<p>Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?</p><p>A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. Furthermore, relatively small protozoan cells dominated in the low productive north, while larger cells became more dominant in the south. The relationship between plankton size structure and productivity was further studied in an experimental system. In agreement with present theories regarding nutrient status of pelagic food webs, increased productivity caused a lengthening of the food chain as well as a change in plankton size structure. While microplankton dominated in nutrient rich treatments pico- and nanoplankton dominated during nutrient poor treament. The flagellate community was dominated by a potentially mixotroph, <i>Chrysochromulina</i> sp., at low nutrient concentrations. To our knowledge this is the first experimental study showing that <i>Chrysochromulina</i> sp. in resemblance with other mixotrophs is favoured by nutrient poor conditions compared to strict autotrophs and heterotrophs.</p><p>During a stratified summer period autotrophic microorganisms in the northern Baltic Sea did not respond to removal of potential predators, indicating that they were primarily limited by inorganic nutrients. An exception was small eucaryotic picoplankton that showed a large response to predator removal. Among the heterotrophic microorganisms direct effect of predation seemed to increase from ciliates, heterotrophic bacteria, small heterotrophic flagellates, medium flagellates to large flagellates. No quick indirect effect was observed, but after four days trophic cascades were detected.</p><p>The relative importance of resource and predation limitation was studied among heterotrophic bacteria, flagellates and ciliates in the northern Baltic Sea. For all these groups, resource limitation seemed to prevail during the summer period. The results also indicated that the relative importance of predation increased with the productivity of the system. To our knowledge there are no earlier measurements on the relative importance of resource and predation limitation for micoorganisms in the pelagic environment.</p>

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish.  Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements. / At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper  2: Accepted; Paper 3: Submitted; Paper  4: Accepted

Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels? A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. Furthermore, relatively small protozoan cells dominated in the low productive north, while larger cells became more dominant in the south. The relationship between plankton size structure and productivity was further studied in an experimental system. In agreement with present theories regarding nutrient status of pelagic food webs, increased productivity caused a lengthening of the food chain as well as a change in plankton size structure. While microplankton dominated in nutrient rich treatments pico- and nanoplankton dominated during nutrient poor treament. The flagellate community was dominated by a potentially mixotroph, Chrysochromulina sp., at low nutrient concentrations. To our knowledge this is the first experimental study showing that Chrysochromulina sp. in resemblance with other mixotrophs is favoured by nutrient poor conditions compared to strict autotrophs and heterotrophs. During a stratified summer period autotrophic microorganisms in the northern Baltic Sea did not respond to removal of potential predators, indicating that they were primarily limited by inorganic nutrients. An exception was small eucaryotic picoplankton that showed a large response to predator removal. Among the heterotrophic microorganisms direct effect of predation seemed to increase from ciliates, heterotrophic bacteria, small heterotrophic flagellates, medium flagellates to large flagellates. No quick indirect effect was observed, but after four days trophic cascades were detected. The relative importance of resource and predation limitation was studied among heterotrophic bacteria, flagellates and ciliates in the northern Baltic Sea. For all these groups, resource limitation seemed to prevail during the summer period. The results also indicated that the relative importance of predation increased with the productivity of the system. To our knowledge there are no earlier measurements on the relative importance of resource and predation limitation for micoorganisms in the pelagic environment.

