Fish populations were sampled by electrofishing at a variety of sites on the Rivers N. Esk (1992-3) and Dee (1993-4) for comparison with sawbill duckling diets from the same rivers. Sampling methods are described and discussed in relation to other methods and in terms of possible biases. Within electrofished samples species distribution were similar on the two rivers, but more fish were caught per unit effort on the N. Esk. Catch results are described in terms of fish numbers and catch weights of each species from different sections of river and from different sampling times over the summers. Special attention is paid to the distribution and size frequency of salmon, because of their importance in the fish communities of the two rivers and as food for sawbill ducklings. The diets of goosander and merganser ducklings on the study rivers are quantified in terms of species of prey in the diet, size/age classes of fish and relative proportions of these species and classes. Estimates of diet are made from the stomach contents of samples of ducklings. Species composition of the diets are then related to the distribution of fish in those parts of the rivers in which the ducklings forage. Sizes of fish in the diets are then related to the sizes of fish in the duckling foraging areas, taking into account the changes in fish size with location and overtime, and the size (and approximate age) of ducklings. For comparison with diets, fish length data from electrofished samples was interpolated by regression between pairs of consecutive samples and adjacent river sections. This provided expected mean river fish lengths for the dates and locations at which broods were sampled.

This collection of papers comprises four sections. The first section deals with the helminth and arthropod parasites recovered from a variety of mammalian hosts, and consists of four chapters. The first chapter deals with the taxonomy of the parasites of mammalian hosts, where some 15 nematode species were either newly described, redescribed or descriptions amended, and the immature stages of an oestrid fly and the adults of two hippoboscid flies described. The second describes the seasonal occurrence of arthropod and helminth parasites recovered from approximately 1 380 antelope, scrub hares, warthogs and bushpigs. In the third chapter some miscellaneous natural and experimental findings of helminths in free-living hosts are presented, amongst others several new host-parasite associations and the proceedings of symposia, while the fourth chapter deals with the pathology of natural infections of impalas with Cooperiodes hepaticae, kudus with Elaeophora sagitta and buffaloes with Parafilaria bassoni. The second section deals with the parasites of freshwater fishes. In the taxonomic part of this section, Chapter 1, one trematode genus is redescribed, and one new trematode species and 14 new nematode species described. In the second chapter, the seasonal occurrence of the helminth parasites of approximately 700 freshwater fish representing 14 species is presented. The third part deals with the helminths of lizards, snakes and crocodiles, where a new Paraspirura species, a new Madathamugadia species and some 14 new species, subspecies and forms of subspecies of the oxyurid genera Spauligodon, Skrjabinodon, Thelandros and Tachygonetria were described. A comprehensive host-parasite list of snakes and lizards is included, as is an equally comprehensive host-parasite list of the pentastome parasites of crocodiles. In the fourth part, two new Tetrameres species are described and the population dynamics of guineafowls and Swainson’s spurfowl discussed. A complete list of the helminth parasites of guineafowls is listed, together with an extended host list of these parasites. / Thesis (PhD)--University of Pretoria, 2009. / Veterinary Tropical Diseases / unrestricted

The introduction of exotic species is one of the greatest threats to freshwater biodiversity. Brown trout are native to Eurasia, but have been introduced to much of the rest of the world, including the United States. In other parts of their introduced range, brown trout have caused substantial negative effects to native species‟ abundances and distributions, and have altered the structure of some aquatic communities. In the United States, studies of some streams and watersheds have shown that brown trout can negatively affect native species, but I found no study that considers the effect of brown trout across a large portion of their introduced range. For this study, I examined if (1) the abundance and distribution of two ecologically different native fish taxa (sculpins and speckled dace) and (2) the structure of entire stream vertebrate assemblages were negatively associated with the presence and abundance of brown trout. I based my analyses on existing, standardized survey data collected across streams of the western United States. I found no relationship between brown trout and the abundance, presence-absence, or probability of detection of sculpins or speckled dace. I also found that brown trout were not associated with the structure of native stream vertebrate assemblages. My results imply that native stream vertebrates in western US streams are able to coexist with brown trout across the western United States, despite the negative effects brown trout can have on some taxa in individual watersheds or rivers.

