Gudrun G. Thorarinsdóttir

Gudrun G. Thorarinsdóttir
Marine and Freshwater Research Institute | MRI · Reykjavik

Ph.D. in marine biology

About

62
Publications
12,131
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628
Citations

Publications

Publications (62)
Article
This pilot study aimed to assess whether depth had an impact on the sexual development and quality of green sea urchin (Strongylocentrotus droebachiensis) gonads, and whether market quality urchins could be found at greater depths than usually fished in Breiðafjörður, west Iceland. Green sea urchins were collected monthly at 32 and 60 m depth sites...
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...
Article
Full-text available
Sea urchins have been harvested for human consumption for more than a millennium, but the fisheries have been badly managed in recent years and poorly documented, resulting in overfishing in many areas. In response to increasing market demand and decreasing supply of sea urchin due to depletion of traditional resources, the exploitation of sea urch...
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
This report introduces the URCHIN project, funded by the Northern Peripheries and Arctic Programme (NPA). It then describes the main techniques used for stock monitoring in sea urchin fisheries around the world, including techniques used in the NPA. Trials in Norway and Iceland run with the aim to develop cheap, effective and reliable methods of st...
Technical Report
Full-text available
This report gives a brief introduction to the URCHIN project, funded by the Northern Peripheries and Arctic Programme (NPA). The scope of the report is also outlined. This is followed by a summary of the sea urchin fishery management techniques that are used in sea urchin fisheries around the world. These are listed in order of size of the fisherie...
Technical Report
Full-text available
This report gives a brief introduction to the URCHIN project, funded by the Northern Peripheries and Arctic Programme (NPA), followed by a summary of the fishing techniques that are used in sea urchin fisheries around the world. The main sea urchin fisheries around the world are then briefly described, together with the fishing techniques that are...
Article
Full-text available
Æ fleiri framandi sjávarlífvera verður vart í strandsjónum við Ísland. Alls er vitað af fimmtán tegundum og hefur um helmingur þeirra numið hér land á undanförnum tveimur áratugum. Meðal þeirra eru sex tegundir þörunga, svifþörungarnir Heterosigma akashiwo, Stephanopyxis turris og Mediopyxis helysia, og botnþörungarnir sagþang (Fucus serratus), rau...
Article
Full-text available
For centuries human populations have moved live shellfish around the world for consumption or aquaculture purposes; being relayed from their area of origin for growout or sale. This is in contrast to the inadvertent anthropogenic spreading of species via e.g. ballast waters. There are inherent risks associated with transfer of shellfish including i...
Chapter
Full-text available
Fourteen non-native marine species have been recorded in Icelandic waters in the last 58 years, nine of them in the last decade. This is a diverse group of species belonging to to phytoplankton, macroalgae, crustaceans, bivalves, tunicates and fish. Four of those species can be considered potentially invasive as they adversely affect the habitats a...
Article
Full-text available
The annual gametogenic cycle in the blue mussel, Mytilus edulis L. was investigated from May 2010 to May 2011 in two locations in north-western Iceland. Food availability (chlorophyll-a) was high in early spring at both sites, with a summer maximum in July in Steingrimsfjördur but an autumn maximum in September in Patreksfjördur. Gonad development...
Article
Full-text available
An ecosystem-based approach to bivalve aquaculture management is a strategy for the integration of aquaculture within the wider ecosystem, including human aspects, in such a way that it promotes sustainable development, equity, and resilience of ecosystems. Given the linkage between social and ecological systems, marine regulators require an ecosys...
Article
Arctica islandica is the longest-lived non-colonial animal found so far, and reaches individual ages of 150 years in the German Bight (GB) and more than 350 years around Iceland (IC). Frequent burrowing and physiological adjustments to low tissue oxygenation in the burrowed state are proposed to lower mitochondrial reactive oxygen species (ROS) for...
Article
Full-text available
Thorarinsdóttir, G. G., Jacobson, L., Ragnarsson, S. Á., Garcia, E. G., and Gunnarsson, K. 2010. Capture efficiency and size selectivity of hydraulic clam dredges used in fishing for ocean quahogs (Arctica islandica): simultaneous estimation in the SELECT model. – ICES Journal of Marine Science, 67: 345–354. Estimates of capture efficiency and size...
Article
In April 2006 a heavy storm caused large quantities of ocean quahogs to be transported from their natural habitat, the soft bottom, where they live buried in the sediment, up onto a hard substratum at a lower depth. There, unable to burrow down again and escape, the clams were easy prey for predators. A year later, the diver revisited the site and...
Article
Full-text available
Jonasson, J. P., Thorarinsdottir, G., Eiriksson, H., Solmundsson, J., and Marteinsdottir, G. 2007. Collapse of the fishery for Iceland scallop (Chlamys islandica) in Breidafjordur, West Iceland. – ICES Journal of Marine Science, 64: 298–308. The stock index of the Iceland scallop (Chlamys islandica) in Breidafjordur on the west coast of Iceland has...
Article
Ocean quahogs off Iceland are large, slow growing clams distributed on the continental shelf around the north Atlantic. The Icelandic stock is most northern and found in the shallowest water. Maximum age may exceed 200 y. Commercial fishing and biological research for ocean quahogs started in 1995 but relatively little biological information is ava...
Article
The effects of temperature on the survival and behaviour of two size classes of Chlamys islandica was investigated in a laboratory study. The scallops were sampled in spring from three localities in Iceland, Breidafjördur (west), Húnaflói (north), and Hvalfjördur (southwest) and again in August from Breidafjördur and Hvalfjördur. Daily observations...
