Operational tools and adaptive management

Regarding nephrops, the current management does not provide adequate safeguards to ensure
that local effort is sufficiently limited to avoid depletion of resources in separate FUs. The
current situation allows for catches to be taken anywhere in the ICES division and this could
imply excessive harvest rates from some parts. Vessels are free to move between grounds,
allowing effort to develop on some grounds in a largely uncontrolled way. Management at the
FU level would address this problem. A continuing problem is the capture of juvenile
haddock and whiting, which are discarded at a high rate and whose populations are presently
much reduced (ICES 2008). Also juvenile cod is taken as bycatch, but this bycatch has been
reduced the last years (Andrews et al 2009).
Though reduced, due to the small mesh size the nephrops trawl fishery still causes relatively
large bycatches of small/juvenile cod, haddock and whiting, all of which are commercially
exploited stocks. In an ecosystem based management this “externality” may imply that
representatives of the mentioned fisheries get a say in the management of the nephrops
fishery. We assume that this is a representative of the cod fisheries. In order to be able to
solve the model analytically, we assume that the income in the nephrops fishery is a proxy for
the activity in this fishery that cause the negative effect on the cod fishery, and that this
negative externality increases linearly in the net income of the nephrops fishery.
Let 0 E j be the incentive scheme of the cod fishers, whereas v0 vE is the incentive
scheme of the authorities. Then, when the cod fishers are allowed a say in the management of
the nephrops fisheries, this results in optimal tax/subsidies rates, which compared to the single
management rates are as given in table 3.13.
Table 3.13 Optimal tax/subsidy rates when there are two principals to have a say in the
management of the nephrops fishery relative to when the fishery is managed by
the authorities alone
Variable v* ρ v*+ρ*
Relationship v* 0 v*+ρ*>w*
Clearly, the cod fisher representative will forward a positive tax rate in its‟ incentive scheme,
which implies that it will deter effort in the nephrops fishery. This is obvious as each unit
harvest in the nephrops fishery implies bycatch of juvenile cod and thus smaller cod stocks,
which in turn gives lower cod catches in the future.
Also, it is clear that compared to a situation when the authorities regulate the nephrops
fisheries alone, they will now, in a situation where the cod fishers have a say, reduce the tax
rate or increase the subsidy rate. The reason is that if the cod fishers‟ representative sets a
high tax in order to limit the nephrops fishery effort, and thus harvest, then the authorities
partly make up for this by setting a low tax, or even a subsidy (when v 0
*
). However, as the
net incentive scheme, i.e. the aggregate of the two tax/subsidy rates exceed the tax/subsidy
rate the authorities would set solo, they reduce the tax/subsidy rate with an amount that is less
than the tax rate offered by the cod fishers‟ representative. As a consequence the aggregate
tax burden on effort in the nephrops fishery (the net incentive scheme) will increase, which in
turn implies that effort, and thus harvest, will decrease, compared to a situation where the cod
fishers have no say in the management of the nephrops fisheries.
This conclusion holds regardless of the relative strength of the interests to the nephrops
fishers or the authorities. Also, if we assume that the nephrops fishers have lower
environmental interests and higher economic and social interests than the authorities, which
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