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Penton, P. M., G. K. Davoren, W. A. Montevecchi, and D. W. Andrews. "Beach and demersal spawning in capelin (Mallotus villosus) on the northeast Newfoundland coast: egg developmental rates and mortality." Canadian Journal of Zoology 90, no. 2 (February 2012): 248–56. http://dx.doi.org/10.1139/z11-132.
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Timing of spawning and site selection in fish are important fitness-related traits that ultimately influence reproductive success. Capelin ( Mallotus villosus (Müller, 1776)), a key forage fish in the north Atlantic, spawn eggs that adhere to sediments on beaches and in demersal (deep-water) habitats throughout their geographic range, resulting in divergent thermal regimes for the incubating eggs. We compare the timing and duration of spawning of capelin and its influence on the developmental and survival rates of eggs between a beach and a demersal spawning site on the northeast Newfoundland coast in 2004 and 2005. Spawning events at the beach were at least 10 days earlier and shorter (2–3 days) relative to the demersal site (8–12 days). Hourly and mean daily incubation temperatures at the beach were higher and more variable relative to the demersal site, resulting in two distinct developmental strategies: low to high mortality and rapid development (beach) versus low mortality and slow development (demersal). Higher egg mortality at beach sites was explained by higher and more variable temperatures and potentially limited oxygen replenishment relative to demersal sites. The divergent biology of beach and demersally spawned eggs suggest that each will respond differently to environmental change and, thus, require different approaches for successful management.
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Angin, Robet Perangin, NFN Sulistiono, Rahmat Kurnia, Achmad Fahrudin, and Ali Suman. "Struktur komunitas sumber daya ikan demersal berdasarkan kedalaman perairan di Laut Cina Selatan (WPP-NRI 711) [Community structure of demersal fish resources based on the depth of the waters in the South China Sea (Indonesia Fisheries Management Zone 711)]." Jurnal Iktiologi Indonesia 17, no. 1 (August 22, 2017): 67. http://dx.doi.org/10.32491/jii.v17i1.305.
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Information on distribution and community structure of demersal fish resources are important to be known as an input to the management of demersal fisheries. This study aimed to analyze the diversity and distribution of demersal fish resources based on the differences in the depth of the waters and the linkages to the environment. Research conducted in the South China Sea in May to June 2015 by operating a trawl gear in the station preset. The method of analysis of demersal fish diversity use some ecological indices i.e Margalef species richness index, Shannon-Wiener diversity index, Pielou evenness index, and Simpson dominance index. The ecological index value then associated with environmental conditions, using principal component analysis. Distribution of the ecological index indicated the stability of communities demersal fish resources getting better with the increase of depth. The most affected to the level of species richness and distribution of demersal fish were the parameters of depth, temperature and salinity, while the abundance distribution of fishes were associated with dissolved oxygen, and water transparency. The implication, that the water environmental conditions greatly affected the distribution and abundance of demersal fish. AbstrakInformasi mengenai persebaran dan struktur komunitas sumber daya ikan demersal penting sebagai bahan masukan untuk pengelolaan perikanan demersal. Penelitian ini bertujuan untuk menganalisis tingkat keanekaragaman dan persebaran sumber daya ikan demersal berdasarkan perbedaan kedalaman perairan, serta keterkaitannya dengan lingkungan. Penelitian dilaksanakan di Laut Cina Selatan pada bulan Mei sampai Juni 2015 dengan mengoperasikan alat tangkap pukat ikan di stasiun yang telah ditetapkan. Metode analisis keanekaragaman hayati ikan demersal menggunakan beberapa indeks ekologi yaitu indeks kekayaan jenis Margalef, indeks keanekaragaman Shannon-Wiener, indeks keseragaman Pielou, dan indeks dominansi Simpson. Nilai indeks ekologi tersebut kemudian dikaitkan dengan kondisi lingkungan, menggunakan analisis komponen utama. Hasil penelitian menunjukkan tingkat kestabilan komunitas sumber daya ikan demersal semakin baik seiring dengan meningkatnya kedalaman. Kedalaman, suhu, dan salinitas merupakan parameter yang paling memengaruhi tingkat kekayaan jenis serta persebaran sumber daya ikan demersal, sedangkan persebaran kelimpahan ikan sangat terkait dengan oksigen terlarut dan kecerahan perairan. Implikasinya, kondisi lingkungan perairan sangat memengaruhi persebaran dan kelimpahan ikan demersal.
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Purwanto, Purwanto. "POTENTIAL PRODUCTION OF DEMERSAL FISH STOCK IN THE MALACCA STRAIT OF INDONESIA." Indonesian Fisheries Research Journal 21, no. 1 (June 1, 2015): 45. http://dx.doi.org/10.15578/ifrj.21.1.2015.45-52.
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Malacca Strait is one of the main fishing areas for demersal fishery in Indonesia. To support the management of that fishery, an assessment of the demersal fish stock was conducted. This study estimated that the maximum sustainable yield and the optimal catch per unit effortof demersal fishery in the Malacca Strait were about 106.8 thousand tons/year and 28.5 tons per unit of Danish seine, respectively, resulting from the operation of 3,752 Danish seines. Unfortunately, fishing effort was higher than its optimum level and the fish stock was over-exploited since 2003. To recover the demersal fish stock to its optimum level and to ensure the optimal fish production from demersal fishery in the Malacca Strait, it was necessary to reduce fishing effort at about 67% from its level in 2011.
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Rocha, Adélia R. M., Ana Paula M. Di Beneditto, Inácio A. Pestana, and Cristina Maria M. de Souza. "Isotopic profile and mercury concentration in fish of the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil." Neotropical Ichthyology 13, no. 4 (December 2015): 723–32. http://dx.doi.org/10.1590/1982-0224-20150047.
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ABSTRACT The aim of this study was to evaluate the isotopic profile and mercury (Hg) concentrations in fish (carnivores, omnivores and detritivores) in the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil. Carbon (δ13C) isotopic analyses revealed that pelagic and benthonic sources are part of the feeding of the fish from the different guilds (-14.0 to -24.8 ‰). The benthic sources are usually enriched in δ13C (-16.9‰, from watershed runoff) compared to pelagic sources because the phytoplankton, important primary producer that supports several pelagic chains, has δ13C signature lighter (-23.9‰). The nitrogen (δ15N) isotopic signatures indicated that most guilds were at the same trophic position (10.0 to 15.5 ‰), except for pelagic omnivorous fish, which had a lower trophic position. Niche overlap was observed among pelagic and demersal carnivorous fish, demersal omnivorous fish, and demersal detritivorous fish. The lower isotopic niche breadth of pelagic carnivorous fish reveals the specialized resource use by this guild. Hg concentrations (ng g-1 dry weight) differed significantly between demersal carnivorous fish (185.3 dry weight; 27.8 wet weight) and demersal omnivorous fish (277.9 dry weight; 41.7 wet weight) and between pelagic omnivorous fish (197.2 dry weight; 29.6 wet weight) and demersal omnivorous fish due to (1) differences in food sources: guilds that fed on bottom resources were more affected by contamination because the sediment is an important Hg accumulator in the study area, and (2) because of its trophic positions. Considering that the fish consumed prey of similar trophic positions, the guilds did not show a well-defined food hierarchy. Therefore, in this study, there was no clear relationship between Hg and δ15N.
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Shuntov, V. P., and O. S. Temnykh. "LONG-TERM AVERAGE BIOMASS AND DOMINANT FISH SPECIES IN THE BOTTOM BIOTOPES OF THE OKHOTSK SEA. PART 1. COMPOSITION AND QUANTITATIVE RATIO OF SPECIES ON SHELVES IN DIFFERENT AREAS OF THE SEA." Izvestiya TINRO 193 (July 9, 2018): 3–19. http://dx.doi.org/10.26428/1606-9919-2018-193-3-19.
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Composition of the demersal fish community in the bottom biotopes of 14 biostatistical areas of the Okhotsk Sea is considered on the data of 9,189 standard trawl catches obtained in 95 expeditions conducted by Pacific Fish. Res. Center (TINRO) in 1977–2010. The most abundant fish species in each area are ranked by biomass. The total demersal fish biomass is estimated as 9583.0 . 103 t (2124.9 . 103 t without pollock and herring). The most numerous demersal species are: pacific cod Gadus macrocephalus, yellowfin sole Limanda aspera, pacific sand lance Ammodytes hexapterus, great sculpin Mycocephalus polyacanthocephalus, and saffron cod Eleginus gracilis.
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Cohen, Daniel M., Nigel R. Merrett, and Richard L. Haedrich. "Deep-Sea Demersal Fish and Fisheries." Copeia 1999, no. 3 (August 2, 1999): 843. http://dx.doi.org/10.2307/1447628.
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Rouleau, C., C. Gobeil, and H. Tjälve. "Cadmium accumulation in coastal demersal fish." Marine Ecology Progress Series 311 (April 13, 2006): 131–43. http://dx.doi.org/10.3354/meps311131.
