Journal articles on the topic 'Demersal specie'
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Miotto, Maiara Larissa, Barbara Maichak de Carvalho, Henry Louis Spach, and Edison Barbieri. "ICTIOFAUNA DEMERSAL NA ALIMENTAÇÃO DO GAIVOTÃO (LARUS DOMINICANUS) EM UM AMBIENTE SUBTROPICAL." Ornitología Neotropical 28 (April 12, 2017): 27–36. http://dx.doi.org/10.58843/ornneo.v28i0.108.
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RESUMO ∙ Informações sobre a dieta de aves marinhas são de grande importância para o entendimento entre as aves e seu ambiente. Sabe‐se que o Gaivotão (Larus dominicanus) costuma forragear descartes de pesca, e que na área amostrada estes descartes são abundantes na modalidade de arrasto, com grande volume de peixes demersais. Foi analisado o hábito alimentar da L. dominicanus no estado do Paraná, Brasil. Os itens alimentares dos pellets foram identificados a fim de demonstrar a importância dos peixes demersais na dieta desta espécie. Os pellets foram amostrados entre agosto de 2011 e julho de 2012 no balneário de Barrancos. Baseado na identificação dos otólitos encontrados nos pellets, foi retrocalculado o comprimento e a massa dos peixes. Nos 120 pellets coletados, foram identificados 228 peixes, de 14 espécies e 3 famílias, destaque para a família Sciaenidae com 11 espécies. Cathorops spixii, Larimus breviceps, Paralonchurus brasiliensis e Stellifer rastrifer foram mais frequentes. Nas análises sazonais L. breviceps, Micropogonias furnieri, P. brasiliensis e S. rastrifer foram encontrados na dieta de L. dominicanus em todas as estações. A análise canônica demonstrou diferenças sazonais significativas na abundância, massa e comprimento dos teleósteos identificados na dieta de L. dominicanus. Este estudo demonstrou a frequente ocorrência de peixes demersais na dieta de L. dominicanus, sugerindo que este tipo de descarte de pesca é uma importante fonte de alimento para as populações locais de esta espécie.ABSTRACT ∙ Demersal fish in the diet of the Kelp Gull (Larus dominicanus) in a subtropical environment Information on the diet of sea birds is of great importance for the understanding between birds and their environment. It is known that the Kelp Gull (Larus dominicanus) is used to forage discards, and that in the area sampled these discards are abundant in trawling mode, with a large volume of demersal fish. The food habit of L. dominicanus was analyzed in the State of Paraná, Brazil. The food items of the pellets were identified in order to demonstrate the importance of demersal fish in the diet of this species. The pellets were sampled between August 2011 and July 2012 on the seaside of Barrancos. Based on the identification of the otoliths found in the pellets, length and mass of fishes were recalculated. In the 120 pellets collected, 228 fishes from 14 species and 3 families were identified, with emphasis on the Sciaenidae family with 11 species. Cathorops spixii, Larimus breviceps, Paralonchurus brasiliensis, and Stellifer rastrifer were most frequent. In the seasonal analyses, L. breviceps, Micropogonias furnieri, P. brasiliensis, and S. rastrifer were found in the diet of L. dominicanus in all seasons. The canonical analysis showed significant seasonal differences in abundance, mass, and length of the teleosts identified in the diet of L. dominicanus. This study demonstrated the frequent occurrence of demersal fish in the diet of L. dominicanus, suggesting that discards are an important source of food for the local populations of this species.
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Murano, Masaaki, and John Mauchline. "DEEP-SEA MYSIDS FROM THE NORTH ATLANTIC OCEAN WITH DESCRIPTION OF FOUR NEW SPECIES." Crustaceana 72, no. 3 (1999): 273–95. http://dx.doi.org/10.1163/156854099503366.
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AbstractSeven species of Erythropini from the northeast Atlantic and one from the northwest Atlantic are dealt with. Four are described as new species, and three are new to science but remain unnamed because of mutilated condition. A known species Katerythrops oceanae, is described for the first time for the male pleopods and a revision of the diagnosis of the genus is presented. Five are pelagic species while three were obtained from the stomach contents of demersal fishes. Huit especes d'Erythropini de l'Atlantique sont traitees, dont sept du nord-est et une du nordouest de cet ocean. Quatre sont decrites comme nouvelles et trois sont nouvelle pour la science, mais non nommees en raison de leur condition mutilee. Les pleopodes males d'un espece connue, Katerythrops oceanae, sont decrits pour la premiere fois et la diagnose du genre est revisee. Cinq especes sont pelagiques et trois proviennent de contenus stomacaux de poissons demersaux.
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Prince, Jeremy D. "Ecosystem of the South East Fishery (Australia), and fisher lore." Marine and Freshwater Research 52, no. 4 (2001): 431. http://dx.doi.org/10.1071/mf00042.