Based on a field study and several mesocosm experiments, I evaluated the use of pigments as chemotaxonomical biomarkers for phytoplankton community composition in the Baltic Sea and I examined effects of inorganic nutrients on the dynamics of carotenoids and thiamine (vitamin B1) at the phytoplankton–copepod level in marine pelagic food webs. My results show that HPLC pigment analysis combined with CHEMTAX data processing was an accurate alternative to microscopic analysis of Baltic Sea phytoplankton. Experimental supply of N, P and Si affected copepod growth and biochemical status via changes in biomass and composition of their phytoplankton diet. Net population growth rates were generally higher when phytoflagellates dominated (low Si:N ratio) and lower when diatoms dominated (high Si:N ratio). Copepod body concentrations of astaxanthin decreased with fertilization. Correlations with reduced under-water irradiance were consistent with the photo-protective function of this antioxidant. Thiamine concentrations in phytoplankton also decreased with fertilization. In copepods, low Si:N ratios resulted in higher thiamine concentrations than high Si:N ratios. Thiamine concentration and degree of phosphorylation were useful as indicators of thiamine shortage both in phytoplankton and copepods. The concentrations of thiamine and astaxanthin in the copepod communities were positively correlated. As copepods constitute a major link between pelagic primary producers and higher trophic levels, fertilization effects may be responsible for astaxanthin and thiamine deficiencies in salmon suffering from the M74 syndrome, which appeared concurrently with large-scale eutrophication in the Baltic Sea. As both thiamine and astaxanthin are deficient in M74-affected salmon, there is a need for physiological and molecular investigations of possible interactions between the two compounds in living cells.

The larger pelagic crustacean fauna of the Gully submarine canyon is described for the first time, based on three annual summer surveys. The larger Crustacea are a significant part of the Gully fauna, and are dominated by cold temperate species, in particular the northern krill Meganyctiphanes norvegica and the decapod Sergestes arcticus. In all, at least 69 species were collected from the surface to bathypelagic depths, with seventeen being new Canadian records. With the exception of M. norvegica, inter-annual variation in the dominant species was minor. The species assemblage varied primarily with depth surveyed and diel cycle, and not year. Comparing the larger pelagic crustaceans in the Gully and over the adjacent continental slope showed that overall species number, biomass, and abundance were all greater in the canyon, the biomass of S. arcticus particularly showing a positive “Gully effect”.

L’anchois et la sardine appartiennent à la guilde des petits poissons pélagiques, qui tiennent une place considérable à l’échelle des écosystèmes et des pêcheries. Ces deux espèces sont très largement répandues dans les mers et océans du globe et souvent occupent les mêmes écosystèmes. Leurs populations montrent d’importantes fluctuations interannuelles de biomasses, dont les tendances ne suivent pas les mêmes schémas, voire sont parfois déphasées. Une littérature croissante suggère que ces dynamiques sont dues à des sensibilités relatives aux conditions environnementales différentes induites par des traits biologiques distincts. Bien que de prime abord anchois et sardines semblent très similaires, ils montrent notamment des stratégies alimentaires et reproductives quelque peu différentes. Comprendre ces divergences biologiques et de stratégies d’histoire de vie apparait donc essentiel pour appréhender les dynamiques passées et éventuellement anticiper les évolutions futures de ces stocks. L’objectif de cette thèse est de déterminer en quoi se démarquent ces deux espèces en termes de traits biologiques et d’histoire de vie sur une base physiologique. En effet, du fait de la complexité de potentielles interactions entre les traits biologiques et de leurs évolutions ontogéniques, il convient, pour répondre à cette question, de mettre en œuvre une approche intégratrice via la modélisation bioénergétique à l’échelle du cycle de vie. Dans un premier temps l’étude a été dédiée à un indice de condition : la densité énergétique (contenu énergétique par unité de masse). La densité énergétique résulte de nombreux processus physiologiques, intégrant ainsi l’historique des dépenses énergétiques diverses face aux gains acquis via l’alimentation. L’analyse de cet indice a notamment permis d’identifier divers effets sur la condition énergétique du poisson : l’espèce, la taille, la saison et la zone géographique. En lien avec l’énergie observée, un modèle du cycle de vie a été paramétré pour les deux espèces dans le golfe de Gascogne, afin de disposer d’un outil intégrateur, exploratoire et prédictif. Il