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H.-J., Wagner, and Mattheus U. "Pineal organs in deep demersal fish." Cell and Tissue Research 307, no. 1 (January 1, 2002): 115–27. http://dx.doi.org/10.1007/s00441-001-0482-y.
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Johnson, Andrew F., Maria Valls, Joan Moranta, Stuart R. Jenkins, Jan G. Hiddink, and Hilmar Hinz. "Effect of prey abundance and size on the distribution of demersal fishes." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 1 (January 2012): 191–200. http://dx.doi.org/10.1139/f2011-138.
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Many demersal fish species rely on benthic prey as food sources for part of, or in some cases, all of their life history. We investigated the relationships between prey and predator abundance and prey size and predator mouth gape size for nine demersal fish species. Of the species analysed, four showed a significant positive increase in abundance with increasing prey abundance. Prey size is thought to be an important parameter for demersal fish that are limited in their feeding potential by their mouth gape size, as it influences consumption rate and energy expenditure while foraging. The relationship between prey size and mouth gape was investigated using both stomach content data and prey availability data. Stomach content analysis revealed positive relationships between maximum prey size and predator mouth gape size for six of the species. Indications of prey size selectivity were only seen in the environment for European hake ( Merluccius merluccius ), highlighting the potential importance of prey size over prey abundance for this species. The results demonstrate that prey abundance and size are of significance for some demersal fish species feeding primarily on benthos and will help in defining habitat requirements of demersal fish species.
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Suprapto, Suprapto. "INDEKS KEANEKARAGAMAN JENIS IKAN DEMERSAL DI PERAIRAN TARAKAN." BAWAL Widya Riset Perikanan Tangkap 6, no. 1 (December 31, 2015): 47. http://dx.doi.org/10.15578/bawal.6.1.2014.47-53.
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Perairan Tarakan termasuk daerah penangkapan sumber daya ikan demersal dan udang cukup potensial di KalimantanUtara. Tingginya tingkat eksploitasi ikan demersal dengan menggunakan trawlmenyebabkan keragaman jenisnya rendah. Penelitian ikan demersal dilakukan di perairan Tarakan pada bulanMei,Agustus dan Nopember 2012. Tujuan penelitian adalah untuk memperoleh indeks keanekaragaman jenis ikan demersal. Data spesies ikan demersal dikumpulkan dari hasil tangkapan jaring trawl yang dioperasikan oleh kapal motor 20GT dengan metode sapuan area. Hasil penelitian menunjukkan bahwa jumlah taksa ikan demersal sebanyak 86 spesies yang tergolong kedalam45 famili. Komposisi jenis hasil tangkapan trawl didominasi oleh famili Leiognathidae (ikan petek), Sciaenidae (ikan gulama), Harpadontidae (ikan nomei),Apogonidae (ikan serinding) danMullidae (ikan bijinangka). Status keanekaragaman jenis termasuk dalamkategori sedang dengan indeks “Shanon-Wiener” (H’)berkisar antara 1,7-2,5 sedangkan indeks kekayaan “Margalef” (R1 ) berkisar antara 7-8. Penyebaran spesies ikan demersal bersifat sedang dengan indeks kemerataan jenis (E) rata-rata sebesra 0,5.Kelimpahan ikan demersal tidak ada yang dominan, ditunjukkan oleh nilai indeks kemerataan jenis “Pielou” (E) rata-rata sebesar 0,4.Tarakan and adjacent waters is one of potentially fishing ground of demersal fish resources in north Kalimantan. High exploitation by trawler tend to decreased of biodiversity of demersal fish in this area. Research has been conducted in the waters of Tarakan duringMay, August and November 2012. The aim of this research is to get species diversity indices of demersal fish, which is expected to be useful as one of the data capacity for sustainable fisheries management policy. Data obtained by using trawl fishing gear with a sweept area method.The results showed that demersal fish species richness 86 species, belonging to 45 families. Dominant family are Leiognathidae, Sciaenidae, Harpadontidae, Apogonidae andMullidae. Result of analysis indicate that species diversity in Tarakan waters in the medium category. Status of biodiversity consist of: range value diversityindices “Shanon-Wiener” (H’) was 1.7 to 2.5; species richness indices of “Margalef” (R1 ) are between 7-8; evenness indices of “Pielou” (E 1) was 0,5 and dominant indices “Pielou” (E) an average of 0.4.
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Piontkovski, Sergey A., H. E. Hamed S. Al-Oufi, and Nadir M. Al-Abri. "Fish landings and Oman shelf area." Journal of Agricultural and Marine Sciences [JAMS] 21 (January 1, 2016): 25. http://dx.doi.org/10.24200/jams.vol21iss0pp25-32.
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Data from five field surveys carried out along the shelf in the 20-250m depth range and historical data on artisanal fishery were analyzed. A positive linear relationship between the demersal fish biomass and the shelf area was pronounced for a certain (intermediate) stratum only: 50-100m. No statistical link was found for the strata above it (25-50m) and beneath it (100-150m and 150-250m). The pronounced one was associated with the low boundary of the oxygen minimum zone impinging on the shelf. Annual landings of demersal fishes in the region with the largest shelf area exceeded landings in the region with the smallest area by as much as 1.6 times. The ratio of small pelagic to demersal fish landings decreased as a factor of 10, from small to large shelf areas.
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Tuapetel, Friesland, Delly DP Matrutty, and Welem Waileruny. "Diversity of Demersal Fish Resources in Ambon Island Waters." Jurnal Iktiologi Indonesia 18, no. 3 (February 9, 2019): 223. http://dx.doi.org/10.32491/jii.v18i3.315.
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The waters surrounding Ambon Island is a potential fishing gound for demersal fish resources, yet information regarding species diversity is still slightly understood. This research aimed to analyze the diversity of species and size of demersal fish around Ambon Island oceans. Data was collected based on experimental fishing using fish trap at two locations, in northern and southern waters of Ambon Island. The data were collected by experimental capture using fishing gear at two locations, namely northern waters (March-April 2015) and south of Ambon Island (July-October 2016). Methods of demersal resource diversity analysis are several ecological indexes i.e. Shannon-Wiener diversity index, Pielou uniformity index, and Simpson's dominance index. The result showed that 21 family and 57 species with details of 35 species in the northern waters and 32 species in the southern water. Species diversity based on Shannon-Wiener Index (H´) ranged between 1,61-3,10 while species evenness index (E) was around 0,83-0,95. The abundance of demersal fish was not dominated by any fish species, showed by the average Simpson index of dominant (D) around 0,05-0,26.AbstrakPerairan Pulau Ambon termasuk daerah penangkapan sumber daya ikan demersal yang potensial, namun informasi ke-anekaragamannya masih sangat sedikit. Penelitian ini bertujuan untuk menganalisis kekayaan jenis dan keanekara-gaman ikan demersal di perairan Pulau Ambon. Pengambilan data dilakukan dengan cara penangkapan eksperimental dengan menggunakan alat tangkap bubu pada dua lokasi yakni perairan utara (Maret-April 2015) dan perairan selatan Pulau Ambon (Juli-Oktober 2016). Metode analisis keanekaragaman sumber daya ikan demersal menggunakan bebe-rapa indeks ekologi yakni indeks keanekaragaman Shannon-Wiener, indeks keseragaman Pielou, dan indeks dominansi Simpson. Hasil penelitian menunjukkan bahwa di perairan Pulau Ambon teridentifikasi 21 famili dan 57 spesies de-ngan rincian 35 spesies di perairan utara dan 32 spesies di perairan selatan. Status keanekaragaman jenis indeks Shannon-Wiener (H´) berkisar 1,61-3,10 sedangkan indeks keseragaman jenis (E) sebesar 0,83-0,95. Kelimpahan ikan demersal tidak ada yang dominan, ditunjukkan oleh indeks dominan Simpson (D) sebesar 0,05-0,26.
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Nurulludin, Nurulludin, Thomas Hidayat, and Asep Mamun. "KEPADATAN STOK IKAN DEMERSAL DAN UDANG DI SAMUDERA HINDIA BARAT SUMATERA PADA MUSIM PERALIHAN II." Jurnal Penelitian Perikanan Indonesia 22, no. 3 (January 16, 2017): 139. http://dx.doi.org/10.15578/jppi.22.3.2016.139-146.
