Marine protected areas (MPAs) are created to manage people’s behavior in their use of coastal and marine resources. Although MPAs have strived to deliver the objects of resource protection, they often face challenges in translating the accrued benefits into enhanced livelihoods of local communities in and around their areas of jurisdiction. We used Mnazi Bay-Ruvuma Estuary Marine Park (MBREMP) in Tanzania to appraise the scenario of pro-poor conservation. The purpose of comparison between park and non-park villages was done to verify the hypothesis that establishment and operations of MPAs impairs local socio-economic practices without robust provision of alternative livelihood safety nets. Agriculture remains a persistent livelihood occupation both in park and non-park villages. Artisanal fishing is a substantial livelihood occupation in seafront villages but a secondary activity in overall. Income and expenditure patterns indicated that non-park villages are better off with significantly high income to expenditure ratios. Fishing make the most contribution to income in sea front villages as agriculture is doing in non-fishing villages. Impacts on livelihoods emanate from disrupted resource use patterns which significantly influence the communities’ perception on need, role and overall acceptance of the marine park. Traditional access and user rights are marred by MPA operations putting at stake livelihood security of the communities therein. Alternative strategies have not yet been given due thrust and local communities remain insecure in accessing political assets such as cooperatives, community credit schemes and financial assets such as government and/or commercial banking sponsored schemes and loans. Local communities are already carrying the costs of denied access to livelihood sources, but the marine park is not quick enough to translate the accrued value and benefit of the improved resource base in enhancing local communities’ livelihood and welfare. Reducing pressure on marine resources through sound management interventions will have to be accompanied by mitigating measures to safeguard household food security, such as compensation, and developing alternative sources of income. There is still considerable polarization between conservation and socio-economic welfare of the people. MPAs should focus on combining resource management with livelihood opportunities that provide economic benefits in the short-run to address economic disruptions emanating from disrupted access to the once common resources.