s’agit d’un modèle bioénergétique basé sur la théorie du « Dynamic Energy Budget » (DEB). Ce cadre vise à prédire le cycle de vie d’un organisme, en fonction de forçages environnementaux, en simulant la résultante des différents flux d’énergies qui s’y produisent. Cette approche a notamment permis de souligner le caractère particulièrement structurant des stratégies reproductives sur le cycle bioénergétique annuel des deux espèces. / Anchovy and sardine belong to the guild of small pelagic fish and are of peculiar importance at the scales of ecosystems and fisheries. Both species are worldwide spread and commonly occur in the same ecosystems. They display large interannual variability in biomass with markedly different trends or even asynchronous. A growing literature suggests that those dynamics are due to respective sensibility to environmental conditions driven by different biological traits. A priori both species are very similar but show slightly distinct feeding behaviours and reproductive strategies. Understanding divergences in both species biology and life history strategies is thus crucial to understand and predict past and future dynamics of these stocks. The aim of this PHD is to assess how both species diverge in terms of biological and life history traits on a physiological basis. Owing to the complexity of biological traits, potential interactions among these traits and ontogenetic evolutions, to answer this question an integrative approach based on a bioenergetics model of the whole life cycle is requested. First the study focus on a condition index: the energy density (energy content per unit of mass). Energy density integrates historic of numerous physiological processes, both gain from food and diverse metabolic expenses. This analysis shows effects on the bioenergetics cycle of the fish, namely species, size, season and geographic area. Linked with bioenergetics data, a full life cycle model has been parametrised for both species in the Bay of Biscay, in order to get an integrative, predictive and exploratory tool. This model is based on the “Dynamic Energy Budget” theory. This theory aims at predicting the life cycle of an organism, using environmental forcing, by simulating energy fluxes inside the organism. This modelling approach underlines the particularly significant feature of reproductive strategies on the bioenergetics annual cycle of both species.

Biodiversity of planktonic crustaceans, cladocerans and copepodans in southbohemian Naděje fishponds system were studied. Both fishpond and non-fishpond (pools, canals, sand-pits, river) localities were observed. Samples were taken from pelagic and littoral zones. Total of 21 species of copepodans and 44 species of cladocerans were recorded over whole area. Hypothesis {\clq}qA higher fish management intensity and higher fish stock cause a lower diversity of zooplankton in a pelagic zone`` was proven. Suppressed species are able to survive in a smaller space (littoral zones, pools, canals, fishponds with a lower fish stock and other non-fishpond localities), where predation pressure is not so strong. None or mild decline of a species diversity can be observed in large areas rich in different water ecosystems, with a reasonable management and production intensity. Different methods of sampling were also compared, those of {\clq}qprolovení litorálních partií`` proved good with the view of effectiveness.

Submitted by (edna.saturno@ufrpe.br) on 2016-07-27T14:57:21Z No. of bitstreams: 1 Rodrigo Barbosa Acioli de Oliveira.pdf: 1281699 bytes, checksum: af3b5b3f4c17c790ad47750c27fe13be (MD5) / Made available in DSpace on 2016-07-27T14:57:21Z (GMT). No. of bitstreams: 1 Rodrigo Barbosa Acioli de Oliveira.pdf: 1281699 bytes, checksum: af3b5b3f4c17c790ad47750c27fe13be (MD5) Previous issue date: 2009-02-27 / The objective of this study was to obtain information regarding tuna fish quality captured in the northwestern coast of Brazil from December 2007 until December 2008. The levels of histamine in export type tuna caught in the coast of Rio Grande do Norte by the technique of pelagic trawl were determined. It was investigated the efficiency of two objective parameters of quality, levels of bioactive amines and color evaluation, which were related to the classification performed by a trained evaluator. The influence of the capture of live or dead fish on the quality of meat was also investigated. Among the 180 samples of fresh tuna analyzed, 95% did not contain histamine. Only nine samples contained histamine at levels that ranged between 4.92 and 6.90 mg/kg. The results indicated that the practices of handling and fishing gear used by companies of Rio Grande do Norte, Brazil, ensured the achievement of good quality fish. The levels of bioactive amines in 68 samples of tuna categorized into six levels of quality by experienced painelist were determined. The polyamines(spermine and spermidine), were