Academic literature on the topic 'Pelagic zone'
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Journal articles on the topic "Pelagic zone"
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Karpaeva, A. Yu. "Seasonal changes in the taxonomical structure and abundance of phytoplankton in the pelagial and littoral zones of Obsterno Lake." Proceedings of the National Academy of Sciences of Belarus, Biological Series 68, no. 2 (2023): 136–46. http://dx.doi.org/10.29235/1029-8940-2023-68-2-136-146.
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We studied the seasonal changes in the taxonomic composition and abundance of phytoplankton in the littoral and pelagial zones of Obsterno Lake. A number of important differences recorded for the littoral and pelagic zones. The abundance in the littoral zone is higher in April, August and December. In other months it is higher in the pelagic zone. In the same months, the species richness in the littoral zone is also higher. These differences were influenced by such factors as biogenic elements (nitrogen and phosphorus), as well as the temperature factor.
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Mardyani, Yeyen, Tahmat Kurnia, and Luky Adrianto. "PENGELOLAAN PERIKANAN SKALA KECIL DI PERAIRAN PESISIR KABUPATEN BANGKA DENGAN PENDEKATAN BIOEKONOMI." Jurnal Kebijakan Sosial Ekonomi Kelautan dan Perikanan 10, no. 2 (2020): 91. http://dx.doi.org/10.15578/jksekp.v10i2.9305.
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Pengelolaan perikanan skala kecil di Kabupaten Bangka pada beberapa kurun waktu terakhir menunjukkan produktivitas yang semakin menurun. Hal ini disebabkan oleh pengelolaan ruang laut yang tidak hanya dimanfaatkan sebagai daerah penangkapan ikan, tetapi juga sebagai wilayah eksploitasi penambangan laut. Penelitian ini bertujuan untuk mengetahui status pemanfaatan perikanan skala kecil di perairan Kabupaten Bangka. Penelitian dilakukan dengan menggunakan data primer dan sekunder; analisis bioekonomi digunakan pada ketiga zona daerah penangkapan ikan (DPI) dengan memisahkan sumberdaya ikan pelagis dan demersal untuk melihat status pemanfaatan perikanan pada masing-masing zona. Ketiga zona daerah penangkapan ikan didasarkan pada kondisi eksisting menurut RZWP3K Provinsi Kepulauan Bangka Belitung, yaitu: Zona A (DPI dengan IUP), Zona A1 (DPI dengan IUP tanpa kegiatan), dan Zona B (DPI tanpa IUP). Hasil penelitian menunjukkan bahwa perikanan pelagis Zona A cenderung economical overfishing; sedangkan perikanan demersal sudah menunjukkan kondisi economical overfishing; Zona A1 berada pada kondisi underfishing; serta Zona B berada pada kondisi underfishing. Pemanfaatan perikanan Zona A dan A1 tidak mencapai 50% TAC; sedangkan pada Zona B hanya 15% TAC. Agar pemanfaatan perikanan baik pelagis ataupun demersal dapat berkelanjutan baik secara ekologi maupun ekonomi, pengelolaan perikanan skala kecil di perairan Kabupaten Bangka perlu dilakukan pengelolaan input pada upaya tangkap yang berbeda-beda pada tiap zona serta pengelolaan ekologi dan ekosistem.Title: Management of Small-Scale Fisheries in The Coastal Waters of Bangka Regency with Bioeconomic ApproachManagement of small-scale fisheries in Bangka Regency has recently shown decreased productivity. This is caused by the management of marine area which is not only used as a fishing ground, but also as an area of exploitation for off-shore mining. Based on these conditions, this study aims to determine the level of utilization of small-scale fisheries in the waters of Bangka Regency. This research uses primary and secondary data; bio-economic analysis was carried out in the three fishing ground zones by separating pelagic and demersal fish resources to see the utilization status of each zone. The three fishing ground zones are based on the existing fishing ground conditions according to RZWP3K Bangka Belitung Islands Province, namely: Zone A (fishing ground with IUP), Zone A1 (fishing ground with IUP without activities), and Zone B (fishing ground without IUP). The results showed that Pelagic Zone A fisheries tend to be economical, whereas demersal fisheries have shown economical overfishing; Zone A1 is under fishing; Zone B is under fishing. The utilization of fisheries in Zone A and A1 does not reach 50% TAC, while in Zone B it is only 15% TAC. For the utilization of pelagic and demersal fisheries to be sustainable both ecologically and economically, the management of small-scale fisheries in Bangka Regency waters needs to carry out input management for different fishing efforts in each zone as well as ecological and ecosystem management.
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Rustad, Turid. "Pelagics: What are the opportunities and challenges?" Open Access Government 40, no. 1 (2023): 406–7. http://dx.doi.org/10.56367/oag-040-11115.
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Pelagics: What are the opportunities and challenges? Turid Rustad from the Norwegian University of Science and Technology provides an overview of pelagic fish and the impact of the growing global demand for food. Pelagic fish are fish that live in the pelagic zone of oceans or lakes – that is, in the open part of the oceans. The pelagic zone makes up the main part of the oceans, and therefore, a large number of species live in this zone. Some of the pelagic fish live in areas close to the coast – that is, at depths of around 200 m while other species live in the open ocean and at depths below the continental shelf. The coastal group of fish includes anchovies, sardines, shad and menhaden, while tuna, mackerel, swordfish and sharks belong to the ocean group, however, there are no strict boundaries between the groups.
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Nelwan, Alfa. "KAPASITAS PENANGKAPAN IKAN PELAGIS KECIL DI PERAIRAN PANTAI BARAT SULAWESI SELATAN (FISHING CAPACITY OF SMALL PELAGIC FISH IN OF WEST COAST OF SOUTH SULAWESI)." Fish Scientiae 1, no. 2 (2016): 117. http://dx.doi.org/10.20527/fs.v1i2.1184.
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Kapasitas penangkapan adalah ukuran kemampuan yang dikerahkan oleh berbagai jenis unit penangkapan ikan yang tergabung sebagai suatu armada penangkapan ikan untuk memperoleh hasil tangkapan. Penelitian ini menganalisis trend dan kapasitas penangkapan ikan pelagis kecil di perairan pantai barat Sulawesi Selatan. Delapan jenis alat penangkap yang signifikan di Selat Makassar, perairan barat Provinsi Sulawesi Selatan adalah payang, pukat pantai, pukat cincin, jaring insang hanyut, jaring lingkar, jaring insang tetap, bagan perahu dan bagan tancap. Produksi dari 8 unit penangkapan berdasarkan 6 jenis ikan pelagis kecil, yaitu (1) kembung (Rastrelliger sp), (2) layang (Decapterus sp), (3) lemuru (Sardinella longiceps), (4) selar (Selaroides spp), (5) tembang (Sardinella fimbriata), (6) teri (Stolephorus spp). Total upaya penangkapan ikan tahunan dari kedelapan jenis unit penangkapan ikan tersebut dihitung untuk kurun waktu selama 20 tahun (1987-2006) dengan menerapkan standardisasi berdasarkan kemampuan setiap jenis unit penangkapan ikan. Analisis dilakukan untuk mengidentifikasi trend CPUE dan kapasitas penangkapan ikan pelagis kecil menggunakan metode Peak to Peak Analysis di tiga zona perairan pantai, yaitu perairan laut dangkal (zona A), perairan bentuk teluk (zona B) dan perairan laut dalam (zona C), Tren CPUE di ketiga zona menunjukkan cenderung menurun dalam kurun waktu 30 tahun, dimana tren menurun CPUE di zona C menunjukkan lebih besar dibandingkan zona lainnya. Kapasitas penangkapan di zona A, perlu mereduksi jumlah unit penangkapan sebesar 6%, sedangkan di zona B sebesar 5% dan zona C sebesar 11% untuk mencapai produksi optimal.Fishing capacity can be regarded as a total mobilized capability made by fishing fleet to produce catch. This research analyze trend and fishing capacities of small pelagic fish in off west coast of South Sulawesi. There are 8 significant fishing unit operated in off west coast of South Sulawesi ; these are payang, beach seine, purse seine, drift gill net, encircling gillnet, fixed gill net, boat liftnet, fixed liftnet. The fish production data cover 6 types of fish, i.e. Indian mackerel, anchovy, sardines, scads, and trevally caught by 8 types fishing unit. Annual fishing effort and CPUE over a period of 30 years (1977-2006) were calculated after a standardization considering variability in capture capability and fisheries development. Analysis was conducted for identifyng CPUE trend and fishing capacities of small pelagic fish using Peak to Peak Analysis. The study area was divided into three regions, i.e, around Spermonde Island (zone A), off Polman and Pinrang district (zone B) and off Majene dan Mamuju district (zone C). CPUE trend in three water zone showed to decrease for 30 year of period, where decreasing CPUE trend at zone C was higher than other zones. Fishing capacities in zone A need to be reduced of fishing effort for 6%, whereas in zone B was 5% and zone C was 11%.
