Recreational fishing is a very important leisure activity and one of the most important ways how humans influence freshwater habitats and wild fish populations. Both fish-eating predators and socio-economic trends play a major role in recreational fishing. This thesis found that the Eurasian otter feeds mainly of small (5-10 g) and very abundant fish species of low angling value. In this case, gudgeon Gobio gobio dominated in the otter diet. The overlap between catches of otters and anglers was very low, and commercially important salmonids made up only 10 % of the otter diet by biomass. Cormorants also prey mostly on smaller (10-100 g) a very abundant fish species. In this case, roach Rutilus rutilus dominated in the cormorant diet. The overlap between catches of cormorants and anglers was also quite low. Commercially important fish species made up less than 10 % of the cormorant diet. Even though cormorants consume mostly smaller fish, they are potentially removing fish that serve as prey for piscivores, and they are also removing smaller fish that would grow into angling size. The Atlantic salmon Salmo salar reintroduction programme has not yet been successful. However, cormorant predation is not the main reason for its low success. The main problem is somewhere on the lower River Elbe in...

This report examines three different machine learning algorithms and their effectiveness for predicting recreational fishing success. Recreational fishing is a huge pastime but reliable methods of predicting fishing success have largely been missing. This report compares random forest, linear regression and multilayer perceptron to a reasonable baseline model for predicting fishing success. Fishing success is defined as the expected weight of the fish caught. Previous reports have mainly focused on commercial fishing or limited the research to examining the impact of a single variable. In this exploratory study, multiple attributes and multiple algorithms are examined to determine if supervised machine learning is a viable tool to predict recreational fishing success. Recreational fishing success can potentially be predicted by a large number of attributes, which may be different for different species. In this report, data is fetched from multiple sources and combined into a unified data format. The primary source of data is a database from the fishing app FishBrain, containing data of over 250000 logged catches. Another is the World Weather Online API which supplies weather data. The report focuses on the four most common species in the database, largemouth bass, Micropterus salmoides, northern pike, Esox lucius, rainbow trout, Oncorhynchus mykiss and European perch, Perca fluviatilis with a focus on largemouth bass since it has the most data available. Algorithms are evaluated using the Weka data mining software. Hyperparameters are found using cross-validation and some data is used as a test set to validate the results after cross-validation. Results are measured as the error compared to a baseline algorithm. Random forest is the most effective algorithm in the experiments, reducing error compared to the baseline for all the examined fish species. It is also found that no single variable affects the chosen metric of fishing success much, but rather a combination of most of the examined variables is needed to give optimal predictions. In conclusion, the random forest algorithm can be used to predict fishing success across multiple species. It performs significantly better than linear regression, multilayer perceptron and the baseline on crossvalidation and on the testing set. / I denna rapport evalueras tre olika maskininlärningsalgoritmer och deras effektivitet för att förutsäga framgång inom sportfiske. Sport- fiske är en mycket populär hobby, men pålitliga metoder att förutsäga framgångsrikt sportfiske saknas. Denna rapport jämför random forest, linjär regression och flerlagers neurala nätverk mot en rimlig baselinealgorithm för att förutsäga framgång inom sportfiske. Framgång defineras som fiskens förväntade vikt i kg. Tidigare undersökningar har huvudsakligen fokuserat på kommersiellt fiske eller begränsat undersökningen till påverkan av en enskild variabel. I denna studie undersöks flera attribut och algoritmer för att avgöra om övervakad maskininlärning är ett användbart verktyg för att förutsäga framgång inom sportfiske. Framgång inom sportfiske kan potentiellt påverkas av ett stort antal attribut som kan vara olika för olika arter. I denna studie hämtas data från ett flertal källor som kombineras i ett unifierat dataformat. Den primära datakällan är en databas tillhörande sportfiskeappen FishBrain som innehåller över 250000 loggade fångster. En annan källa är World Weather Online:s API som bidrar med väderdata. Rapporten fokuserar på de fyra vanligaste arterna i databasen, largemouth bass, Micropterus salmoides, gädda, Esox lucius, regnbågsöring, Oncorhynchus mykiss och europeisk abborre, Perca fluviatilis med ett särskilt fokus på largemouth bass eftersom den har mest data tillgängligt. Algoritmerna evalueras med hjälp av data mining-verktyget Weka. Hyperparametrar bestäms med hjälp av korsvalidering och en delmängd av datan separeras och används för att validera resultaten efter korsvalidering. Resultaten mäts relativt en baseline-algoritm. Random forest är den mest effektiva algoritmen i experimenten och reducerar felet jämfört med baseline-algoritmen för alla undersökta fiskarter. Inget enskilt attribut påverkar slutresultatet mycket utan det behövs en kombination av flera attribut för att ge optimala prediktioner. Slutsatsen blir att random forest kan användas för att förutsäga framgång inom sportfiske för flera olika fiskarter. Den presterar signifikant bättre än linjär regression, flerlagers neuralt nätverk och baselinealgoritmen på korsvalidering och på testdelmängden.