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Kepadatan stok ikan merupakan indikasi dari potensi perikanan di suatu wilayah yang sangat penting diketahui. Tujuan tulisan ini membahas tentang laju tangkap, kepadatan stok dan perkiraan biomassa ikan demersal serta udang. Penelitian sumber daya ikan demersal dan udang di Samudera Hindia Barat Sumatera dilakukan dengan menggunakan Kapal Riset Baruna Jaya IV (1.200 GT) pada bulan Oktober dan November 2015 (Musim peralihan II). Penghitungan kepadatan stok menggunakan metode sweept area dengan panjang tali ris atas dari jaring trawl 36 m, kecepatan kapal saat menarik jaring berkisar 2,5 – 3 knot, lama penarikan jaring maksimal 1 jam. Perairan Samudera Hindia Barat Sumatera terdiri dari 151 spesies yang tergolong dalam 59 famili. Famili ikan demersal yang dominan tertangkap (5 besar), yaitu Leiognathidae sebesar 23,6 %, Trichiuridae 9,8%, Haemulidae 8,0%, Engraulididae 6,6%, dan Polynemidae 6,05%. Famili udang yaitu Penaeidae (79,08%), Scyllaridae 19,49%, dan Solenoceridae 1,43%. Rata-rata laju tangkap ikan demersal 205,80 kg/jam, dengan kepadatan stok 6,66 ton/km2 dan udang 2,30 kg/jam dengan kepadatan stok 0,053 ton/km2. Biomassa ikan demersal diperkirakan sebesar 470.122 ton dan udang 3.706 ton. Fish stock density is an index of stock abundance indicating the fish resources potential in a region. This paper discusses the catch rate, stock density and biomass estimates of the demersal fish and shrimp resources. Research on the demersal fish and shrimp resources in the Indian Ocean-Western Sumatera conducted using the Research Vessel Baruna Jaya IV (1200 GT) carried out during October and November 2015 (2nd intermonsoon season). Stock density was estimated through the swept area method. The trawl used has 36 m headrope, trawling speed of 2.5 - 3 knots, and maximum towing time was 1 hour. It was found that the fish resources in the waters of the Indian Ocean-Western Sumatera consisted of 151 species belonging to 59 families. The top five dominant fish families caught were Leiognathidae of 23.6%, Trichiuridae 9.8%, Haemulidae 8.0%, Engraulididae 6.6%, and Polynemidae 6.05%, while the shrimp families were Penaeidae of 79.08%, Scyllaridae 19.49%, and Solenoceridae 1.43%. The average catch rate of demersal fish was 205.80 kg/hour, with a stock density of 6.66 tons/km2 and shrimp of 2.30 kg/hour with a stock density of 5.3 kgs/km2. The estimated biomass of demersal fish was 470,122 tons and shrimp was 3,706 tons.
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Angin, Robet Perangin, Sulistiono Sulistiono, Rahmat Kurnia, Achmad Fahrudin, and Ali Suman. "KEPADATAN DAN STRATIFIKASI KOMPOSISI SUMBER DAYA IKAN DEMERSAL DI LAUT CINA SELATAN (WPP – NRI 711)." Jurnal Penelitian Perikanan Indonesia 22, no. 3 (January 16, 2017): 161. http://dx.doi.org/10.15578/jppi.22.3.2016.161-172.
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Informasi distribusi kepadatan stok dan komposisi ikan demersal sangat penting untuk diketahui sebagai bahan masukan guna keberhasilan pengelolaan perikanan. Untuk itu dilakukan penelitian yang bertujuan untuk mengetahui komposisi, kepadatan stok dan sebaran sumber daya ikan demersal di Laut Cina Selatan. Penelitian dilaksanakan pada Mei sampai Juni 2015 dengan menggunakan scientific echosounder BIOSONICS DT-X dan frekuensi 120 KHz. Untuk verifikasi data akustik terutama komposisi jenis dilakukan pengoperasian trawl. Hasil penelitian menunjukkan komposisi jenis ikan demersal di Laut Cina Selatan meliputi 147 spesies dari 55 famili. Stratifikasi komposisi dikedalaman 20-30 m, 30-40 m, 40-50 m, 50-60 m, dan 60-70 m masing masing didominasi oleh ikan dari famili Leiognathidae, Lutjanidae, Nemipteridae, Tetraodontidae, dan Serranidae. Estimasi kepadatan stok sumber daya ikan demersal di Laut Cina Selatan berkisar antara 0,16 – 2,85 ton/km2 dengan rata-rata kepadatan 1,05 ton/km2. Information about density distribution and composition of demersal fish stocks is very important to be known as an input for the success of fisheries management. Current research aimed to determine the composition, stock density and distribution of demersal fish resources in the South China Sea. The research was conducted in May to June 2015 using scientific echosounder BIOSONICS DT-X and frequency of 120 KHz. Trawler sampling was done to verify the acoustic data, especially for species composition. The results show that the species composition of demersal fish in the South China Sea consisted of 147 species of 55 families. The stratification of the composition at the respective depth of 20-30 m, 30-40 m, 40-50 m, 50-60 m and 60-70 m, were dominated by fish families of Leiognathidae, Lutjanidae, Nemipteridae, Tetraodontidae, and Serranidae. The estimated stock density of demersal fish resources in the South China Sea ranged from 0.16 to 2.85 tonnes/km2 with the average of 1.05 tonnes / km2.
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Oktaviyani, Selvia, Mennofatria Boer, and Yonvitner. "ANALISIS DEGRADASI DAN DEPRESIASI SUMBERDAYA IKAN DEMERSAL PADA PERIKANAN DOGOL DI PERAIRAN SELAT SUNDA (Degradation and Depreciation Analysis of Demersal Fish Resources on Dogol Fisheries in Sunda Strait)." Marine Fisheries : Journal of Marine Fisheries Technology and Management 6, no. 2 (October 7, 2016): 119. http://dx.doi.org/10.29244/jmf.6.2.119-128.
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ABSTRACT<br /><br />Dogol is one type of fishing gear which is operated by fisherman in Sunda Strait with demersal fishes as dominant catches, such as goatfish, threadfin brean, ponyfish, Indian halibut and drums.The utilization was done throughout the year and without control can lead to overfishing. The aim of this research is to estimate degradation and the depreciation rate of demersal fish resources of dogol fisheries in Sunda Strait. This research was conducted on February until July 2014 in Coastal Fishing Port (PPP) Labuan, Pandeglang, Banten. Data was collected through interview and questionnaire methods to dogol fisherman and other stakeholders, as well as time series data from Ministry of Marine Affairs Pandeglang district. The results showed that the average value of degradation and depreciation rate of demersal fish resources were 0,26-0,42 and 0,26-0,43 respectively. Those values still below 0,5, it means that demersal fish resources on dogol fisheries in Sunda Strait has not been degraded and depreciation. But, the CPUE values tended to decrease, so was needed preventive action, such as restriction of fishing effort and increase the mesh size to preserve the sustainability of demersal fish resources.<br /><br />Keywords: Degradation, demersal fish, depreciation, dogol, Sunda Strait<br /><br />ABSTRAK<br /><br />Dogol merupakan salah satu jenis alat tangkap yang dioperasikan oleh nelayan di Perairan Selat Sunda dengan hasil tangkapan dominan yaitu ikan demersal seperti ikan biji nangka, kurisi, peperek, sebelah dan tigawaja. Kegiatan pemanfaatan yang dilakukan sepanjang tahun dengan tidak adanya pengontrolan dapat mengakibatkan tangkap lebih. Tujuan penelitian ini adalah untuk mengetahui laju degradasi dan laju depresiasi sumberdaya ikan demersal pada perikanan dogol di Perairan Selat Sunda. Penelitian dilaksanakan pada bulan Februari hingga Juli 2014 di Pelabuhan Perikanan Pantai (PPP) Labuan, Pandeglang, Banten. Pengumpulan data dilakukan melalui metode wawancara dan kuisioner terhadap nelayan dogol dan stakeholder lainnya serta data time series perikanan tangkap DKP Kabupaten Pandeglang. Hasil menunjukkan bahwa sumberdaya ikan demersal memiliki pola produksi yang berfluktuasi. Rata-rata nilai koefisien degradasi dan depresiasi sumberdaya ikan demersal adalah 0,26-0,42 dan 0,26-0,43 secara berurutan. Nilai-nilai tersebut masih dibawah 0,5, artinya sumberdaya ikan demersal pada perikanan dogol di Perairan Selat Sunda diduga belum mengalami degradasi dan depresiasi. Namun, nilai CPUE cenderung mengalami penurunan, sehingga diperlukan tindakan preventif seperti pembatasan upaya tangkap dan peningkatan ukuran mata jaring untuk menjaga kelestarian sumberdaya ikan demersal.<br /><br />Kata kunci: Degradasi, ikan demersal, depresiasi, dogol, Selat Sunda
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Kennedy, James, Sigurður Þ. Jónsson, Halldór G. Ólafsson, and Jacob M. Kasper. "Observations of vertical movements and depth distribution of migrating female lumpfish (Cyclopterus lumpus) in Iceland from data storage tags and trawl surveys." ICES Journal of Marine Science 73, no. 4 (December 23, 2015): 1160–69. http://dx.doi.org/10.1093/icesjms/fsv244.