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Simbolon, Domu, Ririn Irnawati, Budy Wiryawan, Bambang Murdiyanto, and Tri Wiji Nurani. "FISHING ZONE IN KARIMUNJAWA NATIONAL PARK." Jurnal Ilmu dan Teknologi Kelautan Tropis 8, no. 1 (2016): 129–43. http://dx.doi.org/10.29244/jitkt.v8i1.12501.
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ABSTRACTKarimunjawa National Park (KNP) consists of 7 zones i.e., core, protection, tourism, residence, rehabilitation, cultivation, and traditional fisheries utilization zone. Fishing activities in the traditional fisheries utilization zone (TFUZ) was not optimal because of limited of fishing zone information. The objective of this study was to determine the fishing zone based on major fish for each fishing gear. This study was conducted in KNP from October to December 2009. The major fish resources were determined through analyses of comparative performance index (CPI). Fish resource potential was analyzed by bio-economic model. The existence of fish resources were used as a basis of arrangement of fishing gear arround the fishing zone, through consideration of fishing gear characteristics, the characteristics of waters, the probabilities of conflict, degradation of fish resources, and regulations. Map of fishing zones were created using geographicl information system. Results showed that potential fishes around the TFUZ were reef fishes such as trevallies, yellow tail, and grouper. The potency of reef fishes was about 149 tons/year and pelagic fish of 19,080 tons/year. Fishing zones around the TFUZ consisted of (1) area of 0-3 miles from coastal line which was allocated as the fishing zone of reef fishes using hand line and fish trap, (2) area of 3-4 miles from coastal line which was allocated as demersal fishing zone using bottom gillnet, (3) area of 0-4 miles from coastal line which was allocated as pelagic fishing zone using surface gillnet, and (4) area that more than 4 miles which was allocated as pelagic fishing zone using dynamic fishing gear (troll line), and boat lift net. Keywords: fishing zone, reef fish, pelagic fish, gillnet, Karimunjawa
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Strand, Espen, and Geir Huse. "Vertical migration in adult Atlantic cod (Gadus morhua)." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 12 (2007): 1747–60. http://dx.doi.org/10.1139/f07-135.
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We investigate the trade-offs associated with vertical migration and swimming speed of Atlantic cod (Gadus morhua) using an adaptive individual-based model. Simulations with varying distribution and occurrence of prey, with and without swimbladder constraints, and visual predation were performed. Most simulations resulted in cod migrations between the bottom and pelagic zones. In simulations with high probability of encountering pelagic prey, the cod spent the daytime in the pelagic zone, moving to the bottom to feed only when no pelagic prey were encountered. At night the cod stayed in the pelagic zone to attain neutral buoyancy. In simulations with low occurrence of pelagic prey or high visual predation pressure, the cod remained at the bottom feeding on the consistently present benthic prey. If the pelagic prey occurred far above the sea floor or there were no benthic prey, the cod abandoned all bottom contact. The study thus predicts that the probability of encountering energy-rich pelagic prey is the key factor in driving vertical migration in adult cod. Buoyancy regulation is further shown to be an important constraint on vertical migration.
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Bogomilova Beshkova, Mihaela, Roumen Kirilov Kalchev, Borislava Petrova Gyosheva, Detelina Stojanova Belkinova, and Stefania Laslo Klayn. "Phytoplankton Community of the Pelagic and the Macrophyte-Rich Littoral Zone in Some Bulgarian Inland Waters." Transylvanian Review of Systematical and Ecological Research 24, no. 3 (2022): 23–34. http://dx.doi.org/10.2478/trser-2022-0017.
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Abstract Statistically significant differences between phytoplankton of the pelagic area and littoral zone, overgrown with macrophytes, were observed in seven reservoirs and three natural lakes. Both total biomass and species diversity of the phytoplankton were higher in the macrophyte settlements than in the pelagic zone. Regarding biomass, the divisions of Pyrrhophyta and Cryptophyta were the main contributors to the similarity of the pelagic areas while the pennate Bacillariophyta were the main contributors to the similarity of macrophyte zones. The phytoplankton structure in the littoral zone differed also within the same water body but in sites with different macrophyte dominant species, as the differences concerned mainly the ratio between pennate diatoms and conjugatophyceans.
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Rosalina, Dwi. "ANALISIS STRATEGI PENGEMBANGAN PERIKANAN PELAGIS DI KABUPATEN BANYUASIN PROVINSI SUMATERA SELATAN." Jurnal Kebijakan Sosial Ekonomi Kelautan dan Perikanan 1, no. 1 (2020): 63. http://dx.doi.org/10.15578/jksekp.v1i1.9255.
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Kajian ini merupakan analisa pengembangan strategi perikanan pelagis di Kabupaten Banyuasin. Kajian ini bertujuan untuk (i) menentukan teknologi penangkapan ikan pelagis yang efektif, efisien dan berkelanjutan berdasarkan aspek biologi, teknis, sosial, ekonomi, dan keramahan lingkungan; (ii) menentukan alokasi jumlah unit penangkapan ikan pelagis yang optimum; dan (iii) menentukan strategi pengembangan alat tangkap ikan pelagis. Kajian ini menggunakan metode pemeringkatan (scoring), analisa optimum, analisa finansial usaha serta analisa SWOT. Hasil kajian menunjukkan bahwa rawai hanyut merupakan teknologi penangkapan ikan yang relatif lebih efektif, efisien dan berkelanjutan daripada alat tangkap jaring insang hanyut dan bagan tancap. Alokasi unit penangkapan rawai hanyut yang direkomendasikan sebanyak 51 unit. Hasil analisis kelayakan usaha alat tangkap rawai hanyut di Kabupaten Banyuasin menunjukkan keuntungan Rp. 18.767.666, nilai NPV Rp. 55.855.075, Net B/C sebesar 2,22 dan nilai BEP untuk nilai produksi per tahun Rp. 39.055.258 dan volume produksi per tahun 23.669 kg, nilai ROI 41 %, nilai IRR 48 %. Strategi pengembangan alat tangkap pelagis kecil di Kabupaten Banyuasin yangdisarankan adalah (i) optimalisasi usaha perikanan pelagis; (ii) pengembangan usaha perikanan pelagis di jalur 6 – 10 mil laut; (iii) peningkatan manajemen usaha perikanan pelagis; (iv) peningkatan skala usaha armada penangkapan ikan pelagis; dan (v) pembenahan fasilitas sarana dan prasarana perikanan.Title: Analysis of Strategy for Pelagic Fishery Development in the Banyuasin Regency of South Sumatera Province This research is an analysis strategy for pelagic fishery development in the Banyuasin Regency of South Sumatera Province. The objectives of the research (i) to determine more effective, efficient and sustainable fishing technology for pelagic fish based on biological, technical, social, economic and environment aspects; (ii) to assess optimum allocation for pelagic fish catching unit; and (iii) to determine development strategy of pelagic fisheries. This research used scoring method, optimum allocation, financial and SWOT analysis. This research results indicated that drift long-line fishing technology is more effective, efficient and sustainable than drift gillnet and lift-net. Suggested numbers of optimum allocation of fishing unit consist of 51 unit drift long-line. Output of feasibility analysis of drift long-line fishery indicated profit of IDR 18,767,666, NPV value was IDR 55,855,075, Net B/C was 2.22, the BEP value was IDR 39,055,258 that equal to production 23,669 kg, the ROI and IRR value were 41% and 48. This research suggested following development strategies of pelagic fisheries in Banyuasin Regency namely (i) optimization of drift long-line for pelagic fishery, (ii) focussing development pelagic fish fishery in 6-12 mile zone; (iii) increasing management effort of fisheries business; (4) revitalization of fisheries infrastructures and facilities; and (v) empowering scale of fishing fleet and its technology.