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A description of the marine ecosystem that sustains fisheries production around south-eastern Australia is based on a synthesis of fisher lore of the demersal trawling sector, a review of the literature and a decade of the author’s field observations. A wide range of species are fished demersally in the South East Fishery (SEF). Until recently, managers and researchers have often implicitly assumed that many of these demersally caught species were neritic and lived in close association with the seabed. In contrast, fisher lore emphasizes the pelagic and oceanic nature of the commercial resource together with its environmentally forced variability. This paper substantially supports the views of the fishers. Up to 90%of the primary production of the SEF ecosystem may be garnered by fish foraging through extensive, but relatively sparse, oceanic phytoplankton and gelatinous zooplankton communities. Sporadically, climatic conditions cause oceanographic features to interact with shelf-break features and create ephemeral hotspots of primary production along the shelf break. Fish of the SEF take advantage of these productivity events to aggregate for feeding and breeding and their episodes of aggregation and dispersion cause the large seasonal variations in catchability observed with the shelf-break species. Implications for ecosystem management are briefly discussed.
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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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Olaso, Ignacio, Francisco Sánchez, Cristina Rodríguez-Cabello, and Francisco Velasco. "The feeding behaviour of some demersal fish species in response to artificial discarding." Scientia Marina 66, no. 3 (September 30, 2002): 301–11. http://dx.doi.org/10.3989/scimar.2002.66n3301.
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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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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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Auster, Peter J., Jeff Godfrey, Anya Watson, Amy Paquette, and Greg McFall. "Behavior of prey links midwater and demersal piscivorous reef fishes." Neotropical Ichthyology 7, no. 1 (March 2009): 109–12. http://dx.doi.org/10.1590/s1679-62252009000100014.
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Pelagic and demersal guilds of piscivorous fishes are linked by a variety of biological and physical processes that mediate interactions with common prey species. Understanding the behaviors of predators and prey can provide insight into the conditions that make such linkages possible. Here we report on the behaviors of mid-water piscivorous fishes and the responses of prey that produce feeding opportunities for demersal piscivorous fishes associated with "live bottom" ledge habitats off the coast of Georgia (northwest Atlantic Ocean). Prey taxa reduced nearest neighbor distances and retreated towards the seafloor during predatory attacks by mid-water fishes. Demersal fishes subsequently attacked and consumed prey in these ephemeral high density patches. No predation by demersal fishes was observed when prey species were at background densities. If the predator-prey interactions of demersal piscivorous fishes are commonly mediated by the predatory behavior of midwater piscivorous fishes and their prey, such indirect facilitative behaviors may be important in terms of the population processes (e.g., prey consumption and growth rates) of these demersal fishes.
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Gray, CA, and NM Otway. "Spatial and temporal differences in assemblages of demersal fishes on the inner continental shelf off Sydney, south-eastern Australia." Marine and Freshwater Research 45, no. 4 (1994): 665. http://dx.doi.org/10.1071/mf9940665.
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Variations in assemblages of demersal fishes occurring in different depths of water (30, 60 and 100 m) on the inner continental shelf off Sydney are described. Assemblages comprised a diverse and abundant ichthyofauna; many species were of economic importance. Classification analyses showed that assemblages of demersal fishes at 30 and 60 m depth were most similar to each other and that they consistently differed from those at 100 m depth. This difference may reflect a change in the demersal ichthyofauna from a nearshore to an offshore assemblage. The depth-delineated differences between assemblages agree with those found in similar studies on demersal fishes in coastal waters elsewhere. The distributions and relative abundances of many species differed markedly among depths, but such differences were not always consistent between localities or throughout time. Despite this, some species showed some temporal affinity with a particular site and/or depth. The study confirmed spatial and temporal variabilities in the demersal fish fauna in coastal waters off Sydney; such heterogeneity must be considered when future studies are designed.
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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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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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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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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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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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Suman, Ali, Budi Iskandar Prisantoso, Fayakun Satria, and Enjah Rahmat. "KOMPOSISI JENIS, PENYEBARAN, DAN KEPADATAN STOK IKAN DEMERSAL LAUT DALAM DI PERAIRAN SAMUDERA HINDIA SELATAN JAWA DAN BARAT SUMATERA." Jurnal Penelitian Perikanan Indonesia 13, no. 1 (February 9, 2017): 43. http://dx.doi.org/10.15578/jppi.13.1.2007.43-52.
