Biomass of slow life history species increases as local bottom trawl effort decreases in the Celtic sea

Type Article
Date 2021-07
Language English
Author(s) Mérillet LaureneORCID1, 2, 3, Pavoine SandrineORCID1, Kopp DorotheeORCID2, Robert MarianneORCID2, Mouchet Maud1
Affiliation(s) 1 : UMR 7204 MNHN-UPMC-CNRS Centre d’Ecologie et de Sciences de la COnservation, 43 Rue Buffon, CP135, 75005, Paris, France
2 : Ifremer, Unité de Sciences et Technologies Halieutiques, Laboratoire de Technologie et Biologie Halieutique, 8 Rue François Toullec, 56100, Lorient, France
3 : Institute of Marine Research (Havforskningsinstituttet), Ecosystem Processes Team, Nordnesgaten 33, 5005, Bergen, Norway
Source Journal Of Environmental Management (0301-4797) (Elsevier BV), 2021-07 , Vol. 290 , P. 112634 (12p.)
DOI 10.1016/j.jenvman.2021.112634
Keyword(s) Community weighted mean, Assembly processes, Biological traits, Elasmobranchs, Area closure

Due to its selective removal, fishing pressure has long influenced the dynamics of species based on their life history traits. Sensitivity to fishing increases along a “fast-to-slow” gradient of life history strategies, and the “slow” species (large, long-lived, late-maturing, giving birth to few large offspring) require the most time to recover from fishing. In the North East Atlantic, after having reached extreme levels, fishing pressure has decreased since the 1980's due to management measures such as total allowable catch (TAC) or area closure. An effect on the distribution of species as well as a potential recovery could be expected. However, temporal patterns of life history strategies are rarely linked to management measures. In addition, a larger emphasis is often put on exploited or emblematic sensitive species but rarely on assembly processes at the ecosystem scale (both commercial and non-commercial species). Based on a 17-year time series of 101 taxa (fishes, elasmobranchs, bivalves, cephalopods and crustaceans), we observed a negative relationship between the biomass of taxa sensitive to fishing and bottom trawling pressure, as well as an increase in their total biomass in the Celtic Sea. Over the whole area, stochasticity appeared as the dominant assembly process. Deterministic assembly processes were at play in the centre of the area where significant overdispersion (caused by the presence of both slow and fast taxa) were observed. The absence of sensitive taxa from the rest of the Celtic Sea appeared to be caused mainly by a historical effect of environmental filtering when fishing was high. At the local scale, we related the decrease in fishing pressure to the increase in biomass of five of the most sensitive taxa. This local decrease in fishing pressure, resulting from the implementation of an area closure, highlights the positive effect of such management measures in less than two decades.

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