extensive margins of fishing mortality can be approximately controlled by a single post-trip levy
on retained catch provided the survivability of discards is sufficiently high.
The tax on landings is denoted per angler-day and is proportional to the survivability of
discards. If all catch dies regardless of its disposition, then no regulatory control on landings is
warranted and the tax on angler-days collapses to a fee on harvest. This may be the case in many
deepwater fisheries.
The instrument for angler density is envisioned as a per-head subsidy to be administered
at the trip level for each vessel. This subsidy increases at an increasing rate with the optimal
density. Furthermore, the subsidy per head goes to zero as the mortality of discards decreases. If
there is no catch mortality apart from landings then there is no external dynamic implication to a
skipper’s choice of the number of passengers and the competitive market for angler days
properly accounts for the remaining intra-vessel static externalities.
The taxes on catch-augmenting inputs are characterized as being levied on a seasonal
basis per vessel (assuming that inputs are fixed over that horizon). They increase in the
effectiveness of the factor in fostering catch and, as with the subsidy on angler density, the input
tax declines to zero as survivability of discards increases. Without a direct dynamic externality
from excess fishing power itself, mortality is controllable through a single levy on landings and
the free market leads to the proper configuration of fishing inputs in long-run bioeconomic
equilibrium.
The final tax is a seasonal levy per vessel that is designed to remove any rents available
to the marginal entrant when evaluated at the optimal number of vessels. This “permit” fee
could also be administered through the selling or leasing of transferable rights to participate as a
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