Browsing Master's theses in international fisheries management by Title
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- Browsing Master's theses in international fisheries management by Title
Browsing Master's theses in international fisheries management by Title
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Msigwa Chando, Catherine (Master thesis; Mastergradsoppgave, 31-May-2002)[+][-]
Abstract: Women play crucial roles in fisheries, particularly on the post harvest level. Despite this, they are noticeably absent from the discussion of many development programmes in fisheries. The focus is mainly on the needs and interests of men, neglecting women. Women are hardly involved in the planning and decision making or in the implementation and management of the projects. Therefore this study examined the importance of involving both women and men equally during planning of the fishery projects. The study tried to relate to different theories on women in development (WID), gender and development (GAD) and women, environment and alternative development (WED). A total of 88 persons in connection with Mbegani Fisheries Development Centre (Mbegani FDC), Mafia Island Marine Park (MIMP) and with people in villages where these institutions have been involved: Mlingotini and Bagamoyo nearby Mbegani FDC and Juani and Jibondo at Mafia. The findings show that the involvement of women and men in the planning of the projects varied. At Mbegani FDC a female orientation has been weak and womens participation in planning have been lacking from the very beginning and until to day. The same can be said about the projects in Bagamoyo and Mlingotini although the projects were aimed at women and sometimes both at men and women. However, women have participated in the implementation processes. In the projects related to MIMP, women have been integrated in the planning process from the very beginning and at all levels as a result of planned actions. Women are members in steering committees and leaders of their groups. There is a special gender officer in the MIMP structure as well as in the villages. Women have also been well trained. In this way their income generating projects are successful and reflect the sustainability of the resources. Some of the women have also involved themselves in other kind of development activities. I have therefore concluded that awareness of womens needs and participation of women and men in the planning process seem crucial for the success of the fisheries projects. URI: http://hdl.handle.net/10037/317 File(s) in this item: 1
thesis.pdf (657.7Kb) -
Wang, Shou (Master thesis; Mastergradsoppgave, 29-May-2009)[+][-]
Abstract: In teleost fish, gill plays an important role of controlling ion transport mechanisms for the maintenance of ion- and osmoregulatory homeostasis in both fresh water and seawater. Leptin mRNA expression has been found in several fish species, and was also found in gills of Arctic charr (Salvelius alpinus) in this study. However, no study has been reported on the function of leptin in the gills of fish. The question arise f Leptin may have some function related to ion- and osmoregulation in fish gills. In this study, Arctic charr were sampled during their smolting period in freshwater. Seawater tolerance, as well as gill Na+, K+-ATPase activity of the fish increased from winter to spring in these fish, showing that they smoltified. There was no change in gill leptin mRNA expression during and after smolting in the fish acclimated to freshwater and hence, the results gave no evidence for a paracrine role of leptin in the regulation of the adaptational changes in gill during smolting. It can not be excluded, however, that leptin may be involved in the changes taking place in the gill in association with seawater exposure, and future studies must include sampling of gill tissue, and analyses of leptin mRNA expression after seawater transference. URI: http://hdl.handle.net/10037/2004 File(s) in this item: 1
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Dyspriani, Polite (Master thesis; Mastergradsoppgave, 29-May-2007)[+][-]
Abstract: Shrimp world production in the last few years has shown very high growth rates. It is marked by an increasing of production volume, and by shifting from capture to aquaculture fisheries within the production system. This has occurred mostly regarding to the brackish water pond. For some years, the government has had to face hard choices in order to ensure shrimp aquaculture developed sustainable. The desire and temptation to pursue the excessive development of shrimp production as a source of foreign currency often conflicted with concerns for ecosystem health, social justice, food safety, livelihoods and food security. The Fisheries Revitalization Program is one of the main driving forces behind establishing a governance system that allows the stakeholders to play an effective role in managing fisheries sustainable. The program utilizes political support to encourage sustainable livelihood by creating economic growth, providing job and alleviating poverty. The Fisheries Revitalization Program focuses on the development of three important economic commodities, namely shrimp, skipjack and seaweed. The study focuses on the shrimp revitalization program, by using the governance concept to analyze how the mechanisms and effects of the program so far. The findings are the contributions and commitments from the three societal institutions (state, market and civil society) needed to play roles in the shrimp governance system, and local institution needs to be developed. Key words: governance, revitalization, sustainable, local institution URI: http://hdl.handle.net/10037/1008 File(s) in this item: 1