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Næsje, T. F., B. Jonsson, O. T. Sandlund, and G. Kjellberg. "Habitat Switch and Niche Overlap in Coregonid Fishes: Effects of Zooplankton Abundance." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 12 (1991): 2307–15. http://dx.doi.org/10.1139/f91-271.
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Vendace (Coregortus albula) in Lake Mjøsa lived in the pelagic zone and gillnet catches were correlated with water temperature (r2 = 0.457, p < 0.005). Whitefish (Coregonus lavaretus) exploited both epibenthic and pelagic areas. Whitefish with body lengths between 25 and 35 cm moved from the epibenthic to pelagic zone during summer; other length groups remained in epibenthic habitats. The pelagic fish returned to epibenthic areas in the autumn. Cladocerans were important food items for both fish species in the pelagic zone. The large copepod Limnocalanus macrurus was eaten only by vendace whereas surface insects were more important prey for whitefish. This suggests that vendace is the more specialized zooplanktivore. The pelagic gillnet catch of whitefish and the pelagic habitat overlap between whitefish and vendace increased with increasing zooplankton densities at depths between 0 and 50 m (r2 = 0.609 and 0.494, respectively, p < 0.01). During spring and autumn we observed a time lag between the change in zooplankton abundance and habitat switches of whitefish. The fish moved to the more profitable habitat several days after food availability had changed, indicating an element of learning in choice of habitat.
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Naud, Marc, and Pierre Magnan. "Diel onshore–offshore migrations in northern redbelly dace, Phoxinus eos (Cope), in relation to prey distribution in a small oligotrophic lake." Canadian Journal of Zoology 66, no. 6 (1988): 1249–53. http://dx.doi.org/10.1139/z88-182.
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Northern redbelly dace, Phoxinus eos (Cope), exhibit diel onshore–offshore migrations in a small oligotrophic Quebec lake. The fish swim in shoals in the littoral zone during the day, migrate to the pelagic zone at sunset, where the shoals break up into single fish, and then go back to the littoral zone at sunrise. Dace eat mainly two cladocerans, Daphnia and Holopedium. Zooplankton sampling indicated that Daphnia were significantly more abundant in the pelagic zone than in the littoral zone, and Holopedium were rarely found in the littoral zone. Dace showed a significant preference for a dense cover habitat over a sparse cover habitat in the littoral zone during the day. Our results support the hypothesis that dace migrate to the pelagic zone at sunset to increase their feeding efficiency on zooplankton. The foraging benefits of remaining in the offshore zone may be offset by increased risk of predation by brook charr, Salvelinus fontinalis (Mitchill), during the daylight hours, thus resulting in diel onshore–offshore migrations.
Dissertations / Theses on the topic "Pelagic zone"
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Cook, April B. "Deep-Pelagic (0-3000m) Fish Assemblage Structure Over the Mid-Atlantic Ridge in the Area of the Charlie-Gibbs Fracture Zone." W&M ScholarWorks, 2011. https://scholarworks.wm.edu/etd/1539617899.
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Only a miniscule fraction of the world’s largest volume of living space, the ocean’s mid-water biome, has ever been sampled. As part of the International Census of Marine Life field project Mid-Atlantic Ridge Ecosystems (MAR-ECO), a discrete-depth trawling survey was conducted in 2009 aboard the NOAA ship Henry B. Bigelow to examine the pelagic faunal assemblage structure and distribution over the Charlie-Gibbs Fracture Zone (CGFZ) of the northern Mid-Atlantic Ridge. This is the first MAR-ECO project aimed specifically at describing diel vertical migration as a distributional phenomenon. Discrete-depth sampling from 0-3000 m was conducted during both day and night in similar locations using a Norwegian “Krill” trawl with five codends that were opened and closed via a pre-programmed timer. Seventy-five species of fish were collected, with a maximum diversity and biomass observed between depths of 700-1900 m. An incremental gradient in sea surface temperature and underlying watermasses, from northwest of the CGFZ zone to the southeast, was mirrored by a similar gradient in ichthyofaunal diversity. Using multivariate analyses, eight deep-pelagic fish assemblages were identified, with depth as the overwhelming discriminatory variable. Strong diel vertical migration (DVM) of the mesopelagic fauna was a prevalent feature of the study area, though the numerically dominant fish, Cyclothone microdon (Gonostomatidae), exhibited a broad (0-3000 m) vertical distribution and did not appear to migrate on a diel basis. In all, 3 patterns of vertical distribution were observed in the study area: a) DVM of mesopelagic, and possibly bathypelagic, taxa; b) broad vertical distribution spanning meso- and bathypelagic depths; and c) discrete vertical distribution patterns. Overall species composition and rank order of abundance of fish species agreed with two previous expeditions to the CGFZ (1982-83 and 2004), suggesting some stability in the ichthyofaunal composition of the study area, at least in the summer. Frequent captures of putative bathypelagic fishes, shrimps, and squid in the epipelagic zone (0-200 m) were confirmed. The results of this expedition reveal distributional patterns unlike those previously reported for open ocean ecosystems, with the implication of increased transfer efficiency of surface production to great depths in the mid-North Atlantic.
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[Verfasser], Fadeev, Antje [Akademischer Betreuer] Boetius, Daniel [Gutachter] Sher, and Kai-Uwe [Gutachter] HinÂÂrichs. "Ecological observations of pelagic bacterial and archaeal communities in the Atlantic-Arctic boundary zone / Fadeev ; Gutachter: Daniel Sher, Kai-Uwe HinÂÂrichs ; Betreuer: Antje Boetius." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1179349725/34.
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Verfasser], Fadeev, Antje [Akademischer Betreuer] [Boetius, Daniel [Gutachter] Sher, and Kai-Uwe [Gutachter] HinÂÂrichs. "Ecological observations of pelagic bacterial and archaeal communities in the Atlantic-Arctic boundary zone / Fadeev ; Gutachter: Daniel Sher, Kai-Uwe HinÂÂrichs ; Betreuer: Antje Boetius." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1179349725/34.
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Ahmed, Jeyid Mohamed Ahmed. "Relations environnement et évolution spatio-temporelle des petits poissons pélagiques dans le système d'upwelling de la zone NW Africaine." Thesis, Littoral, 2016. http://www.theses.fr/2016DUNK0438/document.
