• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 12
  • 5
  • 5
  • 5
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Aspects of the biology of two inshore sparid fishes (Diplodus sargus capensis and Diplodus cervinus hottentotus) off the south-east coast of South Africa

Mann, Bruce Quintin January 1992 (has links)
The blacktail, Diplodus sargus capensis and the zebra, Diplodus cervinus hottentotus, sparid fishes endemic to South Africa, are important components of the recreational shore-fishery. To provide a basis for the management of these fish, aspects of the biology of both species were investigated in the Tsitsikamma National Park (TNP). In particular, the role of the TNP was evaluated as a management option for the conservation of both species. Examination of stomach contents showed that juveniles of both species fed predominantly on amphipods, polychaetes and harpacticoid copepods. Adult !h. sargus were omnivorous and fed opportunistically on a wide variety of reef associated invertebrates and algae including echinoids, polychaetes, anthozoans, ascidians and rhodophytes. The diet of adult D. cervinus was more specialized with a preference shown for polychaetes and amphipods. Seasonal differences were apparent in the diets of both species where considerably more amphipods were consumed in winter than in summer. Feeding requirements of both species were reflected in their habitat preferences. Visual underwater assessment revealed that both species were most abundant on turbulent inshore reefs (1-10m). !h. sargus were observed over a wide variety of reef associated habitats. In the literature they have also been recorded in the surf zone of sandy beaches and in the lower reaches of estuaries. !h. cervinus, on the other hand, were more specific in their habitat requirements and were observed in greatest abundance on inshore reefs, often in close association with caves or overhangs. A comparison between the relative abundance and size structure of both species in the TNP with that of an exploited area immediately adjacent to the reserve, showed no significant differences. This was attributed to the low level of exploitation by rock-and-surf anglers occurring in the exploited study area, as well as the possibility of seeding of eggs and larvae, or emigration of adults from the TNP. An investigation of the reproductive biology of both fish showed that !h. sargus had an extended summer spawning season while in !h. cervi nus it was more restricted. Detailed histological examination of gonadal development showed that !h. sarqus were dygynous with partial protandry occuring in the male population. ~ cervinus were shown to be rudimentary hermaphrodites. Size at 50% maturity in ~ sargus and ~ cervinus was determined at 225 and 285mm fork length respectively, corresponding to ages of 4 and 6 years. An age and growth study based on the examination of sectioned otoliths showed that both species were slow growing capable of reaching ages in excess of 20 years. Growth in ~ sargus and ~ cervinus was described by the von Bertalanffy growth equations: L(t) = 309.44(1-e-0 . 247[t+l. 048 l) and L(t) = 396.85(1-e-0.146[t+2.148J) respectively. Life history characteristics of D. sargus and D. cervinus including slow growth, late maturation and occupation of a localised, demersal habitat showed that both species were vulnerable to the effects of over-fishing. Due to the present increase in the number of participants and the decrease in catch per unit effort in the recreational shore-fishery, more stringent management recommendations were proposed to ensure the adequate protection of both species. These included an increased minimum size limit and a decreased bag limit for both species. Based on the residency shown by both species and their high relative abundance in the TNP, marine reserves were considered to be a valuable addition to the suite of management options available for the conservation of these species . In this respect the reserve provided both protection for the spawner stock as well as the potential to seed adjacent areas.
2

Taxonomy and life history of the zebra seabream, Diplodus cervinus (Perciformes: Sparidae), in southern Angola