thesis.pdf (959.9Kb) -
Wellem, Xolela (Master thesis; Mastergradsoppgave, 29-May-2009)[+][-]
Abstract: Foreign fishing vessels are landing catches in South African ports, however, there are number of issues, procedures and persons involved in the process to facilitate those vessels into port. So this study concerns understanding and law implications as diversified from the actual practicing of the law. The legal analysis boils down to textual analysis to see whether national achievements are more or less well bestowed within the limits of the international - as well as national law in communication, co-operation and coordination of what is the laws efforts to control overfishing, black listed and other illegal, unreported and unregistered fishing. URI: http://hdl.handle.net/10037/1998 File(s) in this item: 1
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Hulse, Kirkman Joe Roe (Master thesis; Mastergradsoppgave, 30-May-2005)[+][-]
Abstract: This thesis an effort is made to present the indigenous knowledge of marine ecosystems in the communities of Sandy bay (Miskito) and Punta Aguila (Rama) of Nicaragua. The aim is to identify and show how these fishing communities are using and transmitting their knowledge for resource harvesting and management. As indigenous people are facing changes in their daily life; conflict of resources use, land tenure, variation in the ecosystem and the environment in which they live their knowledge change and the communities to adopt new methods of management. The people Punta Aguila and Sandy Bay harvest lobster, turtle, fish from the sea. They also do agriculture activities for their subsistence. My research problem focuses on their knowledge of the marine ecosystem and whether their knowledge is used for management purpoes. How are these perceptions, ideas and beliefs shared within the communities? The theories of indigenous knowledge is the theoretical framework for this thesis . The methods used to collect primary data during the two months of fieldwork in the two communities, undertaken in July and August, 2004 were; • structured, intensive interviews with fishermen and –women who live from the sea , • conversations on tape recorder, • workshop and groups discussion to identify the different fishing grounds • observation of activities and daily life in the communities . The presentation of the primary data is mostly of qualitative character. The material presented shows that these indigenous communities do have extensive knowledge of the ecosystem. Despite their knowledge, and in spite of the management systems introduced by the government and other institutions, the marine resources are threatened with overfishing. I also found that outside fishing operations were seen as an intrusion and as a threat to the natural resources. While the communities may have knowledge relevant to the management of the natural resources and the balance of the ecosystem, management authorities pay little attention to such knowledge. This knowledge has been a way of interacting with nature and the environment for improving their lives and bringing harmony with their God. URI: http://hdl.handle.net/10037/314 File(s) in this item: 1
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Nguyen, Thanh Binh (Master thesis; Mastergradsoppgave, 02-Jun-2003)[+][-]
Abstract: This paper presents the importance, the state of affairs and the development strategies of the state-owned enterprises in the Fishery sector of Vietnam. The purpose is, firstly, to review state-owned enterprise reform literature of relevance to Vietnam. Secondly, the reform of state-owed enterprises in Vietnam particularly in the Fisheries Sector is reviewed to determine the important issues and problems as well as the its role in the renovation process of Vietnamese fisheries state-sector enterprises. Finally, the opportunities, conditions, and obstacles for the reform are identified in the sector economic development. The review of the state-owned enterprise reform in Vietnam suggests that the diversification of ownership is one of the most important factors affecting successes of the economic reform. There is a need for accelerating equitisation of state-owned enterprises to have more involvement of private sectors. In the Fisheries sector, inefficient operations of fisheries state-owned enterprises have imposed financial burden on the national budget. Data