Parmi les nombreuses activités exercées sur les systèmes socio-écologiques littoraux, la pêche récréative a connu un essor important devenant ainsi un enjeu de développement durable. En France, les défauts de gouvernance de l'État dans la gestion du DPM invitent à s'interroger sur la pertinence et la faisabilité d'une co-gestion de ces pratiques de loisir. Ce paradigme, se voulant une alternative à une gestion top-down, prône la participation accrue des populations locales dans la gestion de l'environnement pour améliorer ses résultats. L'île d'Oléron ne déroge pas à ces constats qui sont renforcés par les modifications sociétales spécifiques aux territoires insulaires. Dans le cadre de recherches dont l'objet d'étude est une problématique sociétale, il est approprié de faire appel à une approche interdisciplinaire pour améliorer la pertinence des réponses apportées. Concernant la pêche à pied récréative à l'étrille, les résultats obtenus en biologie et en écologie mettent en évidence des caractéristiques qui semblent indiquer un faible impact potentiel à court comme à long termes de ces perturbations ponctuelles sur les populations locales. D'un point de vue sociétal, la pertinence d'une co-gestion de la pêche récréative est clairement établie par les nombreux conflits d'usages impliquant les pêcheurs récréatifs, le manque de moyens pour gérer la pratique et acquérir des données scientifiques, le manque de concertation, etc. La dynamique de développement du territoire oléronais et les initiatives locales à l'instar des conflits d'usages soutiennent l'idée de l'existence d'une « fenêtre politique » pouvant permettre la mise en place d'une co-gestion de la pratique dans les prochaines années, sous réserve d'une communication suffisante et d'une réelle volonté des acteurs concernés par la gestion de la pratique. / Among several other activities practice on coastal socio-ecological system, recreational fishing ones have significantly increased over the past few years, becoming an issue for sustainable development. In France, the weakness of states governance concerning DPM management, questions the relevancy and feasibility of a co-management policy for these leisure activities. This paradigm, constituting a good substitute for top-down management, recommends an increased participation of local populations for managing environments and improving their outcomes. Oléron Island is thus affected by these observations, which are intensified by societal changes distinguishing island territories. In the current research context, aiming at solving societal problematic, it is relevant to consider an interdisciplinary approach to provide relevant answers. Concerning recreational shellfish gathering targeting the velvet swimming crab, results in biology and ecology highlight some characteristics which should indicate a weak short and long terms potential impact of the disturbances affecting local populations. As regards to societal aspects, the relevancy of co-management is clearly demonstrated by several land-use conflicts, a lack of means to manage the practice and scientific data, the lack of consultation, etc. The territorial dynamic and local initiatives, as well as land-use conflicts, underline the existence of a “political window” which should allow the implementation of a co-management process for recreational fishing in the following years, subject to further efficient communication and a real desire from stakeholders concerned by the management of this practice.

