There can be little doubt that well managed, well thought out marine protected areas can do wonders for marine life, and even the human communities that depend on the ocean for their livelihoods.  Within the imaginary boundaries of the protected area, populations of plants and animals flourish. 

Fish grow larger and get older – which means they themselves are able to produce not just more, but ‘fitter’ offspring which are more likely to survive and have offspring of their own.  These offspring in turn not only help rebuild the populations within the protected area but, depending on the species, may permanently leave the protected area to live in other parts of the ocean. 

This ‘spillover’ can support and rebuild populations that have suffered from our lack of self-control.  As these populations rebuild, they in turn form the backbone of sustainable ocean use – particularly fishing, but also other pursuits such as tourism and recreation.  Back inside the protected area, the community of plants and animals becomes more resilient to disaster, and may even help humans and marine life adapt to our changing climate. 

Designating an area ‘protected’ isn’t enough to ensure that these benefits are delivered.  Marine protected areas perform best when they are well enforced no take zones that have been in place for at least 10 years.  Location is vital.  They should be placed where they offer conservation value, not just where they will disrupt people the least, and creating networks rather than portfolios of single marine protected areas can help populations to sustain themselves.  Isolated locations often work better, primarily because they are less likely to be disrupted or degraded by human activities close to the protected area.  Size also matters, with bigger often performing better, partly because you are more likely to encompass the entire home range of the species you want to protect within the protected area. 

Which raises an interesting question – what happens when the animals you want to protect regularly move outside the boundaries of the protected area? 

This article was written for (and can be read in full in) The Marine Professional - a publication of the Institute of Marine Engineering, Science & Technology (IMarEST)