Ingibjörg G. Jónsdóttir

Ingibjörg G. Jónsdóttir
Marine and Freshwater Research Institute | MRI · Demersal Division

Ph.D.

About

52
Publications
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423
Citations

Publications

Publications (52)
Technical Report
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The report describes the implementation and main results of the Icelandic Groundfish Survey, carried out during 28 February to 24 March 2022. This standardized survey has been conducted annually since 1985 and the present results are compared with those of previous years.
Method
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Handbók þessi lýsir framkvæmd rannsóknaverkefnisins „Stofnmæling botnfiska á Íslandsmiðum“ (SMB) sem fer fram í marsmánuði á hverju ári. Í handbókinni er nákvæmlega lýst fyrirhugaðri framkvæmd verkefnisins í mars 2022, m.a. umfangi gagnasöfnunar, hvernig safna eigi líffræðilegum upplýsingum, skráningu mælinga, veiðarfæri og veiðiaðferðum. Einnig er...
Article
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ÁRIÐ 2017 veiddist brislingur (Sprattus sprattus) í fyrsta sinn á Íslandsmiðum svo vitað sé. Á næstu árum fjölgaði brislingum sem veiddust við landið og í rannsóknarleiðangri í mars 2021 fengust alls 375 brislingar, einkum fyrir Suður- og Vesturlandi. Í leiðöngrum haustið 2021 fengust um 300 brislingar, nokkrir við Suðurland og í Faxaflóa en flesti...
Article
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Migration and behaviour of Icelandic cod Tagging studies have been used to study migration of Icelandic cod since 1904. Results from data storage tags (DSTs) have revealed two different behaviour patterns, coastal cod that mainly inhabits coastal waters shallower than 200 m and frontal cod migrating to offshore frontal areas during the feeding peri...
Article
Reliable information on the structure of fished populations can help align management units with the ecology of target species. One way to attain such information lies in accurately defining the scales at which groups of fish vary in key attributes-the chemical markers within otoliths providing well known examples. Here, motivated by current uncert...
Technical Report
Full-text available
Farið er yfir framkvæmd og helstu niðurstöður stofnmælingar hrygningarþorsks með þorskanetum (SMN, netarall) sem fór fram í 26. sinn dagana 25. mars til 27. apríl 2021. This report describes the implementation and main results of the gillnet survey of spawning cod in Icelandic waters (SMN) carried out for the 26th time between 25 March and 27 Apri...
Technical Report
Full-text available
Gerð er grein fyrir framkvæmd og helstu niðurstöðum stofnmælingar botnfiska á Íslandsmiðum sem fram fór dagana 1.‐23. mars 2021. Niðurstöður eru bornar saman við fyrri ár, en verkefnið hefur verið framkvæmt með sambærilegum hætti ár hvert frá 1985. The report describes the implementation and main results of the Icelandic Groundfish Survey, carrie...
Article
Knowledge of dispersal and migration of juvenile fish is essential for understanding the underlying processes responsible for population structure and recruitment variation. We explored the dispersal patterns of juvenile cod in waters around Iceland from putative nursery grounds to provide insights into their population structure. About 6000 juveni...
Technical Report
Full-text available
Annual shrimp surveys have been conducted since 1988. In 1989, a small juvenile bag was attached to the shrimp trawl. The juvenile bag had 6 mm mesh size and collected small animals and juvenile shrimp. The main purpose of this report is to compile results from measurements from the juvenile bag, but the collection was stopped in 2016. Information...
Technical Report
Full-text available
The report describes the implementation and main results of the Icelandic Groundfish Survey, carried out between 27 February and 20 March 2020. This standardized survey has been conducted annually since 1985 and the present results are compared with those of previous years.
Method
Full-text available
Handbók um stofnmælingu botnfiska á Íslandsmiðum sem hófst 27. febrúar 2020. Lýst er framkvæmd verkefnisins, m.a. umfangi gagnasöfnunar, hvernig safna eigi líffræðilegum upplýsingum, skráningu mælinga, veiðarfæri og veiðiaðferðum. Einnig eru fyrirmæli um það hvernig aðferðum skuli beitt við tog og gefnar nákvæmar staðsetningar og aðrar upplýsingar...
Technical Report
Full-text available
Nýliðun er lykilþáttur varðandi viðgang fiskistofa. Upplýsingar um nýliðun eru mikilvægar í stofnmati enda segja þær til um fjölda einstaklinga sem bætast munu við stofna og veiðar á komandi árum. Hrygningarstofn þorsks við Ísland hefur farið stækkandi á síðustu árum en á sama tíma hafa fáir sterkir árgangar þorsks komið inn í stofninn. Í þessari s...
Technical Report
Full-text available
Laxalús er snýkjudýr á laxfiskum í sjó og er mikið skaðræði fyrir fiskeldisfyrirtæki sem eyða miklum tíma og fjármunum í að hefta magn þeirra með ýmsum aðferðum. Ein þeirra leiða sem notuð hefur verið eru lyf sem eiga að drepa lúsina. Lyfin hafa reynst ágætlega í þessari baráttu en vandamálið er að þau geta einnig haft neikvæð áhrif á önnur krabbad...
Technical Report
Full-text available
Gerð er grein fyrir framkvæmd og helstu niðurstöðum stofnmælingar botnfiska á Íslandsmiðum sem fram fór dagana 26. febrúar til 20. mars 2019. Niðurstöður eru bornar saman við fyrri ár, en verkefnið hefur verið framkvæmt með sambærilegum hætti ár hvert frá 1985.
Article