Angelerfolg hängt vom Fischverhalten ab und selektiver Fang aufgrund vererbbarer Verhaltensmerkmale kann sich auf Fischpopulationen auswirken. Die anglerische Vulnerabilität ergibt sich aus einer Kombination aus dem Zustand des Fisches, dem Zusammentreffen mit dem Fanggerät und den Eigenschaften desselben. Höhere Aktivität sollte die Begegnungswahrscheinlichkeit mit dem Fanggerät und dadurch die Vulnerabilität steigern. Ziel dieser Arbeit war es zu verstehen, wie Bewegungsmuster die Vulnerabilität durch die Angelfischerei beeinflussen. Dazu habe ich das Verhalten von vier Arten (Karpfen, Cyprinuscarpio, Schleie, Tinca tinca, Barsch, Perca fluviatilis, und Hecht, Esox lucius) in einem See mittels akustischer Telemetrie gemessen. Zudem habe ich verhaltensselektives Angeln auf Benthivore (Karpfen und Schleie) von festen Plätzen mit dem mobilen Angeln auf einen aktiven Raubfisch (Barsch) und einen Lauerjäger (Hecht) verglichen. Barsche wurden gezielt von freiwilligen, unterschiedlich versierten Anglern in GPS-überwachten Booten beangelt, um zu verstehen, wie Anglerfähigkeiten verhaltensbasierte Selektion beeinflussen. Für die individuell wiederholbare Aktivität von Karpfen, Schleie und Barsch lag keine Angelselektivität vor, da das Zusammentreffen mit Fanggeräten in keinem Zusammenhang mit der Vulnerabilität stand. Beim Barsch hingegen hing die Vulnerabilität mit der Habitatwahl zusammen. Die Geschicklichkeit der Angler verstärkte die Selektion durch höhere Mortalität. Für große Hechte mit großem Aktionsradius kann ein auf Begegnungen basierender Mechanismus nicht ausgeschlossen werden. Zusammenfassend lässt sich sagen, dass die wichtigsten Verhaltensweisen, die die Vulnerabilität durch die Angelfischerei ausmachen und nach denen eine Selektion erwartet wird, häufig erst nach dem Zusammentreffen von Fisch und Fischer stattfinden. Jedoch kann die Bedeutung dieser Fisch-Fischer Begegnungen für die Vulnerabilität art- und fischereispezifisch sein. / Capturing fish by angling depends on fish behaviour. Selective capture based on heritable behaviours may have ramifications for fish populations and fishing communities, but the behavioural components of angling vulnerability are unclear. Conceptually, vulnerability derives from a combination of a fish’s internal state, gear encounter rate and gear quality. Accordingly, greater activity or space use is expected to increase vulnerability via elevated encounter rates with fishing gear. However, behaviourally selective angling may also interact with angler behaviour (e.g. skill). My aim was to understand the role of fish movement and space use in driving angling vulnerability. I measured the behaviour and angling vulnerability of four species (viz. carp, Cyprinus carpio, tench, Tinca tinca, perch, Perca fluviatilis, and northern pike, Esox lucius) using whole-lake high resolution acoustic telemetry. Perch were targeted by variably skilled anglers in GPS tracked boats to understand how skill affects selection. I have therefore contrasted behaviourally selective angling of benthivores (carp and tench) targeted from fixed angling sites, an active top predator (perch) targeted by searching anglers and an ambush predator (northern pike) targeted by searching anglers. Angling was unselective for repeatable carp, tench or perch activity and movement as encounter was unrelated to vulnerability. Vulnerability related to perch habitat choice as shown by a latitudinal division of captured and uncaptured perch and high skilled anglers only strengthened selection via greater enacted mortality. Finally, large pike with greater space use were most vulnerable to angling and an encounter based mechanism cannot be ruled out. In conclusion, the key behaviours distinguishing angling vulnerability, upon which selection should be expected, frequently operate after a fish-fisher encounter, but the importance of fish-fisher encounters for vulnerability may be species and fishery specific.