Article
Full-text available
The annual gametogenic cycle in the blue mussel, Mytilus edulis L. on Eysturoy in the Faroe Islands was investigated from June 1996 to June 1997. Histological preparations of the gonads showed evidence of gonad development throughout the year with the main development period between November and March. Spawning was protracted lasting from May until...
Article
Studies evaluating the reproductive pattern of Mytilus edulis L. were conducted in western and eastern Iceland at two sites at about the same latitude but with different temperature regimes. Mussels were sampled once or sometimes twice a month during two years in Breidifjördur, western Iceland and one year at Mjoifjördur, eastern Iceland. Gonad dev...
Article
Full-text available
The seasonal pattern of bivalve spat settlement in Eyjafjordur, North Iceland, was investigated using artificial collectors of monofilament netting over 14 months (March 1998—January 2000) at 5, 10 and 15 m depth. SCUBA divers replaced the collectors at 4-weekly intervals. Twelve bivalve species settled on the collectors but only Mytilus edulis and...
Article
Full-text available
Abundance of ocean quahog (Arctica islandica) was estimated with underwater photography and a hydraulic dredge at 15 m depth in Önundarfjördur, NW Iceland. Abundance estimates based on counts of siphons from the underwater photographs were much higher than from analysis of the dredge catches. A total of seven taxa were identified from photographs,...
Article
Full-text available
In the present study three experiments were carried out out to measure the overall efficiency of a commercial hydraulic dredge used to surway ocean quahog in Icelandic waters. Direct effects of hydraulic dredging activity on ocean quahog populations by estimating size selectivity of the dredge and rate of shell breakage were evaluated. The mean dre...
Article
Abundance of ocean quahog (Arctica islandica) was estimated with underwater photography and hydraulic dredge at 15 m depth in Önundarfjördur, NW Iceland. Abundance estimates based on counts of siphons from the underwater photographs were much higher than from analysis of the dredge catches. A total of seven taxa were identified from photographs, of...
Article
Annual gametogenic cycle in ocean quahog, Arctica islandica, was investigated using specimens collected regularly from a near shore population in north-western Iceland from December 1997 to November 1998. Gonads from 450 adult quahogs with shell length ranging from 65 to 106 mm were examined after being prepared by standard histological techniques....
Article
Full-text available
Ocean quahogs, Arctica islandica, were collected in February 1994 from near-shore populations off north-west Iceland for determination of developmental stages relative to size, age, and sex. A microscopic examination of histologically prepared tissue of 206 ocean quahogs showed that s6 specimens (31-70 mm shell length) were immature and could not b...
Article
A hydraulic dredge survey was conducted during January – June 1994 in north-west, north and east Iceland, to provide a first assessment of ocean quahog, Arctica islandica (Mollusca: Pelecypoda) resources in these areas. Ocean quahog was found in significant concentrations and high density. The combined high-density areas were 91.7 km2 with a minimu...
Article
Annual cycles of gamete development in Mytilus edulis L. in south-west Iceland were investigated during 1986 to 1987. Histological preparations of the gonads showed that all individuals were fully mature in the beginning of June in both years and one spawning period was recorded each year at a sea temperature of 10-12oC. The main spawning took plac...
Article
The feasibility of hanging culture of Mytilus edulis in Hvalfjördur, south-west of Iceland was investigated. The spat of the blue mussel settled on ropes in great intensity in September. Two years after settlement a marketable size was reached (50 mm). Theo growth was related to food availability, measured as chlorophyll-a rather than temperature....
Article
Shell length-meat weight relationships were analyzed for the ocean quahog, Arctica islandica, for three geographic areas in Iceland. The allometric growth curves for the three areas were: northwest area, W = 0.0000567 L3.08; north area, W = 0.000173 L2.75; east area, W = 0.0000929 L2.92. However, when the allometric growth model was used, the three...
Article
During two years, from September 1989 to September 1991, a study was carried out to evaluate the potential of pearl net cultivation of Iceland scallop, Chlamys islandica (O.F Müller), in Breidafjördur, west Iceland. In September 1989 1-year-old spat (mean height 9.8 mm±2.0 s.d.) were transferred from collectors to pearl nets suspended from flotatio...
Article
Annual cycles of gamete development in male and female Chlamys islandica (O.F. Müller), in Breidafjördur, west Iceland, were investigated for 2 years (August 1988–August 1990) by histological and stereological techniques. Spermatogenesis proceeded rapidly after spawning in July and continued while food was available. During winter a resting phase w...
Article
Spat of the Iceland scallop Chlamys islandica (O.F. Müler), was artificially collected, using onion bags of 6 mm mesh size filled with monofilament of 0.4 mm, and polyethylene bags of 4.5 mm mesh size filled with monofilament of 0.2 mm. The spat collectors were placed at 25–35 m depth in Breidafjördur on the west coast of Iceland, in the middle of...

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Project (1)
Project
The URCHIN project aims to utilise the sea urchin resource present in the northern arctic regions. The challenges of fishing, sustainable and responsible harvesting of stocks, legislation and supply chains for sea urchin products from isolated and environmentally harsh and challenging areas in the Northern and Arctic region will be addressed. The challenges will be overcome through innovation and national and transnational technology transfer. http://urchinproject.com