You should first try to establish how much of "jobs" were exisitng before making the area into an PLA  

Ask Heather Leslie at the University of Maine Darling Marine Center

When was the area declared? or is it a planned area? You would need to evaluate (if you are still on time) the "jobs" pre-declaration, and then in the future compare them with the post-declaration. Hopefully you will be able to evaluate which kind of jobs are supposed to get lost, and focus on them. In some places jobs are not formal or regular, and therefore quite difficult to quantify. But a combination of quantitative and qualitative methods should give you an idea. There might be some jobs created with the declaration, so it would be good to include them in your study. Many times declaration of protected areas are designed to generate an alternative "job" or activity for those who will loose their jobs or subsistence activities. Check for example Galera-San Francisco in Ecuador http://institutonazca.org/downloads/ca_mpa_galera_san_francisco/private_incentives_to_conserve_ecuadors_coast.pdf

You can also contact Instituto Nazca if you want to get the details  of the Agreement they made with local fishermen to ensure that it was economically viable and that the reserve would benefit the environment AND the community. This declaration is a couple of years old, so they might have monitored some socio-economic indicators similar to what you need.

The impact of PAs and PLAs on employment and even on biodiversity conservation is under-researched. For the reader you may wish to define PLAs versus (or as subset of) PAs. The latter are generally publicly owned, or by a dedicated foundation and are (currently) without residents, while PLAs may include privately owned land as well villages. However, hybrids exist both in Europe and Africa. Some NPs are inhabited, include private land ownership and or land lease (mines) or both.

My experience is that additional local employment may be created in/around PAs/PLAs in the tourist and hospitality industry. Such local employment is only of substance in sparsely settled areas. In more densely populated areas the number of additional job is rather inconsequential. 

Thank you all for your answers.

Aliyu Salisu Barau: Thank you. There is a problem that PLA is not declared. It was only purpose but because of displeasure of mayors and businessmen it was not declared so I do not know the numbers of unemloyment after declaration. Reduction of jobs is only objection of mayors why they do not want to declare PLA there. They do not know if it is true, but they tried use this claim and I would like to tell them: It is not true, PLA do not reduce jobs, but I need to have any support :)

Mark D Bertness: Thank you, I will try it.

Carolina Garcia: Thank you so much for ideas how can I compare it. The area is not PLA yet, it is planning but there are so much displeasures. It is the reason why the area is not protected. In my opinion there will be more jobs thanks to tourism that will increase and there is no job that is supposed to get lost. But it is only my opinion and I need some examples to support my opinion. Thanks for Nazca and Ecuador, I hope it could be the right support.

Hi Martina, 

Limited political support is many times an issue, especially because it can be a result of a perceived community opposition, rather than real consensus against it. You can look at various examples of benefits from protected areas (Check Google Scholar, for example MASCIA, M. B., CLAUS, C. A. and NAIDOO, R. (2010), Impacts of Marine Protected Areas on Fishing Communities. Conservation Biology, 24: 1424–1429., and go from there: which references did they include, who has cited them, or run your own search). The truth is that there is no formula to calculate the impacts (positive nor negative) of protected areas, because each area is different: ecological, socio-economic, cultural, political factors vary. The process of designation itself, or the governance of the area, can be a huge problem. While you can gather your evidence for the decision-makers, what you might need to do is go through a process that builds local support and legitimizes the creation of a PLA: for example, look at Hartz-Karp, J. 2007. How and why deliberative democracy enables co-intelligence and brings wisdom to governance. Journal of Public Deliberation, 3(1): 6, or Schusler, T. M., Decker, D. J. & Pfeffer, M. J. 2003. Social learning for collaborative natural resource management. Society & Natural Resources, 16(4): 309-326, and again, have a look at the references or look for articles that cite them: there are many ways in which stakeholders can participate in a meaningful constructive way, and then politicians are more limited by a more consensual position in the community. This is all happy thinking of course, because if behind the opposition there are some powerful actors moving the strings, and there are (hidden?) interests behind the political opposition, then you might need a different approach (strategic communication and advocacy campaigns, etc).  

Can you please check the following links? Those three books can be helpful:

http://www.eastwestcenter.org/publications/rural-livelihoods-and-protected-landscapes-co-management-wetlands-and-forests-banglades

http://www.eastwestcenter.org/publications/making-conservation-work-linking-rural-livelihoods-and-protected-area-management-bangla

http://www.eastwestcenter.org/publications/connecting-communities-and-conservation-collaborative-management-protected-areas-bangla

A.T.M. Rafiqul Hoque: Thank you a lot, I will follow in a few days. I am sure it will be helpful.

Chris Kirkby has evaluated the economic benefits of preserving land for ecotourisim vs. other uses (logging, agriculture, etc.) in the Peruvian Amazon. Citation to one of his more recent papers: Kirkby, Christopher A., et al. "The market triumph of ecotourism: an economic investigation of the private and social benefits of competing land uses in the Peruvian Amazon." PLoS One 5.9 (2010): e13015.

Jared D. Wolfe: Thank you for helpful article, it is amazing what people could find. Thank you so much.

Werner, 

thank you for the article, I will read it in few days. Every information is valuable for me. Unfortunately, my German is not so good to be able to read the articles, but perhaps with the help of a dictionary, I could find out a little. But the english one will be better.

Thank you and have a nice day.