found, however, the levels did not differ suggesting that this parameter objective in itself was not sufficient to distinguish the different levels of quality of yellowfin tuna and bigeye tuna. No significant differences were found in the values of the colorimetric coordinates (CIEL*, CIEa*, CIEb* and CIEC*) in samples of tuna classification 1, 2+, 2H, 2, 2- and 3. The conditions dead or alive at the time of slaughter showed no influence on the production of bioactive amines indicating that other factors may be involved. However, the samples were in excellent state of freshness, because were found significant levels of spermine and spermidine, rather low levels of cadaverine, putrescine, histamine, tyramine, phenylethylamine, agmatine, serotonin and tryptamine. / Este trabalho teve como objetivo obter informações sobre a qualidade dos atuns capturados na região nordeste do Brasil. Os teores de histamina de atuns tipo exportação capturados no litoral do Rio Grande do Norte pela técnica de espinhel pelágico foram determinados de dezembro de 2007 a dezembro de 2008. Investigou-se a eficiência de dois parâmetros objetivos de qualidade, teores de aminas bioativas e avaliação cor, que foram relacionados com a classificação realizada por um avaliador treinado. A influência da captura de peixes vivos ou mortos sobre a qualidade da carne também foi investigada. A presença de histamina não foi detectada em 95% das 180 amostras de atum fresco analisadas. Apenas nove amostras continham histamina em teores que variaram de 4,92 a 6,90 mg/kg. Estes resultados indicaram que as práticas de manipulação e a arte de pesca utilizadas pelas empresas do Rio Grande do Norte, Brasil, asseguraram a obtenção de peixes de boa qualidade. Os teores de aminas bioativas em 68 amostras de atum categorizadas em seis níveis de qualidade por avaliador experiente foram determinados. Foram encontradas as poliaminas espermina e espermidina, no entanto, os teores não diferiram entre si indicando que esse parâmetro objetivo por si só não era suficiente para distinguir os diferentes níveis de qualidade da albacora laje e albacora bandolim. Também não foram encontradas diferenças significativas nos valores das coordenadas colorimétricas (CIE L*, CIE a*, CIE b* e CIE C*) nas amostras de atum da classificação 1, 2+, 2H, 2, 2- e 3. As condições vivo ou morto no momento de abate demonstraram não exercer influência sobre a produção de aminas bioativas indicando que outros fatores podem estar envolvidos, porém, as amostras encontravam-se em excelente estado de frescor, pois foram encontrados teores significativos de espermina e espermidina, em detrimento de baixos teores decadaverina, putrescina, histamina, tiramina, feniletilamina, agmatina, serotonina e triptamina.

Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2010. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-10-17T13:04:09Z No. of bitstreams: 1 Stefan Cruz Weigert.pdf: 7836131 bytes, checksum: 7123df61e1d6d620cadcbc3f856e5539 (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-10-17T16:42:57Z (GMT) No. of bitstreams: 1 Stefan Cruz Weigert.pdf: 7836131 bytes, checksum: 7123df61e1d6d620cadcbc3f856e5539 (MD5) / Made available in DSpace on 2013-10-17T16:42:57Z (GMT). No. of bitstreams: 1 Stefan Cruz Weigert.pdf: 7836131 bytes, checksum: 7123df61e1d6d620cadcbc3f856e5539 (MD5) Previous issue date: 2010 / Como típico ambiente marinho dominado por corrente de contorno oeste, a margem continental brasileira apresenta uma baixa produtividade biológica, especialmente no pelagial. Processos oceanográficos como frentes termais, vórtices e áreas de ressurgência determinam alterações nas características físico-químicas, através de processos de mistura e renovação de nutrientes. Tais feições oceanográficas podem aumentar a produtividade e concentrar biomassa. A metodologia hidroacústica é amplamente aplicada para prospectar, mapear e estimar a abundância de pequenos peixes pelágicos, bem como em estudos de ecologia das espécies, correlacionando as ocorrências de agregações biológicas a processos oceanográficos de enriquecimento. Dados satelitais da cor do oceano e de TSM têm sido frequentemente utilizados para mapear processos oceanográficos, especialmente por proporcionar uma visão sinóptica bidimensional dos oceanos a nível global, com alta resolução espacial e temporal dos dados. O presente estudo teve por objetivo principal correlacionar padrões de distribuição e abundância de organismos pelágicos a processos oceanográficos que operam em escalas da ordem de dezenas a centenas de milhas náuticas e de dias a meses, através da análise de dados hidroacústicos e ambientais coletados in situ, a partir de cinco cruzeiros de pesquisa realizados entre o Chuí e a costa do Ceará, e de dados satelitais. A análise dos dados de densidade acústica, associados às informações satelitais permitiu avaliar a relação entre processos de larga escala espaço temporal e o acúmulo de