| 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 |
| 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 |
| Abstract: | Ghana’s find of oil and gas in commercial quantities marks the beginning of a billion-dollar industry. The exploration and production of it is a major industrial development but its negative impacts on fisheries can never be underestimated. The research questions to be answered are: how is it likely that the fisheries in Ghana will be affected by the expanding oil and gas activities? What kinds of measures have been introduced to safeguard the fisheries? What can be done to mitigate harms and to secure a peaceful co-existence between the petroleum and the fisheries sectors? Purposive and random samplings were used to select one hundred and eighty respondents in the Cape Three Points community during field survey in the month of June and July 2011. Key informants were interviewed and field observations were also made. The result shows that standard of living of respondents is generally low and they lack social amenities in the community. The general perception of the respondents (75.6 %) is positive because they are expecting the oil and gas activities to boost their livelihood activities and increase income. The majority of the respondents with positive perception are women engaged in fish related activities, petty trading and farming. 36.2% of respondents asserted that the oil and gas activities would bring great loss in the quantity of fish catch. These were mostly fishermen and fishmongers. Even though the 36.2% is quite marginal, it still confirms the assertion that fish catch may reduce. Restriction imposed by naval officials in charge of the rigs, the incident of oil spillage and pollution are other major concern by the respondents. The government is enacting some laws and policies which can safeguard the fisheries if well implemented, however local communities and stakeholder involvement is not adequate. Also the institutions lack the human resources and the capacity to implement these policies. Recommendations are therefore made to ensure peaceful co-existence between fisheries and the oil and gas sector. Keywords: Oil and gas activities, fisheries, mitigation, livelihoods, Western Region, Ghana |
| URI: | http://hdl.handle.net/10037/4356 |
| 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 |
| Abstract: | Atlantic salmon export plays an important role in the total Norwegian seafood export. EU countries are currently the main markets for Norwegian salmon export. China is one of the countries which are expected to have an increased demand for Norwegian salmon. Norwegian fresh salmon exporters are currently facing the trade barriers with respect to new inspection regime and high transportation costs when they export fresh salmon to China. This study is investigating whether Coolnova salmon, fresh frozen salmon using proton magnetic freezing technology, may break the trade barriers of Norwegian fresh salmon export to Mainland China. Firstly is the meaning of preferred fresh quality of Norwegian Atlantic salmon and secondly is the potential market value of the Coolnova salmon for the wholesalers and the supermarket in Hong Kong estimated. A sample of fresh chilled, Coolnova and frozen salmon fillets were tested by wholesalers and supermarket managers who gave their quality judgement recorded in a questionnaire. Different perceptions and attitudes were expressed related to both quality factors like fatness and colour influenced by the different fish feeding, sizes and fillet cuts of the tested salmon samples as well as factors related to the application of novel freezing and thawing technologies where Coolnova salmon has its advantage. The results show that freshness is a preferred product attribute of salmon characterized by appearance as a distinctive orange colour, clear white oil lines and a hard texture and smooth and juicy taste. The results indicate that Coolnova salmon after fresh-frozen and thawed, may satisfy the markets requirements for freshness and furthermore gain a cost advantage by the opportunity to move distribution from an expensive fresh airfreight to a low cost frozen sea freight. Frozen salmon can be kept in freezers for a long time without quality degradation and would thereby not be affected by the new quality inspection regime which hampers the fresh fish import to China. Coolnova salmon can thus break the trade barrier of Norwegian fresh quality salmon imposed by the Chinese government. |
| URI: | http://hdl.handle.net/10037/3810 |
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