dc.contributor.advisor | Nilssen, Einar M. | |
dc.contributor.author | Windsland, Kristin | |
dc.date.accessioned | 2014-09-26T08:18:53Z | |
dc.date.available | 2014-09-26T08:18:53Z | |
dc.date.issued | 2014-10-01 | |
dc.description.abstract | To improve local economy, the red king crab (Paralithodes camtschaticus) was introduced to the Barents Sea by Soviet scientists in the 1960s. Adapting well to the new environment, the growing population gradually invaded new areas along the coast of northern Norway. The red king crab has become a valuable marine resource but as an introduced species, it is also a potential threat to the ecosystem. To meet the management goals, more knowledge about the growth, mortality and dispersal of the species is essential. This thesis attempts to provide this knowledge.
In paper I, we developed Bayesian hierarchical models to estimate growth parameters of the von Bertalanffy growth function using tag-recapture data. Allowing for individual variability led to increased precision in estimated lengths and to more realistic values for the growth parameters. The length-at-relative age of small males were overestimated, while those of small females were not. This is believed to be due to differences in growth patterns after maturity.
In paper II, we explored the dispersal behaviour and extent of dispersal of red king crab in Norwegian waters. The results indicated that the range expansion of this species is a result of both the existence of long-distance dispersers and time-dependent slow migration by short distance-dispersers and that there is a substantial dispersal of crabs out of the quota-regulated area.
In paper III, estimates of annual total mortality were calculated using length-converted catch curves in three time-periods that represented different levels of exploitation. Natural mortality was estimated using a linear regression of total mortality and exploitation rate and by using indirect methods based on life-history parameters. The steady increase in total mortality of males is consistent with the increase in exploitation level while the increase in female mortality is surprising. The estimates of natural mortality ranged from 0.23-0.44 year-1; the larger values are probably an overestimate due to unaccounted bycatch mortality while the lower ones are consistent with life-expectancy. | en |
dc.description.doctoraltype | ph.d. | en |
dc.description.popularabstract | En av hovedkonklusjonene i denne avhandlingen er at spredningen av bestanden ikke bare skyldes individer som vandrer lange distanser i løpet av kort tid, men at også individer som vandrer korte avstander per år bidrar til spredning ved at distansene summeres. Over tid vil 1 av 2 individer ha potensial til å vandre fra en fjord til en annen. Avhandlingen viser videre at en del krabber vandrer ut av det kvoteregulerte området. Det er derfor viktig at innsatsene i det frie fisket og desimeringsfiske opprettholdes. Dødeligheten har økt siden 1994, for både hanner og hunner. For hannkrabber er økningen i dødelighet sammenfallende med kvoteøkningen, mens økning for hunnkrabber er overraskende. I denne avhandlingen er det også blitt konstruert vekstkurver for hann- og hunnkrabber som viser at individuell vekst i norske farvann er sammenlignbar med vekst i opprinnelsesområdet. Videre vises det at kongekrabben modnes kun 19 mnd før den rekrutteres til det kommersielle fisket, hvilket kan forårsake problemer for rekrutteringen. | en |
dc.description.sponsorship | Havforskningsinstituttet | en |
dc.description | The papers of this thesis are not available in Munin: <br/>1. Windsland, K., Hvingel, C., Nilssen, E. M., Sundet, J. H.: 'Evaluation of von Bertalanffy growth curves for the introduced red king crab (Paralithodes camtschaticus) in Norwegian waters', Fisheries Research (2013), vol. 145:15-21. Available at <a href=http://dx.doi.org/10.1016/j.fishres.2013.03.003>http://dx.doi.org/10.1016/j.fishres.2013.03.003</a> <br/>2. Windsland, K., Hvingel, C., Nilssen, E. M., Sundet, J. H.: 'Dispersal of the introduced red king crab (Paralithodes camtschaticus) in Norwegian waters: a tag-recapture study', ICES Journal of Marine Science (2014), online before print. Available at <a href=http://dx.doi.org/10.1093/icesjms/fst241>http://dx.doi.org/10.1093/icesjms/fst241</a> <br/>3. Windsland, K.: 'Total and natural mortality of red king crab (Paralithodes camtschaticus) in Norwegian waters: Catch curve analysis and indirect estimation methods' (manuscript). | en |
dc.identifier.isbn | 978-82-8266-087-7 | |
dc.identifier.uri | https://hdl.handle.net/10037/6735 | |
dc.identifier.urn | URN:NBN:no-uit_munin_6335 | |
dc.language.iso | eng | en |
dc.publisher | UiT The Arctic University of Norway | en |
dc.publisher | UiT Norges arktiske universitet | en |
dc.rights.accessRights | openAccess | |
dc.rights.holder | Copyright 2014 The Author(s) | |
dc.rights.uri | https://creativecommons.org/licenses/by-nc-sa/3.0 | en_US |
dc.rights | Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) | en_US |
dc.subject | VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 | en |
dc.subject | VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488 | en |
dc.subject | VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 | en |
dc.subject | VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 | en |
dc.title | The invasive red king crab (Paralithodes camtschaticus):
Mortality, individual growth and dispersal
in Norwegian waters | en |
dc.type | Doctoral thesis | en |
dc.type | Doktorgradsavhandling | en |