Bertarelli-Annual-Report-2024-FULL - Flipbook - Page 40
Bertarelli Foundation
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Divergent Responses of
Pelagic and Benthic Fish Body
Size Structure to Remoteness
and Protection from Humans
Letessier, T.B., Mouillot D., Mannocci, L., Jabour
Christ, H., Mohammed Elamin, E., Mohamed Elamin, S.,
Friedlander, A.M., Hearn, A., Juhel, J.-B., Kleiven, A.R.,
Moland, E., Mouquet, N., Nillos-Kleiven, P.J., Sala, E.,
Thompson, C.D.H., Velez, L., Vigliola, L., Meeuwig, J.J.
(2024). Science https://doi.org/10.1126/science.adi7562
Animal body-size variation influences multiple processes
in marine ecosystems but is hard to measure consistently
across midwater and seabed habitats. Stereo baited
remote underwater video stations (BRUVS) represent
a unifying, non-destructive, and fisheries-independent
method that can estimate relative abundance and body
size across virtually any marine system. This study
combined records from multiple surveys inside and
outside marine protected areas (MPAs) across the Atlantic,
Indian, and Pacific Oceans, totalling 823,849 individual
fish, representing 139 families and 1460 species. While
there was evidence of human impacts throughout oceans
and habitats, midwater fish size structures were found to
be more vulnerable to human pressure than their seabed
counterparts. Human impacts across midwater fish size
classes indicate that it is not just the large predators that
are vulnerable but also the smaller-sized species which
underpin major fisheries, such as anchoveta and sardines.
For seabed-dwelling fish, size indicators are comparatively
less sensitive, so other indicators such as biomass or
functional diversity should be considered.
To conserve and rebuild populations of midwater fish,
highly protected MPAs are required in remote locations,
including on the High Seas, and further expansion of
pelagic fisheries should be curtailed. Effective protection
of seabed fish can be achieved through MPAs placed in
accessible locations, which should also be prioritised to
rebuild coastal habitats and ecosystems.
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