Sökning: "otoliths"

Visar resultat 1 - 5 av 10 uppsatser innehållade ordet otoliths.

  1. 1. Otolith morphology of sprat (Sprattus sprattus) along the Swedish west coast

    Master-uppsats, SLU/Dept. Of Aquatic Resources

    Författare :Francesco Saltalamacchia; [2018]
    Nyckelord :European sprat; Otolith; shape analysis; wavelet;

    Sammanfattning : The population structure of sprat (Sprattus sprattus) in the Swedish Kattegat – Skagerrak has been at present not well investigated, and the boundaries between the management unit in this region and the larger stock occurring in the North Sea are also highly uncertain, posing issues to the successful management of the stock in this area. In this study, variations in otolith shape among several samples from the Swedish west coast, southern North Sea and Norwegian fjords north of Bergen were studied to investigate the effectiveness of shape analysis for characterise the population structure in the study area, and evaluate whether differences could be used to assign individual fish to their origin. LÄS MER

  2. 2. A diet study of post-breeding Great cormorants (Phalacrocorax carbo sinensis) on Gotland

    Master-uppsats, SLU/Dept. of Wildlife, Fish and Environmental Studies

    Författare :Anton Larsson; [2017]
    Nyckelord :Baltic sea; regurgitated pellets; otoliths; prey species composition; sea birds;

    Sammanfattning : The Swedish population of great cormorant (Phalacrocorax carbo sinensis) has rapidly increased to over 40 000 breeding couples since the EU-protection 1980. Since the cormorant are high efficient predators living in large colonies, they are accused for reducing fish populations and competing with fishery. LÄS MER

  3. 3. Northern pike Esox lucius growth rates in sub populations of freshwater and sea water origins in the Baltic Sea : Otolith method approach

    Master-uppsats, Linnéuniversitetet/Institutionen för biologi och miljö (BOM)

    Författare :Nelson Mbawala; [2016]
    Nyckelord :Esox lucius; otolith; polishing; staining; core; annuli; growth rate and age;

    Sammanfattning : Northern pike or pike Esox lucius is total piscivorous fish species found in the brackish and freshwater ecosystems of the Northern hemisphere. It is a top predator and keystone species that causes cascading effects in these ecosystems. Otoliths have been used to estimate age and growth rates in most fishes. LÄS MER

  4. 4. Life history trade-offs in Anadromous Burbot Lota lota (Linnaeus 1758) from Rickleån and Sävarån, Northern Sweden

    Master-uppsats, SLU/Dept. of Wildlife, Fish and Environmental Studies

    Författare :Mikael Sandberg; [2015]
    Nyckelord :life history trade-offs; anadromous burbots; Bothnian Bay; Rickleån; Sävarån; otoliths;

    Sammanfattning : Anadromous burbots Lota lota (Linnaeus 1758) from two similar rivers in the Gulf of Bothnia area, Sävarån and Rickleån, Northern Sweden, were compared. The aim was to test for and explain differences in ecology. Spawning burbots in Sävarån were smaller, younger, grew slower and were more densely populated. LÄS MER

  5. 5. Assessing the importance of freshwater tributary systems for the recruitment of Eurasian Perch (Perca fluviatilis) in Baltic Sea Coastal Ecosystems

    Master-uppsats, SLU/Dept. Of Aquatic Resources

    Författare :Joe Wastie; [2014]
    Nyckelord :Perch; Freshwater systems; Coastal areas; Coastal ecosystems;

    Sammanfattning : Populations of one of the most important predatory fish species within Baltic Sea coastal ecosystems, the Eurasian Perch (Perca fluviatilis), have declined in some coastal areas during recent decades. This has caused negative effects on an ecological, commercial, and cultural scale, and protection and restoration of recruitment areas (perch spawning grounds) are believed to be an important player in supporting future stocks. LÄS MER