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Abstract Lumpfish (Cyclopterus lumpus) is a high latitude species most abundant in Arctic and sub-Arctic waters of the North Atlantic. Vertical behaviour of this fish is unclear as it is often caught by both pelagic and demersal trawls. To gain greater insight into its behaviour, 41 female lumpfish caught during the Icelandic Groundfish Survey (IGFS) in March were tagged with data storage tags (DSTs); the IGFS finishes ∼1 week before the beginning of the lumpfish fishing season (20 March). Data retrieved from returned tags were compared with information on depth and distribution of catches of lumpfish from the IGFS. Thirteen tags were returned with days at liberty ranging from 20 to 61 d. Maximum depth recorded was 308 m (maximum depth of the tag) but based upon interpolation of temperature recordings, one fish may have descended to ∼418 m. Lumpfish displayed a range of vertical behaviours termed demersal, surface, and pelagic. During March, most exhibited either demersal or pelagic behaviour but the time spent in surface behaviour increased from March to April. During demersal behaviour, depth was rarely constant indicating the fish were not stationary. Both DST and catch data from the IGFS indicate that lumpfish exhibit diel patterns in vertical behaviour. As lumpfish frequently exhibit demersal behaviour, the use of the IGFS to monitor changes in abundance is justified. As lumpfish spend a significant amount of time in both the pelagic and demersal zone, they should be considered as a semi-pelagic (or semi-demersal) fish during this life stage/time of year.
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Moore, Cordelia H., Euan S. Harvey, and Kimberly P. Van Niel. "Spatial prediction of demersal fish distributions: enhancing our understanding of species–environment relationships." ICES Journal of Marine Science 66, no. 9 (August 18, 2009): 2068–75. http://dx.doi.org/10.1093/icesjms/fsp205.
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Abstract Moore, C. H., Harvey, E. S., and Van Niel, K. P. 2009. Spatial prediction of demersal fish distributions: enhancing our understanding of species–environment relationships. – ICES Journal of Marine Science, 66: 2068–2075. We used species distribution modelling to identify key environmental variables influencing the spatial distribution of demersal fish and to assess the potential of these species–environment relationships to predict fish distributions accurately. In the past, predictive modelling of fish distributions has been limited, because detailed habitat maps of deeper water (>10 m) have not been available. However, recent advances in mapping deeper marine environments using hydroacoustic surveys have redressed this limitation. At Cape Howe Marine National Park in southeastern Australia, previously modelled benthic habitats based on hydroacoustic and towed video data were used to investigate the spatial ecology of demersal fish. To establish the influence of environmental variables on the distributions of this important group of marine fish, classification trees (CTs) and generalized additive models (GAMs) were developed for four demersal fish species. Contrasting advantages were observed between the two approaches. CTs provided greater explained variation for three of the four species and revealed a better ability to model species distributions with complex environmental interactions. However, the predictive accuracy of the GAMs was greater for three of the four species. Both these modelling techniques provided a detailed understanding of demersal fish distributions and landscape linkages and an accurate method for predicting species distributions across unsampled locations where continuous spatial benthic data are available. Information of this nature will permit more-targeted fisheries management and more-effective planning and monitoring of marine protected areas.
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Hanchet, Stuart M., Andrew L. Stewart, Peter J. McMillan, Malcolm R. Clark, Richard L. O'Driscoll, and Michael L. Stevenson. "Diversity, relative abundance, new locality records, and updated fish fauna of the Ross Sea region." Antarctic Science 25, no. 5 (February 18, 2013): 619–36. http://dx.doi.org/10.1017/s0954102012001265.
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AbstractTwo surveys were carried out in the Ross Sea region during February and March 2004 and 2008 from the New Zealand RVTangaroa. Fishes were sampled on the continental shelf and slope of the Ross Sea, and on adjacent seamounts to the north, mainly using a large demersal fish trawl and a large mesopelagic fish trawl. Parts of the shelf and slope were stratified by depth and at least three random demersal trawls were completed in each stratum, enabling biomass estimates of demersal fish to be calculated. Fish distribution data from these two surveys were supplemented by collections made by observers from the toothfish fishery. A diverse collection of over 2500 fish specimens was obtained from the two surveys representing 110 species in 21 families. When combined with previous documented material this gave a total species list of 175, of which 135 were from the Ross Sea shelf and slope (to the 2000 m isobath). Demersal species-richness, diversity and evenness indices all decreased going from the shelf to the slope and the seamounts. In contrast, indices for pelagic species were similar for the slope and seamounts/abyss but were much lower for the shelf.
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Nordhagen, Anna, Abu Ansar Md Rizwan, Inger Aakre, Amalie Moxness Reksten, Lauren Michelle Pincus, Annbjørg Bøkevoll, Al Mamun, et al. "Nutrient Composition of Demersal, Pelagic, and Mesopelagic Fish Species Sampled Off the Coast of Bangladesh and Their Potential Contribution to Food and Nutrition Security—The EAF-Nansen Programme." Foods 9, no. 6 (June 3, 2020): 730. http://dx.doi.org/10.3390/foods9060730.
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Fish is a major part of the Bangladeshi diet, but data on the nutrient composition of marine fish species are sparse. Mesopelagic fish may be a new potential resource of food and nutrients; however, nutrient composition data are lacking. The aim of this study was to provide nutrient composition data of fish species sampled off the coast of Bangladesh and determine their potential contribution to recommended nutrient intakes (RNI). Seven species from the pelagic, mesopelagic, and demersal zones were sampled from the coast of Bangladesh with Dr. Fridtjof Nansen in 2018. Three pooled samples containing 15-840 individuals from each species were analysed at the Institute of Marine Research, Norway. The demersal species contained substantially lower concentrations of nearly all nutrients, whereas the mesopelagic species generally were more nutrient dense. All species, except for the demersal species Bombay duck (9% dry matter), were found to contribute ≥100% to the RNI of vitamin B12, eicosapentaenoic acid, docosahexaenoic acid, and selenium. All species, except for the demersal fish species, contributed ≥25% to the RNI of six or more nutrients. The data presented in this paper are an important contribution to the Bangladeshi food composition table and contribute to the understanding of fish as an important source of micronutrients.
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Zhao, Jing, Jie Cao, Siquan Tian, Yong Chen, and Shouyu Zhang. "Evaluating Sampling Designs for Demersal Fish Communities." Sustainability 10, no. 8 (July 24, 2018): 2585. http://dx.doi.org/10.3390/su10082585.
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Fish communities play an important role in determining the dynamics of marine ecosystems, while the evaluation and formulation of protective measures for these fish communities depends on the quality and quantity of data collected from well-designed sampling programs. The ecological model was used first to predict the distribution of the demersal fish community as the “true” population for the sampling design. Four sampling designs, including simple random sampling, systematic sampling, and stratified sampling with two sampling effort allocations (proportional allocation and Neyman allocation), were compared to evaluate their performance in estimating the richness and biodiversity indices of the demersal fish community. The impacts of two different temperature change scenarios, uniform temperature and non-uniform temperature increase on the performance of the sampling designs, were also evaluated. The proportional allocation yielded the best estimates of fish community richness and biodiversity relative to a synthetic baseline. However, its performance was not always robust relative to the simulated temperature change. When the water temperature changed unevenly, systematic sampling tended to perform the best. Thus, it is important to adjust the strata for a stratified sampling when the habitat experiences large changes. This suggests that we need to carefully evaluate the appropriateness of stratification when temperature change-induced habitat changes are large enough to result in substantial changes in the fish community.
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Momigliano, Paolo, Henri Jokinen, Antoine Fraimout, Ann-Britt Florin, Alf Norkko, and Juha Merilä. "Extraordinarily rapid speciation in a marine fish." Proceedings of the National Academy of Sciences 114, no. 23 (May 22, 2017): 6074–79. http://dx.doi.org/10.1073/pnas.1615109114.
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Divergent selection may initiate ecological speciation extremely rapidly. How often and at what pace ecological speciation proceeds to yield strong reproductive isolation is more uncertain. Here, we document a case of extraordinarily rapid speciation associated with ecological selection in the postglacial Baltic Sea. European flounders (Platichthys flesus) in the Baltic exhibit two contrasting reproductive behaviors: pelagic and demersal spawning. Demersal spawning enables flounders to thrive in the low salinity of the Northern Baltic, where eggs cannot achieve neutral buoyancy. We show that demersal and pelagic flounders are a species pair arising from a recent event of speciation. Despite having a parapatric distribution with extensive overlap, the two species are reciprocally monophyletic and show strongly bimodal genotypic clustering and no evidence of contemporary migration, suggesting strong reproductive isolation. Divergence across the genome is weak but shows strong signatures of selection, a pattern suggestive of a recent ecological speciation event. We propose that spawning behavior in Baltic flounders is the trait under ecologically based selection causing reproductive isolation, directly implicating a process of ecological speciation. We evaluated different possible evolutionary scenarios under the approximate Bayesian computation framework and estimate that the speciation process started in allopatry ∼2,400 generations ago, following the colonization of the Baltic by the demersal lineage. This is faster than most known cases of ecological speciation and represents the most rapid event of speciation ever reported for any marine vertebrate.
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FUJITA, TOSHIHIKO. "Community Ecology of Offshore Demersal Fish Assemblages." BENTHOS RESEARCH 1993, no. 44 (1993): 1–17. http://dx.doi.org/10.5179/benthos1990.1993.44_1.
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Wilhelmsson, Dan, Torleif Malm, and Marcus C. Öhman. "The influence of offshore windpower on demersal fish." ICES Journal of Marine Science 63, no. 5 (January 1, 2006): 775–84. http://dx.doi.org/10.1016/j.icesjms.2006.02.001.