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Penelitian bertujuan untuk mengkaji komposisi jenis, penyebaran, dan kepadatan stok ikan demersal laut di perairan ZEEI selatan Jawa dan barat Sumatera. Data yang dianalisis merupakan hasil survei yang dilakukan bulan September sampai dengan Oktober 2004 dengan menggunakan K.M. Baruna Jaya IV. Estimasi kepadatan stok dilakukan dengan menggunakan metode sapuan dengan pengambilan contoh acak bertingkat. Hasil penelitian menunjukkan bahwa komposisi jenis ikan demersal laut dalam di perairan selatan Jawa terdiri atas 169 spesies ikan, 31 spesies krustasea, dan 20 spesies Chepalopoda. Komposisi hasil tangkapan ikan didominasi oleh ikan ashiro (Lamprogrammus niger) sekitar 45% dan ikan layur (Trichiurus lepturus) sekitar 22%. Di perairan barat Sumatera ditemukan komposisi jenis hasil tangkapan meliputi 281 spesies ikan, 42 spesies krustasea, dan beberapa spesies Chepalopoda serta jenis yang dominan adalah ikan ashiro (Lamprogrammus niger) sekitar 20% dan Hoplosthethus sp. sekitar 17%. Jenis ikan demersal laut dalam yang memiliki penyebaran paling luas adalah Chlorophtalmus nigromarginatus di perairan selatan Jawa dan Diretmoides pauciradiatus di perairan barat Sumatera. Kelimpahan stok ikan demersal laut dalam tertinggi ditemui pada kedalaman 700 sampai dengan 1.100 m dan terendah didapatkan pada kedalaman 200 sampai dengan 400 m. Kepadatan stok ikan demersal laut dalam berkisar antara 0,8 sampai dengan 39,9 ton km-2 di perairan selatan Jawa dan berkisar 0,2 sampai dengan 7,4 ton km-2 di perairan barat Sumatera. The objective of this research is to study species composition, distribution, and stock density of deep sea demersal fish in the southern Java and western Sumatera of the Indian Ocean EEZ waters. The study was done based on the data collected from the survey conducted between September and October 2004 using Baruna Jaya IV research vessel. The study was basically conducted by applying swept area method with stratified random sampling. The results show that the species composition of deep sea demersal in southern off Java waters consisted of 169 in fishes, 31 in crustaceans, and 20 in chephalopods. The catch of deep sea demersal fish was dominated by ashiro (Lamprogrammus niger) about 45%and hair tail (Trichiurus lepturus) about 22%. Species composition of deep sea demersal fish in west off Sumatera waters consisted of 281 species of fishes, 42 species in crustaceans and some types of chepalopods. The dominant species was Lamprogrammus niger (ashiro) with about 20% of the total catch and Hoplosthethus sp. with about 17% of the total catch. The widest species distribution of is resource was Chlorophtalmus nigromarginatus in southern off Java waters and Diretmoides pauciradiatus in western off Sumatera waters. The highest abundances of deep sea resources were caught at the depth of 700 to 1,100 m and the lowest at the depth of 200 to 400 m. Stock density in southern off Java waters was 0.8 to 39.9 ton km-2 and about 0.2 to 7.4 ton km-2 in western off Sumatera waters.
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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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Hogans, W. E. "Review of Sarcotretes Jungersen, 1911 (Copepoda: Pennellidae) from midwater and demersal fishes in the north Atlantic Ocean." Canadian Journal of Zoology 66, no. 6 (June 1, 1988): 1371–75. http://dx.doi.org/10.1139/z88-201.
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The genus Sarcotretes, parasitic copepods from midwater and demersal fishes in the Atlantic Ocean, is reviewed. The taxonomic status of the six nominal species is discussed. Two species, S. scopeli, from midwater fishes, and S. eristaliformis, from demersal fishes, are tentatively considered valid members of the genus. The remaining species (S. inflexus, S. lobatus, S. gempyli, and S. nodicornis) are probable synonyms of the type species, S. scopeli. A detailed description of S. scopeli from six midwater host species is presented.
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Galarza, J. A., G. F. Turner, E. Macpherson, and C. Rico. "Patterns of genetic differentiation between two co-occurring demersal species: the red mullet (Mullus barbatus) and the striped red mullet (Mullus surmuletus)." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 9 (September 2009): 1478–90. http://dx.doi.org/10.1139/f09-098.
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The accurate identification of genetic partitioning is of primarily importance when devising conservation management strategies for today’s marine resources. The great variety of genetic structure displayed by demersal species underscores the need for the identification of common patterns that can be found across species. Here, we analyse allele frequency variation at 10 microsatellite loci of two congener demersal fish, the red mullet ( Mullus barbatus ) and the striped red mullet ( Mullus surmuletus ), from the Atlantic Ocean and the Mediterranean Sea. The results indicate that two different gene flow patterns exist between these species. The red mullet’s genetic distribution was found to be highly structured, resembling that of a metapopulation composed by independent, self-recruiting subpopulations with some connections between them. The striped red mullet displayed less genetic heterogeneity within the Mediterranean Sea and a substantial gene flow reduction between the Atlantic Ocean and Mediterranean Sea. Our results indicate that gene flow patterns in the demersal environment can be substantially different between closely related species with highly comparable biology, suggesting that biogeographic boundaries can affect demersal species in a different way despite common ecological features and spatial overlap. We conclude that the delimitation of such boundaries could be determined by the fine differences in life history traits between species.
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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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Hidayat, Thomas, and Nurulludin Nurulludin. "INDEKS KEANEKARAGAMAN HAYATI SUMBERDAYA IKAN DEMERSAL DI PERAIRAN SAMUDERA HINDIA SELATAN JAWA." Jurnal Penelitian Perikanan Indonesia 23, no. 2 (November 14, 2017): 123. http://dx.doi.org/10.15578/jppi.23.2.2017.123-130.