Biodiversity is a key concept for conservation and management and is fundamental for ecosystem-based approaches. It is of importance to consider whole areas in which communities and their ecological processes can be maintained. To effectively manage ecosystems for sustainable use and conservation, it is important to understand changes in the ecosys...
Technical Report
Full-text available
Growth and age of shrimp in Arnarfjörður and Ísafjarðardjúp was studied from data collected in annual shrimp surveys from 1988 to 2015. Mean length of 1-year and older old shrimp was higher in Ísafjarðardjúp compared with Arnarfjörður and it is likely due to higher bottom sea temperature in Ísafjarðardjúp. Age at first spawning was lower in Ísafjar...
Technical Report
Full-text available
Little information is available on predation on Norway lobster in Icelandic waters. Other invertebrates, like northern shrimp, is a common prey of cod and haddock, but cod and haddock predation on Norway lobster has not been studied extensively in Icelandic waters. We summarise the main findings from diet analysis conducted between 2008 and 2016 in...
Technical Report
Full-text available
Shrimps are a diverse group of crustaceans, and are found both in fresh water and the sea. They are important prey in the food web as various species feed on shrimp. There is only one commercial species, northern shrimp, in Icelandic waters, whereas many other shrimp species have been found around Iceland. In this report we will list the shrimp spe...
Article
Length is one of the main factors determining fecundity of shrimp. Therefore, changes in length distribution where larger individuals disappear from the stock may affect the relative egg production (REP) of the stock. The main objective of this study was to use fecundity of shrimp to estimate changes in REP of four inshore shrimp stocks in the peri...
Article
Full-text available
Catch Per Unit Effort (CPUE) data and survey biomass indices of Arnarfjordur (NW-Iceland) shrimp stock (Pandalus borealis) were used as tuning series for a Surplus Production Model (SPM) fitted using three different types of software. It is observed that many of the model assumptions in the SPM are violated in this analysis. The average estimation...
Article
Northern shrimp (Pandalus borealis) are protandrous hermaphrodites that reproduce first as males, go through a transition phase and transform to females, and then spawn as such for the rest of their lives. No clear consensus exists as to which factors influence the activation of the sex change process, but one possible factor is population density....
Technical Report
Full-text available
Many surveys were conducted by Hafrannsóknastofnun (MFRI) in the sixties and seventies to search for new shrimp fishing grounds around Icelan and many new areas were discovered. In the report we give an overview of the main results from surveys conducted in 18 areas in 1961-2016. Data from the MFRI database was used, but some data was missing. Furt...
Technical Report
Full-text available
Frjósemi rækju við Ísland var fyrst skoðuð í mars 1978 og næstu sýnum var safnað veturinn 2015/2016. Veturinn 2015/2016 var frjósemi rækju skoðuð á fimm svæðum við Ísland; Arnarfirði, Ísafjarðardjúpi, Húnaflóa, Skjálfanda og við Snæfellsnes. Frjósemi er metin með því að telja fjölda eggja. Frjósemin var mismunandi milli svæða og var hún marktækt læ...
Article
Full-text available
Knowing movement and structure of fish populations is a prerequisite for effective spatial fisheries management. The study evaluates migration patterns and connectivity of two groups of cod (Gadus morhua) associated with offshore feeding and nursery grounds. This was achieved by investigating (i) migration pathways of cod tagged at the feeding area...
Article
Changes in stock size of a top predator have been found to cascade through the trophic levels but the mechanism has not been fully clarified. Using data from annual trawl surveys within a fjord during 1988-2015, we present evidence that changes in abundance of cod Gadus morhua and haddock Melanogrammus aeglefinus have an immediate effect on the dis...
Article
Northern shrimp (Pandalus borealis) is targeted by commercial fisheries but is also an important prey in the marine food web. In this study, stomach content data were used to study predation on shrimp by three gadoid species, cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus), in six inshore areas around Icela...
Technical Report
Full-text available
The first shrimp fishing grounds in Icelandic waters were discovered in 1924 in Ísafjarðardjúp. The commercial shrimp fishing started in 1935. Shrimp research was initiated in the early 1970's but since 1988 the Marine Research Institute has conducted a standardized annual shrimp survey in inshore and offshore areas to provide an index of the north...
Article
Full-text available
In this paper, symbiosis of two benthic species in Icelandic waters was observed on underwater images; Lebbeus polaris, which is a cold water shrimp and Bolocera tuediae, which is a common sea anemone. Both are found in Icelandic waters but information about their biomass, distribution and behaviour is limited. Shrimps are commonly found to live sy...
Article
The brown shrimp (Crangon crangon) is widely distributed in the coastal areas of the eastern Atlantic, but was only recently found in Icelandic waters. In this study, annual and seasonal changes in population abundance of brown shrimp southwest of Iceland were recorded from 2005 to 2014 in order to see whether the species has established itself in...
Technical Report
Full-text available