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Abstract A significant expansion of offshore windpower is expected in northwestern Europe in the near future. Little is known about the impacts it may have on the marine environment. Here, we investigate the potential for wind turbines to function as artificial reefs and fish aggregation devices (FADs), i.e. whether they would locally increase fish densities or alter fish assemblages. Fish communities and habitat composition were investigated using visual transects at two windpower farms off the southeastern coast of Sweden, central Baltic Sea. Fish abundance was greater in the vicinity of the turbines than in surrounding areas, while species richness and Shannon–Wiener diversity (H′) were similar. On the monopiles of the turbines, fish community structure was different, and total fish abundance was greater, while species richness and diversity (H′) were lower than on the surrounding seabed. Blue mussels and barnacles covered most of the submerged parts of the turbines. On the seabed, more blue mussels and a lesser cover of red algae were recorded around the power plants than elsewhere. Results from this study suggest that offshore windfarms may function as combined artificial reefs and fish aggregation devices for small demersal fish.
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Suwartiningsih, Nurul, Indri Setyowati, and Resa Astuti. "Microplastics in Pelagic and Demersal Fishes of Pantai Baron, Yogyakarta, Indonesia." Jurnal Biodjati 5, no. 1 (May 30, 2020): 33–49. http://dx.doi.org/10.15575/biodjati.v5i1.7768.
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Yogyakarta is the second-largest producer of plastic waste in Indonesia. Plastic waste in the waters can be degraded into microplastics that can enter the body of a fish. This study aimed to determine the presence of microplastics in the digestive tract of several species of fish in Pantai Baron, Yogyakarta, Indonesia. This research was an exploratory research conducted in April-September 2019 at Pantai Baron, Yogyakarta. Two species of each pelagic and demersal fish samples were taken by buying fish caught by fishermen. The digestive tract of fish was extracted with 10% KOH, filtered, then visual identification. Microplastic types were estimated by FT-IR spectrometry. The amount of microplastic of all fishes was done by Kruskal-Wallis test while the number of microplastics of the two categories of fish was compared with the Mann-Whitney test. A correlation analysis was carried out between the length of the fish, the weight of the digestive tract, and the number of microplastics found. Microplastic shape, color, size, and type data were analyzed descriptively. A total of 78 of the 80 (97.50%) fish from four species studied contained microplastics with a total number as many as 3,651 (mean 45.60 ± 44.31 microplastic/individual). About 100% of pelagic fish samples contained microplastics, while only 95% of demersal fish samples contained microplastics. Mann-Whitney test results showed the number of microplastic/ individual was significantly different between pelagic and demersal fish (p <0.05). The most dominant shape of microplastic was fiber (53.14%), film (36.97%) and fragments (9.89%). The type of polymers detected was polyamide. The results showed that pelagic fish swallowed more microplastics than demersal fish did because of the microplastic nature that is lightweight and floats. Microplastic characteristic data can be used to estimate the main source of microplastic pollution in Pantai Baron so it can be managed appropriately.
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Toledo, Pamela, Audrey M. Darnaude, Edwin J. Niklitschek, Vilma Ojeda, Raphaël Voué, Félix P. Leiva, Maylis Labonne, and Cristian B. Canales-Aguirre. "Partial migration and early size of southern hake Merluccius australis: a journey between estuarine and oceanic habitats off Northwest Patagonia." ICES Journal of Marine Science 76, no. 4 (December 6, 2018): 1094–106. http://dx.doi.org/10.1093/icesjms/fsy170.
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Abstract Partial migration is a key adaptive strategy, increasingly observed across multiple taxa. To investigate partial migration and life-cycle diversity of Merluccius australis in northwestern Patagonia, we analysed isotopic (δ13C, δ18O) and elemental (11B, 23Na, 24 Mg, 55Mn, 86Sr, 138Ba) compositions of otoliths from juveniles, sub-adults, and adults to identify nursery origins, habitats used, and migratory behaviours of multiple cohorts (1990–2005). Influence of early size upon migration was assessed by comparing back-calculated sizes at demersal recruitment between resident and migratory adults. Although partial migration occurred at both estuarine and oceanic nursery habitats, migratory behaviour was more frequent in fish of estuarine origin (59%) than in fish of oceanic origin (17%). Adults of estuarine origin dominated both estuarine (92%) and oceanic (77%) sampling areas. Although we found no significant differences in size at demersal recruitment between oceanic-resident and oceanic-migratory fish, a strong relationship between size at demersal recruitment and migratory behaviour appeared in fish of estuarine origin, whose probability of migration increased from 5% to 95% as demersal recruitment size increased from 18.8 to 23.6 cm. Further research on M. australis life cycle is required to incorporate sub-population processes into the stock assessment and management models being used for this overexploited species.
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Amezcua, Felipe, Alfonso Portillo, and Felipe Amezcua-Linares. "Feeding habits of the toothed flounder Cyclopsetta querna (Paralichthyidae) of the south-east Gulf of California." Journal of the Marine Biological Association of the United Kingdom 91, no. 6 (June 2, 2010): 1225–30. http://dx.doi.org/10.1017/s0025315410000603.
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Feeding habits of the toothed flounder Cyclopsetta querna caught in the south-east Gulf of California were studied. Specimens were collected via demersal fish surveys. Results of this study show that C. querna is a predator that focuses on fish inhabiting the bottom and in particular on tonguefish (Symphurus sp.), midshipman fish (Porichthys sp.) and moray eels (Muraenidae). The diet of the toothed flounder did not vary significantly throughout the period of study, and neither size nor sex-related variations in diet composition were observed. Simpson's index indicates a limited trophic niche breadth with a diet dominated by a limited number of taxa. The estimated TROPH value for C. querna is similar to that estimated for other demersal top predators from the studied area; therefore, the toothed flounder can be considered a top carnivore from the demersal community in the Gulf of California.
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Hislop, J. R. G. "The demersal fishery in the Clyde Sea Area." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 90 (1986): 423–37. http://dx.doi.org/10.1017/s0269727000005133.
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SynopsisData from the Clyde demersal fishery during the period 1960 to 1984 are presented. Annual landings of demersal species at Chde ports in recent years have ranged from 4000 to 10,000 tonnes, with a first sale value of £2–5 million. In the 1960s the fishery was undertaken mainly by seine-net vessels, but the present fleet consists largely of dual-purpose light/Nephrops trawlers. The demersal fishery is seasonal and during the winter and spring there is an influx of ‘stranger’ vessels. Five species (cod, whiting, saithe, hake and haddock) make up more than 80% of the demersal landings from the Clyde. The landings of saithe have fluctuated very considerably during the period under review. Other relatively important species are dogfish, plaice, skate and ray and angler fish. In general the Clyde fishery represents only a small proportion of the total Scottish landings but in recent years landings of hake from the Clyde grounds have averaged approximately 40% of the Scottish hake total. The Clyde demersal fishery depends to a large extent on young fish and both the total annual landings and the relative importance of the principal species fluctuate from year to year in response to variations in the strength of the recruiting year classes. The catch rates of the principal species vary greatly throughout the year. Although there is no conclusive evidence that the Clyde populations are self-contained, all the major species are known to spawn within or close to the area and tagging experiments have suggested that there may not be much mixing between Clyde fish and those from surrounding areas. This may in part, however, reflect the fact that fishing intensity within the Clyde is high and fish are recaptured before they have had time to leave the area. For management purposes, the Clyde demersal stocks are included in ICES Sub-area VI.
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Machias, A., I. Karakassis, M. Giannoulaki, KN Papadopoulou, CJ Smith, and S. Somarakis. "Response of demersal fish communities to the presence of fish farms." Marine Ecology Progress Series 288 (2005): 241–50. http://dx.doi.org/10.3354/meps288241.
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BARRERA-ORO, ESTEBAN. "The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the southern Scotia Arc and west Antarctic Peninsula." Antarctic Science 14, no. 4 (December 2002): 293–309. http://dx.doi.org/10.1017/s0954102002000111.
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The role of fish in the Antarctic food web in inshore and offshore waters is analysed, taking as an example the coastal marine communities of the southern Scotia Arc (South Orkney Islands and South Shetland Islands) and the west Antarctic Peninsula. Inshore, the ecological role of demersal fish is more important than that of krill. There, demersal fish are major consumers of benthos and also feed on zooplankton (mainly krill in summer). They are links between lower and upper levels of the food web and are common prey of other fish, birds and seals. Offshore, demersal fish depend less on benthos and feed more on zooplankton (mainly krill) and nekton, and are less accessible as prey of birds and seals. There, pelagic fish (especially lantern fish) are more abundant than inshore and play an important role in the energy flow from macrozooplankton to higher trophic levels (seabirds and seals). Through the higher fish predators, energy is transferred to land in the form of fish remains, pellets (birds), regurgitation and faeces (birds and seals). However, in the general context of the Antarctic marine ecosystem, krill (Euphausia superba) plays the central role in the food web because it is the main food source in terms of biomass for most of the high level predators from demersal fish up to whales. This has no obvious equivalent in other marine ecosystems. In Antarctic offshore coastal and oceanic waters the greatest proportion of energy from the ecosystem is transferred to land directly through krill consumers, such as flying birds, penguins, and seals. Beside krill, the populations of fish in the Antarctic Ocean are the second most important element for higher predators, in particular the energy-rich pelagic Myctophidae in open waters and the pelagic Antarctic silver fish (Pleuragramma antarcticum) in the high Antarctic zone. Although the occurrence of these pelagic fish inshore has been poorly documented, their abundance in neritic waters could be higher than previously believed.