Šiame darbe nagrinėjamas mėgėjiškos žūklės valstybinis valdymas Lietuvoje. Darbe aptariami mėgėjiškos žūklės valdymo pasiekimai kitose šalyse bei mėgėjiškos žūklės vaidmuo darniajame vystyme. Tyrimas taip pat atskleidžia esamas mėgėjiškos žūklės valdymo problemas Lietuvoje teisiniame, organizaciniame ir aplinkosauginiame lygmenyje. Valdymo trūkumams nustatyti pasitelktos suinteresuotų asmenų – meškeriotojų nuomonės. Buvo atlikta jų apklausa, kurioje dalyvavo 825 žmonės. Magistro darbą sudaro įvadas, dešimt skyrių, išvados ir rekomendacijos bei naudotų literatūros šaltinių sąrašas. Darbą sudaro dvi pagrindines dalys. Pirmoji dalis supažindina su esama situacija mėgėjiškos žūklės sektoriuje Lietuvoje ir pasaulyje, aptaria meškeriojimo teisinį reglamentavimą, žuvų išteklių naudojimą. Antroji dalis supažindina su mėgėjiškos žūklės valdymo aspektais ir atskleidžia šio valdymo problemas ir trūkumus, supažindina su meškeriotojų nuomonėmis valdymo klausimais bei įvertina ekonominį mėgėjiškos žūklės potencialą viešajame ir privačiame sektoriuje. Tyrimo metu nustatyta, kad valstybinis mėgėjiškos žūklės valdymas yra neefektyvus ir kad esantis mėgėjiškos žūklės ekonominis, aplinkosauginis ir socialinis potencialas yra labai menkai naudojamas valstybės. Darbe pateikiamos rekomendacijos ir pasiūlymai identifikuotom problemom spręsti. Darbas turėtų būti naudingas ir įdomus aplinkos apsaugos, ichtiologijos, gamtos išteklių valdymo, rekreacinio turizmo specialistams, meškeriotojams. / This paper presents the research of angling management in Lithuania. There are some examples of successful management of angling in other countries as well as recreational fishing role in sustainable development. The research also reveals the current angling management problems in Lithuania in the legal, organizational and environmental levels. To identify weaknesses in the angling management there was executed survey of really stakeholders. Totally the 825 anglers took part in it and their opinions are presented here. The thesis consists of an introduction, ten chapters, conclusions and recommendations, and used references. Paper can be divided into two main parts. The first part presents the current situation of recreational fishing in Lithuania and the world, also discusses the angling legislation and stocks of fish resources in general. The second part discusses the angling management and reveals aspects of the management problems and shortcomings, and introduces the anglers views on governance issues. Also there are evaluating the economic potential of the recreational fishing in the public and the private sector. The study set out that recreational fishing management is ineffective in Lithuania. The governance is using only a small part of possible advantages and benefits from recreational fishing. After conclusions of research you can find the recommendations to solve identified problems of management. This paper would be useful and interesting for ichtiologists... [to full text] / В работе анализируется государственное управление в области любительского (рекреационного) рыболовства. Представлены результаты и опыт других государств и выявляются проблемы управления любительского рыболовства в Литве на юридическом, организационном и природоохранном уровнях. Работа представляет интерес для ихтиологов, специалистов по управлению природными ресурсами, специалистов в области рекреационного рыболовства.

MORO, Pietro Simon. Prospecção do estoque de robalo-peva (Centropomus parallelus) no litoral do Paraná, através da pesca esportiva. 2008. 132 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Fortaleza-CE, 2008 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T14:03:53Z No. of bitstreams: 1 2008_dis_psmoro.pdf: 2639439 bytes, checksum: 4150101baf0cf24111738e4e5b850429 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-20T14:04:06Z (GMT) No. of bitstreams: 1 2008_dis_psmoro.pdf: 2639439 bytes, checksum: 4150101baf0cf24111738e4e5b850429 (MD5) / Made available in DSpace on 2016-07-20T14:04:06Z (GMT). No. of bitstreams: 1 2008_dis_psmoro.pdf: 2639439 bytes, checksum: 4150101baf0cf24111738e4e5b850429 (MD5) Previous issue date: 2008 / The snooks are fishes very appreciated food item by fish consumers and recreational fishermen, for they are endowed with a high quality flesh and put up a fierce fight when captured with line-and-hook. Such characteristics make this taxon a target for a host of users, objectives and needs (commercial and recreational fishing) which, together with loss of habitat space (mangroves), attest to its fragility. Over the recent years, a catch reduction of the fat snook, Centropomus parallelus, has been implied by recreational and artisanal fishermen of Paraná State. For lack of fishery statistics that would enable the investigation