of financial performance of fisheries enterprises including state general corporations and equitised companies is employed to observe changes of their profitability, operating efficiency, and leverages. Nonetheless, restricted accessibility of records of state-owned enterprise financial performance caused some limitations of analysis of financial and economic performances. The empirical result shows that equitised companies have been operating much more efficiently than preequitisation. The state capitals are being invested with higher returns and more significantly, budgetary burden was removed. Some obstacles such as incomplete and irrelevant regulations and lack of broad-based consensus of equitisation have accounted for lags of the reform process. It is necessary to create a more effective policy and legal frameworks, more incentives for actors participating in the process and more stable macroeconomic environments. URI: http://hdl.handle.net/10037/333 File(s) in this item: 1
thesis.pdf (242.7Kb) -
Amoako, Mary (Master thesis; Mastergradsoppgave, 08-Jun-2006)[+][-]
Abstract: A survey was carried out to investigate the prevalence and mean intensities of ectoparasites infestation on the gills and skin mucus of Nile tilapia (Oreochromis niloticus) in some selected fish farms in the Ashanti region of Ghana. Pond water quality was also determined. Oral on-farm interviews on pond management practices were carried out on the farms. The results obtained revealed three types of ectoparasites namely; Trichodina sp., monogeneans and Tetrahymena sp. of which the first two were prevalent on most farms. Tetrahymena sp. was found on one farm. The physico-chemical parameters and management practices were very similar in all farms. There were no strong relationships between ectoparasite prevalence and intensity and the physico-chemical properties and the management practices on the farms. the ectoparasites occurrences in infected farms might have been due to a chance effect. The general low prevalence and intensities of ectoparasites recorded in the infected farms is an indication that the Nile tilapia has a biotic mechanism which might have enabled it to reduce the growth rate of ectoparasite intra-population. The ectoparasites do not seem to pose a threat for the aquaculture industry in the Ashanti region as observed in this study, but measures have to be taken to secure the industry from unforeseen incidents, for instance in the introduction of non-endemic parasite species in the future. URI: http://hdl.handle.net/10037/297 File(s) in this item: 1
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Sønvisen, Signe Annie (Master thesis; Mastergradsoppgave, 22-May-2003)[+][-]
Abstract: Resource management in the coastal zone involves a large number of stakeholders and resource users, from traditional fishermen and recreational housing owners to state and municipal government. The aim of this study is to show how spatial scarcity in Norwegian aquaculture is not solely a technical definition, but scarcity also depends upon the social context in which it operates. That is, what has influenced Norwegian aquaculture policy in spatial terms? This question is answered by looking at how allocation of space has developed from the early 1970s and to the present, what actors were involved, what arguments did they use and what was the spatial outcome of the chosen policies. Through a literature review, I have shown how discourses of regional policy, industrial policy, environmental policy and health policy have affected the spatial allocation of aquaculture licenses in the past. Moreover, I show that these discourses are a part of a larger coastal zone management discourse, which is becoming increasingly popular. Thus, scarcity of space in aquaculture is defined within the discursive framework that it operates. URI: http://hdl.handle.net/10037/324 File(s) in this item: 1
thesis.pdf (683.0Kb) -
Mutatina, Alieth (Master thesis; Mastergradsoppgave, 15-May-2008)[+][-]
Abstract: Coastal resources are overexploited and thus coastal livelihoods provides very little in terms of micro-economy. Seaweed farming activities have been considered as alternative income generating activities in Tanzanian coastal communities. Nonetheless, the sustainability of seaweed industry is dependent on the nature of interactions between the three orders of governance and the governability depends on how well the governing system matches with the system to be governed. Through fitting primary and secondary data obtained from seaweed farmers in Mlingotini village into governance models and theories, this thesis analyzed the interactions and the roles being played by three governance institutional elements: state, market and civil society as mariculture industry as concerned in Tanzania. In order observe the accomplishment of good governance principles, the system to be governed should understand and differentiate between the needs for local community, the accountability of the governing system as well as capacities available to the governing