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Godbold, J. A., D. M. Bailey, M. A. Collins, J. D. M. Gordon, W. A. Spallek, and I. G. Priede. "Putative fishery-induced changes in biomass and population size structures of demersal deep-sea fishes in ICES Sub-area VII, Northeast Atlantic Ocean." Biogeosciences 10, no. 1 (January 25, 2013): 529–39. http://dx.doi.org/10.5194/bg-10-529-2013.
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Abstract. A time series from 1977–1989 and 2000–2002 of scientific trawl surveys in the Porcupine Seabight and adjacent abyssal plain of the NE Atlantic was analysed to assess changes in demersal fish biomass and length frequency. These two periods coincide with the onset of the commercial deep-water fishery in the late 1970s and the onset of the regulation of the fishery in the early 2000's, which allowed us to investigate changes in the relationship between total demersal fish biomass and depth between the pre- and post commercial fishing periods, as well as changes in the biomass (kg km−2) depth distribution and length frequency distribution of the most dominant fish species. Our results show a decline in total demersal fish biomass of 36% within the depth range of the commercial fishery (< 1500 m). Whilst there were significant declines in target (e.g. Coryphaenoides rupestris decreased by 57%) and non-target (e.g. C. guentheri and Antimora rostrata) species, not all species declined significantly. Changes in the overall length-frequency distribution were detected for 5 out of the 8 dominant species occupying depth ranges both within and outside the maximum depth for commercial trawling. This suggests that whilst there is evidence for likely fishery impacts on the biomass distribution of the demersal fish population as a whole, species-specific impacts are highly variable. It is clear that changes in population structure can extend beyond the depth at which fishing takes place, highlighting the importance for also considering the indirect effects on deep-sea fish populations.
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Godbold, J. A., D. M. Bailey, M. A. Collins, J. D. M. Gordon, W. A. Spallek, and I. G. Priede. "Putative fishery-induced changes in biomass and population size structures of demersal deep-sea fishes in ICES Sub-area VII, North East Atlantic Ocean." Biogeosciences Discussions 9, no. 8 (August 10, 2012): 10757–83. http://dx.doi.org/10.5194/bgd-9-10757-2012.
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Abstract. A time series from 1977–1989 and 2000–2002 of scientific trawl surveys in the Porcupine Seabight and adjacent Abyssal Plain of the NE Atlantic was analysed to assess changes in demersal fish biomass and length frequency. These two periods coincide with the on-set of the commercial deep-water fishery in the late 1970s and the on-set of the regulation of the fishery in the early 2000's and allowed us to investigate changes in the relationship between total demersal fish biomass and depth between the pre- and post commercial fishing periods, changes in the biomass (kg km2) depth distribution and length frequency distribution of the most dominant fish species. Our results show a decline in total demersal fish biomass of 36% within the depth range of the commercial fishery (< 1500 m). Whilst there were significant declines in target (e.g. Coryphaenoides rupestris decreased by 57%) and non-target (e.g. Coryphaenoides guentheri and Antimora rostrata) species, not all species declined significantly. Changes in the overall length-frequency distribution were detected for 2 species (Coryphaenoides armatus, Synaphobranchus kaupii), but only at depths greater than 1800 m (outside the maximum depth for commercial trawling). This suggests that whilst there is evidence for likely fisheries impacts on the biomass distribution of the demersal fish population as a whole, species-specific impacts are highly variable. It is clear that changes in population structure can extend beyond the depth at which fishing takes place, highlighting the importance for also considering the indirect effects on deep-sea fish populations.
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Mason, James, A. W. Newton, D. W. McKay, and J. A. M. Kinnear. "Fisheries in the Orkney area." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 87, no. 1-2 (1985): 65–81. http://dx.doi.org/10.1017/s0269727000004164.
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SynopsisFishing has long played an important part in the economy of Orkney. Local vessels are all small, and fish predominantly inshore for shellfish. Demersal and pelagic fish are abundant in the offshore waters around Orkney, but these exposed waters can be fished only by large vessels from more distant ports, so that few fish are landed in the islands.Gadoids, especially haddock, cod and whiting, form the bulk of the demersal fish caught at Orkney. Stocks of all three are giving cause for concern, with declining spawning stock biomass and reduced recruitment. With the coming of processing, more local landing of demersal fish might occur. The closure of the herring fishery in 1977 was followed by a great expansion of mackerel fishing, but with the lifting of the ban west of 4CW in 1981, herring catches have once again become valuable. Because of fishing pressure, landings of both species are subject to quota restrictions.In recent years, the traditional fisheries for lobsters and crabs have been supplemented by a new fishery for scallops. Lobster stocks are now under some pressure. Conditions around Orkney appear suited to farming filter-feeding bivalve molluscs, and culture and marketing of Pacific oysters has started.
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Furness, Evie, and Richard K. F. Unsworth. "Demersal Fish Assemblages in NE Atlantic Seagrass and Kelp." Diversity 12, no. 10 (September 23, 2020): 366. http://dx.doi.org/10.3390/d12100366.
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Global fisheries are in decline, calling for urgent evidence-based action. One such action is the identification and protection of fishery-associated habitats such as seagrass meadows and kelp forests, both of which have suffered long-term loss and degradation in the North Atlantic region. Direct comparisons of the value of seagrass and kelp in supporting demersal fish assemblages are largely absent from the literature. Here, we address this knowledge gap. Demersal fish were sampled using a baited camera to test for differences between habitats in (1) the species composition of the fish assemblages, (2) the total abundance and species richness of fishes, and (3) the abundances of major commercial species. Seagrass and kelp-associated fish assemblages formed two significantly distinct groupings, which were driven by increased whiting (Merlangius merlangus) and dogfish (Scyliorhinus canicula) presence in seagrass and higher abundances of pollock (Pollachius pollachius) and goby (Gobiusculus flavescens) in kelp. The abundance, diversity, and species richness did not change significantly between the two habitats. We conclude that seagrass and kelp do support unique demersal fish assemblages, providing evidence that they have different ecological value through their differing support of commercial fish species. Thus, this study improves the foundation for evidence-based policy changes.
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Farriols, M. Teresa, Francesc Ordines, Pierluigi Carbonara, Loredana Casciaro, Manfredi Di Lorenzo, Antonio Esteban, Cristina Follesa, et al. "Spatio-temporal trends in diversity of demersal fish assemblages in the Mediterranean." Scientia Marina 83, S1 (January 9, 2020): 189. http://dx.doi.org/10.3989/scimar.04977.13a.
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The high species richness, coupled with high proportion of endemism, makes the Mediterranean one of the world’s ‘biodiversity hotspots’. However, the continuous increase in fisheries in the last few decades has led to the overexploitation of their main commercial stocks. Using fishery-independent data collected under the framework of the MEDITS trawl surveys carried out over the last 20 years, we study the demersal fish diversity pattern in the Mediterranean at a large spatial and temporal scale to determine whether it is being affected by the general fishing overexploitation of the demersal resources. The detected diversity trends are compared with the spatio-temporal variation in bottom trawl fishing effort in the Mediterranean. Our results show a stability and even recovery of demersal fish diversity in the Mediterranean together with higher diversity values on the continental shelves of the Balearic Islands, Sardinia, Sicily and the Aegean Sea. At large temporal and spatial scales, the high diversity of demersal assemblages in the Mediterranean is associated with a reduction in bottom trawl fishing effort. The inclusion of species other than target ones through diversity indices is important in the implementation of an ecosystem-based fisheries management.
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Riley, Stephen C., Edward F. Roseman, S. Jerrine Nichols, Timothy P. O'Brien, Courtney S. Kiley, and Jeffrey S. Schaeffer. "Deepwater Demersal Fish Community Collapse in Lake Huron." Transactions of the American Fisheries Society 137, no. 6 (November 2008): 1879–90. http://dx.doi.org/10.1577/t07-141.1.
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Ekau, Werner. "Demersal fish fauna of the Weddell Sea, Antarctica." Antarctic Science 2, no. 2 (June 1990): 129–37. http://dx.doi.org/10.1017/s0954102090000165.