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Le système d'upwelling nord-ouest africain au large du Maroc, de la Mauritanie, de la Gambie et du Sénégal est le système le plus productif au monde en termes de productivité primaire. Elle se traduit par une importante biomasse de poissons principalement dominée par les petits poissons pélagiques qui sont les principales ressources vivantes exploitées de la région. Dans un contexte de gestion partagée par plusieurs pays des ressources halieutiques de la région, comprendre les facteurs qui contrôlent la répartition spatiale de ces populations et l'évolution de leurs abondances est un enjeu crucial pour les pêcheries et le développement socio-économique de la région. Le but principal de cette thèse est d'une part de décrire les variations saisonnières et interannuelles de l'environnement marin de l'upwelling des Canaries le long de la Côte nord-ouest de l'Afrique, et d'autre part de relier ces variations avec les dynamiques spatio-temporelles de ces principales espèces d'importance commerciale. Nous avons utilisé différents jeux de données disponibles et développé différentes approches afin d'avoir une vision la plus complète possible du fonctionnement de cet écosystème. Ainsi, nous avons combiné des données satellitaires, des données de campagnes scientifiques acoustiques, des statistiques de pêche et des analyses de formes d'otolithes. Le long des côtes NW africaines (10°-35° N), nos données nous ont permis d'identifier trois régions avec une saisonnalité et une intensité de l'upwelling bien différencié. La région présente une forte variabilité latitudinale et temporelle des conditions environnementales. La partie sud de la zone (~ entre 10° et 24°N) se caractérise par des eaux plus chaudes et plus riche en Chlorophylle-a que la partie nord. La majeure partie de la variabilité des paramètres environnementaux étudiés est due à la saisonnalité (>60%). Au cours de la période d'étude (2002-2012), nous avons noté une tendance significative au réchauffement allant de 0.01°C. à 0.04°C.an-¹ et un renforcement général de l'upwelling, mais une tendance à la baisse de la concentration en Chl a dans l'ensemble de la zone étudiée. Il existe un gradient latitudinal sud-nord de la phénologie du bloom de phytoplancton (période, durée et l'ampleur du bloom). Cependant, il n'y a pas de tendances interannuelles significatives de la phénologie du bloom phytoplanctonique ni de corrélations ou tendances avec les paramètres physiques de l'environnement étudié (SST, indice d'upwelling, vent). L'écosystème du courant des Canaries se caractérise par le couple sardines/sardinelles. L'anchois, bien que présent dans cet écosystème, ne joue pas un rôle aussi important que dans les autres systèmes d'upwelling. Les relations entre les abondances d'anchois, de sardines et de sardinelles avec les paramètres environnementaux ont été étudiées à différentes échelles à l'aide de modèles additifs généralisés (GAM). Les résultats de notre étude indiquent que les variations spatio-temporelles de l'abondance de l'anchois et de la sardinelle sont davantage contrôlées par le gradient thermique que par la productivité biologique. La sardine semble être plus contrôlée par une fenêtre environnementale optimale d'intensité d'upwelling et de température "optimal upwelling and temperature windows". Nous avons pu pour la première fois mettre en évidence l'existence d'une alternance temporelle d'abondance entre l'anchois et la sardine comme cela est connu dans d'autres systèmes d'upwelling. Enfin, pour contribuer à la connaissance sur la structuration des populations de la sardinelle ronde qui préoccupent les scientifiques et les gestionnaires des pêches, nous avons mené une étude sur l'analyse de la forme des otolithes. L'existence possible de plusieurs stocks de sardinelle en lien avec des structures océanographiques ne confortent pas la politique de gestion actuelle qui considère un stock unique au large de la côte NW africaine<br>The North West African upwelling system off Morocco, Mauritania, Gambia and Senegal is the most productive system in the world in terms of primary productivity. This productivity results in a large fish biomass dominated by small pelagic fish which are the main living resources exploited in the region. In a context of shared management of fisheries resources by several countries in the region, understanding the factors that control the spatial distribution of populations of small pelagic fish and the evolution of their abundances is a crucial issue for fisheries and the socio-economic development of the region. The main objective of this thesis is to describe the seasonal and interannual variations of the marine environment of the Canary upwelling along the Northwest coast of Africa and to link these variations with the spatio-temporal dynamics of the main small pelagic species of commercial importance of this zone. We have used different sets of data available and developed different approaches in order to have a complete view of the functioning of this ecosystem. Thus, we have combined satellite data, acoustic scientific survey data, fishing statistics and analysis of otolith shapes. Along th NW African coasts ( 10° - 35° N), our data allowed us to identify three regions with a well-differentiated seasonality and intensity of upwelling. The region has a high latitudinal and temporal variability of environmental conditions. The southern part of the zone (between 10° and 24° N) is characterized by warmer and richer Chlorophyll-a waters than the northern part. The majority of the variability of the environmental parameters studied is due to seasonality (> 60%). During the study period (2002-2012), we noted a significant warming trend ranging from 0.01° C to 0.04°C. yr-¹ and a general reinforcement of ipwelling, but a downward trend in Chl a concentration in the whole study area. There is a south-north latitudinal gradient of the phenology of the phytoplankton bloom (period, duration and magnitude of the bloom). However, there are no significant interannual trends in phytoplankton bloom phenology or correlations or trends with the physical parameters of the environment studied (SST, upwelling index, wind). The Canary current ecosystem is characterized by the sardine/ Sardinella pair, Anchovy, althought present in this ecosystem, plays no more important role than in other upwelling systems. The relationships between the abundances of anchovies, sardines and sardinella with environmental parameters have been studied at different scales using generalized additive models (GAM). The results of our study indicate that the spatial and temporal variations of the abundance of anchovy and sardinella are controlled more by the thermal gradient than by the biological productivity. The sardine seems to be more controlled by an "optimal upwelling and temperature windows". We were able for the first time to demonstrate the existence of a temporal alternation of abundance between anchovy and sardine as is known in other upwelling systems. Finally, in order to contribute to the knowledge of population structure of the round sardinella that concern scientists and fisheries managers, we conducted a study of the shape of otoliths. The possible existence of several stocks of sardinella in connection with oceanographic structures do not support the current management policy which considers a single stock off the African NW coast
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Isselmou, Braham Braham Cheikh Baye. "Les pêcheries pélagiques de la ZEE mauritanienne : nouvelles méthodes pour de nouvelles connaissances." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20248/document.
Full textAbstract:
Les contextes national et international sont marqués par une prise de conscience de plus en plus grande de l’importance du poisson pour la sécurité alimentaire des populations des pays sous-développés. En Mauritanie, les petits pélagiques constituent une source de protéines animales accessibles aux faibles pouvoirs d’achat et contribuent à garantir la sécurité alimentaire de nombreuses populations. Malgré la présence d’une variabilité naturelle importante des espèces pélagiques, ce travail de thèse montre qu’il existe des éléments de stabilité dans l’écosystème pélagique dans la zone nord-ouest africaine. L’hypothèse de la présence des stocks sédentaires au niveau des zones de nourriceries en Mauritanie et au Sénégal est démontrée. La répartition spatio-temporelle des sardinelles en relation avec la dynamique de l’océan (upwelling, température de surface et chlorophylle) a été examinée. L’analyse des statistiques de la pêche sur une série de plus de trente (30) ans ne soutiennent pas l’immigration en provenance du Sénégal vers la Mauritanie d'Avril à Septembre selon l’hypothèse de Boëly (1978). Ce travail de thèse examine des hypothèses de migrations possibles des sardinelles dans la zone nord-ouest africaine et d’importantes implications en matière de gestion sont discutées. Pour finir, ce travail est replacé dans son contexte plus global de l’aménagement de la pêcherie des petits pélagiques. De nouvelles perspectives pour l’application des techniques géostatistiques (indicatrices et co-krigeage) et modélisation statistique sont envisagées pour l’étude de la dynamique des stocks des sardinelles et chinchards<br>National and international context marked by an awareness of growing importance of pelagic fish for food security of people in underdeveloped countries . The depletion of demersal species also makes this extremely important resource for the future pelagic fisheries in Mauritania. Mauritanian EEZ is characterized by the existence of a favorable development of several species hydro-climatic and morphological phenomena , small pelagic species that represent more than 90% of the fisheries potential is about one million tones. The major problems facing the management of these species is understanding the roles played by them in their biogeography intrinsic spatio- temporal dynamics ( short-lived , aggregation , etc. ..) and the evaluation of their abundances . Assessment of exploited fish stocks is a priority. However, the recurring difficulty of evaluations of these fisheries, naturally very unstable, often reflected a lack of precision in the methods used , the incompleteness of the data ( which is also a problem of sampling) or sampling uncontrolled .The Mauritanian small pelagic fisheries are multi-species (sardines , horse mackerel , sardinella ) . In addition to the data provided by the logbooks including the holding is mandatory for industrial units, survey data for the landing craft and coastal segment often used to calculate the abundance, acoustic surveys , are an important means for quantify the abundance and study the distribution of these resources. The data collected by observers on board fishing industrial units are also a source of important information.Based on these data , this work aims at the reconstruction of the main series of abundances of small pelagic stocks in the northern part of West Africa , to be used in the adjustment of stock assessments models. Given the importance of the environmental component in very large fluctuations observed, the integration of this dimension in the analysis of this series catches the role of each of these factors (fisheries and environment) in the variability of abundance seasonal and amplitude of their migration.In addition to these conventional data Mauritania introduced on board commercial fishing vessels with VMS . This system allows the transmission by satellite to the body control the ship's position every hour is an important technological advance. This new type of data could therefore be a new source for estimating abundance and fishing effort of small pelagic species through appropriate statistical methods. A method for the interpretation in terms of paths abundance index was applied. The coupling of VMS and logbook will help to improve the definition of nominal fishing effort and catch location at fine spatial and temporal.The general problem is how to improve the estimation of the abundance of small pelagic stocks , understand fluctuations in the abundance and migration strategy of the species as well as tactics and strategies implemented by fleets to fish resources whose behavior is often erratic . It is therefore to adresse several issues in particular:What is the trend of the evolution of the abundance of pelagic species in the North West African area? The interpretation of the trajectories in terms of VMS fishing can it be used to map the abundance of key species? What are the seasons abundances? Environmental parameters they play an important role on the distribution of species? Will there a difference between tactics and strategies of the different fleets fishing for small pelagic? Data logs and data collected by observers on board can be used as a priori knowledge? To address these issues , we proceed to the mobilization of all relevant time series and implement innovative statistical and geostatistical methods , some of which applied for the first time in the sub -region for these stocks
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Ciftci, Nilhan. "Determination Of Potential Favorable Zones For Pelagic Fish Aggregation (anchovy) In The Black Sea Using Rs And Gis." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606160/index.pdf.