Winkler, Alexander Claus January 2014 (has links)
The zebra sea bream, Diplodus cervinus (Sparidae) is an inshore fish comprised of two boreal subspecies from the Gulf of Oman and the Mediterranean / north eastern Atlantic and one austral subspecies from South Africa and southern Angola. The assumption of a single austral subspecies has, however, been questioned due to mounting molecular and morphological evidence suggesting that the cool Benguela current is a vicariant barrier that has separated many synonymous inshore fish species between South Africa and southern Angola. The aims of this thesis are to conduct a comparative morphological analysis of Diplodus cervinus in southern Angola and South Africa in order to classify the southern Angolan population and then to conduct a life history assessment to assess the life history impact of allopatry on this species between the two regions. Results of the morphological findings of the present study (ANOSIM, p < 0.05, Rmeristic = 0.42) and (Rmorphometric = 0.30) along with a concurrent molecular study (FST = 0.4 – 0.6), identified significant divergence between specimens from South Africa (n = 25) and southern Angola (n = 37) and supported stock separation and possibly sub-speciation, depending on the classification criteria utilised. While samples from the two boreal subspecies were not available for the comparative morphological or molecular analysis, comparisons of the colouration patterns between the three subspecies, suggested similarity between the southern Angola and the northern Atlantic / Mediterranean populations. In contrast, the colouration patterns between the southern Angolan and South African specimens differed substantially, further supporting the morphological and molecular results. The distinct morphological divergence between the southern Angolan and South African populations was not reflected within the life history traits of both populations. A combination of methods, including length/age frequency analyses, adult sex ratios and histological analysis was used to determine that this species is a rudimentary hermaphrodite in southern Angola. Peak spawning season was observed between June and July. The overall sex ratio (M: F) was 1:1.52 with females dominating smaller younger size classes and 50% maturity was attained at 210 mm FL and 4.6 years. Females [L(t) = 287.5(1-e⁻°·¹⁸⁽t⁻²·⁸⁴⁾)] grew significantly faster (LRT, p < 0.05) than males [L(t) = 380.19(1-e⁻°·°⁶⁽t⁻⁷·¹²⁾)]. The higher maximum age of the southern Angolan population of D. cervinus (43 years) was older than that of South African individuals sampled in the tsitsikamma national park. The similarities in the life history of the two austral populations are probably a consequence of similar selective pressures in the similar warmtemperate habitats. Evidence to support the above comments was found in the feeding study which showed that the South African and Angolan populations were almost identical, with both populations feeding primarily on amphipods and polychaete worms throughout ontogeny. In contrast, the diet of their boreal conspecifics from the Mediterranean was different, where larger individuals tended to select larger, and more robust, prey items. The life history differences observed between the boreal and austral populations can be attributed to either sampling bias or environmental factors. Sampling biases included the use of different age and growth estimation techniques, while the environmental factors would include differential selective pressures most likely driven by different resource availability and exploitation. The present study provides crucial baseline life history information of a potentially exploitable species off southern Angola as well as information on the life history plasticity of the species. Unfortunately, the current lack of uniformity in the methods used to estimate life history parameters between studies conducted on the boreal and austral populations have complicated our understanding of the evolution of various life history trends in sparid fish. From a management perspective however, the results from the present study can be used to propose management strategies for an emerging trap fishery in southern Angola. Using a balanced exploitation fishery approach (harvesting up to the size-at-100% maturity), the size of the fish traps entrance was calculated based the morphological information from this and other small sparid species that are targeted and was estimated to be 62 mm.
3

EFECTO DE LA INCLUSIÓN DE FUENTES PROTEICAS Y LIPÍDICAS EN LA ALIMENTACIÓN DEL SARGO PICUDO "Diplodus puntazzo"

Nogales Mérida, Silvia 02 December 2011 (has links)
El sargo picudo es una especie promisoria para la producción acuícola española, aunque ésta ya se encuentra en mercados como Italia, Grecia y Chipre entre otros. Una de las ventajas que tiene sobre las especies que actualmente copan el mercado español, es su hábito alimenticio, su fácil reproducción y el hecho de que se puede emplear la misma infraestructura para su producción, además de ser una especie que goza actualmente de un precio competitivo en el mercado. Todas las ventajas anteriormente citadas hacen de esta especie una de las especies potenciales para su producción a nivel comercial. No obstante, para la producción de la misma no se cuenta con piensos específicos, sino que se emplean piensos de dorada para su alimentación. Por ello, el objetivo de la presente tesis ha sido el incluir parcialmente el turtó de girasol (TG) y concentrado proteico de guisante (CPG) en dietas para el sargo picudo. De igual forma sustituir parcialmente el aceite de pescado (AP) por aceite de soja (AS) y manteca de cerdo (MC). En los experimentos de inclusión de TG no se encontraron diferencias en el crecimiento de los peces alimentados con las dietas con 0, 12, 24 y 35% tanto en la fase de pre-engorde como de engorde. De igual forma, no se alteraron ni el perfil ni la eficiencia de la retención aminoacídica con la inclusión de esta fuente vegetal. Al observar la histología del intestino e hígado, no se observó ninguna modificación significativa, por lo que se podría indicar que la inclusión de hasta un 35% TG en la dieta para sargos picudos no afectaría ni la calidad del animal ni su salud en periodos inferiores a l60 días de alimentación. No obstante, al final de la fase de engorde, el crecimiento se ralentizó debido posiblemente al descenso gradual de la temperatura, y a que tal vez, los peces entraron en fase reproductiva, ya que similar resultado se observó en los sargos de engorde alimentado con fuentes lipídicas alternativas en la misma época del año. / Nogales Mérida, S. (2011). EFECTO DE LA INCLUSIÓN DE FUENTES PROTEICAS Y LIPÍDICAS EN LA ALIMENTACIÓN DEL SARGO PICUDO "Diplodus puntazzo" [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13831 / Palancia
4

