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Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 57-62). Also available on the World Wide Web.

At the 1996 World Fisheries Congress, Donald A. McCaughran declared seventyfive years of regulatory success for the International Pacific Halibut Commission. The Commission's mandate was to reverse the precipitous decline in halibut stocks that had become apparent in the 1910's, and save this fishery from economic extinction. The biologists and fishermen who sat on the Commission assumed that the appropriate biological target was the one that yielded the maximum sustainable harvest. Using a bioeconomic model of the fishery and regression analysis, I argue the Commission's use of global quotas to achieve its biological goal of maximum sustained yield was most certainly an economic failure. I also argue its policies were very likely a biological failure, as well. While arguably accomplishing its biological goal of the maximum sustainable yield in 1960, dynamic bioeconomic theory indicates their policies probably destabilized the biological fishery. The paper will first sketch the historical background of the industry. Then the regulatory history will be discussed. Then the economic literature will be reviewed as it applies to the Pacific halibut industry. Finally, the historical data will be examined and the proposition that the regulatory management of the halibut fishery was a success will be tested. The period 1928 to 1960 is covered as it provides both reliable data and a continuous period of regulation, at the end of which the biological goal of maximum sustainable yields was apparently achieved. In conclusion, I find that statistically the fishermen were insensitive to the direct effects of the quota and the total quantity of fish available, and instead responded to the quota's indirect effects on the fishermen's costs, which induced the inflow of greater fishing capital than otherwise would have occurred.

At the 1996 World Fisheries Congress, Donald A. McCaughran declared seventyfive years of regulatory success for the International Pacific Halibut Commission. The Commission's mandate was to reverse the precipitous decline in halibut stocks that had become apparent in the 1910's, and save this fishery from economic extinction. The biologists and fishermen who sat on the Commission assumed that the appropriate biological target was the one that yielded the maximum sustainable harvest. Using a bioeconomic model of the fishery and regression analysis, I argue the Commission's use of global quotas to achieve its biological goal of maximum sustained yield was most certainly an economic failure. I also argue its policies were very likely a biological failure, as well. While arguably accomplishing its biological goal of the maximum sustainable yield in 1960, dynamic bioeconomic theory indicates their policies probably destabilized the biological fishery. The paper will first sketch the historical background of the industry. Then the regulatory history will be discussed. Then the economic literature will be reviewed as it applies to the Pacific halibut industry. Finally, the historical data will be examined and the proposition that the regulatory management of the halibut fishery was a success will be tested. The period 1928 to 1960 is covered as it provides both reliable data and a continuous period of regulation, at the end of which the biological goal of maximum sustainable yields was apparently achieved. In conclusion, I find that statistically the fishermen were insensitive to the direct effects of the quota and the total quantity of fish available, and instead responded to the quota's indirect effects on the fishermen's costs, which induced the inflow of greater fishing capital than otherwise would have occurred. / Arts, Faculty of / History, Department of / Graduate

Commercial aquaculture for marine species is gaining importance in todays industry. Over fishing of the natural recource has sadly meant that many of the higher predators halibut, turbot, seabass, sea bream and tuna are now financially suitable for the industry. This thesis covers a wide range of topics involving two of the most valuable marine species, namely the Atlantic halibut and European seabas, from broodstock to larval first-feeding. Broodstock husbandry and especially nutrition are often the last to receive attention. This study shows that careful management of the broodstock, firstly by the close timing of stripping, secondly enhancement of the broodstock diet with n-3 and n-6 HUFA can increase both fecundity and egg quality right up to the point where the larvae switch from endogenous to exogenous feeding. The implications for the industry for these two species are twofold. Firstly, The identification that halibut eggs can be fertilised within 6 hours of ovulation with no detrimental effects on fertilisation rates and subsequent egg performance means that eggs could be transported to specialist egg and larval rearing units. Thus the potential exists for the industry to be divided into separate units dealing with different stages of the life cycle much like the salmon industry. Secondly, the development of an artificial pelleted brood stock diet would mean that problems of consistency and quality and also the dangers of disease infection via the feed can be removed from broodstock management. The stage of first-feeding for halibut is still considered to be the main bottleneck in the production of this species. The current work has shown that small systems of 100-1 can be used to successfully rear halibut larvae. Although careful consideration must be made of the system design to ensure that predator (larvae) and prey (Artemia) remain homogeneously dispersed. Also, the need to use rotifers at first feed has been shown to be unecessary. However, nutrition of first-feeding larvae still requires the use of wild zooplankton to ensure successful pigmentation. Yet, Artemia supplied with commercial enrichments still perform adequately in terms of their overall growth.