Full textAbstract:
Fishing is a significant source of food, and constitutes an important source of income in Turkey. Due to the large extent required to analyse the distribution of fish stocks, information derived from satellites play an important role in fisheries applications.
Chlorophyll concentration and sea surface temperature (SST) are the most significant parameters which define the fish habitat. The accuracy of these parameters in the Black Sea taken from two different satellites, namely Sea-viewing Wide Field-of-views Sensor (SeaWIFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) are evaluated. Results indicate that both satellites give good estimates of SST but the algorithms overestimate the chlorophyll concentration values. MODIS products are used in the subsequent analyses due to their high correlation with in-situ measurements relative to SeaWIFS products. The cause of the overestimation of chlorophyll concentration is further examined and a general description of environmental variability in Black Sea is done using MODIS products.
Anchovy, the most important commercial fish in Turkey, has been selected as the target specie of the study. Level 3 weekly average MODIS chlorophyll and SST products are processed using remote sensing (RS) and geographic information systems (GIS) integration to estimate potential favorable zones for pelagic fish aggregations.
Two different decision rules are employed to generate fish stock maps, simple additive weigthing (SAW) and fuzzy additive weigthing (FSAW). The resultant maps are used to visualize the general distribution of Anchovy in Turkish Seas from May 2000 to May 2001. The resultant thematic fish stock maps generated by FSAW analysis represents the uncertainity in the environment better than the ones generated by SAW analysis.
7
Dindinaud, Francois. "Approche intégrée des conditions physico-chimiques affectant les cortèges biologiques de la partie fluviale de l'estuaire de la Gironde." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0010/document.
Full textAbstract:
Les estuaires, situés à l’interface entre les domaines continental et marin, constituent des zones essentielles dans les échanges de matières. Ils jouent dès lors un rôle capital pour les cycles biogéochimiques et biologiques et subissent, par ailleurs, des pressions climatiques et anthropiques croissantes depuis plusieurs décennies. Le présent travail a été focalisé sur les peuplements benthiques et pélagiques présents dans la partie fluviale (Garonne et Dordogne) de l’estuaire de la Gironde, zone àtrès faible salinité où ces peuplements n’avaient encore jamais été étudiés. Alors que la méiofaune, composée principalement de Nématodes, s’est avérée relativement abondante dans les domaines intertidal et subtidal, le macrobenthos est apparu composé essentiellement d’Oligochètes en intertidal et complètement absent en subtidal. La grande plasticité du copépode dominant Eurytemora affinis a été confirmée, celui-ci occupant une niche écologique différente dans la partie fluviale de l’estuaire par rapport à la zone haline. L’importance de la température plutôt que la qualité du pool nutritif sur la productivité d’E. affinis a été démontrée, mettant en évidence une fois de plus la grande adaptabilité de cette espèce dans un habitat très fluctuant. L’étude de l’habitat benthique et pélagique, notamment en terme de qualité du pool nutritif disponible pour les organismes, a démontré que la contribution de la matière organique réfractaire d’origine terrestre est dominante. La contribution du micro phytobenthos à la composition de la matière organique sédimentaire et pélagique a aussi été mise en évidence. Enfin,l’étude des communautés planctoniques dans la partie fluviale de l’estuaire de la Gironde a montré que l’espèce E. affinis y occupe une position clef<br>Being at the interface between continental and marine systems, estuaries are essential areas for matter exchanges. Therefore, they play a crucial role in biological and biogeochemical cycles. In addition to natural fluctuations, these systems have also undergone increasing climate and anthropogenic pressures for several decades. The present work focused on the benthic and pelagic assemblages in the fluvial section (Garonne and Dordogne rivers) of the Gironde estuary, a low salinity area where these communities had never been studied. Meiofauna, mainly composed ofnematodes, was found in relatively high abundance in both intertidal and subtidal zones.Macrozoobenthos was essentially composed of oligochaetes in the intertidal, while it was totally absent in the subtidal areas. The high plasticity of the dominant copepod Eurytemora affinis was confirmed, with a different ecological niche in the freshwater section of the estuary compared to the haline area downstream. The importance of temperature rather than the quality of the nutrient pool on the productivity of E. affinis was demonstrated, thereby confirming the great adaptability of thisspecies to a highly fluctuating habitat. Study of benthic and pelagic habitat, especially in terms of quality of the nutrient pool available to the organisms, showed that the contribution of refractoryorganic matter with a terrestrial origin is dominant. A significant contribution of microphytobenthos to the composition of sedimentary and pelagic organic matter was also highlighted. Finally, the study of planktonic communities in the fluvial part of the Gironde estuary showed that the species E. affinis occupies a key position in this part of the estuary
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Ubertini, Martin. "Déterminisme de la remise en suspension des diatomées benthiques au travers du couplage benthos-pelagos." Caen, 2012. http://www.theses.fr/2012CAEN2056.