Επίδραση του περιβάλλοντος στην επιθετική συμπεριφορά των ιχθυδίων μυτακίου Diplodus puntazzo (CETTI, 1777)

Χριστοδουλοπούλου, Σταυρούλα 04 August 2009 (has links)
Στην παρούσα εργασία μελετήθηκε η εκδήλωση της επιθετικής συμπεριφοράς στα ιχθύδια μυτακιού. Συγκεκριμένα, βιντεοσκοπούνταν ομάδες ψαριών σε τέσσερεις διαφορετικές πυκνότητες (0,125, 0,250, 0,500, 1 άτομο ανά λίτρο)(α πείραμα) και σε τρεις διαφορετικές θερμοκρασίες περιβάλλοντος (17, 20, 23°C)(β πείραμα), σε τρεις διαφορετικές ώρες της ημέρας (9:00, 14:00, 19:00), και σε σχέση με την πληρότητα του στομάχου σε τροφή (πριν-μετά το τάισμα). Συνολικά καταγράφηκαν δύο κύρια πρότυπα συμπεριφοράς, η επιθετικότητα (περιλάμβανε τα εξής: «απειλή», «κυνήγι ανάμεσα σε 2 ή 3 άτομα», «φίλημα», «χορός», «ανταπόδοση») και η βόσκηση. Η καμπύλη απόκρισης και των δύο κύριων προτύπων συμπεριφοράς ως προς την πληθυσμιακή πυκνότητα είχε κωδωνοείδη μορφή (p<0,05). Η ένταση και των δυο προτύπων συμπεριφοράς αυξήθηκε σημαντικά από την πυκνότητα 0,125 σε αυτή των 0,250-0,500 άτομα ανά λίτρο (p<0,05). Η θερμοκρασία επέδρασε σημαντικά (p<0,05) σε ορισμένα από τα πρότυπα. Στην πυκνότητα 5 άτομα/L η θερμοκρασία επέδρασε σημαντικά στις κατηγορίες ανταπόδοση, επίδειξη πτερυγίων επιτιθέμενου, επιθέσεις σε μαύρα ηττημένα άτομα και στη βόσκηση (p<0,05). Στην πυκνότητα 20 άτομα/L η θερμοκρασία επέδρασε σημαντικά στις κατηγορίες κυνήγι ανάμεσα σε 2 άτομα, την ανταπόδοση, επιθέσεις από μαύρα επιτιθέμενους άτομα, επίδειξη πτερυγίων επιτιθέμενου επιθέσεις σε μαύρα ηττημένα άτομα και στη βόσκηση (p<0,05). Αντιθέτως, ο χρόνος της ημέρας και η πληρότητα του στομάχου δεν επέδρασαν σημαντικά (p>0,05) και στις δύο περιπτώσεις. / We examined the effect of population density (0,125, 0,250, 0,500, 1 individuals per litre)(1st experiment) and environmental temperature (17, 20, 23°C)(2nd experiment), daytime (9:00, 14:00, 19:00) and stomach fulfilment (before-after feeding) on aggressiveness of juvenile Diplodus puntazzo. Two main behavioural patterns were determined, aggressiveness and grazing. Aggressiveness was exhibited in the form of: threat, hunting between 2 or 3 individuals, “kissing”, “dancing” and “pay back”. The response curve of both main behavioural patterns against population density was bell-shaped (p<0.05). The temperature had greatly affected some of the patterns(p<0.05). In density 5 ind./l the temperature affected the following categories “pay back”, “fins1”, “attacks at black defeated individuals” and “grazing”. In density 20 ind./l the temperature had greatly affected the category of “hunting between 2 individuals”, “pay back”, “attacks from black defeated individuals”, “finis 1”and “grazing”. The stomach fulfilment and daytime did not affect any of the behavioural patterns (p>0.05).
5

Movement bahaviour of three South African inshore sparid species in rocky intertidal and shallow subtidal habitats

