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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Who is catching what? A survey of recreational fishing effort and success ontaiāpure and mātaitai management areas

Kallqvist, Emma January 2009 (has links)
Marine recreational fishing is a highly developed activity and has an increasingly global following. In New Zealand, over 30 % of the population participate in recreational fishing and the annual harvest of some species is larger than the commercial catch. It is therefore vital for resource management to include data on recreational take. Since marine recreational fishing and charter boat fisheries in New Zealand are managed outside the Quota Management System (QMS), Area Management Tools (AMT) such as taiapure (local fishery), mataitai (reserves) rahui (temporary closures) can be used to ensure sustainability of certain coastal areas affected by fishing and other activity. The Akaroa Harbour Taiapure was established in 2006 and is currently the only taiapure in Canterbury. The main objective with this study was to characterise the recreational fishery in the Akaroa Harbour Taiapure in order to provide management solutions for this area. Three surveys were set up whereby two were specifically designed to record the recreational take landed on the four most frequently used slipways in Akaroa Harbour. A third survey was to gauge local resident‟s perception on recreational fisheries over time. Both qualitative and quantitative methods were used and appropriate statistical analysis applied. Over 451 intercept interviews were conducted on slipways on Banks Peninsula and 138 trip records were returned. Main findings include significant differences in target and landed species, also a shift in areas mostly fished since the previous survey in 1997 by the Ministry of Fisheries. The most frequently landed fish in this study included blue cod, flounder, rock lobster and perch. The perception survey revealed a strong community bond to recreational fishing and a need for increased local input in the management of the Akaroa Harbour Taiapure. The three surveys are recommended to be continued over time in order to create a data base on recreational fishing and also to document local and indigenous knowledge on marine conservation.
2

Early magmatism and the formation of a ‘Daly Gap’ at Akaroa Shield Volcano, New Zealand

Hartung, Eva January 2011 (has links)
The origin of compositional gaps in volcanic deposits remains controversial. In Akaroa Volcano (9.6 to 8.6 Ma), New Zealand, a dramatic compositional gap exists between basaltic and trachytic magmas. Previously, the formation of more evolved magmas has been ascribed to crustal melting. However, the interpretation of new major and trace element analysis from minerals and bulk-rocks coupled with the mechanics of crystal-liquid separation offers an alternative explanation that alleviates the thermal restrictions required for crustal melting models. In a two-stage model, major and trace element trends can be reproduced by polybaric crystal fractionation from dry melts (less than 0.5 wt.% H2O) at the QFM buffer. In the first stage, picritic basalts are separated from an olivine-pyroxene dominant mush near the crust-mantle boundary (9 to 10 kbar). Ascending magmas stagnated at mid-crustal levels (5 to 6 kbar) and fractionated an olivine-plagioclase assemblage to produce the alkali basalt-hawaiite trend. In the second stage, trachyte melt is extracted from a crystal mush of hawaiite to mugearite composition at mid-to-upper crustal levels (3 to 5 kbar) after the melt has crystallised 50 vol.%. The fractionated assemblage of plagioclase, olivine, clinopyroxene, magnetite, and apatite is left in a cumulate residue which corresponds to the mineral assemblage of sampled ultramafic enclaves. The results of trace element modelling of Rayleigh fractionation using this extraction window is in close agreement with the concentrations measured in trachyte (= liquid) and enclaves (= cumulate residue). The compositional gap observed in the bulk-rock data of eruptive products is not recorded in the feldspar data, which show a complete solid solution from basalt and co-magmatic enclaves to trachyte. Complexly zoned plagioclases further suggest episodical magma recharge events of hotter, more mafic magmas, which lead to vigorous convection and magma mixing. In summary, these models indicate that the Daly Gap of Akaroa Volcano formed by punctuated melt extraction from a crystal mush at the brittle-ductile transition.

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