Full textAbstract:
La remise en suspension du microphytobenthos est un processus clé du couplage benthos-pelagos dans de nombreux écosystèmes marins côtiers. Si les facteurs physiques comme l’hydrodynamisme ou le vent participent largement à cette remise en suspension, la macrofaune benthique joue également un rôle primordial par les processus de bioturbation. De plus, les diatomées benthiques, constituant la communauté la plus importante du microphytobenthos, sont capables de modifier leur propre remise en suspension par l’excrétion de substances exopolymériques limitant l’érosion du sédiment. La complexité de la remise en suspension réside donc dans la multiplicité des variables physiques, chimiques et biologiques associées. L’objectif de cette étude était donc de mieux comprendre la remise en suspension des diatomées benthiques à l’échelle de l’écosystème, par l’étude du couplage benthos-pelagos au niveau de deux écosystèmes côtiers contrastés comme à l’échelle des processus impliqués par l’étude de la remise en suspension en érodimètre. La remise en suspension joue un rôle primordial dans les écosystèmes estuariens et modifie l’équilibre des systèmes de façon saisonnière. Les caractéristiques sédimentaires des écosystèmes conditionnent la remise en suspension par l’interaction de l’état physiologique du biofilm et de la structure des mélanges sablo-vaseux. La présence de faune rajoute un degré d’interaction, à l’exemple de la coque Cerastoderma edule qui se révèle être un acteur majeur du couplage benthos-pelagos<br>La remise en suspension du microphytobenthos est un processus clé du couplage benthos-pelagos dans de nombreux écosystèmes marins côtiers. Si les facteurs physiques comme l’hydrodynamisme ou le vent participent largement à cette remise en suspension, la macrofaune benthique joue également un rôle primordial par les processus de bioturbation. De plus, les diatomées benthiques, constituant la communauté la plus importante du microphytobenthos, sont capables de modifier leur propre remise en suspension par l’excrétion de substances exopolymériques limitant l’érosion du sédiment. La complexité de la remise en suspension réside donc dans la multiplicité des variables physiques, chimiques et biologiques associées. L’objectif de cette étude était donc de mieux comprendre la remise en suspension des diatomées benthiques à l’échelle de l’écosystème, par l’étude du couplage benthos-pelagos au niveau de deux écosystèmes côtiers contrastés comme à l’échelle des processus impliqués par l’étude de la remise en suspension en érodimètre. La remise en suspension joue un rôle primordial dans les écosystèmes estuariens et modifie l’équilibre des systèmes de façon saisonnière. Les caractéristiques sédimentaires des écosystèmes conditionnent la remise en suspension par l’interaction de l’état physiologique du biofilm et de la structure des mélanges sablo-vaseux. La présence de faune rajoute un degré d’interaction, à l’exemple de la coque Cerastoderma edule qui se révèle être un acteur majeur du couplage benthos-pelagos
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Weigert, Stefan Cruz. "Relação entre feições oceanográficas e distribuição de organismos pelágios acusticamente detectados na costa do Brasil." reponame:Repositório Institucional da FURG, 2010. http://repositorio.furg.br/handle/1/4032.
Full textAbstract:
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Previous issue date: 2010<br>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.<br>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.
10
Nair, Preetha G. "Studies on major small pelagic fishes along the Kerala Coast with respect to the Potential Fishery Zone (PFZ) advisories." Thesis, 2015. http://eprints.cmfri.org.in/10763/1/Preetha%20G%20Nair%20Ph.D%20thesis.pdf.
Full textAbstract:
Indian National Centre for Ocean
Information Services (INCOIS),
Hyderabad, India provides fishery
forecast services all along the Indian
coast free of cost, referred to as
‘Potential Fishery Zone (PFZ)
Advisories’. These services include georeferenced
maps showing marked regions
where probability of finding sizeable
schools of fishes is high. These advisories
are provided to help the fisher folks to
improve their income from fishing by
saving engine fuel for searching and
locating fish stocks. Based on 124 controlled fishing
experiments carried out in the PFZ and
Non-PFZ zones along the Kerala coast
during 2008-2012 periods, the present
study evidenced that commercially
important fishes were abundant in the
PFZ, forming richer fisheries compared to
the non-PFZ areas. The profit from
controlled experiments showed
consistently higher values in the PFZ than
that in the non-PFZ. The highest profit
during the entire controlled fishing
experiments was obtained when the catch
was dominated by relatively high-priced
fishes such as tunas, carangids, seer
fishes and mackerel. Indian oil sardine
was the major single species obtained
during the Northeast Monsoon
(November-February), whereas, Indian
mackerel dominated during the Southwest
Monsoon (June-October) and Spring
Intermonsoon (March – May) periods.
Anchovies were found to dominate only
in two fishing experiments in the entire
study period. The analyses of catch data of the small
pelagic fishes of interest (Indian oil
sardine, Indian mackerel and
Commerson’s anchovy) showed that the
PFZ advisories better predicted the
catches of Indian oil sardine during the
Northeast Monsoon (November-
February) and Indian mackerel during the
rest of the period. Conversely, the catch
data of controlled experiments showed
that PFZ advisory has less efficiency to
support the exploitation of anchovies.
Attempts have been made to outline the
recurrent PFZ along the Kerala coast
based on the advisories generated for the
study period (2008-2012). Altogether
432 PFZ advisories were digitised and
month-wise repeat PFZs have been
demarcated. In general, most of the very
prominent recurrent PFZs were found
within the 50m depth contour. The
highest number of recurrent PFZs was in
December, January and February. On the
other hand, the lowest number of
recurrent PFZs was found in April, May
and June. Plankton components in the diet of
Indian oil sardine, Indian mackerel and
Commerson’s anchovy based on
fortnightly fish samples analysed during a
year period are presented. Coscinodiscus,
Nitzschia, Pleurosigma and Thalassiosira
were found in the gut of Indian oil
sardine almost throughout the year,
whereas microzooplankton was mostly
dominant only during the October –
December period. Coscinodiscus and
Tintinids were predominant in the gut of
Indian mackerel throughout the year.
Furthermore, Thalassiosira, Ceratium,
Dinophysis, Protoperidinium, Pyrophacus
and copepods were also found in the gut
of Indian mackerel almost throughout the
year. The dominant value index showed
the dominance of phytoplankton,
microzooplankton and copepods in the
diet of Indian mackerel throughout the
year, indicating their almost equal
preference for both phytoplankton and
zooplankton. The food items in the gut
content of Commerson’s anchovy showed
characteristic difference from both Indian
oil sardine and Indian mackerel and found
to be a zooplankton feeder predominantly
feeding on copepods, fish eggs,
ostracods, lucifers and tintinids.
The environmental observations based
on monthly field sampling carried out in
two locations (10m and 20m depth
contours) situated off Kochi are
presented. During seven out of nine
observations, PFZ bands were observed
around 10m location. High values of
chlorophyll (> 3mg m-3) were found in
August, September and October, which
could be attributed to the combined effect
of Cochin backwater influx and
upwelling. The seasonal evolution of
hydrographical parameters showed
significantly higher concentration of
nutrients and chlorophyll during the
Southwest Monsoon period compared to
the rest of the sampling. The chlorophyll
concentration was found to be
significantly higher in 10m location
(PFZ) compared to the 20m location
(non-PFZ). The status of the Length-Weight
Relationship (LWR) and condition factor
of Indian oil sardine, Indian mackerel and
Commerson’s anchovy along the Kerala
coast is presented. The LWR of
Commerson’s anchovy is the very first
detailed report from this region. LWR
and condition factor of Indian mackerel
and Oil sardine were not significantly
different from the values reported in the
historical studies, indicating that these
parameters are not affected significantly
by the expected long-term environmental
changes. The results of the growth and maturity
studies of the small pelagic fishes of
interest have been discussed. The
analyses were based on a fortnightly
sampling carried out in two major landing
centres during 2010 – 2011 periods.
The maximum life span of Indian oil
sardine was estimated to be 2.63 years.
Two peaks of recruitment of juveniles to
the fishery were observed; a large peak
during July - August and a small peak in
February - March. The length at first
maturity was calculated as 15.7 cm while
the length at first capture was 15 cm,
suggesting that the peak exploitation of
the species occurs before they attain
sexual maturity. Comparison of the length
at first maturity of oil sardine reported in
historical studies with the present study
shows that only minor variation exists
between the two. The life span of Indian
mackerel is estimated to be 2 years. The
recruitment pattern showed the presence
of mature mackerel all year round.
However, two recruitment peaks of
Indian mackerel were evident; June to
August and February to March with the
highest recruitment in July (28%).
Probability of capture of mackerel
showed higher values (22.43 cm) than
the length at first maturity (17.7 cm)
indicating that their peak exploitation
occurs after attaining sexual maturity. Long-term changes in length at first
maturity of Indian mackerel indicated a
prominent decrease in length in the recent
decade, probably indicating a response to
the long-term environmental changes.
The present study on the growth and
maturity parameters of Commerson’s
anchovy forms the first such study from
Indian waters and the life span of the
species was found to be 3.06 years. Two
recruitment peaks of Commerson’s
anchovy were observed; first during
February – March and a second during
June - July. The probability of capture of
Commerson’s anchovy showed that they
get exposed to maximum exploitation
after they attain maturity. Lack of past
data on length at first maturity of
Commerson’s anchovy from the Indian
coast hindered a possible comparison
with the present data.