Along its Red Sea coast Eritrea possesses not less than 350 Islands. Dahlak Kebir, the largest of all is located approximately 50kms off the coast of Massawa, the busiest port of Eritrea. Topographically, relatively low relief limestone encircled by clean waters, abundant coral reefs and bountiful of fish species are the dominant features of the Islands. Nevertheless, their rich resources are so far not harnessed. They are inhabited by small fishing communities. One could only witness a small hotel and few houses scattered here and there, except for the presence of a military base on both Dahlak Kebir and in the near by Nakura Islands. The archaeological site of the Necropolis, a large early Islamic cemetery, and nearby ancient cisterns and pre Islamic cemetery, lies on the southwestern side of the Island. The story of Dahlak and its ruins are clear testimony that the archipelago has a mine of very rich history that needs to be explored. In the 7th century, for instance, it was through these Islands that the Islamism has infiltrated and eventually penetrated deep into various parts of Eritrea and Ethiopia. In between the beginning of the 8th and mid-9th century, the archipelago was conquered and occupied by various external powers such as the Byzantine Empire. In the 13th century, during the period of internal uprising in the Arab world, Dahlak established its own autonomous Sultanate. In latter years, Portuguese and Ottoman Kingdoms used to control the Islands and to assert their supremacy in the Red Sea. In 16th century, however, Dahlak was exclusively occupied by the Ottomans and was used as a launching ground to conquer and control the costal part and highland of Eritrea. Finally, in the 1870s Mohammed Ali of Egypt became master of the Islands. Dahlak was also known to have been the centre of trade for slaves on the Horn from the beginning of its occupation by Ottomans until its occupation of the Islands and the Red Sea coast by the Egyptians. (Eritrean travel and trade manual 2000) The prospect of the Dahlak Archipelago for the development of a successful tourist industry in Eritrea could undoubtedly be feasible. The low-lying coral chains where these volcanic Islands are located is amazingly tantalizing, fascinating and picturesque beyond description. Environmentally unpolluted, they are hygienic health-wise and could therefore be the primary attractions for tourists. Clean water and warm climate being their outstanding features, tourists could easily be lured to enjoy themselves without much ado about worrying their welfare, given their graceful natural environment is protected from deteriorations by contamination. White sandy beaches, protective bays and lagoons, provide excellent conditions for diving, snorkeling, sailing wind surfing and other sport activities. (Travel Trade Manual of Eritrea, 2000) / Dissertation (MPhil (Tourism Management))--University of Pretoria, 2008. / Tourism Management / MPhil / unrestricted

The purposes of this study were to gain a better understanding of anglers and angler preferences and to examine differences between subgroups of anglers based on level of specialization. Understanding these similarities and differences between user groups will provide valuable input for more effective fisheries management. A randomized mail survey was sent to resident, adult fishing-license holders in Utah. A 68% response rate yielded 1216 usable returns for data analysis. An analysis of three recreation specialization dimensions (participation, equipment and investment, and lifestyle) and further analysis of participation and investment variables were used to develop a typology of Utah anglers. Three specialization subgroups and four typology subgroups were then compared to determine differences in motivations for fishing, preferences toward various fishing and management attributes and the desirability of available fish species. Anglers with different levels of specialization differed significantly in their motivations for fishing, preferences for fishery resource attributes and desirability ratings of available fish species. Typology subgroups were found to not differ significantly in motivations, preferences or species desirability ratings. However, level of participation (number of fishing trips taken in past year) and investment (money invested in fishing equipment) were each valuable in identifying differences in motivations and preferences, but not in species desirability ratings. By identifying sportsmen constituencies based on specialization characteristics, managers can better provide fishing opportunities consistent with angler needs. Fisheries managers will have a tool to match sportsmen with the type of setting and management strategy desired or to match the management to the sportsmen, thus maximizing satisfaction.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19532号 / 理博第4192号 / 新制||理||1602(附属図書館) / 32568 / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 渡辺 勝敏, 教授 疋田 努, 教授 曽田 貞滋 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

In three locations of the middle stream of the river Stropnice the electrofishing has been carried out repeteadly. According to stated population characteristics in the period before and after autumn fishing, the influence of Fishery Nové Hrady Ltd. on composition of river ichtyocenosis was set. During the electrofishing basic physical and chemical parameters of water were also stated.

