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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.
41

Exploring complexities of fishery closures using octopus movements : an individual-based modelling approach

Berrío-Martínez, Jineth January 2022 (has links)
Temporary closures of octopus fishing areas constitute a promising co-management measure that aims to improve local governance, food security and incomes in coastal small-scale fishing communities. Although positive social and economic outcomes of temporary closures are increasingly reported, the underlying social-ecological and ecological interactions, and their impact on closure benefits are rarely studied. This lack of systemic understanding may lead to undesired outcomes. Here, I extend an existing agent-based model of temporary closures to explore the influence of individual octopus movements on ecological outcomes and fishers’ benefits in Zanzibar. First, I conceptualized the octopus closure system by analyzing empirical qualitative data and literature. Next, I iteratively developed and tested an individual-based model extension. This extension simulates between-den movements across a hypothetical seascape and formalizes intrinsic attributes of Octopus cyanea such as movement patterns and maturity stages. I analyzed the effects of varying closure size of fishing grounds temporarily closed to illustrate potential implications for outcomes of octopus closures. Simulation results show that individual octopus movements triggered by fishing activities have noticeable impacts on octopus sizes, their spatial and temporal distribution, and fishers’ catches, particularly when considering different social groups that depend on the fishery. Scenarios with closures in place show higher mean octopus weight in closed areas in contrast to open-access areas. Mean catches for women foot-fishers are lower compared to freedivers’ catches and even slightly lower when allowing octopuses to move in response to disturbance in all scenarios. Catch rates and distribution of mature octopuses are highly sensitive to closure size revealing a social-ecological trade-off when implementing larger closures. This study demonstrates an approach to integrating individual octopus movements and interactions between fishers and octopuses in a fishery management context, and suggests that reactive movement of octopus contributes to unequal distribution of the closure benefits between different social groups. / Octopus and People In Novel Transdisciplinary Simulations (OctoPINTS project)
42

Tourism and marine resource conservation tentacle in tentacle? Zanzibari hotels as biosphere stewards in support of octopus closures

Bohlin, Michael January 2020 (has links)
Tourism fuels the Zanzibari economy but adds to the depletion of marine resources. However, the concept of corporate biosphere stewardship suggests that companies with consolidated power can influence sustainability pathways. Can tourist hotels practically support octopus closures, a novel conservation tool, as a way towards sustainable marine resource consumption? I address this issue by making the first known attempt to estimate Zanzibari hotels’ seasonal and annual octopus demand, mapping their value chain structure and identifying the nature of their demand. The study relies on semi-structured interviews of 31 respondents (hotel staff, hotel suppliers, market traders, food importers and key informants) and official data. I assess the demand of hotels to range between 16 to 27 percent of the mean 2008-2018 annual catch in Zanzibar. Hence, this consumer power hotels may confer agency for them to contribute to resource conservation such as octopus closures. Hotels may support closures particularly if they match seasonality in octopus price and demand. However, hoteliers’ use of a wide sourcing network including imports may lead to diluted price signals hampering understanding and incentives to protect the local octopus supply. Additionally, hoteliers’ weight preferences largely correspond with the Zanzibari voluntary minimum weight limit, but do not align with the desired outcome of bigger octopus from closures. The typical practise of purchasing fresh octopus and limited freezer capacity of hotels may also limit their agency to support octopus closures. This study makes a novel contribution of linking octopus conservation with tourism. It furthermore nuances the concept of corporate biosphere stewardship by assessing the practical potential of Zanzibari tourism, a less consolidated industry, to contribute to marine resource conservation.  Further research into local biosphere stewardship of value chains within low-income country contexts should investigate differences in use of consumer power by small as opposed to large-scale businesses. In addition, similar assessments could benefit from research into local spatial and relational value chains, and their influence on hoteliers’ capacity to perceive of supply status through price signals, not only for octopus but seafood in general. / Utalii unakuza uchumi wa zanzibar lakini umekubwa na kupungua kwa rasilimali za bahari. Ingawaje, dhana ya uhirika wa kibailogio stewardship umependekeza kua nguvu ya mashirikiano ya makampuni yanaweza kuchangia njia endelevu. Inawezekana kwa mahoteli ya kitalii yakatoa msaada wa vitendo wa kufungia pweza wasivuliwe kwa kipindi maalumu, kama zana ya uhifadhi wa mazingira ambayo ni njia ya kupelekea matumizi endelevu ya matumizi ya rasilimali ya bahari? Ninaangalia suala hili kwa kufanya majaribio ya kwanza kwa kukadiria mahitaji ya pweza kwa hoteli za Zanzibar kwa msimu na kwa kila mwaka, kuyaainisha maeneo ya mnyororo wa thamani na kutambua maumbile ya upungufu wake. Utafiti huu ulikuwa ni wa muundo wa mahojiano ya wazi na watu 31 walihojiwa (wafanyakazi wa hoteli, wasambazaji wa mahoteli, wauzaji wa masokoni, wasafirihaji na watu wengine wanohusika) na taarifa za takwimu. Nilipima mahitaji ya mahoteli kwa asilimia kati ya 16 mpaka 27 ya jumla 2008-2018 upatikanaji wa kila mwaka kwa zanzibar. Hivyo basi nguvu ya maoteli wanaweza kua mashirika ya kuchangia uhifadhi wa rasilimali kama kufungia mwamba kwa uvuvi wa pweza. Mahoteli yanaweza kuwasaidia kufungwa kwa mwamba kwa uvuvi wa pweza hasahasa ikiwa watafanana kwa msimu na kwa upatikanaji. Ingawaje wenye mahoteli wanatafuta chanzo kikubwa ikiwemo kuagiza kutoka nje ambayo inaweza kushusha bei na ni ishara ya kuzuia kutoa motisha ya kulinda usambazaji wa ndani. Kwakuengezea wenye mahoteli uzito wanaoupendelea unawiana na ule wa kiwango cha chini cha Zanzibar, lakini hayaendani na matokeo ya matakwa yao ya pweza wakubwa wakati wa kufungia mwamba kwa uvuvi wa pweza. Mahoteli hayawezi kuwa kama mashirika ya kusaidia kufungs pweza kutokana na kutaka pweza ambao wametoka kuvuliwa na vilevile uwezo mdogo wa majokofu yao kuweza kuhifadhi pweza hao. Utafiti huu utaleta mchango mpya baina ya uhifandhi wa pweza na utalii. Na vilevile itaelezea dhana ya mashirikiano ya kibiosphere stewardship kwa kuchunguza umuhimu halisi wa utalii wa Zanzibar, muunganiko mdogo wa wadau katika kuchangia uhifadhi wa rasilimali za bahari. Tafiti zijazo zinazohusiana na biosphere stewardship ya mtiririko wa thamani kwa muktadha wa nchi zenye kipato kidogo zifanye uchunguzi juu ya tofauti ya nguvu ya watumiaji wadogo wadogo inavyoenda kinyume na biashara kubwa. Kwa kuengezea uchunguzi kama huo utanufaisha watu wa hali za chini na mahusiano ya mnyororo wa thamani na mchango wao kwa uwezo wa wenye mahoteli kutambua hali ya usambazaji kupitia bei zake si kwa pweza peke tu bali ni kwa vyakula vya baharini vyote.

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