Watt-Pringle, Peter Andrew January 2009 (has links)
This study investigated the movement behaviour of three inshore South African sparids – blacktail (Diplodus sargus capensis), zebra (Diplodus cervinus hottentotus) and white musselcracker (Sparodon durbanensis), popular inshore fishery species caught in appreciable numbers along much of the South African coast. The first study component examined movements of juveniles in a rocky intertidal nursery area at Schoenmakerskop near Port Elizabeth. Juveniles in a single gully were tagged with Visible Implant Elastomer (VIE) and resighted at the study site on snorkelling gear over a seven-month period. Tagged zebra and musselcracker displayed limited movement between potential low tide refuges, being observed repeatedly in the same gully over the full duration of the study. However, blacktail displayed greater movements and were seen infrequently in the later period of the study, probably having undergone an ontogenetic habitat shift to subtidal areas. There was evidence that blacktail maintain use of their intertidal nursery over high tide, during which the other two species moved into shallower areas adjacent to their low tide refuge. The results of three national tagging programs were analysed to determine the movement patterns of adolescent and adult fishes. The coast-wide ORI-WWF National Voluntary Tagging Program and two dedicated research programs in marine protected areas (MPAs) at De Hoop MPA and Tsitsikamma National Park (TNP) recorded few large-scale movements of tagged adult blacktail, zebra and juvenile musselcracker. High spatial-resolution data from the TNP suggested movements were usually on scales far smaller than one km. Together with long periods at liberty for many recaptured individuals, this suggests these fishes are longterm residents of small home range areas. However, tagged musselcracker over 600 mm forklength (adults) were observed to make large-scale movements, including some in excess of 800 km from Eastern Cape to KwaZulu-Natal waters. Predominantly eastward movements of adults recaptured during the spawning season indicate seasonal spawning migrations that occur in different regions of the coast. These enable the use of prevailing oceanographic currents to disperse eggs and larvae to suitable rocky nursery habitat. The third component of this study made use of high-resolution data on the temporal and spatial distribution of catches by scientific angling in the TNP to examine the daily activity patterns of the study species in relation to diel and tidal cycles, and habitat use. Blacktail capture probability was correlated with the diurnal light cycle, with peaks close to twilight suggesting elevated crepuscular foraging activity. Catches of blacktail, zebra and small musselcracker were correlated with the tidal cycle, foraging peaking over high tide periods. All three species used shallow inshore habitats extensively for foraging, blacktail showing a preference for sandy areas, while zebra and small musselcracker preferred shallow reef. Capture probability of larger musselcracker, however, was unrelated to habitat, possibly evidence of increasing area and habitat use with an ontogenetic change in diet. The lifetime movement patterns of these three species are discussed in relation to conservation measures and their management in South African fisheries. Restricted movement throughout post-settlement life for blacktail and zebra, and during the juvenile phase for musselcracker, makes local populations vulnerable to overexploitation. At present, MPAs probably play an important role in protecting local blacktail and zebra populations from overexploitation, and limited post-settlement movements mean the degree of larval dispersal between protected and adjacent areas will likely determine the effectiveness of MPAs in enhancing fisheries for these species. By contrast, MPAs likely provide recruits to fisheries for musselcracker during ontogenetic movements and dispersal from MPAs during spawning migrations. MPAs only offer partial protection to adult musselcracker populations in the spawning season, but this could nevertheless be significant under high levels of exploitation.
6

Structure génétique et dispersion en milieu marin : le cas de l'oursin commun Paracentrotus lividus et du sar commun Diplodus sargus.

Penant, Gwilherm 10 May 2012 (has links)
Le contexte lié au changement global et aux risques encourus par la biodiversité ont conduit les gestionnaires à développer des outils afin de préserver notre environnement et la biodiversité De nombreuses questions ont alors été soulevées notamment au sujet de la connectivité entre populations à préserver et de la définition des aires protégées. En milieu marin cette question soulève le problème des capacités de dispersion et du lien entre durée de la phase larvaire et flux de gènes. Dans ce contexte nous avons choisi d'étudier la connectivité entre populations de deux espèces à valeur commerciale et patrimoniale que sont l'oursin commun Paracentrotus lividus et le sar commun Diplodus sargus. Dans le cas de P. lividus, l'étude combinant plusieurs jeux de données utilisant des marqueurs moléculaires différents, à la fois produits pendant ce travail de thèse et issus de la littérature, a mis en évidence une différenciation génétique significative insoupçonnée à l'échelle régionale (40km) pour une espèce présentant une phase larvaire pélagique pouvant atteindre un mois. Cette étude a également permis de caractériser l'intensité et la direction des flux de gènes entre les bassins océaniques du sud-est de l'Atlantique Nord, de la Méditerranée et de l'Adriatique. / The context related to global change and risks of biodiversity loss have led managers to develop tools to help preserve our environment and the associated biodiversity. Many questions have been raised especially concerning the connectivity between populations and the definition of marine protected areas. These questions raise the problem of dispersal abilities and of the relationship between pelagic larval duration and gene flow. In this context we have chosen to study the connectivity between populations of two species of high commercial and patrimonial values: the edible sea urchin Paracentrotus lividus and the white seabream Diplodus sargus. In the case of P. lividus, the study combining several data sets and using different molecular markers, produced during this work or obtained from the literature, showed unexpected significant genetic differentiation at the regional scale (40km) for a species with a pelagic larval duration of up to one month. This study also allowed us to characterize the intensity and direction of gene flow between ocean basins of the southeastern North Atlantic, Mediterranean Sea and Adriatic Sea. Indeed gene flow was asymmetric and oriented from the Atlantic to the Mediterranean Sea and from the Adriatic Sea and to the Mediterranean Sea. These findings raise important questions about the origin of these different levels of differentiation and led me to make several assumptions on the impact of phenomena such as local adaptation, selective effects coupled with endogenous barriers, hydrological factors and / or biogeochemical. Several research perspectives are proposed to test these hypotheses.
7