Thesis (PhD (Food Sc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Consumers have the right to accurate information on the fish products they purchase to enable them to make educated seafood selections that will not endanger their own wellbeing or the wellbeing of the environment. Unfortunately, marine resource scarcity, financial incentives and inadequate or poorly enforced regulations have all promoted the mislabelling of fish species on global markets, the results of which may hold economic, conservation and health consequences. The primary aims of this study were to determine the most commonly available fish species on the South African market, to establish and compare DNA-based methods for the unambiguous identification of these species and to utilise the most applicable methods to evaluate the extent of mislabelling on the local fisheries market. The results from surveys of n = 215 restaurants and n = 200 retail outlets in four South African provinces (Western Cape, Kwa-Zulu Natal, Eastern Cape and Gauteng) indicated that 34 and 70 nominal fish types were available in restaurants and retail outlets, respectively, the most common of which were kingklip, salmon and hake. Over 30% of the fish species being sold were of conservation concern, while several outlets marketed specially-protected, illegal-to-sell species in South Africa. Fish purveyors were poorly equipped to provide information on the identity, origin, production method (farmed/wild) and sustainability of the fish they were selling and the labelling of many packaged fish products was in contravention with South African regulations. Data were published for the first time comparing the efficiency of five methods (urea-SDS-proteinase K, phenol-chloroform, salt extraction, SureFood PREP kit and Wizard Genomic DNA Purification kit) for the extraction of DNA from the muscle tissue of fish species available in South Africa. The SureFood kit was identified as the most suitable method for DNA extraction from fish muscle, extracting significantly (P < 0.05) higher DNA yields than all other methods evaluated and being simple and safe to use. A comprehensive reference library of genetic information was compiled for the first time that contains sufficient DNA sequence data from different mitochondrial DNA loci (16S ribosomal RNA (rRNA), 12S rRNA and cytochrome c oxidase I (COI) genes, as well as the control region) to allow the explicit identification of 53 fish species in South Africa. Although 16S and 12S rRNA gene sequencing allowed the identification of most fish to the genus level, the discrimination of closely-related, congeneric species was problematic when based on these gene regions. Conversely, the vast majority (98%) of fish examined could be readily differentiated by their COI sequences, with only members of the genus Thunnus requiring supplementary control region sequencing for species confirmation. Lastly, sequencing of the COI region was used to show that 9% of fish samples collected from local seafood wholesalers and 31% of samples from retail outlets were mislabelled. This study has established that fish mislabelling is a reality on the South African market and that DNA-based methods should be applied by both industry and regulatory bodies to deter illegal activities and to promote transparency on the domestic fisheries market. / AFRIKAANSE OPSOMMING: Verbruikers het die reg tot akkurate informasie rakende die visprodukte wat hulle aankoop. Hierdie inligting sal hulle bemagtig om ingeligte seekos keuses te maak wat voordelig sal wees vir beide die verbruiker se eie, sowel as die omgewing, se voortbestaan. Ongelukkig het 'n gebrek aan seelewebronne, geldelike aansporings en onvanpaste of swak geïmplimenteerde regulasies gelei tot die verkeerde etikettering van visspesies op die wêreldmarkte. Dit mag ekonomiese-, bewarings- en gesondheidsgevolge inhou. Die primêre doelwitte van hierdie studie was om te bepaal watter visspesies die algemeenste beskikbaar is in die Suid-Afrikaanse mark, om DNS-gebaseerde metodes vir die duidelike identifisering van hierdie spesies te vind en te vergelyk, en om die mees gepaste metodes te gebruik om die omvang van verkeerde etikettering in die plaaslike vismarkte te evalueer. Die resultate van opnames van n = 215 restaurante en n = 200 winkels in vier Suid-Afrikaanse provinsies (Wes-Kaap, Kwa-Zulu Natal, Oos-Kaap en Gauteng) het gewys dat 34 en 70 nominale visspesies in onderskeidelik restaurante en kleinhandelaars beskikbaar was. Koningklip, salm en stokvis was die mees algemene spesies. Meer as 30% van die visspesies wat te koop was is van bewaringsbelang, terwyl verskeie winkels spesiaal-beskermde, onwettig-om-te-verkoop spesies in Suid-Afrika bemark het. Visverkopers was swak bemagtig om informasie oor die identiteit, oorsprong, produksiemetode (teel/wild) en volhoubaarheid van die vis wat hulle verkoop het te kon gee. Verder was die etikettering van baie verpakte visprodukte in stryd met Suid-Afrikaanse regulasies. Vir die eerste keer is data gepubliseer wat vyf metodes (ureum-SDS-proteïenase K, fenolchloroform, sout-ekstraksie, SureFood PREP stel en Wizard Genomic DNS suiwering stel) vergelyk in hul doeltreffendheid om DNS vanuit die spierweefsel van visspesies wat in Suid-Afrika beskikbaar is te ekstraheer. Die SureFood stel is as die mees geskikte metode vir DNS ekstraksie vanuit visweefsel geïdentifiseer aangesien die DNS opbrengs betekenisvol (P < 0.05) hoër was met hierdie metode, en dit ook 'n eenvoudige en veilige metode is om te gebruik. 'n Omvattende verwysingsbiblioteek van genetiese informasie wat voldoende DNS volgordebepalingsdata van verskillende mitokondriale DNS lokusse (16S ribosomale RNS (rRNS), 12S rRNS en sitochroom c oksidase I (COI) gene, sowel as die kontrolegebiede) bevat, is vir die eerste keer opgestel om die besliste identifisering van 53 visspesies in Suid-Afrika toe te laat. Alhoewel 16S en 12S rRNS geenvolgordebepaling die identifisering van meeste visse op genusvlak toegelaat het, was die diskriminasie van naby-verwante, gelyksoorting spesies problematies wanneer hierdie geengebiede gebruik is. Die oorgrote meerderheid (98%) vis wat ondersoek is geredelik onderskei op grond van hul COI volgordebepalings, met slegs lede van die genus Thunnus wat addisionele kontrolegebied volgordebepaling vir spesies bevestiging vereis het. Laastens, is volgordebepaling van die COI-gebied gebruik om te wys dat 9% van die vismonsters van plaaslike seekosgroothandelaars en 31% van die monsters van kleinhandelaars verkeerd geëtiketteer is. Hierdie studie het bevestig dat die verkeerde etikettering van vis in Suid-Afrika 'n realiteit is, en dat DNS-gebaseerde metodes gebruik moet word deur die industrie sowel as die regulerende liggame om onwettige aktiwiteite teen te werk en om deursigtigheid in plaaslike vismarkte te bevorder.