The 2016 meeting of WGECO was held at the ICES HQ in Copenhagen, Denmark from 6–13 April 2015. The meeting was attended by 17 delegates from 13 countries, and was chaired by Anna Rindorf (Denmark). The work conducted was centred on six Terms of Reference and two advisory requests concerning indicators of Good Environmental Status (GES) of the benth...
Article
Full-text available
Northern shrimp (Pandalus borealis) are considered to represent localized populations in inshore and offshore Icelandic areas, with limited connectivity during adult stages. Due to potentially high larval drift it is unlikely that genetic differences are observed between nearby locations. Hence other methods, like phenotypic characters, are commonl...
Article
A B S T R A C T The age information of commercially important species is crucial in fisheries management. Age of various fish and molluscan species has routinely been determined by counting annual growth bands deposited within the hard structures. In crustaceans such structures were previously believed to be lost and replaced due to molting. Howeve...
Article
Full-text available
The study analyses the home ranges and spatial segregation of spawning components of Icelandic cod Gadus morhua based on: (1) conventional tag (CT) recaptures and (2) depth, temperature and tidal locations from electronic data storage tags (DSTs). A total of 5987 CT recapture positions from tagging in geographically distinct spawning grounds from 1...
Article
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The spectral sensitivity of visual pigments in vertebrate eyes is optimized for specific light conditions. One of such pigments, rhodopsin (RH1), mediates dim-light vision. Amino acid replacements at tuning sites may alter spectral sensitivity, providing a mechanism to adapt to ambient light conditions and depth of habitat in fish. Here we present...
Article
Full-text available
The distribution of the deep-water shrimp, Northern ambereye Hymenodora glacialis, was studied using observations and stomach content data of Atlantic cod Gadus morhua and Greenland halibut Reinhardtius hippoglossoides from three annual surveys in Icelandic waters. These surveys cover the continental shelves and slopes down to 1500 m depth around I...
Article
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Despite an increase in northern shrimp (Pandalus borealis) female biomass in the past years, the recruitment of the offshore population north and northeast of Iceland has remained very low. In this study the influence of abiotic and biotic factors were studied in relation to shrimp recruitment. Two factors, cod (Gadus morhua) abundance and summer s...
Article
Full-text available
Northern shrimp Pandalus borealis is found in both inshore and offshore areas around Iceland, where it has supported an important commercial fishery. However, in the past 15 yr the northern shrimp population has decreased in size and collapsed in most of the inshore areas. In this study, the importance of Atlantic cod Gadus morhua on northern shrim...
Article
Full-text available
We investigated the behaviour patterns of coastal (relatively stationary in shallow waters) and migratory frontal (offshore) types of Atlantic cod Gadus morhua in Icelandic waters using information from data storage tags (DSTs). Consistent and repeated patterns of migration were observed for both coastal and frontal cod, with characteristic DST pro...
Article
Full-text available
Chemical fingerprinting was used to discriminate spatial groups of juvenile cod (Gadus morhua) and to backtrack spawning cod in Icelandic waters to their area of origin as 0-group juveniles. Juvenile 0-group cod were collected around Iceland in August 1996 and 1997 to establish the spatial distribution of otolith chemistry at the juvenile stage. Sp...
Article
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Growth and condition (both somatic and hepatosomatic index) of Atlantic cod spawning at different locations around Iceland was studied in relation to the Pan I locus. South of Iceland cod carrying the Pan IAB and Pan IBB genotypes were more frequent while cod carrying the Pan IAA genotype was more frequent north of Iceland. Differences in growth we...
Article
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Jónsdóttir, I. G., Marteinsdottir, G., and Campana, S. E. 2007. Contribution of different spawning components to the mixed stock fishery for cod in Icelandic waters. – ICES Journal of Marine Science, 64: 000–000. Otolith chemistry and length-at-age were used to estimate the contribution of different spawning components to the harvested stock of cod...
Article
Full-text available
Otolith chemistry was used to study the stock structure of Icelandic cod Gadus morhua. Otoliths were collected from spawning cod at 12 and 17 different spawning locations around Iceland during the spawning season in 2002 and 2003, respectively. The otolith elemental composition of cod spawning north and south of Iceland differed substantially from...
Article
Full-text available
2006. Otolith shape and temporal stability of spawning groups of Icelandic cod (Gadus morhua L.). e ICES Journal of Marine Science, 63: 1501e1512. During the past 5e10 years, studies exploring small-scale structure of cod populations have provided accumulating evidence for the existence of local populations. In Iceland, all cod have been thought to...

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Projects (3)
Project
Groundfish surveys carried out in Icelandic waters by the Marine and Freshwater Research Institute. Main goals are to study changes in abundance, condition and distribution of demersal fish in Icelandic waters, thereby improving the precision of stock assessments.