system. Analyzing social impacts of seaweed farming along the coast of Tanzania provide positive and useful insights on the industry but in addition to that, this study also found that the governance system should consider improving the production chain which seems to be necessary for the seaweed industry along the coast. I therefore concluded that, along with launching SDSP in 2005 in Tanzania the governance instruments should be corresponding to the reality such that the concern should not be only to increase seaweed production, but also to consider missing essential instruments for making seaweed business sustainable including trainings on business skills and planning. Including mariculture related courses in academic institution syllabuses such as FAST-UDSM, (just as aquaculture courses) or under biotechnology courses in Botany department- UDSM or in other Fisheries Institutions will be a great achievement to sustain seaweed industry in Tanzania. URI: http://hdl.handle.net/10037/1426 File(s) in this item: 1
thesis.pdf (948.6Kb) -
Onandia Calvo, Iñigo (Master thesis; Mastergradsoppgave, 05-Jun-2012)[+][-]
Abstract: The aim of this research was to prove a mandatory square mesh panel in the Basque trawling fleet operating in the ICES subzones VIIIabd. Selectivity parameters were calculated for the dual selection system (70 mm codend + 100 mm square mesh panel in extension piece) and for commercial codends (70 mm codend), with the aim to compare them and determine the effect of the square mesh panel in the overall selectivity of the gear for three selected species (Hake, Red mullet and Pout), using a three compartment setup (codend, codend cover and square mesh panel cover). The low escape-panel contact found in the selected species, especially in the case of the hake can be attributed to different factors such as passive behaviour in the trawl, high turbidity and high trawling speed. The data were analyzed with the software SELNET that enables the analysis of data for experimental designs involving multiple compartments by means of complex selection models. URI: http://hdl.handle.net/10037/4664 File(s) in this item: 1
thesis.pdf (2.054Mb) -
Shangina, Olga Alexandrovna (Master thesis; Mastergradsoppgave, 23-May-2007)[+][-]
Abstract: Export–import relationships are very complex and are regulated by different legal instruments. Incoterms 2000 is one of the most important issues in the international seafood trade. Its use varies depending on business environments, countries and companies involved. The most common factors affecting the choice of delivery terms from Incoterms 2000 are volume/value of the consignment, control over delivery, common practice, legislation obstacles, etc. Countries participating in seafood trade have different practices in the use of terms of delivery that can be stipulated by various factors such as location of the country itself and its suppliers, economical and legal regulations, and others. Seafood importers in each country have a unique set of factors that are crucial for the choice of delivery terms. Accordingly, identifying these factors is important for understanding the relationships and the decision making processes in the exporter-importer dyads. Relationship quality may be also associated with the choice of Incoterms 2000, because it plays a significant role in decision making. This is especially important when the decisions concern risk distribution and risk transfer from the exporter to the importer in supply chains, in other words the choice of delivery terms. This paper deals with investigating the factors influencing the choice of terms of delivery in seafood export from Norway to Japan and Russia. Special attention is paid to the evaluation of the perceived relationship quality by the importers and the association of the relationship quality with its possible influence on the use of Incoterms 2000. URI: http://hdl.handle.net/10037/969 File(s) in this item: 1
hovedoppgave.pdf (796.7Kb) -
Yohannes, Felegeselam (Master thesis; Mastergradsoppgave, 02-Jun-2003)[+][-]
Abstract: This study has been conducted in the northern most Rift Valley lake fishery – lake Ziway. Catch & effort and economic data have been used to analyze its fishery. The aim of the analysis was to review the present management situation of the lake and to apply bioeconomic theory to estimate the maximum and economic yields of the lake. The Schaefer’s surplus production model has been employed to estimate the maximum sustainable yield, effort that takes the maximum sustainable yield and maximum economic yield together with EMEY. The values of MSY, EMSY, MEY, and EMEY are 3537 t/yr, 2660 boats/yr, 1011 t/yr, and 412 boats/yr respectively. Lake Ziway is the 3rd biggest rift valley lake next to lake Abaya and Chamo. It has a potential yield of about 15% of the country’s major lakes potential and it contributes also about 24% of the yield of all major lakes. Its socio-economic importance is found to be the highest in the region where it is situated. The analysis shows also that lake Ziway produces double fold of the yield of the biggest lake in the country. All years written as EC are equivalent to GC – 7 and/or 8 years. URI: http://hdl.handle.net/10037/296 File(s) in this item: 1