Unionoid mussels are globally threatened and their conservation requires species-specific knowledge on their ecology and parasite-host interaction. Unio crassus is one of Europe’s most threatened unionoid species and has a temporary obligate parasitic life stage (glochidia) on fish. A lack of suitable hosts is probably a major limitation for mussel recruitment, but host species composition, suitability and availability in time and space have yet to be fully explored. This thesis examines different aspects of the host fish species, including their composition, suitability and ecological importance, in relation to U. crassus, using both field and laboratory studies. The effects of mussel and host density on mussel reproductive potential were considered, as were aspects of evolutionary adaptations between mussels and fish and how climate change may affect their interaction. The results show that U. crassus is a host generalist, parasitizing a variety of fish species. Host suitability and density, which varied among fish species and rivers, affected the level of glochidia encapsulation, hence mussel reproductive potential, more so than the density of mussels taking part in reproduction. Ecologically important hosts included both highly suitable primary hosts, and less suitable hosts that were highly abundant. Whether or not U. crassus has specific adaptations to its hosts to enhance juvenile transformation remains unclear. No distinct pattern of local adaptation was found, nor was there an effect of host fish presence on the timing of glochidia release by adult mussels. Instead, temperature played a major role, with results suggesting that changes in spring water temperature regimes can cause temporal and spatial mismatches in the mussel-host interaction. This thesis indicates that investigations of local mussel-host interactions help in identifying mechanisms important for unionoid conservation management and prioritization. / Många sötvattenmusslor har en komplex livscykel där larverna (glochidier) under sin utveckling till frilevande musslor parasiterar på gälarna hos lämpliga värdfiskar. Flera av våra musslor, såsom den tjockskaliga målarmusslan (Unio crassus), är globalt hotade och för att kunna bevara och förvalta dessa arter på bästa sätt behöver vi lära oss mer om deras ekologi och samspelet mellan musslan och dess värdfiskar. Avsaknaden av värdfiskar innebär förmodligen en stor begränsning för rekryteringen av juvenila musslor, men det finns trots detta en begränsad kunskap om hur artsammansättningen i fisksamhället och dess tillgänglighet påverkar musselpopulationer.  Min avhandling undersöker olika aspekter av interaktioner mellan U. crassus och dess värdfiskar, som hur värdfisksamhällen och fiskarters värdlämplighet påverkar musslans reproduktionspotential. Jag har även studerat hur tätheter av olika fiskarter och vuxna musslor påverkar rekryteringen, eventuella evolutionära anpassningar samt om en förhöjd temperatur skulle kunna påverka interaktionen mellan U. crassus och dess värdfiskar. Resultaten visar att U. crassus är en generalist som parasiterar på en mängd olika fiskarter. Jag fann dock en stor variation i dominerande fiskarter och lämpliga värdar mellan olika åar, vilket påverkade reproduktionspotentialen hos musslorna mer än vad tätheten vuxna musslor som deltog i reproduktionen gjorde. Som ekologiskt viktiga värdar fanns således både särskilt lämpliga, primära värdarter, men också mindre lämpliga arter som förekom i höga tätheter. Ingen tydlig lokal anpassning kunde observeras, och fiskens närvaro påverkade inte tidpunkten för när de vuxna musslorna släppte sina glochidielarver. Däremot fann jag att temperaturen spelade en viktig roll för musslans reproduktion, där ökad temperatur föreslås ha negativa effekter på interaktionen mellan musslan och dess värdfiskar. Avhandlingen visar på vikten av att studera interaktioner mellan den tjockskaliga målarmusslan och dess värdar på lokal skala för att bättre kunna identifiera och prioritera viktiga naturvårdsåtgärder. / UnioCrassusforLIFE (European LIFE+ project: LIFE10 NAT/SE/000046)

Thesis (M.Sc. (Physiology)) -- University of Limpopo, 1993. / Refer to the document / University of Limpopo Research Office