Timescales of reserve benefits

[Callum Roberts]

CEMRINO wrote:

"Marine reserves are well-known for allowing the recovery of fish 
stocks within the reserve, which can lead to 1. some fish wandering 
outside the preserve and getting caught, thus increasing total fish 
catches.  2. Increased maximum fish size leading to greatly 
increased egg & larvae production to re-seed other overfished areas 
by dispersal.  3.  Increased fish size and density necessary for dive 
tourism.  Bohnsack (1994) has argued eloquently for point 2.  But I 
would like to propose that point 1 is actually the most critical in the 
short term.  This is because developing countries like the Philippines 
have little or no capacity for enforcement of regulations.  IF 
FISHERMEN FIND THEIR CATCHES INCREASING AFTER THE 
ESTABLISHMENT OF A MARINE RESERVE, THEY WILL BECOME ITS 
STRONGEST DEFENDERS.

A response to the interesting and very encouraging posting by 
CEMRINO, relating particularly to point 1 above. Overspill from 
reserves is clearly one important mechanism by which they can 
benefit fishers. However, I doubt that the timescale over which such a 
benefit will occur will be much faster than that over which benefits 
from increased egg production accrue. Fish densities need to build 
up in reserves before significant export of juveniles and adults will 
occur. By this time, reserves should also be acting as an egg source 
for replenishment of fishing grounds. In the short term (2-3 years) it is 
likely that reserves will impose a cost on fishers. In the longer term, 
the benefits from reserves are likely to greatly outweigh the start-up 
costs. Garry Russ has shown empirically a delayed overspill from a 
Philippine reserve, taking approximately nine years befored he could 
detect enhanced abundance of fish adjacent to the reserve. Joshua 
Nowlis and I have done some modelling work to look a timescales 
and magnitudes of costs and benefits of reserve creation. If you 
would like a copy of the paper email Josh (jnowlis at uvi.edu) or me.
        Overcoming short-term costs of reserve establishment may be a 
difficult hurdle for poor fishers who are already struggling hard to 
make a living. There is a very good case for development projects 
seeking to establish reserves to help people over this hump with 
some form of subsidy, compensation or alternative livelihood 
provision. That would give reserves a better fighting chance of 
getting to the stage where they begin pouring benefits back directly to 
the fishing community, and they attract the support of fishers on their 
own merits.

Best wishes,

Callum Roberts


Nowlis, J.S. and C.M. Roberts (in press) You can have your fish and 
eat it too: theoretical approaches to marine reserve design. Proc. 8th 
Int. Coral Reef Symposium, Panama.


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Dr Callum Roberts
Dept of Environmental Economics and Environmental Management
University of York
York, YO1 5DD
UK
Tel: +44 (0)1904 434066; Fax: +44 (0)1904 432998; email 
cr10 at york.ac.uk
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