Thesis (Ph.D.)--Memorial University of Newfoundland, 1999. / Restricted until June 2000. Bibliography: leaves 222-240.

Studying calcium carbonate (otoliths) and calcium phosphate (fins, scales, bones) hard structure chemistry has numerous applications in the fisheries field for both freshwater and marine environments. The overall thesis objectives were: 1.) to provide an integrated and multidisciplinary approach to understanding the incorporation of trace elements and isotopes into biomineralized hard structures, and 2.) to apply this multidisciplinary perspective in the examination of element marking, stock discrimination, and migration in teleost fish species found within the Canadian Polar North. Varying physiological mechanisms within fishes control the uptake of essential and non-essential trace elements and isotopes during biomineralization processes. Essential life elements such as zinc and magnesium are controlled by their own uptake regulation systems whereas non-essential elements such as strontium and barium are controlled primarily by calcium uptake at the gills driven by internal calcium homeostasis. Secondarily, environmental trace elements compete with calcium and with each other for uptake at the gills. The ability of certain hard structures such as bones, fins, and scales to remobilise calcium and associated calcium-like elements, plays a role in the prolonged high concentrations of strontium that were observed in otolith marking of Greenland Halibut, Reinhardtius hippoglossoides. High doses of strontium chloride resulted in a prolonged expulsion of excess strontium. Strong associations of Dolly Varden Char, Salvelinus malma malma, with groundwater allowed discrimination of populations among studied river systems using otolith strontium and barium, and strontium isotopes. Calculation of otolith strontium freshwater baselines allowed for a quantitative method to examine migration histories of Arctic Char, S. alpinus, in Canada and western Greenland. Migration seaward was related to ease of access to estuary and marine habitats. Easy access to estuaries resulted in migration at a young age and small size whereas longer rivers resulted in a delay of migration to older ages and larger sizes. Understanding the role of fish physiology in association with calcium homeostasis provided a stronger basis for understanding the incorporation and presence of trace elements and isotopes found within biomineralized hard structures. These studies underscore the utility of microchemical studies for elucidating biological phenomena, thus linking the aspects of biology, physiology, and geology. / February 2017

Thesis (M.M.S.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 83-90.

In the present study, muscle growth and flesh quality have been investigated from both commercially farmed Atlantic halibut (Hippoglossus hippoglossus) (Aga marine AS, Norway)and halibut obtained from small-scale trials at Mørkvedbukta Research Station (Bodø University College, Norway). Morphometric techniques have been utilized to investigate fast muscle growth in halibut ranging from circa 2 g to 100 kg, and it was established that fast muscle fibre recruitment ceases when the fish attain approximately 81 and 177 cm, in the case of males and females, respectively. Different muscle fibre types were distinguished using histochemical (myosin ATPase and succinic dehydrogenase) and immunohistochemical (S-58, an antibody against slow muscle myosin) staining techniques. Females recruit twice as many fast muscle fibres compared to males, which allows them to reach a larger final size. Furthermore, the seasonal growth patterns during a one year production cycle in commercial farmed halibut revealed a winter depression in growth leading to loss of biomass, which was attributed to the maturation of males. Commercial farmed fish of equal size (~1.5 kg) showed sexual dimorphism of fast muscle fibre number, caused by a significantly higher rate of fast muscle fibre recruitment in females. During the winter season fast muscle fibres shrunk significantly, especially in male fish, as a consequence of loss of appetite, low water temperatures and sexual maturation. None of the female fish matured during the trial. Flesh quality of halibut deteriorated during winter and spring, since it had a softer appearance and significantly lower myotomal protein content, particularly in males. Cathepsin activity was measured using spectroscopy and showed a strong negative correlation to protein content, displaying a seasonal variation. The proteolytic depletion of fast muscle proteins affected the water holding capacity of the muscle (determined by centrifugation), which showed concomitant changes with the increase in cathepsin activity and drop in protein content. Despite the soft appearance, the firmness (shear force) of the flesh increased during the winter. The hydroxylysyl pyridinoline cross-link content of the collagen matrix, determined by HPLC, showed a strong correlation to the fillet texture. The increased firmness during the winter, a period of little (female) or negative growth (males), was probably due to an increased cross-linking of the collagen compartment. Partial sequences of IGF-I and IGF-II were cloned from fast muscle of Atlantic halibut, and their relative gene expression levels were determined along with those of cathepsin B, cathepsin D and IGF-IRa in male halibut using qPCR during a fasting and refeeding trial. Transcript levels of cathepsin B and to some extent cathepsin D were significantly higher during fasting than refeeding, suggesting an increased enzyme production during periods of food deprivation. A temporary increase in IGF-I transcripts was observed after 7 days refeeding suggesting that this growth factor is involved in muscle growth control. Both IGF- IRa and IGF-II were down-regulated during refeeding.