Books on the topic "Pelagic zone"
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V, Fedorov V. Pelagicheskie i bentopelagicheskie ryby tikhookeanskikh vod Rossii: V predelakh 200-milʹnoĭ ėkonomicheskoĭ zony. Izd-vo VNIRO, 1998.
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United States. Congress. House. Committee on Resources. Subcommittee on Fisheries Conservation, Wildlife, and Oceans. H.R. 3331, the Atlantic Highly Migratory Species Conservation Act; H.R. 3390, the Atlantic Highly Migratory Species Conservation Act; H.R. 3516, to prohibit pelagic longline fishing in the exclusive economic zone in the Atlantic Ocean: Hearing before the Subcommittee on Fisheries Conservation, Wildlife, and Oceans of the Committee on Resources, House of Representatives, One Hundred Sixth Congress, second session, February 8, 2000, Washington, DC. U.S. G.P.O., 2000.
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H. R. 3331, the Atlantic Highly Migratory Species Conservation Act; H. R. 3390, the Atlantic Highly Migratory Species Conservation Act; H. R. 3516, to Prohibit Pelagic Longline Fishing in the Exclusive Economic Zone in the Atlantic Ocean. Independently Published, 2020.
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Menz, A. The Fishery Potential and Productivity of the Pelargic Zone of Lake Malawi/Niassa. Natural Resources Institute, 1995.
Find full textBook chapters on the topic "Pelagic zone"
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Ulloa, Osvaldo, Jody J. Wright, Lucy Belmar, and Steven J. Hallam. "Pelagic Oxygen Minimum Zone Microbial Communities." In The Prokaryotes. Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-30123-0_45.
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Benndorf, J., R. Koschel, and F. Recknagel. "The pelagic zone of Lake Stechlin." In Lake Stechlin. Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5506-6_16.
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Vinogradov, A. K., Yu I. Bogatova, and I. A. Synegub. "Pelagic Zone Subsystem of the Marine Ports Aquatories." In Ecology of Marine Ports of the Black and Azov Sea Basin. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63062-5_2.
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Dokulil, Martin, Alois Herzig, and Albert Jagsch. "Trophic relationships in the pelagic zone of Mondsee, Austria." In Trophic Relationships in Inland Waters. Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0467-5_22.
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Parkhomenko, Aleksandr V. "Phosphorus Fluxes in the Pelagic Zone of the Black Sea." In Coastal Research Library. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-57577-3_19.
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Dupouy, C. "Discoloured Waters in the Melanesian Archipelago (New Caledonia and Vanuatu). The Value of the Nimbus-7 Coastal Zone Colour Scanner Observations." In Marine Pelagic Cyanobacteria: Trichodesmium and other Diazotrophs. Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-015-7977-3_11.
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Azam, F., B. C. Cho, D. C. Smith, and M. Simon. "Bacterial Cycling of Matter in the Pelagic Zone of Aquatic Ecosystems." In Large Lakes. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84077-7_24.
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Schindler, Daniel E., Stephen R. Carpenter, Kathryn L. Cottingham, et al. "Food Web Structure and Littoral Zone Coupling to Pelagic Trophic Cascades." In Food Webs. Springer US, 1996. http://dx.doi.org/10.1007/978-1-4615-7007-3_9.
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Povero, P., M. Chiantore, C. Misic, G. Budillon, and R. Cattaneo-Vietti. "Land forcing controls pelagic-benthic coupling in Adelie Cove (Terra Nova Bay, Ross Sea)." In Ecological Studies in the Antarctic Sea Ice Zone. Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-59419-9_17.
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Duhamel, Guy. "The Pelagic Fish Community of the Polar Frontal Zone off the Kerguelen Islands." In Fishes of Antarctica. Springer Milan, 1998. http://dx.doi.org/10.1007/978-88-470-2157-0_5.
Full textConference papers on the topic "Pelagic zone"
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Takhteev, V. V., D. A. Batranin, I. O. Eropova, E. B. Govorukhina, and S. I. Didorenko. "NIGHT MIGRATION COMPLEX OF ENDEMIC AMFIPOD AS AN INDICATOR OF ENVIRONMENTAL STATE BAIKAL LAKE." In V International Scientific Conference CONCEPTUAL AND APPLIED ASPECTS OF INVERTEBRATE SCIENTIFIC RESEARCH AND BIOLOGICAL EDUCATION. Tomsk State University Press, 2020. http://dx.doi.org/10.17223/978-5-94621-931-0-2020-37.
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With the ongoing anthropogenic eutrophication of the Lake Baikal there is an increase in the abundance not only of aquatic vegetation, but also organismsconsumers. As consumers of vegetable detritus are crustaceans – amphipods, which, by eating detritus, partially reduce the pollution of the lake with rotting organic matter. A significant increase in their number is evidenced by the increase in the abundance of amphipods in the nocturnal migratory complex in the coastal pelagic zone.
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Peterman, David, Charles N. Ciampaglio, and Christopher C. Barton. "THE HYDROSTATICS OF PALEOZOIC ORTHOCONIC CEPHALOPODS (NAUTILOIDEA) WITH IMPLICATIONS FOR EARLY COLONIZATION OF THE PELAGIC ZONE." In 52nd Annual North-Central GSA Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018nc-311874.
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Kaglyan, A. E., D. I. Gudkov, S. I. Kireev, L. P. Yurchuk, and M. A. Menkovska. "LEVELS OF RADIONUCLIDE CONTAMINATION OF FISH OF VERSHYNA LAKE IN THE CHORNOBYL EXCLUSION ZONE." In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022v/4.2/s16.59.
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The levels of specific activity of 90Sr and 137Cs in fish of one of the most polluted reservoirs of the Chornobyl Exclusion Zone (ChEZ) - Vershyna Lake. During the research period from 2011 to 2021 for all studied fish of the lake. The peak ranges of the specific activity of radionuclides are noted at the level of 32960-213300 (average value 67832-22936) Bq/kg for 90Sr and 838-25907 (4811-569) Bq/kg for 137Cs. It is shown that at the current stage, the specific activity of 90Sr in the ichthyofauna of the lake exceeds the permissible levels, which are accepted in Ukraine for fish products in more than 942-6094, and 137Cs - in 6-173 times. The 90Sr/137Cs ratio in lake fish is in the range of 3-108. The distribution of radionuclides in the organs and tissues of silver crucian carp is given. Estimated dose rate of fish irradiation of the Vershyna Lake. As shown by the results of studies of the ichthyofauna of Vershyna Lake , the maximum average dose rate irradiation was noted in representatives of bentophagous Prussian carp (149,5-12,1 ?Gy/h), the minimum - in the pelagic Sunbleak (56,2-5,1 ?Gy/h). It was noted, that 90Sr is the dominant radionuclide in the formation of the total radiation dose of fish from Vershyna Lake (in contrast to all other investigated reservoirs of the ChEZ).
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Kostoski, Goce, and Orhideja Tasevska. "SEASONAL DYNAMICS OF THE PLANKTON ROTIFERA, CRUSTACEA (COPEPODA AND CLADOCERA) COMMUNITY FROM THE PELAGIAL OF LAKE PRESPAN - KAZAN LOCATION." In 53rd Annual Conference of the Serbian Water Pollution Control Society. SERBIAN WATER POLLUTION CONTROL SOCIETY, 2024. http://dx.doi.org/10.46793/voda24.187k.
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Within the PONT project, the diversity of representatives of Rotifera, Crustacea (Copepoda and Cladocera), which are the most abundant food for ichthyofauna, was monitored. Their saprobiological affiliation and abundance was determined. The material was collected from the pelagic zone, Kazan locality, and processed by standard limnological methods. The presence of 9 representatives of Rotifera, 5 Cladocera, 3 Copepoda and one representative of Mollusca was noted It is characteristic for all species that they are found in waters rich in calcium and waters with an acidic environment. While, in terms of electrical conductivity, they are found both in waters with low and in waters with high electrical conductivity. Based on the saprobiological affiliation of the species, they range from 1.1 to 2.2 saprobity index
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Chi, Sang-Bum, Wonnyon Kim, Cheong-Kee Park, Chanmin Yoo, Youngtak Ko, and Jai-Woon Moon. "Relationship Between Manganese Nodule Distribution and Deep-Sea Sediment Properties in the Northeastern Pacific." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83773.