of this telltale resource depletion, the present research work endeavored to carry out a preliminary stock assessment based on the survey of recreational fishing tournaments and on the study of that species’ growth. The database was gathered by controlling the catches of nine of the mentioned tournaments, having C. parallelus and Centropomus undecimalis as target species, organized by the Paraná State Recreational Fishing League (LPPE), from November, 2005 to September, 2007 in the estuaries of Paranaguá Bay and Guaratuba Bay (25o441S – 48o22’W). A total of 3,290 specimens of C. parallelus were sampled for their total length ranging from 10.0 to 69.0 cm and of 158 specimens of C.undecimalis in the range of 14,0 – 68,0 cm. The strong specific dominance of over 95% justified the emphasis of this investigation on the fat snook. The weight-length relationship showed an isometric somatic development for the two species. The mean catch per unit effort (CPUE) was estimated as 0.977 individuals per hour and 0,328 kg per hour. For the growth studies, only 159 specimens were submitted to the extraction of sagittae otoliths, while all the others were released according to the catch-and-release rules required by the LPPE. Based on the analysis of otoliths’s microstructure, the von Bertallnafy growth parameters were estimated by means of different backcalculation methods (Fraser-Lee, linear BPH, linear SPH, and potential BPH and SPH) and fiting of the growth curve (Ford-Walford and electronic routine). The most adequate growth parameters in the species’ population dynamics were K = 0.13, L¥ = 79.0 cm and t0 = 0. The ELEFAN I technique has borne out the estimates arrived at through the length-at-age analysis. The longevity and the natural mortality coefficient were estimated as 23 years and 0.33, respectively. The average values of optimum catch length and age correspond to Lopt = 43.0 cm and topt = 6 years. About 95% of the maximum biomass were found to occur in the range from 38.0 cm (5 years) to 47.0 cm (7 years). The preliminary stock assessment of C. parallelus on the Paraná State coast, carried out by means of length composition analysis and age structure of the stock reported by recreational fishing tournaments, indicated the occurrence of growth overfishing, that is, large numbers of juveniles and few adult (>35.0 cm) specimens are captured, what characterizes an age-related unbalanced population / Os robalos são peixes muito apreciados pelo público consumidor de pescado e pelos pescadores amadores, pois possuem carne de excelente qualidade e proporcionam grande combatividade quando capturados com linha. Tais características tornam este grupo de peixes alvo de distintos usuários, finalidades e necessidades (pesca comercial e pesca amadora), que aliadas à perda de parte do habitat (manguezais) indicam sua fragilidade. Nos últimos anos, uma redução nas capturas de robalo-peva (Centropomus parallelus) vem sendo sugerida pelos pescadores amadores e artesanais no litoral do Paraná. Na ausência de estatísticas pesqueiras que possibilitassem investigar a suposta deplecção deste recurso, o presente trabalho buscou realizar uma avaliação preliminar deste estoque, fundamentada no acompanhamento de campeonatos de pesca esportiva e no estudo do crescimento da espécie. Os dados foram obtidos através do acompanhamento das capturas de 9 torneios de pesca esportiva, direcionados às espécies C. parallelus e Centropomus undecimalis, realizados pela Liga Paranaense de Pesca Esportiva (LPPE), entre novembro de 2005 e setembro de 2007, nos estuários Baía de Paranaguá e Baía de Guaratuba (25º 44’ S e 48º 22’ W). Foram registrados 3.290 exemplares de C. parallelus, com comprimentos totais compreendidos entre 10,00 e 69,00 cm e 158 exemplares de C. undecimalis, com comprimentos entre 14,00 e 68,00 cm. A forte dominância específica (>95%) justificou a ênfase deste trabalho sobre C. parallelus. A relação pesocomprimento indicou desenvolvimento somático isométrico para as duas espécies. A média da Captura por Unidade de Esforço (CPUE) foi estimada em 0,977 exemplar/embarcação/hora e 0,328 Kg/embarcação/ hora. Para o estudo do crescimento, foram abatidos somente 159 exemplares para a extração dos otólitos sagittae, todos os demais exemplares registrados (3290), foram soltos dentro das regras de pesque-e-solte exigidas pela LPPE. A partir da análise da macroestrutura dos otólitos, foram estimados os parâmetros de crescimento de von Bertalanffy através de distintas metodologias de retrocálculo (Fraser-Lee, BPH linear, SPH linear, BPH potencial e SPH potencial) e de ajuste da curva de crescimento (Ford-Walford e rotina eletrônica). Os parâmetros mais adequados aos conhecimentos anteriores sobre a biologia da espécie foram K= 0,13, L = 79,0 cm e t0 = 0. A