Avaliação do resíduo do processamento de pescado para o desenvolvimento de co-produtos visando o incremento da sustentabilidade na cadeia produtiva / Evaluation of fish processing residue and development of coproducts aiming increase the sustainability of production chain

Sucasas, Lia Ferraz de Arruda 05 April 2011 (has links)
Atualmente, os consumidores valorizam produtos com garantia de qualidade e que sejam obtidos de cadeias ecologicamente corretas e socialmente justas. A rastreabilidade da cadeia produtiva possui importância fundamental para o aumento do consumo de pescado. Um dos principais gargalos da cadeia produtiva é o reduzido aproveitamento do resíduo do processamento. A elaboração de silagem de pescado é uma alternativa para minimizar os problemas ambientais e de sanidade, provenientes do resíduo de pescado, porém esta deve ser preparada com agentes acidificantes sustentáveis e que sejam selecionados através de análise de mercado levando em consideração os riscos ambientais e para a saúde humana, o custo e a facilidade de compra do agente acidificante, um dos objetivos dessa pesquisa. A utilização do ácido cítrico aparentou ser a melhor escolha. Avaliou-se o desempenho de 180 alevinos de sargo (Diplodus sargus) (21,30 ± 0,87 g) alimentados com 6 dietas isoenergéticas (3.941 kcal/kg), contendo dois níveis de proteína bruta PB (35 e 45%) e três níveis de inclusão (0, 10 e 20%) de silagem de resíduos provenientes da indústria conserveira da cidade do Porto, Portugal. Não houve mortalidade e as dietas experimentais foram bem aceitas. Não houve diferença (P<0,05) no consumo das rações, fator de condição, índice hepatossomático, índice de conversão alimentar e ganho de peso. É possível a inclusão de até 20% de silagem em dietas para o sargo e sugere-se a utilização das rações formuladas contendo 45% de PB por apresentarem menor custo de produção e empregarem maior quantidade de material residual proveniente do processamento de pescado. Em Portugal, o setor pesqueiro ocupa espaço destacado entre as atividades econômicas. A relevância desta cadeia produtiva resulta, essencialmente, do fato de que o pescado é componente fundamental da alimentação e responsável por elevado número de empregos da população. No Brasil, com o aumento do número de indústrias beneficiadoras, o resíduo desta atividade tornou-se um sério problema. Buscou-se classificar o resíduo do beneficiamento da tilápia do Nilo (Oreochromis niloticus), conforme a Associação Brasileira de Normas Técnicas (ABNT NBR 10004:2004), foram coletadas vinte e quatro amostras; três em cada período (ago/07, set/2007, out/2007, dez/2007, fev/2008, mai/2008, jul/2008, ago/2008). Todas as amostras foram classificadas como Classe II, do tipo Não Inerte devido aos teores de chumbo, manganês, surfactantes e ferro. Esses resíduos devem ser destinados a aterros sanitários construídos conforme normas específicas. Entretanto, estão sendo descartados de forma irregular, diretamente em recursos hídricos ou enterrados sem tratamento com riscos ao ambiente e à saúde humana e animal pela possibilidade de lixiviação de metais / Currently, consumers value products with assurance of quality and obtained from environmentally friendly and socially just chain. The traceability of the commodity chain has fundamental importance to increase the fish consumption. One of the main bottlenecks in the commodity chain is the reduced utilization of processing residue. The elaboration of fish silage is an alternative to minimize the environmental and sanity problems from fish residue. In order to select the most appropriate acid for the preparation of chemical fish silage, market analysis considering environmental and human risks, cost and supply of acidifying agent was performed. The use of citric acid seems to be the best choice. The performance of 180 bream fingerlings (21.30 ± 0.87 g) fed six isoenergetic diets (3,941 kcal/kg) containing two levels of crude protein - CP (35 and 45%) and three levels of inclusion of silage (0, 10 and 20%) was evaluated. There was no mortality and the experimental diets were well accepted. There was no difference (P<0.05) in diets intake, condition factor, hepatosomatic index, food conversion ratio and weight gain. Weight gain and food conversion ratio were 9.61 g and 2.77, 9.23 g and 2.99, 9.95 g and 3.04, 11.81 g and 2.86, 13.41 g and 2.14, and 11.36 g and 2.41 for treatments 1 (35% CP; 0% inclusion), 2 (35% CP, 10% inclusion), 3 (35% CP, 20% inclusion), 4 (45% CP; 0% inclusion), 5 (45% CP, 10% inclusion) and 6 (45% CP, 20% inclusion), respectively. Therefore, it is possible to include up to 20% of fish silage in diets for bream and suggests the use of diets containing 45% CP because of their lower cost of production and for using higher amount of residual material from fish processing. The fisheries sector occupies an important position in the economic activities in Portugal. Its relevance is due to fish being a fundamental component of food and responsible for employment opportunities. In Brazil, the increasing number of fish processing industries, the residue of this activity has become a serious problem. The residue from the processing of Nile tilapia (Oreochromis niloticus) was classified according to the Brazilian Association of Technical Standards (ABNT NBR 10004:2004). A total of twenty-four samples were collected, three in each period (Aug/07, Sep/2007, Oct/2007, Dec/2007, Feb/2008, May/2008, Jul/2008, Aug/2008). All analyzed samples were classified as Class II, Non Inert, due to the lead, manganese, iron and surfactants levels. These wastes should be disposed of in landfills constructed according to environmental standards. However, they are being improperly disposed, dumped directly into water or buried without proper treatment, providing risk to the environment and human and animal health due to possible leaching of metals
8