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Penelitian telah dilakukan di perairan Samudera Hindia Selatan Jawa pada bulan September-Oktober 2015. Peneletian ini bertujuan mendapatkan informasi indeks keanekaragaman jenis ikan demersal, yang diharapkan dapat dijadikan sebagai salah satu bahan pertimbangan dalam menentukan kebijakan pengelolaan perikanan. Pengumpulan data spesies dilakukan melalui survei pukat dasar (bottom trawl) menggunakan KR. Baruna Jaya IV (1200 GT). Hasil penelitian mendapatkan 70 spesies ikan demersal yang tergolong dalam 36 famili. Spesies yang mendominasi adalah famili Sciaenidae (ikan tigawaja), Trichiuridae (ikan layur) dan Ariidae (manyung), Haemulidae (ikan kaci-kaci) dan Mullidae (kuniran). Tingkat keanekaragaman jenis ikan demersal termasuk dalam kategori “sedang” dengan indeks “Shanon-Wiener” (H’) berkisar 2,5. Indeks kekayaan jenis “Margalef” (R1 ) sebesar 7,9. Penyebaran diantara spesiesnya bersifat sedang, dengan indeks kemerataan jenis “Pielou” (E) rata-rata 0,30 dan tidak banyak jenis yang mendominasi kelimpahannya, dengan nilai indeks dominasi (C) rata-rata sebesar 0,12. The research was conducted in the Indian Ocean southern part of Java during September-October 2015. This research aims to examine species diversity indices of demersal fish. Data collection was carried through a survey bottom trawl using KR. Baruna Jaya IV (1200 GT). The results showed that catch consisted of 70 species (36 families). The dominant families were the Sciaenidae, Trichiuridae Ariidae, Haemulidae and Mullidae. The level of species diversity of demersal fish was medium category. The species diversity indices of “Shanon-Wiener” (H ‘), “Margalef” (R1), Evennes indices of “Pielou” (E1) and dominant indices (C) were 2.5, 7.9, 0.30 and 0.12, respectively.
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Kousteni, Vasiliki, Paraskevi K. Karachle, Persefoni Megalofonou, and Evgenia Lefkaditou. "Cephalopod prey of two demersal sharks caught in the Aegean Sea (eastern Mediterranean)." Journal of the Marine Biological Association of the United Kingdom 98, no. 1 (October 3, 2017): 81–88. http://dx.doi.org/10.1017/s002531541700159x.
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This study concerns the cephalopod species that are part of the diet of the small-spotted catshark Scyliorhinus canicula and the longnose spurdog Squalus blainville sampled by commercial trawlers in the Aegean Sea from 2005 to 2012. Based on the examined cephalopod beaks, 15 species were identified belonging in six families of Teuthida, one of Sepiida and two of Octopoda. The diversity of cephalopod prey species was higher for S. canicula (N = 15) than for S. blainville (N = 10). Nektonic cephalopods comprised the majority (>72%) of the preyed species by both sharks, among which about 55% inhabit the demersal zone and 45% the mesopelagic. In the diet of S. canicula, the demersal squid Illex coindetii and the pelagic sepiolid Heteroteuthis dispar were equally represented composing 20% of prey specimens, followed by the small-sized squid Abralia veranyi and the demersal sepiolid Rossia macrosoma. The latter species was substituted in the diet of S. blainville by the demersal medium-sized octopod Scaeurgus unicirrhus, which with the equally represented three other species, composed 50% of the cephalopod prey. Differences observed between S. canicula and S. blainville in the condition of beaks retained in their stomach contents and in the variation of prey species diversity by predator specimen size, may imply differences in their foraging tactics (hunting for prey vs scavenging on the bottom), habitats and stomach evacuation frequency.
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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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Corrigan, Shannon, Charlie Huveneers, Adam Stow, and Luciano B. Beheregaray. "A multilocus comparative study of dispersal in three codistributed demersal sharks from eastern Australia." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 3 (March 2016): 406–15. http://dx.doi.org/10.1139/cjfas-2015-0085.
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Demersal elasmobranchs are ecologically important mesopredators but little is known about their population connectivity or dispersal patterns. Here we use a comparative approach based on mitochondrial DNA and nuclear amplified fragment length polymorphism (AFLP) markers to examine spatial genetic structure and dispersal in three closely related demersal elasmobranchs from eastern Australia: Orectolobus halei, Orectolobus maculatus, and Orectolobus ornatus. We found evidence of significant spatial genetic structure, possibly indicating regional philopatry in wobbegongs. The molecular data also indicate that dispersal in wobbegongs may be sex-biased. This represents the first genetic study of dispersal and population connectivity in codistributed demersal sharks. It provides insights into the ecology of dispersal behaviours with implications for conservation management of demersal species.
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Engås, A. "A species-selective trawl for demersal gadoid fisheries." ICES Journal of Marine Science 55, no. 5 (October 1998): 835–45. http://dx.doi.org/10.1006/jmsc.1998.0352.
