in the esti-mations for both assessments, with the biological year showing lower abundance levéis that are closely related to recruitment; this, considers the magnitude of the real composition of the annual class/cohort. On the other hand, the calendar year assessment incorporates the remaining annual classes/cohorts, thereby generating an erroneous estimation of the annual class/cohort abundance. The two models are compared with a likelihood indicator, finding that the assessment using the biological configuration was the best model, with a better fit to the data and greater degrees of explanation.

Despite long-term investigations of the Adriatic Sea in general and extensive research on sardine and anchovy as ecologically and economically important fish species, knowledge concerning their spawning ecology, precisely their possible spawning grounds, is still incomplete. Therefore, two scientific surveys (January, July 2012) were performed, as target species spawn during different periods of the year (sardine - October to April (Sinovčić et al., 2007) and anchovy - April to September (Zorica et al., 2013)). Throughout these surveys, standard vertical plankton tows were made during the daylight at 72 stations in January and 60 stations in July using a WP2 sampler (mouth opening, 0.255 m2; mesh size, 0.200 mm). WP2 net was put vertically down during the calm sea to a depth of 100 m or to 5 m above the seabed in relatively shallow marine area (less than 100 m). Plankton samples were preserved in 4% buffered formalin and transported to the laboratory where they were analysed. Throughout ichtyoplankton analysis of samples collected during the winter survey a total of 506 sardine eggs and 348 larvae were sorted out. The mean sardine egg and larval abundance in the analysed period at positive stations was 57.8 +/- 77.4 eggs/m2 and 29 +/- 25.85 larvae/m2, with peaks of 396 eggs/m2 and 108 larvae/m2 at positive sampling stations. Concerning the summer survey and anchovy early life stages from obtained samples 1489 anchovy eggs and 1036 larvae were isolated. Average abundance of anchovy eggs and larvae was 145.26 +/- 201.27eggs/m2 and 115.11+/- 162.32 larvae/m2, respectively. The highest values of mentioned parameters at positive stations were 800 eggs/m2 and 952 larvae/m2. According to obtained results and their processing within Ocean Data View (odv.awi.de), revile that both species during 2012 spawn above the whole continental shelf and the areas of higher early life stages abundance overlap.

This study integrates fisheries logbook data with observer and vessel monitoring system (VMS) data in order to assess the accuracy of reported data and to develop high-resolution spatial data suitable for use in local-scale marine spatial planning analyses. Spatial assessments were conducted on five nearshore commercial fisheries to provide baseline information to inform spatial management and conservation planning in Algoa Bay, South Africa. Clear spatial patterns in the distribution of fishing effort were apparent for the linefishery, chokka-squid and inshore demersal trawl sectors. Observer and VMS data confirmed the broad spatial distribution of resource-use patterns of logbook data. Combining these data sources allowed higher-resolution spatial indices of fishing effort to be developed, which are suitable for systematic spatial planning on a local scale and can be used for future spatial management and conservation. [ABSTRACT FROM AUTHOR]

During the survey done from 11th to 14th December 2013 in area of Porno pit (Middle Eastern Adriatic) two anchovy (Engraulis encrasicolus, Linnaeus 1758) eggs were caught with standard plankton net (WP2). Eggs were found at two sampling stations (43 °01.188'N, 15° 25.796'E and 43° 06.213'N, 15° 15.138'E). This is a first finding of anchovy eggs in December in the offshore areas of middle-eastern Adriatic Sea. [ABSTRACT FROM AUTHOR]

This study provides the first measurements of the standard respiration rate ( RS) and growth dynamics of European sardine Sardina pilchardus larvae reared in the laboratory. At 15° C, the relationship between RS (µl O2 individual−1 h−1) and larval dry mass ( MD, µg) was equal to: RS = 0·0057(±0·0007, ± s.e.)· MD0·8835(±0·0268), (8-11% MD day−1). Interindividual differences in RS were not related to interindividual differences in growth rate or somatic (Fulton's condition factor) or biochemical-based condition ( RNA: DNA). [ABSTRACT FROM AUTHOR]