Avaliação do resíduo do processamento de pescado para o desenvolvimento de co-produtos visando o incremento da sustentabilidade na cadeia produtiva / Evaluation of fish processing residue and development of coproducts aiming increase the sustainability of production chain

Lia Ferraz de Arruda Sucasas 05 April 2011 (has links)
Atualmente, os consumidores valorizam produtos com garantia de qualidade e que sejam obtidos de cadeias ecologicamente corretas e socialmente justas. A rastreabilidade da cadeia produtiva possui importância fundamental para o aumento do consumo de pescado. Um dos principais gargalos da cadeia produtiva é o reduzido aproveitamento do resíduo do processamento. A elaboração de silagem de pescado é uma alternativa para minimizar os problemas ambientais e de sanidade, provenientes do resíduo de pescado, porém esta deve ser preparada com agentes acidificantes sustentáveis e que sejam selecionados através de análise de mercado levando em consideração os riscos ambientais e para a saúde humana, o custo e a facilidade de compra do agente acidificante, um dos objetivos dessa pesquisa. A utilização do ácido cítrico aparentou ser a melhor escolha. Avaliou-se o desempenho de 180 alevinos de sargo (Diplodus sargus) (21,30 ± 0,87 g) alimentados com 6 dietas isoenergéticas (3.941 kcal/kg), contendo dois níveis de proteína bruta PB (35 e 45%) e três níveis de inclusão (0, 10 e 20%) de silagem de resíduos provenientes da indústria conserveira da cidade do Porto, Portugal. Não houve mortalidade e as dietas experimentais foram bem aceitas. Não houve diferença (P<0,05) no consumo das rações, fator de condição, índice hepatossomático, índice de conversão alimentar e ganho de peso. É possível a inclusão de até 20% de silagem em dietas para o sargo e sugere-se a utilização das rações formuladas contendo 45% de PB por apresentarem menor custo de produção e empregarem maior quantidade de material residual proveniente do processamento de pescado. Em Portugal, o setor pesqueiro ocupa espaço destacado entre as atividades econômicas. A relevância desta cadeia produtiva resulta, essencialmente, do fato de que o pescado é componente fundamental da alimentação e responsável por elevado número de empregos da população. No Brasil, com o aumento do número de indústrias beneficiadoras, o resíduo desta atividade tornou-se um sério problema. Buscou-se classificar o resíduo do beneficiamento da tilápia do Nilo (Oreochromis niloticus), conforme a Associação Brasileira de Normas Técnicas (ABNT NBR 10004:2004), foram coletadas vinte e quatro amostras; três em cada período (ago/07, set/2007, out/2007, dez/2007, fev/2008, mai/2008, jul/2008, ago/2008). Todas as amostras foram classificadas como Classe II, do tipo Não Inerte devido aos teores de chumbo, manganês, surfactantes e ferro. Esses resíduos devem ser destinados a aterros sanitários construídos conforme normas específicas. Entretanto, estão sendo descartados de forma irregular, diretamente em recursos hídricos ou enterrados sem tratamento com riscos ao ambiente e à saúde humana e animal pela possibilidade de lixiviação de metais / Currently, consumers value products with assurance of quality and obtained from environmentally friendly and socially just chain. The traceability of the commodity chain has fundamental importance to increase the fish consumption. One of the main bottlenecks in the commodity chain is the reduced utilization of processing residue. The elaboration of fish silage is an alternative to minimize the environmental and sanity problems from fish residue. In order to select the most appropriate acid for the preparation of chemical fish silage, market analysis considering environmental and human risks, cost and supply of acidifying agent was performed. The use of citric acid seems to be the best choice. The performance of 180 bream fingerlings (21.30 ± 0.87 g) fed six isoenergetic diets (3,941 kcal/kg) containing two levels of crude protein - CP (35 and 45%) and three levels of inclusion of silage (0, 10 and 20%) was evaluated. There was no mortality and the experimental diets were well accepted. There was no difference (P<0.05) in diets intake, condition factor, hepatosomatic index, food conversion ratio and weight gain. Weight gain and food conversion ratio were 9.61 g and 2.77, 9.23 g and 2.99, 9.95 g and 3.04, 11.81 g and 2.86, 13.41 g and 2.14, and 11.36 g and 2.41 for treatments 1 (35% CP; 0% inclusion), 2 (35% CP, 10% inclusion), 3 (35% CP, 20% inclusion), 4 (45% CP; 0% inclusion), 5 (45% CP, 10% inclusion) and 6 (45% CP, 20% inclusion), respectively. Therefore, it is possible to include up to 20% of fish silage in diets for bream and suggests the use of diets containing 45% CP because of their lower cost of production and for using higher amount of residual material from fish processing. The fisheries sector occupies an important position in the economic activities in Portugal. Its relevance is due to fish being a fundamental component of food and responsible for employment opportunities. In Brazil, the increasing number of fish processing industries, the residue of this activity has become a serious problem. The residue from the processing of Nile tilapia (Oreochromis niloticus) was classified according to the Brazilian Association of Technical Standards (ABNT NBR 10004:2004). A total of twenty-four samples were collected, three in each period (Aug/07, Sep/2007, Oct/2007, Dec/2007, Feb/2008, May/2008, Jul/2008, Aug/2008). All analyzed samples were classified as Class II, Non Inert, due to the lead, manganese, iron and surfactants levels. These wastes should be disposed of in landfills constructed according to environmental standards. However, they are being improperly disposed, dumped directly into water or buried without proper treatment, providing risk to the environment and human and animal health due to possible leaching of metals
9

The taxonomy, life-history and population dynamics of blacktail, Diplodus Capensis (Perciformes: Sparidae), in southern Angola