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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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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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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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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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Vilas, Daniel, Maria Grazia Pennino, Jose Maria Bellido, Joan Navarro, Isabel Palomera, and Marta Coll. "Seasonality of spatial patterns of abundance, biomass, and biodiversity in a demersal community of the NW Mediterranean Sea." ICES Journal of Marine Science 77, no. 2 (November 27, 2019): 567–80. http://dx.doi.org/10.1093/icesjms/fsz197.
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Abstract Information on the spatial patterns and habitat preferences of marine species is key to understand the functioning of marine ecosystem and to manage and protect marine resources efficiently. However, the study of spatial patterns of marine ecosystems is challenging because they are dynamic environments that can vary seasonally. We modelled the spatial patterns of abundance, biomass, and biodiversity in a demersal community of the northwestern Mediterranean Sea by season using hierarchical Bayesian spatial models and environmental, physical, and anthropogenic factors. Overall, our findings revealed the importance of seasonality in the spatial patterns of the demersal community, which were mainly driven by sea surface temperature. Results also underlined important patterns of movements of demersal organisms: fishes, cephalopods, and crustaceans showed high densities in the area surrounding the Ebro Delta River in winter mainly driven by species-specific behaviour. Our results are relevant to inform future management measures in the study area, such as seasonal fishing restrictions, or to adapt local marine protected areas to seasonal processes. This study provides evidence of the need to expand current monitoring schemes to capture the seasonality of marine demersal communities for a more comprehensive marine spatial planning framework.
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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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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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Mahon, Robin, Stephen K. Brown, Kees CT Zwanenburg, D. Bruce Atkinson, Kenneth R. Buja, Larry Claflin, Geoffrey D. Howell, Mark E. Monaco, Robert N. O'Boyle, and Michael Sinclair. "Assemblages and biogeography of demersal fishes of the east coast of North America." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 7 (July 1, 1998): 1704–38. http://dx.doi.org/10.1139/f98-065.
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This study describes and maps demersal fish assemblages for the east coast of North America from Cape Hatteras, North Carolina, to Cape Chidley, Labrador, evaluates evidence for interannual shifts in assemblage distribution, and examines the relationship of the assemblages to accepted biogeographical boundaries. Demersal trawl survey data collected from 1975 to 1994 were analyzed. Visual classification of distribution maps for the 108 most abundant demersal species revealed nine species groups, based on both geography and depth distribution. Eighteen assemblage groups were identified using principal components analysis (PCA) and mapped. Assemblage groups were also identified by cluster analysis. Fish assemblages identified by both methods were spatially coherent. Assemblage distribution patterns were not consistent with accepted biogeographical boundaries. The PCA explained only 56.3% of the variance in distribution of the species, indicating that the assemblages should be interpreted as indeterminate, potentially adaptable entities rather than as rigid ecological constructs. Assemblages were persistent in composition through time but appeared to shift in location. The apparent looseness of the assemblages and their persistence through time in spite of severe impacts from fishing suggest that single-species management approaches may not be entirely inappropriate for the major groundfish species in the study area.
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Le Marchand, M., T. Hattab, N. Niquil, C. Albouy, F. Le Loc’h, and FBR Lasram. "Climate change in the Bay of Biscay: Changes in spatial biodiversity patterns could be driven by the arrivals of southern species." Marine Ecology Progress Series 647 (August 13, 2020): 17–31. http://dx.doi.org/10.3354/meps13401.
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Under climate change, future species assemblages will be driven by the movements and poleward shift of local species and the arrival of more thermophilic species from lower latitudes. To evaluate the impacts of climate change on marine communities in the Bay of Biscay, we used the hierarchical filters modelling approach. Models integrated 3 vertical depth layers and considered 2 Intergovernmental Panel on Climate Change (IPCC) scenarios (Representative Concentration Pathway, RCP2.6 and RCP8.5) and 2 periods (2041-2050 and 2091-2100) to simulate potential future species distributions. Results predicted potentially suitable future ranges for 163 species as well as future arrivals of non-indigenous southern species. We aggregated these results to map changes in species assemblages. Results revealed that coastal areas would undergo the highest species loss among the Bay of Biscay species, depending on their vertical habitat (benthic, demersal, benthopelagic or pelagic). Benthic and demersal species were projected to experience a westward shift, which would induce a deepening of those species. In contrast, pelagic species were projected to shift northward. The potential ecological niche for half of the studied species, mostly benthic and demersal, was projected to decrease under climate change. In addition, a high rate of southern species arrivals is expected (+28%). Assessment of community composition showed high species replacement within the 0-50 m isobath, driven by the replacement of native species by southern ones. This could lead to a major reorganization of trophic networks and have socio-economic impacts.
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Heath, M. R., and D. C. Speirs. "Changes in species diversity and size composition in the Firth of Clyde demersal fish community (1927–2009)." Proceedings of the Royal Society B: Biological Sciences 279, no. 1728 (July 6, 2011): 543–52. http://dx.doi.org/10.1098/rspb.2011.1015.