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The demersal fish fauna of the southern and eastern Weddell Sea is described. The following species were recorded for the first time in this area: Aethotaxis mitopteryx, Bathyraja eatoni, B. Maccaini, B. sp2 (FAO-list), Bathydraco marri, Dissostichus mawsoni, Macrourus holotrachys, Muraenolepis sp., Notothenia coriiceps, Notothenia kempi, Psilodraco spec. and Trematomus nicolai. In terms of biomass the dominant species on the very narrow eastern continental shelf were Chionodraco myersi (49%), Trematomus eulepidotus (11%), C. hamatus (7%), T. lepidorhinus (6%), Pagetopsis maculatus (5%) and T. scotti, Cryodraco antarcticus, Cygnodraco mawsoni and Pleuragramma antarcticum (4% each). The highest density of individuals and greatest biomass was found between 400 and 650 m water depth. Here, C. myersi, T. eulepidotus and T. lepidorhinus dominated the catches. The shallow shelf area was inhabited by smaller species such as T. scotti, T. centronotus, P. maculatus, Artedidraco skottsbergii, A. shackletoni, and Prionodraco evansii. In the southern Weddell Sea Akarotaxis nudiceps, Dolloidraco longedorsalis, Gerlachea australis, Pleuragramma antarcticum, and Trematomus loennbergi were dominant. Members of the Channichthyidae occurred only occasionally, most of these are Dacodraco hunteri. The biomass of the demersal fish fauna was estimated to be 0.3 to 1.6 t km−2 on the Vestkapp shelf and 0.1 to 0.4 t km−2 for Gould Bay. Biomass values greater than 1.0 t km−2 were found at the shelf edge.
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Myers, Ransom A., and Noel G. Cadigan. "Density-Dependent Juvenile Mortality in Marine Demersal Fish." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 8 (August 1, 1993): 1576–90. http://dx.doi.org/10.1139/f93-179.
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We examine the hypothesis that population variability is created and regulated in the juvenile stage for demersal marine fish. Juvenile mortality is examined for 17 populations of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), yellowtail flounder (Pleuronectes ferrugineus), and sole (Solea vulgaris) in the North Sea, Irish Sea, Barents Sea, Baltic Sea, and Northwest Atlantic. A latent variable covariance analysis of recruitment time series with measurement error is used to test hypotheses. We found strong evidence of density-dependent mortality within cohorts during the juvenile stage for cod, plaice, sole, and whiting; density-dependent mortality appears to be related to the log of juvenile abundance. There is evidence of negative autocorrelation between adjacent cohorts of cod; this pattern is consistent with density-dependent mortality between adjacent cohorts. The autocorrelations are positive for the flatfish examined. It is possible to obtain estimates of estimation error variances for populations if there are multiple research surveys of the same population. We conclude that the juvenile stage is very important for population regulation in most species but that the source of the variability in year class strength is in the larval stage or very early juvenile stage.
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Kaiser, M. J., M. Bergmann, H. Hinz, M. Galanidi, R. Shucksmith, E. I. S. Rees, T. Darbyshire, and K. Ramsay. "Demersal fish and epifauna associated with sandbank habitats." Estuarine, Coastal and Shelf Science 60, no. 3 (July 2004): 445–56. http://dx.doi.org/10.1016/j.ecss.2004.02.005.
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Suprapto, Suprapto. "INDEKS KEANEKARAGAMAN HAYATI IKAN DEMERSAL DI PERAIRAN ARAFURA." Jurnal Penelitian Perikanan Indonesia 14, no. 3 (February 7, 2017): 321. http://dx.doi.org/10.15578/jppi.14.3.2008.321-335.
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Penelitian tentang indeks keanekaragaman hayati ikan demersal telah dilakukan pada periode tahun 2001 sampai dengan 2006 menggunakan sarana kapal riset KM. Mutiara, KM. Bawal Putih I, dan KM. Mandidihang 02. Data spesies ikan demersal dikumpulkan dari hasil pengambilan contoh penangkapan menggunakan alat tangkap jaring pukat dasar dengan metode sapuan area. Pengambilan contoh dilakukan di sub lahan tepian Laut Arafura (sekitar daerah Mappi sampai dengan Dolak) dan sub lahan tengah Laut Arafura (sekitar Kepulauan Aru). Hasil analisis menunjukkan bahwa status kekayaan jenis ikan demersal sampai dengan tahun 2006 memiliki 149 spesies yang tergolong dalam 71 famili. Ikan-ikan yang cenderung memiliki jumlah individu terbanyak adalah kelompok famili ikan petek (Leiognathidae), gerot-gerot (Pomadasyidae), dan gulamah (Scianidae). Tingkat keanekaragaman jenis ikan demersal di perairan Arafura termasuk dalam kategori sedang. Kondisi komunitas bersifat labil dan cenderung mengalami penurunan. Status keanekaragaman hayati sampai dengan tahun 2006 memiliki indeks keanekaragaman jenis Shanon-Wiener (H’) berkisar 2,22 sampai dengan 2,79; indeks kekayaan jenis Margalef (R1 ) berkisar 4,84 sampai dengan 11,23; indeks keragaman Hill number (N1) berkisar 9,2 sampai dengan 16,3 dan indeks kemerataan jenis Pielou (E) berkisar 0,54 sampai dengan 0,56. Study on biodiversity indices of demersal fish was conducted in the period of 2001 until 2006 by using research vessel MV. MUTIARA, MV. BAWAL PUTIH I, and MV. MANDIDIHANG 02. Species data of demersal fish were collected from fishing samples by using bottom trawl with swept area method. Sampling location in the waters shore of Arafura Sea with sub area Mappi to Dolak and middle area of Arafura Sea (around of Aru Island). Result indicates that status of richness species of demersal fish till year 2006 of 149 species belongging to 71 families were recorded. Dominant families were Leiognathidae, Pomadasyidae, and Scianidae. From diversity analysis it also indicates that species diversity index in the Arafura Sea was at mid level. Condition of fish community was likely labile and the trend of it was decreasing. Index of biodiversity up to 2006 Shanon-Wiener (H’) was 2.22 until 2.79; species richness indices of Margalef (R1 ) were 4.84 until 1.23, diversity number Hill (N1) 9.2 until 16.3, and evenness indices of Pielou (E 1) were 0.54 until 0.56.
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Gordon, J. D. M., O. A. Bergstad, and P. L. Pascoe. "The influence of artificial light on the capture of deep-water demersal fish by bottom trawling." Journal of the Marine Biological Association of the United Kingdom 82, no. 2 (April 2002): 339–44. http://dx.doi.org/10.1017/s0025315402005532.
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Lights were attached to the headline of a bottom trawl during a series of tows at 1000 m depth in the Rockall Trough (north-east Atlantic). There was no significant difference in the overall numerical abundance of demersal fish between the trawl catches with light and the controls with no light. A principal components analysis based on the total fish catch between the experimental and the control stations showed no segregation. At the individual species level significant differences in catch rate were found for eight species. These are discussed in relation to the small amount of available information on the visual systems of deep-sea demersal fish and their diet.
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López-López, Lucía, Izaskun Preciado, Begoña Villamor, Francisco Velasco, Magdalena Iglesias, Enrique Nogueira, Jose Luis Gutierrez-Zabala, and Ignacio Olaso. "Is juvenile anchovy a feeding resource for the demersal community in the Bay of Biscay? On the availability of pelagic prey to demersal predators." ICES Journal of Marine Science 69, no. 8 (July 12, 2012): 1394–402. http://dx.doi.org/10.1093/icesjms/fss117.
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Abstract López-López, L., Preciado, I., Villamor, B., Velasco, F., Iglesias, M., Nogueira, E. Gutierrez-Zabala, J. L., and Olaso, I. 2012. Is juvenile anchovy a feeding resource for the demersal community in the Bay of Biscay? On the availability of pelagic prey to demersal predators. – ICES Journal of Marine Science, 69: . The role that juvenile anchovy (Engraulis encrasicolus) play as a food resource for the demersal community in the southern Bay of Biscay is assessed using 21 years of anchovy abundance data and demersal predator diets. During the study period, a total of 26 fish and elasmobranch species preyed on anchovy either frequently or occasionally. Predators with a crustacean-based diet targeted the smaller anchovy individuals. The size range of anchovy juveniles (centred at 7.5–8.9 cm) was comparable to that of the largest nektonic–benthic crustaceans, but generally smaller than other demersal and pelagic fish prey. Hake (Merluccius merluccius) and megrim (Lepidorhombus whiffiagonis) were the predators that consumed the highest number of anchovy, one of the main prey items driving the variability of their diets. Anchovy consumption conformed only partially to the abundance of anchovy in the southern Bay of Biscay, suggesting that factors other than abundance might condition its availability to demersal predators. Prey size could be one of them, as the size of the anchovy preyed on proved to be significantly smaller than the individuals collected with bottom trawls. However, other factors, such as the vertical position of the shoals of anchovy juveniles, could also constrain anchovy availability to demersal predators.
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Goldman, Sarah F., and George R. Sedberry. "Feeding habits of some demersal fish on the Charleston Bump off the southeastern United States." ICES Journal of Marine Science 68, no. 2 (June 25, 2010): 390–98. http://dx.doi.org/10.1093/icesjms/fsq064.