The recently discovered decapeptide kisspeptin and its G-protein coupled receptor form a signaling system expressed ubiquitously and are implicated in a variety of still poorly characterized functions. In the brain, kisspeptin is secreted by specific neurons and its receptor is localized in GnRH neurons. Kisspeptin signaling has been fully established in the control of the onset of puberty in vertebrates, from fish to mammals. In this study, we characterized the kisspeptin gene in the Senegalese sole and characterized the kisspeptin receptor genes in both the Senegalese sole and in the Atlantic halibut. In contrast to other fish species, the two species analyzed here showed only the presence of one ligand and one receptor, probably as a consequence of the genome reduction characteristic of Pleuronectiformes. However, in both cases we found an alternative splicing mechanism based on intron retention that produces also non-functional isoforms, but whether this is part of a mechanism to control abundance of the active gene product is still not known. We document spatial and temporal changes of expression of kisspeptin and its receptor in the brain, pituitary and gonads related to the annual reproductive cycle. Finally, we present the first evidence of a possible link between energy balance and reproduction mediated by kisspeptin signaling in a non-mammalian vertebrate. / El recentment descobert decapèptid kisspeptina i el seu receptor associat a una proteïna G formen un sistema que s’expressa ubiqüitament i que està implicat en diverses funcions, moltes de les quals encara no estan ben caracteritzades. En el cervell, la kisspeptina és secretada per neurones específiques, mentre que el seu receptor es troba a les neurones GnRH. Aquest sistema s’ha relacionat amb el control de l’inici de la pubertat en diferents vertebrats, des de peixos fins a mamífers. En aquest estudi, hem caracteritzat el gen de la kisspeptina en el llenguado senegalès, i els gens del receptor de la kisspeptina tant a llenguado senegalès com en l’Halibut de l’Atlàntic. Al contrari del que ocorre en moltes altres espècies de peixos, aquestes dues espècies només presenten un gen pel lligand i un gen pel recep- tor. Aquest fet és probable que estigui relacionat amb la reducció de la mida del genoma que han sofert els Pleuronectiformes. Tot i així, en les dues espècies s’hi troba un mecanisme d’empalmament alternatiu conseqüència d’una retenció intrónica que produeix una isoforma no funcional. Ara bé, si aquest mecanisme està relacionat amb el control de l’abundància dels trànscrits de la isoforma funcional encara està per esbrinar. Per altra banda, hem trobat canvis en l’expressió gènica tant en l’espai com en el temps durant un cicle reproductiu dels gens de la kisspeptina i el seu receptor en el cervell, pituïtària i gònades. Finalment, també presentem la primera evidència, en un vertebrat no mamífer, d’una possible relació entre el balanç energètic i la reproducció controlada pel sistema kisspeptina.