Full textAbstract:
Following the repeal in 1962 of a long-standing ban on trawling, yields of demersal fish from the Firth of Clyde, southwest Scotland, increased to a maximum in 1973 and then declined until the directed fishery effectively ceased in the early 2000s. Since then, the only landings of demersal fish from the Firth have been by-catch in the Norway lobster fishery. We analysed changes in biomass density, species diversity and length structure of the demersal fish community between 1927 and 2009 from scientific trawl surveys, and related these to the fishery harvesting rate. As yields collapsed, the community transformed from a state in which biomass was distributed across numerous species (high species evenness) and large maximum length taxa were common, to one in which 90 per cent of the biomass was vested in one species (whiting), and both large individuals and large maximum length species were rare. Species evenness recovered quickly once the directed fishery ceased, but 10 years later, the community was still deficient in large individuals. The changes partly reflected events at a larger regional scale but were more extreme. The lag in response with respect to fishing has implications for attempts at managing a restoration of the ecosystem.
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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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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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Valinassab, T., R. Daryanabard, R. Dehghani, and G. J. Pierce. "Abundance of demersal fish resources in the Persian Gulf and Oman Sea." Journal of the Marine Biological Association of the United Kingdom 86, no. 6 (December 2006): 1455–62. http://dx.doi.org/10.1017/s0025315406014512.
Full textAbstract:
We report on results of a trawl survey during 2003–2004 to assess the abundance of demersal fish resources in the Persian Gulf and Oman Sea. Samples were taken at a total of 316 trawl stations selected following a stratified random procedure. Catch rates (catch per unit area, CPUA) and total biomass were estimated. Total demersal fish biomass was estimated to be approximately 73,000 tonnes in Persian Gulf waters and approximately 39,000 tonnes in the Oman Sea. The lowest CPUA was recorded in the west of the study area (stratum A, approximately 1700 kg/n.m.2) and the highest in the east (stratum Q, 13943.4 kg/n.m.2), although density of commercially important species was higher in the central area (stratum K). Catch rate and biomass varied significantly in relation to seabed depth. Commercially important demersal species made up around 60% of the estimated total biomass. The most abundant species groups were rays, catfish, grunts, nemipterids and carangids. Several important species (e.g. silver pomfret, croakers and sharks) appear to have declined since the late 1970s while others, such as rays and catfish, have increased.
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Tserpes, George, and Panagiota Peristeraki. "Trends in the abundance of demersal species in the southern Aegean Sea." Scientia Marina 66, S2 (June 30, 2002): 243. http://dx.doi.org/10.3989/scimar.2002.66s2243.
Full textAbstract:
The present work identifies trends in the abundance of the main demersal species of the South Aegean Sea utilising catch and effort data derived from an international Mediterranean bottom trawl survey (MEDITS). The experimental surveys were accomplished annually from 1994 to 2000 on 61 pre-defined sampling stations. Selection of stations was based on a depth-stratified random sampling scheme that included five depth strata: 10-50, 50-100, 100-200, 200-500 and 500-800 m. The results suggest the existence of a general increasing trend in the biomass of the demersal species, particularly at the 10-50 m and 500-800 m depth strata. Findings are discussed in relation to the fisheries exploitation pattern and productivity of the area.
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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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ellis, j. r., n. k. dulvy, s. jennings, m. parker-humphreys, and s. i. rogers. "assessing the status of demersal elasmobranchs in uk waters: a review." Journal of the Marine Biological Association of the United Kingdom 85, no. 5 (October 2005): 1025–47. http://dx.doi.org/10.1017/s0025315405012099.
Full textAbstract:
elasmobranch fish are susceptible to over-exploitation by commercial and recreational fisheries and an increasing focus of conservation initiatives. the lack of accurate species-specific landings data in many european fisheries and the paucity of biological data have restricted the types of stock assessment that can be undertaken. hence, other methods of determining the overall status of elasmobranch fish are required. for demersal elasmobranchs around the british isles, the most widely available biological data describe life histories and abundance from fishery-independent surveys. here, we examine the length-distribution of demersal elasmobranchs caught during groundfish surveys, to determine which life history stages are sampled effectively. for these stages, we report trends in abundance and relate the trends to knowledge of the species' biology and fisheries, and to the decline criteria that are used to assess species' status by nature conservation agencies. the analyses show that many large demersal elasmobranchs have been severely depleted in uk waters but that groundfish surveys still provide a good source of data for monitoring changes in status of the more abundant species. for rare and highly depleted species, groundfish surveys often provide good retrospective descriptions of declines, but the surveys have limited power to detect recent changes in status.
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Santos, Régis V. S., Wendell M. M. L. Silva, Ana M. Novoa-Pabon, Hélder M. Silva, and Mario R. Pinho. "Long-term changes in the diversity, abundance and size composition of deep sea demersal teleosts from the Azores assessed through surveys and commercial landings." Aquatic Living Resources 32 (2019): 25. http://dx.doi.org/10.1051/alr/2019022.
