Hvilke faktorer kan bidra til samordning mellom IT og helsetjenesten i norske kommuner? (Et eksplorativt studium)

Masteroppgave informasjonssystemer IS501 - Universitetet i Agder 2017Konfidensiell til / confidential until 01.01.202

Technological creep masks continued decline in a lobster (Homarus gammarus) fishery over a century

Fishery-dependent data are frequently used to inform management decisions. However, inferences about stock development based on commercial data such as Catch-Per-Unit-Effort (CPUE) can be severely biased due to a phenomenon known as technological creep, where fishing technology improves over time. Here we show how trap improvement over nine decades has driven technological creep in a European lobster (Homarus gammarus) fishery. We combined fishing data, experimental fishing with contemporary and older trap types, and information on depletion effects during fishing seasons. The resulting standardized CPUE time series indicates a 92% decline in lobster abundance between 1928 and 2019 compared to 70% if technological creep is not corrected for. Differences are most pronounced within the last 40 years when the most substantial shift in gear technology occurred: an uncorrected CPUE index suggests an 8% increase in lobster abundance during this period, while the corrected CPUE index declined by 57%. We conclude that technological creep has masked a continuous stock decline, particularly in recent decades and largely driven by the shift from one- to two-chambered traps, as well as the ability of newer trap designs to capture larger lobsters. Our study confirms the importance of adequate standardization, including technological development, when using fishery dependent CPUE for monitoring and management of data-limited fisheries.publishedVersio

Efficiency and catch dynamics of collapsible square and conical pots used in the red king crab (Paralithodes camtschaticus) fishery

We compared the capture efficiency and catch dynamics of collapsible square and conical pots used in resource assessment and harvesting of red king crabs (Paralithodes camtschaticus [Tilesius, 1815]) in the Barents Sea. After two days of soaking, square pots caught three times as many crabs as conical pots, and their catches consisted of a higher proportion of male crabs and male crabs larger than 160 mm carapace length compared to the catches in the conical pots. Catches in the square pots did not increase as soak times were increased beyond two days, which indicates equilibrium between the rate of entries into and the rate of exits from the pots. Catches in conical pots, however, increased with increasing soak times up to eight days, the longest soak time examined in this study. These findings demonstrate the higher efficiency of square pots and the importance of understanding catch dynamics when making population assessments based on catchper-unit-of-effort data. The favorable catch characteristics and handling properties of the collapsible square pot may make this pot design suitable for other crab fisheries, as well

Seleksjon i reketrål: overlevelse til reker som selekteres ut i overflaten - Sluttrapport for FHF-prosjekt 901661

Fra 2020 til 2022 ble det gjennomført en rekke forsøk i Skagerrak i forbindelse med seleksjon og overlevelse til dypvannsreker (Pandalus borealis). Hovedmålsettingen var å kvantifisere hvor stor andel av trålsekkseleksjonen av reker som skjer i havoverflaten og undersøke overlevelsen til rekene som selekteres ut her. Overlevelsen til reker som unnslipper i overflaten avhenger av miljøforholdene i overflaten og hvor lenge de eksponeres for disse. Høy dødelighet på utsortert småreke vil være en alvorlig feilkilde i bestandsberegninger og også reduserer utbyttet fra bestanden. Forsøkene ble inndelt i fire arbeidspakker: Kvantifisering av seleksjon i havoverflate og på bunn, adferds- og toleranseundersøkelser, metodeutvikling for overlevelsesforsøk i felt og overlevelsesforsøk i rekefiske (feltforsøk).Seleksjon i reketrål: overlevelse til reker som selekteres ut i overflaten - Sluttrapport for FHF-prosjekt 901661publishedVersio

Bifangstsammensetning i "krepsetrål" i Nordsjøen. Rapport fra tokt med M/S "Ørvur" 03.-15.09.2001

publishedVersio

Bifangstsammensetning i "krepsetrål" i Nordsjøen. Rapport fra tokt med M/S "Ørvur" 03.-15.09.2001

publishedVersio

Red King Crab: Vertical movements of crabs trapped in the odour plume explain differences in catch efficiency between square and conical pots

Presentert på: "ICES Symposium on Fishing Technology in the 21st century. Integrating Fishing and Ecosystem Conservation." 30 October—3 November 200

Efficiency and catch dynamics of collapsible square and conical crab pots used in the red king crab (Paralithodes camtschaticus) fishery

We compared the capture efficiency and catch dynamics of collapsible square and conical pots used in resource assessment and harvesting of red king crabs (Paralithodes camtschaticus [Tilesius, 1815]) in the Barents Sea. After two days of soaking, square pots caught three times as many crabs as conical pots, and their catches consisted of a higher proportion of male crabs and male crabs larger than 160 mm carapace length compared to the catches in the conical pots. Catches in the square pots did not increase as soak times were increased beyond two days, which indicates equilibrium between the rate of entries into and the rate of exits from the pots. Catches in conical pots, however, increased with increasing soak times up to eight days, the longest soak time examined in this study. These findings demonstrate the higher efficiency of square pots and the importance of understanding catch dynamics when making population assessments based on catchper-unit-of-effort data. The favorable catch characteristics and handling properties of the collapsible square pot may make this pot design suitable for other crab fisheries, as well