thesis.pdf (748.3Kb) -
Makhortov, Ivan Nikolaevich (Master thesis; Mastergradsoppgave, 14-Sep-2006)[+][-]
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Sidoryuk, Arina (Master thesis; Mastergradsoppgave, 02-Jun-2006)[+][-]
Abstract: The paper is devoted to consideration of main aspects of internationalization process of the firm. The international marketing literature and findings of previous studies in the area construct theoretical framework for the conceptual model, worked out for the purposes of current research. Empirical study investigates motives for entering the Russian seafood market, perceived barriers and choice of entry mode by Norwegian exporters. It consists of study of four cases from Norwegian seafood industry and interviews with key informants. Results illustrated that perceived barriers against entering the Russian seafood market are outweighed by the main overall stimuli for entering it – growing potential of the market, based on rapid development of retailing sector in Russia and stable demand for seafood among consumers. Such motivation has proactive nature. In the other words, entry is driven by perceived attractiveness of the Russian seafood market. On the modern stage of internationalization of Norwegian seafood companies to Russia the main perceived problem is weak and unstable legal environment in Russia. It’s pointed out as the most important factor, which stipulates preference of exporting as organizational mode for work in Russia over other more risky modes. Further, it was found out that firms use direct exporting. It means that seafood trade with Russia occurs via the Russian importers. On the basis of obtained findings there were worked out implications for Norwegian seafood industry as well as for the Russian authorities. URI: http://hdl.handle.net/10037/231 File(s) in this item: 1
thesis.pdf (715.1Kb) -
Rahman, Fatema (Master thesis; Mastergradsoppgave, 01-Jun-2011)[+][-]
Abstract: Natural transformation is one of the three mechanisms of horizontal gene transfer by which bacteria are able to take up free DNA from the surrounding environment. In natural ecosystems, bacteria preferentially attach to surfaces, forming matrix-enclosed communities known as biofilm. Biofilm cells differ phenotypically and physiologically from their free-floating counterparts. Objective: To estimate transformation frequency in Streptococcus gordonii biofilm and compare that to transformation in a planktonic type of growth. Methods: S. gordonii challis (ATCC 35105) was grown as biofilm in appropriate liquid media. The plasmid vector pVA838 and chromosomal DNA of S. gordonii were used as donor DNA in the transformation assay. Strain-specific synthetic Competence Stimulating Peptide (CSP) was used to induce competence in S. gordonii. The biofilm was grown in polystyrene microtiter wells. Cells in the biofilm were harvested to assess the transformation frequency. Results: The transformation frequency in biofilm bacteria was found to be approximately 6-fold higher than those of planktonic counterparts. Conclusion: This result may either indicate a potential stress-related role of CSP or the fact that CSP participates in the synthesis of bacteriocin-like protein. The finding of enhanced cells in the biofilm in the presence of CSP suggests the involvement of CSP-QS system in the process of biofilm formation. Probably the most confusing finding of this present study was the dramatic increase of the OD value in the liquid culture of S. gordonii after addition of CSP in the early growth phase. This study demonstrated that S. gordonii cells were able to acquire foreign plasmid DNA much more efficiently than their planktonic counterparts in vitro. This finding suggests that biofilm growth mode may provide optimal condition for genetic transformation. URI: http://hdl.handle.net/10037/3529 File(s) in this item: 1
thesis.pdf (455.3Kb) -
Nurhasan, Mulia (Master thesis; Mastergradsoppgave, 22-May-2008)[+][-]
Abstract: The population density of Laos PDR has increased from 15 persons per square km in 1985 to 19 persons in 1995 and to 24 persons in 2005. This has threatened food security, which in Laos PDR is generally synonymous with rice availability. Rice production in Laos rose by 70 percent from 1990 to 2004. Evidence from Vietnam, Malaysia and Central Thailand has shown that the rise of rice production steadily decreases the population of aquatic animals in rice field ecosystems, as a result of higher applications of fertilizers and pesticides. In Laos PDR, the use of fertilizers and pesticides is still minimal, but said to be increasing. The role of aquatic rice field species in rural Laotian diets has been underestimated. Almost 200 species are consumed across the country. These aquatic animals potentially supply most of the vitamins A and B, calcium, iron, sulphur, essential fatty acids and amino acids that