Full textAbstract:
To obtain important baseline information about population dynamics and to provide valuable insights about the possible effects of artisanal fishing on the demersal fish community, this study had three specific objectives: (1) to update the annotated list of demersal teleost species occurring in the Azores (mid-North Atlantic); (2) to describe their depth distribution and related fishery information; and (3) to evaluate annual changes in their observed abundance and length composition. To do this, a time series with about 25 years of scientific data from the commercial fishery and surveys was analyzed. The demersal teleost community was represented by 213 species, predominantly deep-water species, reflecting the main marine habitat in the Azores region. Fishery takes place mainly in the intermediate strata (200–600 m), where the most commercially important species occur. No changing in the fork length (LF) distribution toward small individuals caused by size-selective fishing was detected in this study. The high variability observed in the LF data indicates the need for more accurate studies considering alternative statistical analyses (e.g., generalised linear models) to examine the possible factors (e.g. depth coverage, gear configuration, soak time, and fishing area) that cause this variability. On the other hand, the abundance indices of some commercially important species appear to have declined (Phycis phycis, Pontinus kuhlii, Conger conger, Beryx splendens and B. decadactylus), while others appear to be more stable (Helicolenus dactylopterus) or even increasing (Mora moro). Although the available data are insufficient for a formal assessment on the status of exploited populations, the long-term analysis of commercial landings and survey data was used as a basis to assess deep sea demersal teleost fisheries of the Azores, under a precautionary approach.
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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.
Full textAbstract:
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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Moraes, Leonardo Evangelista, Renato de Mei Romero, Gecely Rodrigues Alves Rocha, and Rodrigo Leão de Moura. "Demersal ichthyofauna of the inner continental shelf off Ilhéus, Bahia, Brazil." Biota Neotropica 9, no. 4 (December 2009): 163–68. http://dx.doi.org/10.1590/s1676-06032009000400016.
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We present an inventory of demersal fishes from the inner continental shelf off Ilhéus, Bahia, Brazil. Three sites were sampled monthly, between March 2003 and February 2005, with standardized bottom trawls (30 minutes, 16 m depth, 22/16 mm mesh). A total of 7.857 specimens were captured, belonging to three species of Chondrichthyes and 95 species of Actinopterygii (77 genera and 40 families). The occurrence of Ampharius phrygiatus represents a southern range extension for this species, which was previously known only from the narrow coastal stretch between Guyana and Maranhão State (Brazil). The record of Synodus poeyi represents the first record of this species in Brazil and in the South Atlantic, as it was previously recorded only in the Caribbean. The general structure of the demersal fish assemblage is described and commented upon.
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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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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.
Full textAbstract:
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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Rocha, Gecely R. A., and Carmen L. D. B. Rossi-Wongtschowski. "Demersal fish community on the inner shelf of Ubatuba, southeastern Brazil." Revista Brasileira de Oceanografia 46, no. 2 (1998): 93–109. http://dx.doi.org/10.1590/s1413-77391998000200001.
Full textAbstract:
Fluctuations in the distribution and abundance of demersal fishes collected by otter trawl on the continental shelf of Ubatuba were examined over a two-year sampling period, in an area up to 50 m depth. A total of 111 species were collected. Seasonal and annual fluctuations in species abundance were related to differences in the distribution of Coastal Water and South Atlantic Central Water masses. The demersal fish fauna in the area was divided into three ecologically distinct communities: Tropical Sciaenid, Subtropical Sciaenid, and Gerreid-Haemulid. The most important one is the Tropical Sciaenid Community, characterized by Ctenosciaena gracilicirrhus, Paralonchurus brasiliensis, and Cynoscion jamaicensis.
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van der Kooij, Jeroen, Sven Kupschus, and Beth E. Scott. "Delineating the habitat of demersal fish assemblages with acoustic seabed technologies." ICES Journal of Marine Science 68, no. 9 (August 8, 2011): 1973–85. http://dx.doi.org/10.1093/icesjms/fsr124.
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Abstract van der Kooij, J., Kupschus, S., and Scott, B. E. 2011. Delineating the habitat of demersal fish assemblages with acoustic seabed technologies. – ICES Journal of Marine Science, 68: 1973–1985. Habitats influence species distribution and, although the seabed is an important habitat factor for demersal species, traditional sampling methods often provide no practical solution to investigating the seabed over large areas. The ability of a multivariate method that utilizes single-beam acoustic seabed data combined with species composition data to define demersal fish habitats was tested. The best model explained 19.4% of the variance observed in the species data and was robust between years. Ten biotopes were identified, each containing species that, either alone or in combination with others, were indicative of that biotope. Using unclassified acoustic seabed data as explanatory variables, discrepancies between the numbers of acoustically distinct classes and species assemblages, as previously reported in the literature, were avoided, while utilizing their relationship with community structure. The study focused on the relationship between simultaneously recorded species composition and seabed data from fishing stations, but because continuous acoustic data along the survey tracks were available between stations, the model could be used to predict the spatial extent of the biotopes. Although the method was developed with the eventual aim of providing a meaningful foundation to the spatial management of mixed fisheries, it could also contribute to applications in spatial planning.