Richardson, Timothy John January 2010 (has links)
The blacktail, Diplodus capensis, is an inshore sparid fish distributed from Mozambique to Angola. This species forms an important component of coastal fisheries within its distribution, one being the subsistence handline fishery in southern Angola. With this fishery being critically important to the livelihoods of local communities, a biological study and stock assessment was conducted to provide information for the management of this species in southern Angola. However, with molecular evidence suggesting that the Benguela current may have separated the southern African populations of many inshore fish species over two million years ago, a morphological, taxonomic analysis was considered necessary to first investigate whether there was evidence for allopatry in this species. A total of 46 morphometric measurements and 18 counts were carried out on specimens collected from various locations in southern Angola and South Africa. Results were analysed using multi-dimensional scaling (MDS) and the significance of clusters was tested using analysis of similarities (ANOSIM). Biological samples of D. capensis were collected monthly from an unexploited area from April 2008 to March 2009. Additional biological samples were collected from the subsistence fishers in an exploited area during May, June and December 2009. Standard biological laboratory techniques were employed for the lifehistory comparison between the exploited and unexploited area. A per-recruit analysis was conducted using the life-history parameters from both areas in order to assess the current status of the subsistence fishery and to investigate the potential short-falls of the per-recruit assessment approach. The morphometric comparison showed that there was not sufficient evidence for speciation between the southern Angolan and South African populations of D. capensis. There was, however, sufficient morphological evidence to suggest that these populations are separate stocks. This indicated that the existing reference points on which the management of the South African population is based are unsuitable for the Angolan population. Diplodus capensis in southern Angola is omnivorous, feeding predominantly on algae, barnacles and mussels. An ontogenetic shift from algae to barnacles and mussels was correlated with allometric growth patterns in their feeding apparatus. This species is a rudimentary hermaphrodite in southern Angola with peak spawning in June and July. The overall sex ratio (M: F) was 1: 4.7 in the unexploited area and 50% maturity was attained at 149.5mm FL and five years. Diplodus capensis in southern Angola exhibits very slow growth with the maximum age observed being 31 years (validated using mark recapture of chemically injected fish). Females [L(t) = 419.5(1-e⁻°·°⁴⁵⁽t⁻³·⁴ ⁾)] grew significantly faster (LRT, p < 0.05) than males [L(t) = 297.4(1-e⁻°·°⁷⁷⁽t⁻²·⁷⁾)], and females dominated the larger size classes and older age classes. In the exploited area, the length and age frequencies were severely truncated, the maximum observed age was greatly reduced (17 years) and the sex ratio was less female biased at 1: 2.2. Although there was no evidence for a physiological response to exploitation through alterations in growth or size/age at sexual maturity between the two areas, there was an increase in the proportion of small females in the exploited area, which may have been a compensatory response for the loss of large females. A combination of an underestimate of longevity, different estimates of the Von Bertalanffy growth parameters and overestimates of the