A major challenge in sustainable fisheries management is
minimizing the impact of fishing on biodiversity. These impacts are most commonly bycatch of
non-target species such as marine birds, marine mammals, turtles, and sharks,
and fishing impacts on sensitive habitats such as corals, sponges and sea
grasses. Fisheries agencies seek to find
the best trade-off between sustainable harvest and biodiversity impact.
Biodiversity impacts of fishing are often area and gear
specific, occurring where there are local concentrations of sensitive habitats
and bycatch of different species. Sensitive habitats are most impacted by mobile bottom contact gear, and
different species tend to be vulnerable to specific gears; e.g. marine birds
tend to be particularly vulnerable to trawling and gillnetting.
Concern about biodiversity protection has led to adoption by
most nations of the Aichi 11 target of “10 per cent of coastal and marine areas,
especially areas of particular importance for biodiversity and ecosystem services,
are conserved through effectively and equitably managed, ecologically
representative and well-connected systems of protected areas and other
effective area-based conservation measures.”
In the latest Editor's Choice, the authors explore the extent to which
biodiversity can best be protected while allowing for catch using area-based
management (regulation of fishing
effort by gear and area). No-take MPAs
are one form of area-based management where no gear is allowed to be used in
some areas. The method used was to find
what combination of area specific effort by gear led to the best combination of
sustainable catch and biodiversity, trading off weighted values for biodiversity
and catch. When all of the weight was
assigned to catch, effort
was found that was equivalent to traditional MSY
levels of effort. When all weight was
assigned to biodiversity, no catch was allowed.
In the two examples presented in this paper, the authors
demonstrate that there are often win-win solutions that allow for high
biodiversity protection and high yield. This is achieved by closing the most sensitive areas or the hotspots
for bycatch to the most impactful gears. The authors found that complete no-take areas were not commonly part of
the optimal solution except when biodiversity was given very high weight and
sustainable harvest very low weight. The
results suggest that other effective area-based conservation measures may be
the best way to preserve marine biodiversity while allowing for sustainable
food production.
Read the full paper in ICES Journal of Marine Science.