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Lauffenburger, Nathan, Alex De Robertis, and Stan Kotwicki. "Combining bottom trawls and acoustics in a diverse semipelagic environment: What is the contribution of walleye pollock (Gadus chalcogrammus) to near-bottom acoustic backscatter in the eastern Bering Sea?" Canadian Journal of Fisheries and Aquatic Sciences 74, no. 2 (February 2017): 256–64. http://dx.doi.org/10.1139/cjfas-2015-0481.
Full textAbstract:
The abundance of walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea is estimated in part through fisheries-independent acoustic trawl (AT) surveys, which currently use acoustic backscatter data down to 3 m above the bottom. A large portion of adult pollock are demersal, and these estimates will become more accurate if the survey is extended closer to bottom. The purpose of this project was to assess the feasibility of extending the AT survey closer to the bottom by estimating the contributions of each demersal fish species to observed acoustic backscatter in the highly diverse near-bottom region. This was accomplished by fitting a regression model to simultaneously collected acoustic backscatter and bottom trawl catch data. Pollock were the dominant source of acoustic backscatter among demersal species, accounting for 85.9% ± 4.8% of acoustic backscatter (mean ± standard deviation). A method was developed to extend the AT survey to within 0.5 m of the bottom, and when applied to the 1994–2014 surveys, pollock biomass increased by a mean of 28% ± 9%.
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Greenstreet, Simon P. R., Axel G. Rossberg, Clive J. Fox, William J. F. Le Quesne, Tom Blasdale, Philip Boulcott, Ian Mitchell, Colin Millar, and Colin F. Moffat. "Demersal fish biodiversity: species-level indicators and trends-based targets for the Marine Strategy Framework Directive." ICES Journal of Marine Science 69, no. 10 (December 1, 2012): 1789–801. http://dx.doi.org/10.1093/icesjms/fss148.
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Abstract Greenstreet, S. P. R., Rossberg, A. G., Fox, C. J., Le Quesne, W. J. F., Blasdale, T., Boulcott, P., Mitchell, I., Millar, C., and Moffat, C. F. 2012. Demersal fish biodiversity: species-level indicators and trends-based targets for the Marine Strategy Framework Directive. – ICES Journal of Marine Science, 69: 1789–1801. The maintenance of biodiversity is a fundamental theme of the Marine Strategy Framework Directive. Appropriate indicators to monitor change in biodiversity, along with associated targets representing “good environmental status” (GES), are required to be in place by July 2012. A method for selecting species-specific metrics to fulfil various specified indicator roles is proposed for demersal fish communities. Available data frequently do not extend far enough back in time to allow GES to be defined empirically. In such situations, trends-based targets offer a pragmatic solution. A method is proposed for setting indicator-level targets for the number of species-specific metrics required to meet their trends-based metric-level targets. This is based on demonstrating significant departures from the binomial distribution. The procedure is trialled using North Sea demersal fish survey data. Although fisheries management in the North Sea has improved in recent decades, management goals to stop further decline in biodiversity, and to initiate recovery, are yet to be met.
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Dunning, M., S. McKinnon, CC Lu, J. Yeatman, and D. Cameron. "Demersal cephalopods of the Gulf of Carpentaria, Australia." Marine and Freshwater Research 45, no. 3 (1994): 351. http://dx.doi.org/10.1071/mf9940351.
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Demersal trawl and dredge surveys of the Gulf of Carpentaria in the early summers of 1990 and 1991 provided the first comprehensive assessment of the cephalopod fauna of this shallow, tropical basin off northern Australia. Twenty-one taxa (comprising five loliginid squids, seven cuttlefishes, seven octopuses and two dumpling squids) were recorded. In addition to hosting species distributed broadly in the Indo-West Pacific (e.g. loliginid squids Sepioteuthis lessoniana, Photololigo cf. chinensis and P. cf. edulis; cuttlefishes Sepia eiliptica and Sepia pharaonis), the Gulf of Carpentaria represents the most northwesterly extent of the range of some eastern Australian species (e.g. Loliolus noctiluca and Sepia whitieyana). Squid catches were lower in the north-western gulf in 1990 and higher in shallower water during the more geographically restricted survey in 1991, whereas cuttlefish were more evenly distributed throughout the different sampling areas in both years. Broad size ranges of both sexes of the four most abundant species (P. cf. chinensis (northern form), P. cf. eduiis, S. eiliptica and S. pharaonis) are indicative of extended spawning seasons, and fully mature individuals of these species were evident throughout the gulf. Cephalopods are a minor component in reported domestic fisheries catches from the Gulf of Carpentaria, where penaeid prawns are targeted. High (though seasonal) squid catch rates were reported annually by Taiwanese trawlers targeting butterfish and squid from certain areas prior to 1979. With the observed population structure of the abundant cephalopod species and relatively high catch rates in some localities during these recent surveys, it is suggested that the cephalopod resources of the Gulf of Carpentaria could support increased commercial fisheries exploitation.