are needed by the villagers. However, national and regional food composition data bases contain very limited info on nutritional composition of these species. These aquatic animals are not consumed in large quantities elsewhere. Field sampling was undertaken in Champasak and Savannakhet provinces for nine species of aquatic animals, including fish, amphibians, crustaceans, molluscs and insects. Additionally four samples of fermented fish sauce were included. The samples were transferred to the University of Tromso for detailed analysis. The objective of the study was to gain knowledge on the nutritional composition of the most significant species included in the diet in Laos areas. As other studies have made estimates of the quantities consumed, the results of this work enable an assessment for the nutritional contribution of aquatic animals to the diet. The work also discusses the impact on nutrition of a possible decrease in the available species biodiversity. This study documented that the aquatic animals that are consumed daily contained high amounts of protein, amino acids, calcium, iron and zinc. On the contrary, they contained a low amount of fat, fatty acids, and vitamin A. Amino acids, iron and zinc are important nutrients for the Laotians. As the food supply of rural households in rice farming areas of Laos is critically dependent on the environment, the sustainable existence of the rice-based aquatic animals is crucial factor to the nutritional status of the Laotians. The objective of biodiversity conservation overlaps local and nutritional needs and should be emphasised in development of national nutrition policies, as well as agricultural development policies and fisheries management practices. Fishery managers and policy makers should integrate pro-poor community-based biodiversity conservation into their ongoing development programmes. URI: http://hdl.handle.net/10037/1434 File(s) in this item: 1
thesis.pdf (3.077Mb) -
Siyema, Tandiwe (Master thesis; Mastergradsoppgave, 18-May-2010)[+][-]
Abstract: This study examines the extent, drivers and the management of overcapacity in the South African Hake Deep Sea Trawl (HDST) fishery. The research methods were quantitatively based on input-based capacity measures and qualitatively based on subjective capacity measures. The majority of the fishing capacity that operates in the HDST fishery was brought over during the recent allocation of fishing rights in South Africa. The utilization of this capacity is limited through TAC reduction and effort control regimes. This leads to capacity underutilization which reduces employment and increases the costs of the HDST fishery. Further, this capacity under-utilization has facilitated a slight recovery of this fishery’s target stock. In economic terms, there is substantial overcapacity in the HDST fishery, indicated by capacity under-utiization. In biological terms, there is no overcapacity in this fishery as capacity utilization is restricted. In social terms, however, there is inadequate fishing capacity in the HDST fishery as capacity under-utilization induced labour-under-utilization. Hence, the above management measures work in favour of the state which is concerned with the biological aspects of the fishery. The industry which is concerned with economic aspects faces overcapacity. URI: http://hdl.handle.net/10037/2496 File(s) in this item: 1
thesis.pdf (2.332Mb) -
Rani, Manira Sultana (Master thesis; Mastergradsoppgave, 27-May-2005)[+][-]
Abstract: Abnormal blastomere morphology may be indicative of low egg viability in fish and therefore represent a useful tool for rapid qualitative assessments for commercial and experimental aquaculture purposes. This work reviews the literature on this subject, and compares early cleavage patterns in a series of preliminary experiments of triploidy induction in Atlantic cod, Gadus morhua. Data from 4 different egg batches showed that cleavage abnormalities were generally higher in cold-shocked groups than control groups, though significantly only in 2 out of 4 experiments. Cell asymmetry was the most common type of cleavage abnormality in all trials, whereas other patterns such as complete separation of blastomeres or cell asymmetry combined with unequal blastomere size were observed in some of the experiments only. There was no significant difference between control and treated groups in terms of survival at any of the developmental stages in all batches. Proportions of abnormal blastomeres were negatively correlated with survival at day 1 while no correlations were observed at embryonation or hatching. This work shows that cold shock treatments applied shortly after fertilization may significantly increase, in some cases, the number of cleavage abnormalities but without affecting general survival at hatching. This would indicate that cleavage patterns abnormalities may not be considered as a good indicator of egg larval viability in such experiments. URI: http://hdl.handle.net/10037/294 File(s) in this item: 1
