This thesis focuses on the implications of exploitation pattern (population selectivity) and population resilience for fisheries sustainability in the NE Atlantic. Novel metrics of exploitation pattern and resilience are introduced and the effects of juvenile protection and resilience erosion on stock size, structure and yields are investigated. Analysis of both empirical and simulated data suggested that high selection of juveniles negatively affects both stock size and yield. A meta-analysis of empirical data for 38 fish stocks showed that fishing mortality of juveniles exceeding half that of mature fish leads to overfishing. Simulation-based analysis illustrated that a mean age-at-capture more than two years higher than mean age-at-maturity secures high yields at low levels of stock depletion. The effects of exploitation pattern on stock status are weaker than those of exploitation rate when empirical data are considered, both at an individual-stock and a cross-stock scale. However, simulation-based analysis revealed that for higher levels of juvenile protection than the ones observed in most empirical stocks, exploitation pattern would be more influential than exploitation rate. These findings suggest that there is a high unfulfilled potential to promote sustainability by protecting juveniles. Besides exploitation pattern, population resilience is another factor whose role in fish population dynamics was examined here. A resilience assessment of Barents Sea cod was carried out using a novel integrated approach combining multivariate analysis and bifurcation theory. This way, the occurrence of a population state shift in 1981, associated with climatic and exploitation effects, was identified. The approach implemented in this resilience assessment is reproducible to any other data-rich population and can be also used at the community- and ecosystem-levels to explain and predict state shifts. As Europe is currently moving towards a more holistic approach in fisheries management through the reform of the Common Fisheries Policy, such quantification and investigation of stock/exploitation attributes beyond stock size and exploitation rate is of great importance.

No description available.

During 1980 and 1981 respectively, 2425 and 4028 yellow perch 150-359 mm were Floy-tagged from June through August at four sites in Indiana waters of Lake Michigan. Most of the 6453 perch were tagged from mid-June to early August and almost 90% were less than 210 mm.An overall recapture rate of 3.2% (204 fish) was obtained by April 1, 1982. Site recapture rates were positively related to the numbers of fish tagged. Slightly over 92% of all fish were tagged at sites M and K and 94.5% of all recaptures originated from these two sites. Second season recaptures accounted for 25.5% of all recaptures. Peak recapture rates occurred in July. Sources of recaptures were 67.6% from sport fishermen, 25.5% from commercial fishermen, and 6.9% from Indiana Department of Natural Resources, Ball State University trawl catches and other sources.Most recaptured perch were in the 150-229 mm length interval, but an apparent size selection by both commercial and sport gear existed towards 180-229 mm perch. The recapture of large numbers of 150-159 mm fish indicated survival of small perch was not an important factor influencing size selection. Information on sizes of fish recaptured by sex and age was insufficient for evaluation.Although straight line movements of up to 166 km occurred, most fish remained near the original tagging sites. Distances traveled were similar for fish from all tagging sites in 1980, 1981 and for second season recaptures. Over 76% of all fish were recaptured in Indiana waters and about 86% traveled less than 32.0 km from the original tagging sites. The majority (64%) of fish leaving Indiana waters were captured nearby at New Buffalo and Union Pier, Michigan. About 68% of all recaptures were received within 60 days of release. Even though considerable variability was evident in the distances traveled with time, no seasonal trends were observed for perch of various sizes.Simple regression analysis of data for combined years revealed only 27% of all variation in distance traveled by perch was accounted for by the time at large (days) prior to recapture. Multiple regression analysis revealed the time at large was more important than fish length in relation to distance traveled, accounting for 27.3% and 0.2% of the explained variability, respectively. Data including second season recaptures more accurately represented these relationships and indicated these variables were poorly related to distance traveled. Examination of residuals showed a dramatic and statistically undesirable increase in unexplained variability was associated with far ranging fish. Other factors should be considered in future multiple regression analyses.Indiana yellow perch stocks appear to be fairly discrete entities. The majority of fish tended to remain periods of at least one year.

Thesis (Ph.D.) - James Cook University, 2005. / Typescript (photocopy) Bibliography: leaves 158-183.

Thèse--Sc. nat.--Paris VI, 1978. / Bibliogr. p. 316-325.

Thesis (M.S.), Natural Resources, University of Wisconsin--Stevens Point, 2004. / Includes bibliographical references (leaves 68-79).

Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 78-88). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 37-43).

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 83-96).