densidade biológica em uma ampla área da ZEE brasileira. A utilização de dados satelitais foi fundamental para observar processos oceanográficos em uma escala espacial mais ampla do que a dos dados coletados in situ, permitindo assim o acompanhamento da evolução de importantes processos oceanográficos, sobretudo na região SE-S. Foi possível traçar um comparativo em termos gerais entre as macrorregiões da costa (SE-S, Central e Nordeste) em termos de complexidade ambiental associada a processos oceanográficos, que é decrescente do sul do Brasil em direção a região nordeste. Na região SE-S a disponibilidade de dados em diferentes estações do ano permitiu avaliar respostas biológicas às diferentes condições ambientais observadas. No período de Inverno obteve-se correlação negativa entre densidade acústica e TSM para a área ao sul do Cabo de Santa Marta Grande e positiva para a área ao norte, indicando a atuação de dois sistemas antagônicos de larga escala espacial, ambos promovendo aumento da densidade biológica. Quando os mesmos dados foram analisados em conjunto não se observou correlação entre o acúmulo de organismos e a TSM, devido à anulação causada pelo antagonismo dos processos. O avanço da massa de água fria transportada de sul para norte no período de inverno promove um importante aporte de energia no extremo sul da área. A primavera/verão corresponde ao período com maior disponibilidade de biomassa na região SES, refletindo a alta produtividade do sistema neste período. Nas regiões Central e Nordeste, devido a homogeneidade e estabilidade em termos de processos oceanográficos não se observa correlação entre densidade acústica e dados satelitais. / As a typical marine environment dominated by western boundary currents, the Brazilian continental margin has low biological productivity, especially in the pelagic system. Oceanographic processes such as thermal fronts, eddies and upwelling areas determine changes in physicochemical characteristics, through processes of mixing and nutrient renovation. These oceanographic features may increase productivity and concentrate biomass. The hydroacoustic method is widely applied to the assessment, mapping and also to estimate the abundance of small pelagic fishes, as well as in ecology of many marine species, in order to correlate the occurrence of biological aggregations to oceanographic processes of enrichment. Satellite data of the ocean color and SST have been frequently used to map oceanographic processes, especially to obtain a two-dimensional synoptic view of the global ocean, with high spatial and temporal resolution. This study aimed to investigate patterns of abundanc and distribution of pelagic organisms and to correlate them to oceanographic processes which operate on scales of the order of tens to hundreds of nautical miles and days to months, through the analysis of hydroacoustic and environmental data collected in situ on five research cruises along the Brazilian coast, from Chui (RS) to the coast of Ceará (CE). The analysis of the acoustic densities associated with satellite information provided the basis to evaluate the relationship between large scale temporal and spatial processes and the accumulation of biological density above a large area of the Brazilian EEZ. The use of satellite data was essential to observe oceanographic processes on a spatial scale larger than the environmental data collected in situ, allowing the observation of the development of major oceanographic processes, specially in the SE-S area. It was possible to draw, in general terms, a comparison among macro regions of the SE-S, Central and Northeast coasts in terms of the environmental complexity associated with the oceanographic processes, which decreases from the south of Brazil towards the northeast. The availability of data to the SE-S region, in three different seasons, allowed to investigate biological responses to different environmental patterns. In the winter it was calculated a negative correlation between acoustic density and SST for the area to the south of Cabo de Santa Marta Grande, and positive for the area to the north, indicating the occurrence of two antagonistic systems of large spatial scale, both associated with high biological density. When those data were analyzed together there was no correlation between the accumulation of organisms and SST, due to the effect caused by the antagonism of the processes. The progressive movement of cold water transported from the south towards the north during the winter promotes a significant amount of new energy in the south part of this region. Spring/summer time was the period with greater availability of biomass in the SE-S region, reflecting the high productivity of the system during this season. In the Central and Northeast zones, due to homogeneity and stability of the oceanographic processes it was not observed correlation between density and acoustic satellite data.