análise das freqüências de comprimento (ELEFAN I) corroborou com as estimativas de crescimento obtidas pela análise dos otólitos. A longevidade (tmáx) e o coeficiente de mortalidade natural (M) foram estimados em 23 anos e 0, 33, respectivamente. O comprimento e a idade ótimos de captura correspondem a Lotimo = 43.0 cm e tótima = 6 anos. Para os comprimentos entre 38,0 cm (5 anos) e 47,0 cm (7 anos), também foram encontrados valores elevados de biomassa relativa, em torno de 95% da biomassa máxima possível. Na avaliação preliminar do estoque de C. parallelus no litoral do Paraná, realizada através da análise da composição em comprimentos e da estrutura etária das capturas registradas nos campeonatos de pesca esportiva, foi constatada a ocorrência de sobrepesca de crescimento, ou seja, a captura de grande quantidade de juvenis e poucos exemplares adultos (>35,0 cm), caracterizando um desequilíbrio na estrutura etária da população

Im ersten Teil meiner Arbeit habe ich den Einfluss von Seeentstehung und fischereilicher Bewirtschaftung auf Artenreichtum und Zusammensetzung der Fischgemeinschaften in kleinen Seen untersucht. Dafür habe ich fischereilich ungenutzte Naturseen als Referenz herangezogen und deren Fischgemeinschaft mit der von unbewirtschafteten Baggerseen, sowie fischereilich genutzten Baggerseen und Naturseen verglichen. Im zweiten Teil meiner Arbeit habe ich die Mechanismen der Totholzrekrutierung in Baggerseen untersucht und die Wichtigkeit von Totholz und anderen Litoralstrukturen im Vergleich zu den klassischen Seenvariablen Nährstoffgehalt und Seemorphologie auf die Fischabundanz im Litoral analysiert. Des Weiteren habe ich die Habitat-spezifischen Effekte auf die artspezifische, litorale Fischabundanz und die Effekte von zusätzlich eingebrachten Totholzbündeln auf die Abundanz typischer Fischarten in Baggerseen analysiert. Ich habe herausgefunden, dass fischereiliche Bewirtschaftung die Anzahl der Fischarten in Bagger- und Naturseen erhöht ohne die Zusammensetzung der Fischgemeinschaft im Vergleich zu fischereilich ungenutzten Naturseen signifikant zu verändern. Im Gegensatz dazu unterscheidet sich die Fischgemeinschaft in fischereilich ungenutzten Baggerseen durch das Fehlen von typischen Seefischarten und eine hohe Variabilität in der Zusammensetzung zwischen den Gewässern. Ich konnte zeigen, dass die litorale Totholzmenge in Baggerseen durch die Baumdichte am Ufer in Kombination mit der Windrichtung, durch fischereiliche Bewirtschaftung in Interaktion mit der Uferneigung und das Alter der Gewässer getrieben wird und entsprechend in jungen Baggerseen niedriger ist als in alten Naturseen. Ich fand heraus, dass Litoralstrukturen, wie Totholz, wertvolle Lebensräume darstellen, wichtige Deskriptoren der art-spezifischen, litoralen Fischabundanz sind und die Fischabundanz grundsätzlich mit der Strukturmenge ansteigt. / In the first part of my thesis, I studied the effects of lake genesis and fisheries management on fish species richness and community composition in small lakes. I used fish communities in unmanaged natural lakes as reference and compared them to unmanaged gravel pit lakes as well as managed gravel pit and natural lakes. In the second part, I investigated the recruitment of littoral deadwood in gravel pit lakes and analysed the importance of deadwood and other littoral structures on littoral fish abundance in gravel pit lakes compared to the lake environmental variables such as nutrient level and lake morphology. I further analysed habitat-specific effects on species-specific littoral fish abundance and focussed explicitly on the effects of deadwood bundles implemented in the littoral zone. I found fisheries management to increase the number of fish species in gravel pit and natural lakes, but not leading to different fish community compositions compared to unmanaged natural lakes. By contrast, unmanaged gravel pit lakes were characterized by a lack of typical lake fish species and a high variation in fish community composition among lakes (β-diversity). I detected littoral deadwood densities in gravel pit lakes to be mainly driven by lake age, riparian tree density in interaction with wind direction and littoral slope in angler-managed lakes, with lowest deadwood densities in shallow areas of angler-managed lakes. Furthermore, deadwood densities were lower in young gravel pit lakes compared to old natural lakes. I detected littoral structures, such as littoral deadwood, as appropriate habitats and important descriptors of the species-specific, littoral fish abundance in gravel pit lakes with generally positive effects of structure extension on fish abundance. Littoral habitat characteristics were mostly of similar, or even higher, importance for fish abundance compared to lake environmental factors.