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Abstract Goldman, S. F. and Sedberry, G. R. 2011. Feeding habits of some demersal fish on the Charleston Bump off the southeastern United States. – ICES Journal of Marine Science, 68: 390–398. The feeding habits of several demersal fish on the upper continental slope were investigated to determine the trophic relationships of these ecologically dominant and commercially important species, and to determine food sources for slope fish off the southeastern United States. Stomach contents were examined from 534 fish, including wreckfish (Polyprion americanus), barrelfish (Hyperoglyphe perciformis), and red bream (Beryx decadactylus). Fish fed on 46 prey taxa, and there were dietary differences among predators. Wreckfish predominantly consumed teleost fish and squid; barrelfish had a diet dominated by pelagic tunicates and some mesopelagic fish and squid; red bream consumed mainly fish, squid, and crustaceans. Seasonal shifts in diet were observed in all three species. Many of the prey items encountered were vertically migrating organisms, which are a critical link between surface waters and the slope ecosystem.
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Gaertner, J. C. "Seasonal organization patterns of demersal assemblages in the Gulf of Lions (north-western Mediterranean Sea)." Journal of the Marine Biological Association of the United Kingdom 80, no. 5 (October 2000): 777–83. http://dx.doi.org/10.1017/s0025315400002745.
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The seasonal organization patterns of demersal assemblages (fish and cephalopods) in the Gulf of Lions were investigated on the basis of a set of bottom trawl surveys. The use of Partial Triadic Analysis (PTA) provided a detailed representation of: (1) the common part of the spatial organization of demersal assemblages at seasonal scale; and (2) the seasonal variability of each species around this common structure. During the course of the study, demersal assemblages exhibited a strong seasonal stability in their organization patterns and only few species showed a strong seasonal variation in their spatial distribution. Demersal assemblages of the Gulf of Lions were structured primarily on the basis of a non depth coast–open sea gradient, which occurred from the coast to the midshelf region. The influence of depth on the structure of fish assemblages appeared to be only of limited importance and mainly restricted to the continental slope area. The PTA combined with contouring technics could be used to improve our knowledge of community structuring factors, and offers a theoretical framework to assess the reproducibility of multispecies structures.
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Labropoulou, Mary, and Costas Papaconstantinou. "Community structure and diversity of demersal fish assemblages: the role of fishery." Scientia Marina 68, S1 (April 30, 2004): 215–26. http://dx.doi.org/10.3989/scimar.2004.68s1215.
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Alemany, Daniela, Oscar O. Iribarne, and Eduardo M. Acha. "Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic." ICES Journal of Marine Science 70, no. 1 (October 26, 2012): 123–34. http://dx.doi.org/10.1093/icesjms/fss166.
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Abstract Alemany, D., Iribarne, O. O., and Acha, E. M. 2013. Effects of a large-scale and offshore marine protected area on the demersal fish assemblage in the Southwest Atlantic. – ICES Journal of Marine Science, 70:123–134. There are few extensive and offshore located marine protected areas (MPAs) in the world oceans and their performance is still being debated. We evaluated the effects of a large-scale offshore MPA located on the Southwest Atlantic Patagonian Shelf (43°S 63°W) on the demersal fish assemblage. Compliance of the Patagonian MPA was assessed by analysing eight years of satellite vessel monitoring system (VMS; 2000–2008) data, which showed compliance and fishing effort concentrated near the protection boundaries. MPA effects were studied by employing a five year database collected by a scientific research vessel in protected and fishing locations, before and after the MPA establishment. We assessed 152 scientific trawling stations using multivariate analysis of fish assemblage structure, fish abundance (discriminating target and non-target species), and mean size and proportion of juveniles of the target species (Argentine hake, Merluccius hubbsi). The identified MPA effects were a trend towards increasing abundance of the demersal fish assemblage, the target and non-target fish species, and hake juvenile size, and a higher proportion of juveniles aged 2+ inside the MPA. These positive trends support the case for offshore, large-scale MPAs.
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Artero, Céline, Simon Marchetti, Eric Bauer, Christophe Viala, Claire Noël, Christopher Koenig, Rachel Berzins, and Luis Lampert. "High-Resolution Acoustic Cameras Provide Direct and Efficient Assessments of Large Demersal Fish Populations in Extremely Turbid Waters." Applied Sciences 11, no. 4 (February 22, 2021): 1899. http://dx.doi.org/10.3390/app11041899.
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Monitoring fish species populations in very turbid environments is challenging. Acoustic cameras allow work in very poor visibility but are often deployed as a fixed observation point, limiting the scope of the survey. A BlueView P900-130 acoustic camera was deployed in rocky marine habitats off the coast of French Guiana in order to assess the total abundance, size structure and spatial distribution of a demersal fish population. The relevancy of using an acoustic camera to achieve these three objectives was evaluated by comparing acoustic data to those obtained from fishing surveys. The detection and identification of large demersal fish species were possible with the shape and size of the acoustic signal and acoustic shadow silhouette as well as swimming behavior. Mobile surveys combined with stationary surveys increased the probability of distinguishing individuals from inanimate objects. Estimated total length based on the acoustic signal underestimated the actual length of fish measured on deck, but the data showed the same trends in spatial and temporal variation. Acoustic cameras overcame the extreme lack of visibility by increasing knowledge of fish use of habitat, therefore providing much more efficiency in the effort, more accurate data on the abundance, size structure and spatial distribution than the fishing method. Thus, despite few limitations, acoustic camera surveys are far superior to fishing surveys in evaluating large demersal fish stock status.
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Borges, Lisa, Alain F. Zuur, Emer Rogan, and Rick Officer. "Modelling discard ogives from Irish demersal fisheries." ICES Journal of Marine Science 63, no. 6 (January 1, 2006): 1086–95. http://dx.doi.org/10.1016/j.icesjms.2006.03.017.
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Abstract Annual discard ogives were estimated using generalized additive models (GAMs) for four demersal fish species: whiting, haddock, megrim, and plaice. The analysis was based on data collected on board commercial vessels and at Irish fishing ports from 1995 to 2003. For all species the most important factors influencing annual discard ogives were fleet (combination of gear, fishing ground, and targeted species), mean length of the catch and year, and, for megrim, also minimum landing size. The length at which fish are discarded has increased since 2000 for haddock, whiting, and plaice. In contrast, discarded length has decreased for megrim, accompanying a reduction in minimum landing size in 2000.
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Demestre, Montserrat, Pilar Sánchez, and Pere Abelló. "Demersal fish assemblages and habitat characteristics on the continental shelf and upper slope of the north-western Mediterranean." Journal of the Marine Biological Association of the United Kingdom 80, no. 6 (December 2000): 981–88. http://dx.doi.org/10.1017/s0025315400003040.
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Continental shelf and upper slope fish communities were studied along the Catalan coast based on 66 experimental bottom otter trawls. A total of 79 demersal fish species were studied by means of cluster analysis and multi-dimensional scaling (MDS) ordination for community structure. Analysis revealed the existence of five major location clusters. Similarity percentage analysis (SIMPER) was determined by comparing the dissimilarity between two groups of samples using the discriminating species. Geomorphological characteristics, bottom substratum and depth showed direct influences on species assemblages. High correlation between the biotic data samples and depth was observed. The fish species assemblages identified five main demersal fish associations which corresponded with the five location clusters and with five benthic sediments (mud of the upper slope, sand and gravel, mud of the shelf, muddy-sand and sand with rocky outcrops).
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Gislason, Henrik, John G. Pope, Jake C. Rice, and Niels Daan. "Coexistence in North Sea fish communities: implications for growth and natural mortality." ICES Journal of Marine Science 65, no. 4 (May 1, 2008): 514–30. http://dx.doi.org/10.1093/icesjms/fsn035.
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Abstract Gislason, H., Pope, J. G., Rice, J. C., and Daan, N. 2008. Coexistence in North Sea fish communities: implications for growth and natural mortality. – ICES Journal of Marine Science, 65: 514–530. For a fish community to persist over time, all species must be able on average to replace themselves on a one-for-one basis over their lifetime. We use this principle and a size-based equilibrium model where asymptotic length is used as a functional trait to investigate how natural mortality should scale with size within and across pelagic and demersal species of North Sea teleosts. The model predicts natural mortality to scale with body length raised to a power of −1.66 at current levels of exploitation. Additionally, natural mortality of demersal species should be proportional to asymptotic length raised to a power of 0.80, so generating a higher natural mortality at a given length for large species than for small ones. The model also suggests that the exponent in the scaling of the von Bertalanffy growth parameter K with asymptotic length should be more negative for pelagic than for demersal species. We test our results by analysing independent estimates of predation mortality, the scaling of maximum recruitment per unit of spawning-stock biomass with asymptotic length, and the general relationship between K and asymptotic length for demersal and pelagic families of fish. All tests are consistent with our modelling results.
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Greenstreet, Simon P. R., Helen M. Fraser, Stuart I. Rogers, Verena M. Trenkel, Stephen D. Simpson, and John K. Pinnegar. "Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community." ICES Journal of Marine Science 69, no. 1 (January 1, 2012): 8–22. http://dx.doi.org/10.1093/icesjms/fsr188.
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Abstract Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.