natural mortality rate in the exploited population resulted in a 92% underestimate of the pristine spawner biomass-per-recruit (SBR) value. An assessment based on the actual pristine SBR estimate from the unexploited area revealed that the subsistence fishery had actually reduced D. capensis to 20% of its pristine SBR levels and highlighted the value of pre-exploitation life-history information for the application of per-recruit models. This study has shown that D. capensis in southern Angola displays life-history characteristics that render it susceptible to overexploitation, even at low levels of fishing pressure. The current lack of infrastructure and enforcement capacity in the fisheries department of Angola renders traditional linefish regulatory tools, such as size limits, bag limits and closed seasons, inappropriate. Therefore, suitably designed marine protected areas are recommended as the best management option for this species.
10

Rôle des enrochements côtiers artificiels dans la connectivité des populations, cas du sar commun (Diplodus sargus, Linné, 1758) en Méditerranée nord-occidentale

Pastor, Jérémy 04 June 2008 (has links) (PDF)
La destruction d'une partie des habitats est souvent la cause principale de leur fragmentation. Or, depuis les années 1960-1970, l'anthropisation du littoral du golfe du Lion a engendré la création d'habitats fragmentés, non pas par une destruction, mais bien par un apport nouveau via l'installation massive d'enrochements côtiers artificiels. Cette étude a eu pour but principal de comprendre le rôle de ces structures en comparaison à des zones naturelles (lagunes, zone rocheuse) dans le maintien des populations de poissons de la côte rocheuse située plus au sud. Le sar commun, poisson caractéristique des zones rocheuses, a été utilisé comme modèle. Des comptages d'adultes et de juvéniles en plongée subaquatique, des marquages directs mais aussi l'utilisation de la microanalyse chimique des otolithes ont été utilisés afin de répondre à ces interrogations. Les aménagements littoraux jouent un rôle de nourricerie non négligeable. Selon les années, les densités de juvéniles sont de 30 à 109 fois supérieures à celles observées sur les habitats naturels, que ce soit sur la côte rocheuse ou dans la lagune. La présence de seulement deux groupes principaux de géniteurs sur la côte catalane française pourrait expliquer de telles différences. Un des deux alimenterait les enrochements côtiers artificiels, il serait situé au cap Leucate. Le second, dans la réserve de Cerbère-Banyuls exporterait des juvéniles vers la côte espagnole suivant un courant dominant nord-sud. De plus, la lagune aurait perdu son rôle de nourricerie au profit des aménagements littoraux. Nos résultats montrent aussi qu'il existe une connectivité lors de la phase adulte entre ces structures côtières et les zones rocheuses naturelles. Elle a lieu principalement au printemps et en automne. 20 % des sars ayant fait leur installation sur les aménagements littoraux les quittent pour la côte rocheuse. Sur cette côte un tiers des sars sont issus d'une installation sur des habitats artificiels de la côte sableuse. Cette étude souligne le rôle majeur que peuvent avoir ces habitats artificiels dans le maintien, voire l'extension des populations de sars communs au niveau de la côte catalane, mais aussi de l'ensemble du golfe du Lion. La fragmentation de l'habitat est dans ce cas positive. Elle pourrait être à l'origine de l'apparition de nouvelles espèces sur la côte du Languedoc-Roussillon comme le sar tambour, Diplodus cervinus et le denti, Dentex dentex

Page generated in 0.1124 seconds