november, 2019
Event Details
Maintaining population diversity and avoiding local depletion is especially challenging in species where the scale of movement is considerably less than the managed region. This is illustrated in a study of two
Event Details
Maintaining population diversity and avoiding local depletion is especially challenging in
species where the scale of movement is considerably less than the managed region. This is
illustrated in a study of two North Sea species; Atlantic cod and sandeel. In both, more than
one population inhabits the North Sea, and there are differences in exploitation rate and
environmental exposure. Differences in growth and maturation schedules among populations
make some more vulnerable to fishing pressure. For sandeel, the risk of regional overfishing
was reduced by ICES changing the assessment areas to reflect the scale of life stage
connectivity and local productivity. In cod, the least productive population remains far from
shore and consequently exploitation was low and abundance was maintained. In contrast
some spawning grounds were extirpated in the highly exploited coastal populations and
maturation schedules changed. While cod started to recover the rate differed among
populations. Aggregative behaviour and fidelity in both species also makes them vulnerable
to localised depletion. Cod spawning aggregations were targeted by fisheries due to increased
catchability but the introduction of seasonal closures appears to have reduced this problem.
In sandeel, within season movements and a preference for certain habitat type appears to
maintain high fishery CPUE leading to the potential for bank scale depletion so area closures
have been used to restrict fishing on less productive banks. While the measures applied seem
to have had some benefit, there is a need for a more formal framework to develop and
evaluate spatial management approaches.
Time
(Friday) 1:00 pm - 2:00 pm
Location
SOI Lecture Theatre
Gatty Marine Laboratory, St Andrews
Speaker organisation
Marine Scotland Science
Organizer
Mark Jamesmaj8@st-andrews.ac.uk
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