Marine Protected Areas ~ Pleasing both conservational and fishing perspectives.

So here I am, yet again, blogging my revision notes in sheer desperation that something will stick in my mind. All I want to do is sit outside and soak up the sun’s rays with a beer (or Pimms) in hand, my friends, my man and some happy summer music. I’ve tried to sit outside and revise, of course I have, but there’s something so very tiring about having the sun on your head all day. Alas, I’ve moved inside… Again.

What have I got in store today then? I’m still on Protected Areas (my exam is tomorrow, oh I need a miracle) and whilst I know I could probably write an okay answer (as in, I’ll be able to muster up some information at least), none of the information that I’m trying to absorb is actually going in.

I’m fairly confident that a question will arise to do with the design of protected areas (or maybe the allocation) and what factors need to be considered in this process. There’s bound to be something although a question didn’t crop up on last year’s exam. I wonder. I made a note on the lecture material that I swore the lecturer had said there is bound to be a question on the design process so, if there isn’t, I’m probably screwed. Anyway…

(Image sourced from: http://blogs.nature.com/climatefeedback/2009/06/a_place_at_the_table_1.html)

Marine Protected Areas ~ Pleasing both conservational and fishing perspectives.

One of the biggest worries concerning conservation managers is probably how big a protected area needs to be. Of course, from a purely conservational approach you’d expect “as big as possible” which is essentially to backing perspective for Pew Environmental Group (and other such foundations). Based on the Species-Area relationship, a larger area of land (or sea) will encompass a larger proportion of species and thus would be the best provider of conservation for meeting those conservation targets set. Concurrent to this, a larger area of protection is likely to encompass great habitat heterogeneity which studies have established has a positive effect on species richness. All in all, it seems like the better option doesn’t it? Have a large protected area and you run a greater chance of meeting those targets.

Unfortunately, as I’m sure you are aware from my last blog post, bigger isn’t necessarily better. Yes larger areas can support more species and have greater habitat diversity, but what about those socio-economic factors that are likely to limit the maximum size extent of these areas. Stakeholder support is a huge element of designing and implementing protected areas that cannot be ignored, without their support (either through economic backing or compliance) the viability of protected areas is likely to fall through. Fishermen, for example, solely depend on fish stocks and the harvesting of such for their well-being. Establishing a marine reserve, a protected area that does not permit any fishing activity whatsoever, therefore displaces these fishermen into alternate areas or preventing them from reaping the benefits of decent fish aggregations. Unless you combine both conservation and fisheries management to create a protected area that makes both parties happy, you’re going to get very little support from these fishermen which can simply reduce the area’s effectiveness due to lack of compliance.

The benefits of marine reserves on adjacent fishing grounds has already been well established through various studies; an increase in biomass, abundance, density, size and species richness is expected with reserves. Halpern assessed the extent these in detail using a myriad of studies in 2003; there was an average increase in abundance by 63%, size by 80%, biomass (a greater indicator of species recovery) by 90% and species richness by 59%. This is excellent news for both conservational and fishery objectives. It is generally well-accepted trait that larger fish have a greater fecundity and produce more eggs and engage in more reproductive activities. A 10kg red snapper, for example, produces 20-fold more eggs than, say, 10 individuals weighing 1kg each. This pattern of increased fecundity has been exhibited in Mombasa Marine National Park, Kenya (paper by Rodwell et al. 2002) with a greater biomass of reproductive individuals within the reserve boundaries.

So, what does this mean for the fishermen? It means they can obtain much greater catches just outside of the boundary therefore everyone is happy. This is termed the spillover effect, whereby the benefits observed within the reserve ‘spill-over’ into adjacent waters, either by the movement of juveniles and adults to external waters or the export of pelagic eggs and larvae. In Mombasa fish traps close to the marine reserve boundaries exhibited a 3X greater increase in catch (despite the greater trap density). A similar story also occurred in St Lucia! The downside to this is it does take a while for the benefits to be seen, as with anything. Fishermen, like politicians, want their results there and then and I don’t blame them, at the end of the day their jobs are affected. It largely depends on the extent of damage that areas has endured, but good responses (i.e. doubled or tripled populations) can be expected within 3-5 years.

Going back to what was said earlier about size, the extent of the spillover effect is proportionate to the edge of the protected area. The probability of fish leaving the given reserve is all dependent on the amount of ‘edge’ the reserve has. So, whilst larger reserves are much better from a conservational perspective, from a fishing perspective they offer very little (since the chance of a fish leaving the area is much slimmer) and less likely to be supported. What constitutes as ‘too large’ depends on the mobility of the species within the reserve and also the local oceanographic conditions (i.e. current speed and habitat type will contribute to the extent of a species’ propagule dispersal abilities).

It’s a difficulty faced by those who design protected areas. The initial ‘protect or don’t protect’ is hindered by a multitude of other factors that may cross one of the areas proposed off of the list. Protecting areas that are already heavily impacted by humans, or areas that are consistently affected by natural disasters means that it is likely these effects are going to infiltrate the reserve boundaries. If so, then a much larger reserve is required otherwise species extinctions and extirpations are likely to occur. This then runs the risk of placing all your eggs into one basket – what happens when the whole reserve is affected by an external threat? What then?

Even after the protected area has been implemented, boundaries have been decided and stakeholders are on board, who is going to manage the area? Is it small enough to be managed by the local population – this has proven to be useful in various studies, but when the issues become too severe it requires regional or even global management, but is this to be from centralised governments or from non-governmental organisations? It is nigh impossible to choose a strategy that can fit every scenario because, in simple terms, one size does not fit all.

I think I’ve gone off on one there, but hopefully it is of some use to those who are interested and plus, it serves me well for my exams. I just now hope that a question relating to this comes up!


References for those papers cited:

Rodwell, L. D., Barbier, E. B., Roberts, C. M. and McClanahan, T. R. (2002) A bioeconomic analysis of tropical marine reserves-fishery linkages : Mombasa Marine National Park. Natural Resource Modeling, 15, 183-197.

Halpern, B. (2003) The impact of marine reserves: Do reserves work and does reserve size matter? Ecological Applications, 13, 117-137.