Le long des côtes nord-ouest africaines, parmi les plus poissonneuses au monde, les ressources halieutiques sont importantes tant du point de vue socio-économique que culturel. Les petits poissons pélagiques sont suivis au niveau sous régional depuis plus de trois décennies en s’appuyant sur les méthodes hydroacoustiques d’évaluation de stocks. Ces campagnes ont ainsi permis de fournir aux gouvernants une base scientifique en matière de prise de décision à des fins d’aménagement des pêcheries pélagiques. Un défi spécifique est de connaitre leur représentativité par rapport aux stocks ciblés. Nous rassurons sur cette représentativité sur la couverture de Sardinella aurita par ces campagnes. Par contre, pour S. maderensis une partie du stock ne serait pas échantillonnée et la méthode n’est pas adaptée pour Illisha africana et Ethmalosa fimbriata. Nous reportons des déplacements vers le nord dans la répartition de S. aurita et d’autres espèces de pélagique, attribués à la redistribution de l'intensité et de la productivité des upwellings [découpé en 5 sous zones du sud Maroc au sud Sénégal], diminuant ainsi l’abondance de la sardinelle dans la région côtière intertropicale. Pour la première fois en utilisant des séries chronologiques d'observation indépendantes à la méso-échelle, nous montrons un changement vers le nord dans la distribution de S. aurita depuis 1995 et l'attribuons au fort réchauffement de l'océan dans la région. De plus les changements spatiaux observés dans la biomasse de S. aurita au cours des 20 dernières années sont du même ordre de grandeur que ceux enregistrés pour les isothermes de surface. De tels changements auront une incidence sur les considérations politiques dans la gestion de la sécurité alimentaire dans plusieurs pays d'Afrique de l'Ouest. / Along the coast of North-West Africa, among the richest waters over the word, fish supply is important at both socio-economic and cultural levels. In this region, the small pelagic fish are the most abundant marine resources and are monitored using hydroacoustic stock assessment methods since more than three decades. These surveys have allowed providing to local authorities a sound scientific basis for deciding about the management of pelagic fisheries. A specific challenge is to know the representativity of these surveys with respect to the stocks targeted. In this work, we confirm this representativity for Sardinella aurita stock while for S. maderensis, a part of the stock could have not been sampled and for pour Ilisha africana and Ethmalosa fimbriata these surveys are not the best tool. Furthermore, Northward shifts in the distribution of sardinella in the Canary Current Large Marine Ecosystem are recorded in this work and have been attributed to the redistribution of upwelling intensity and productivity, resulting in the abundance of sardinella decreasing in the inter-tropical coastal region. Here for the first time using independent observational time series, we report a robust northward shift in S. aurita since 1995 and attribute it to the strong ocean warming in the region. The observed spatial shifts in biomass in the last 20 years are of the same order of magnitude as those recorded for surface isotherms. Such changes will impact policy considerations in the management of food security in several West African countries and should be considered with respect to “Intended Nationally Determined Contributions”.