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In order to identify a potential relationship between the spatial distribution of Mn-nodule and deep-sea sediment properties in the Clarion-Clipperton fracture zone of the northeastern Pacific, physico-chemical properties of deep-sea sediments and photos of sea-floor are analyzed. In general, sediment types in the area show dramatic changes with latitude. Compared to the middle sector (8–12°N) covered with biogenic siliceous sediments, the northern (16–17°N) and southern (5–6°N) areas are dominated by pelagic red clays and calcareous sediments, respectively. Such a difference in sediment types probably produces regional-scale variations in Mn-nodule occurrence with latitude (5–17°N) along longitude (131.5°W). According to the photographic examination, manganese nodules are well exposed on the sea floor in the latitude of >8°N. In connection with the dominant oceanic environment, such observation indicates that calcareous sediments cover the diagenic nodules due to higher primary productivity and sedimentation rate in the latitude of <8°N. In addition, sediments in the latitude of 8–12°N show relatively high shear strength. Considering the operation of miner and environmental effect, highly consolidated B2 and C1 areas (8–12°N), showing higher nodule contents and relatively lower primary productivity, are the most plausible site for commercial mining.
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Ishida, Hiroshi, Nobuhiro Maeda, Tetsuya Miwa, et al. "Characteristics of the Environment Around a Massive Sea-Floor Sulfide Area in the Okinawa Trough." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49987.
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It is necessary to carry out a proper environmental impact assessment for not only the sea-floor massive sulfide area where a special hydrothermal-vent chemosynthetic ecosystem is observed, but also its surrounding area. This paper shows provisional results of the environmental baseline survey conducted at the Izena Cauldron in 2009. Environmental conditions differed clearly between inside and outside of the Cauldron. In the inside area, a high turbidity layer was recognized at ca. 200 m above the sea-floor. In the bottom layer close to the hydrothermal active region, water temperature was slightly higher than the surrounding area with the lower pH, higher concentrations of both carbon dioxide and the dissolved Mn. Inside the Cauldron, the sulfur isotope ratio of the sediment close to a sea-floor massive sulfide was similar to that of the hydrothermal sulfate. In addition, heavy metal concentrations of the sediment were higher inside than outside of the Cauldron. Especially, concentrations of Cd, As and Hg were as high as poisonous levels. These results show the possibility that most of the chemical materials derived from hydrothermal vent remain in the Cauldron. Pelagic shrimps of the family Oplophoridae were widely distributed in the bottom layer inside the Cauldron. The biomass of benthic shrimps which belong to infraorder Caridea was higher inside than outside of the Cauldron. These higher biomass was likely caused by the abundant organic matter. This hypothesis was reinforced by the result of the mooring sediment trap (placed at ca. 50 m above the seafloor) experiment, which demonstrated that the settling particle in the Cauldron was supplied from not only the euphotic zone but also the hydrothermal-vent ecosystem.
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Yamazaki, Tetsuo, Yuta Yamamoto, Naoki Nakatani, and Rei Arai. "Preliminary Economic Evaluation of Deep-Sea REE Mud Mining." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23141.
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Deep-sea rare-earth element-rich mud (REE mud) distributes in pelagic clayey sediment column on ocean seafloor at 4,000–6,000 m deep. The thickness ranges 5–80 m and the burial depth 0–100 m. The REE contents range 600–2,250 ppm in the Pacific and one of the richest, maximum 6,500ppm, has been found near Minami-Tori-shima (Marcus Is.) in Japan’s exclusive economic zones. Assuming a conventional hydraulic excavation and lifting methods, the economy of REE mud mining near Minami-Tori-shima (Marcus Is.) is preliminary examined. Because the contents of valuables in REE mud are low and the ones of wastes are high, quite little chance for the economically feasible mining has been found from the result.
Reports on the topic "Pelagic zone"
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Kittu, Leila R., and Ulf Riebesell. Report on data of ocean alkalinization mesocosm experiment in a temperate zone neritic system. OceanNets, 2025. https://doi.org/10.3289/oceannets_d5.7.
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We hypothesize that responses of natural food webs will depend on the method of OAE applied (CO2-equilibrated vs. non-equilibrated), and on the environmental setting (nutrient conditions, community composition, etc.). During a 54-day mesocosm experiment in May – July 2022, we tested the potential biogeochemical impacts of Ocean Alkalinity Enhancement (OAE) on a temperate, mesotrophic pelagic community in the Raunefjord south of Bergen, Norway. Ten in situ pelagic mesocosms each with a volume of ~55 m3 were deployed in the fjord, enclosing a natural post-bloom plankton community. A CO2 non-equilibrated alkalinity manipulation was achieved by adding sodium hydroxide (NaOH) to create a delta alkalinity gradient of 0, 150, 300, 450 and 600 μmol L-1 in two sets of five mesocosms each. Following the notion that diatoms may be enhanced under silicate-based OAE while coccolithophores would benefit under calcium-based OAE, the experiment was designed to test this hypothesis. To simulate the application of olivine/silicate-based (Mg2SiO4) versus calcium-based (CaCO3) minerals for ocean alkalinity enhancement, corresponding amounts of MgCl2 and CaCl2 were added to the respective mesocosms of each set. This report gives a summary of the datasets so far analyzed.
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Couperus, Bram M., Joey Volwater, Ties Maris, Serdar Sakinan, Lodewijk van Walraven, and Ralf van Hal. Pelagic fish in the Dutch coastal zone : Phase 1 of Monitoring, Research, Nature Enhancement, Species Protection (MONS). Wageningen Marine Research, 2024. https://doi.org/10.18174/679233.
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Couperus, Bram, Serdar Sakinan, and Dirk Burggraaf. Small pelagic fish and zooplankton in the Dutch coastal surf zone during the EGS-II survey in 2017-2018. Wageningen Marine Research, 2020. http://dx.doi.org/10.18174/525593.
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Schling, Maja, Roberto Guerrero Compeán, Nicolás Pazos, Allison Bailey, Katie Arkema, and Mary Ruckelshaus. The Economic Impact of Sargassum: Evidence from the Mexican Coast. Inter-American Development Bank, 2022. http://dx.doi.org/10.18235/0004470.
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This paper assesses the local economic impact of pelagic Sargassum seaweed washed ashore in tourism-heavy coastal zones in the Mexican State of Quintana Roo. The study relies on a carefully designed Geographic Information Systems (GIS) dataset of monthly observations from 2016 to 2019 for 157 beach segments. The dataset comprises an innovate measure of Sargassum seaweed presence, remotely sensed nighttime light intensity as a proxy of economic growth, as well as information on key infrastructure, sociodemographic and beach characteristics. We apply a fixed-effects regression model that controls for general time trends and unobserved, time-invariant differences across observations. We estimate that the presence of Sargassum in a beach segment reduces nighttime light intensity by 17.5%, representing an approximate 11.6% decrease in gross local product. Considering that impacts of Sargassum on local economic activity may be delayed due to reputational effects, our analysis finds that significant lagged effects can be detected up until 12 months after Sargassum was detected on the shoreline. These effect sizes range between a 5.9 and a 9.9% reduction in gross local product. Various robustness checks, including an adjusted measurement of Sargassum and the consideration of potential spatial correlation across beach segments, indicate that estimated impacts are consistently significant and negative across numerous specifications. For one of most tourism-dependent regions in the world, the recurrent influx is one of the most threatening manifestations of climate change. Our research is the first to robustly quantify the economic impact of Sargassum, and highlights the extent to which economic activity is negatively affected by the accumulation of seaweed and how these effects persist over time. The next important step is for both public and private sectors to invest in forecasting systems and containment strategies as well as engage in cleanup efforts to mitigate severe accumulations, inducing economic resilience in coastal communities.