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Korshunova, Ekaterina (Master thesis; Mastergradsoppgave, 05-Jun-2012)[+][-]
Abstract: Polar cod (Boreogadus saida) is considered to be a key species in the Arctic marine ecosystems. Yet detailed or even basic knowledge regarding its biology and adaptations, especially during the polar night, are in many cases poor. No field data is presently available on the gonad development of polar cod, its reproductive biology and associated bioenergetics. Accordingly, polar cod was sampled at different locations in Svalbard waters in August, September, November and January. Gonadosomatic index (GSI) and hepatosomatic (HSI) indices were calculated as indicators of the physiological state of the fish. Maturity stages were determined by microscopic histological techniques. Energy reserves (total lipids, proteins and carbohydrates) were quantified in liver and gonads as well as cellular respiration through Electron Transport System (ETS) activity. Results indicated that polar cod prepared for spawning and started developing their gonads in August and September. The fish with GSI≥4% were considered mature as they had spawned at least once or were preparing for their first spawning. A general increase in GSI was observed together with a general increase in the total energy content in polar cod gonads from August to January. Males showed fully developed gonads in November, i.e. two months earlier than females. HSI and total energy content in liver tended to be constant over time, except for males where HSI was lower in January compared to the other months. Furthermore, only mature males showed a negative correlation between GSI and HSI that indicated a drain of energy from liver to gonads in males. It was hypothesized that female and male polar cod had different reproductive strategies. Based on histological analysis of the gonads, female polar cod were confirmed to be iteroparous and to be able to spawn more than once in their lifetime. Indeed, the presence of post-ovulatory follicles in the ovaries of mature females in August indicated that the fish had spawned the previous winter, while the progressive oocytes at the stages of cortical alveoli and lipid inclusion formation showed that there would be a new reproductive cycle in the coming spawning season. The histology did not allow concluding a similar unequivocal characterisation of the male reproductive strategy and samples from post-spawning period would be needed. However, results tended to show a higher energy investment and a higher metabolic activity in males than females and a decrease in their abundance compared to females with age. It is therefore hypothesized that males may be semelparous. In the harsh Arctic conditions this gender-specific strategy can be a successful opportunity to maximise the reproduction process and maintain high abundance of the polar cod population. Males should always be ready to spawn, because the timing of female gonad development can be different and dependent on environment. URI: http://hdl.handle.net/10037/4357 File(s) in this item: 1
thesis.pdf (2.734Mb) -
Agulló Núñez, Lara (Master thesis; Mastergradsoppgave, 06-Jun-2012)[+][-]
Abstract: Greenland halibut (Reinhardtius hippoglossoides, Walbaum) is a commercially important fish species in the Barents Sea. This fishery has been strongly regulated, including a fishing ban from 1992 to 2009. Studies of fish reproduction are needed to extend the knowledge about this species in order to improve management and to avoid another decay of the stock. This Master Thesis describes the relationships between fecundity (thousands oocytes per female) and length (cm) ("Fecundity=2 ×" 〖"10" 〗^"-6" " × " 〖"Length" 〗^"3.9418" ) and fecundity (thousands oocytes per female) and weight (g) (Fecundity=0.003 × Weigth^1.1251) for Northeast Arctic Greenland halibut based on 138 females taken in November-December 2011 on the continental slope of the Barents Sea. Fecundity was compared to previous data from the same area and it was found to be in the same range as data from 1996, 1997 and 1998. Maturity stages were stated using the new scale proposed by Kennedy et al. (2011) based on oocyte diameter measurements. These data were compared with the maturity stages given at sea, using both a standard macroscopic scale and the macroscopic scale special for Greenland halibut. Differences were found, both with regard to stating of maturity stages and the boundary between mature and immature individuals. Spawning stock size and total egg production were calculated using both methods, and an overestimation of the spawning stock size, as well as of the total egg production, was found when the macroscopic scale was used. Due to the fact that it is difficult to implement the microscopic scale at sea, it is proposed that when using the special macroscopic scale for Greenland halibut females, the boundary of immature females is moved from stage 1 to also include stage 2. URI: http://hdl.handle.net/10037/4355 File(s) in this item: 1
thesis.pdf (1.388Mb)
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