Fishery discards do not compensate natural prey shortage in Northern gannets from the English Channel

Published on Aug 1, 2019in Biological Conservation4.451
· DOI :10.1016/j.biocon.2019.05.040
Tangi Le Bot3
Estimated H-index: 3
(University of Montpellier),
Amelie Lescroel1
Estimated H-index: 1
(Point Blue Conservation Science)
+ 4 AuthorsDavid Grémillet48
Estimated H-index: 48
(University of Montpellier)
Fisheries modify ecosystem balance by harvesting through marine food webs and producing large amounts of discards subsidizing scavengers. Among them, seabirds are the most conspicuous and have been benefiting from anthropogenic food sources generated by fisheries. However, this modified feeding behaviour also exposes them to threats, such as accidental bycatch on fishing gear and ecological traps set by discards of lower nutritional value compared to seabird natural prey. Seabird-fishery interactions have been the focus of numerous studies, but very few integrative investigations tested multi-annual dynamics. To explore this temporal dimension, we performed stable isotopic and body condition analyses, as well as GPS-tracking in Northern gannets (Morus bassanus) over a 12-year period (2005–2017), during which they coexisted with fisheries in the English Channel. We demonstrate that gannets fed either on natural prey, or fishery wastes, but that discard consumption induced increased seabird foraging effort and reduced adult body condition. These changes are concomitant with reduced gannet reproductive success, and reduced growth rate of their breeding population. Our work provides essential, novel understanding of scavengers-fisheries interactions, by showing that fishery discards do not compensate natural prey shortage in the longer term. Altered gannet foraging and fitness strongly suggest pelagic fish depletion threatening Northern gannets in the English Channel. To improve gannet conservation in this ecoregion, fishery discards may be banned, but, efforts should in priority go towards rebuilding Northern gannet pelagic prey populations, particularly by strongly reducing fishing effort on North Atlantic mackerel.
  • References (65)
  • Citations (0)
📖 Papers frequently viewed together
139 Citations
67 Citations
31 Citations
78% of Scinapse members use related papers. After signing in, all features are FREE.
#1David Grémillet (University of Montpellier)H-Index: 48
#2Aurore Ponchon (University of Montpellier)H-Index: 8
Last. Daniel Pauly (UBC: University of British Columbia)H-Index: 93
view all 6 authors...
Summary Fisheries transform marine ecosystems and compete with predators [ 1 ], but temporal trends in seabird-fishery competition had never been assessed on a worldwide scale. Using catch reconstructions [ 2 ] for all fisheries targeting taxa that are also seabird prey, we demonstrated that average annual fishery catch increased from 59 to 65 million metric tons between 1970–1989 and 1990–2010. For the same periods, we estimated that global annual seabird food consumption decreased from 70 to 5...
5 CitationsSource
#1Tangi Le Bot (University of Montpellier)H-Index: 3
#2Amelie Lescroel (Point Blue Conservation Science)H-Index: 1
Last. David Grémillet (University of Montpellier)H-Index: 48
view all 3 authors...
3 CitationsSource
#1Nicolas Courbin (CNRS: Centre national de la recherche scientifique)H-Index: 8
#2Aurélien Besnard (CNRS: Centre national de la recherche scientifique)H-Index: 16
Last. David Grémillet (UCT: University of Cape Town)H-Index: 48
view all 8 authors...
6 CitationsSource
#1Halley E. Froehlich (UCSB: University of California, Santa Barbara)H-Index: 11
#2Nis Sand Jacobsen (UW: University of Washington)H-Index: 11
Last. Jun BoH-Index: 1
view all 11 authors...
Aquaculture is supporting demand and surpassing wild-caught seafood. Yet, most fed aquaculture species (finfish and crustacea) rely on wild-captured forage fish for essential fatty acids and micronutrients, an important but limited resource. As the fastest growing food sector in the world, fed aquaculture demand will eventually surpass ecological supply of forage fish, but when and how best to avoid this ecological boundary is unclear. Using global production data, feed use trends, and human con...
14 CitationsSource
#1Yves Cherel (University of La Rochelle)H-Index: 62
#2Charline Parenteau (University of La Rochelle)H-Index: 8
Last. Charles-André Bost (University of La Rochelle)H-Index: 33
view all 4 authors...
The poorly known winter foraging ecology of the king penguin, a major Southern Ocean consumer, was investigated at the subantarctic Crozet Islands where the largest global population breeds. Blood δ¹³C and δ¹⁵N values were used as proxies of the birds’ foraging habitat and diet, respectively, and circulating prolactin levels helped in determining the birds’ reproductive status. Plasma prolactin concentrations showed that king penguin adults of unknown breeding status (n = 52) that were present a...
2 CitationsSource
#1Henri Weimerskirch (CNRS: Centre national de la recherche scientifique)H-Index: 86
#2Dominique P. Filippi (Wellington Management Company)H-Index: 4
Last. Samantha C. Patrick (University of Liverpool)H-Index: 20
view all 5 authors...
Despite international waters covering over 60% of the world's oceans, our understanding of how fisheries in these regions shape ecosystem processes is surprisingly poor. Seabirds are known to forage at fishing vessels, with potential deleterious effects for their population, but the extent of overlap and behavior in relation to ships are poorly known. Using novel biologging devices, which can detect radar emissions to record the position of boats and seabirds, we measured the true extent of the ...
16 CitationsSource
#2Peter Gerard Beninger (MBL: Marine Biological Laboratory)H-Index: 1
Last. Dominique SellierH-Index: 2
view all 4 authors...
Abstract The geographic distribution and populations of cliff-nesting seabirds are essential elements in the assessment of their ecological roles and status. Here, a geographic mapping approach was used to visualize the biogeography of European seabirds. This approach was conducted at two temporally separated time intervals: 2004–2010 was compared to 1982–1988. Three biogeographic regions were identified: Arctic, Boreal and Ibero-Atlantic. The data show that species richness has remained stable ...
2 CitationsSource
#1T.L. Catchpole (Centre for Environment, Fisheries and Aquaculture Science)H-Index: 20
#2Ana Ribeiro-Santos (Centre for Environment, Fisheries and Aquaculture Science)H-Index: 2
Last. Tim Gray (Newcastle University)H-Index: 23
view all 5 authors...
Abstract A feasibility study was conducted on the impacts of the new Common Fisheries Policy (CFP) rules requiring catches in regulated fisheries to be landed and counted against quotas of each Member State - the landing obligation (LO), and that catch of species subject to the LO below a minimum conservation reference size (MCRS) be restricted to purposes other than direct human consumption. The aim was to estimate the level of discarded fish likely to be covered by the new rules, the impact of...
15 CitationsSource
#1Victoria Warwick-Evans (University of Liverpool)H-Index: 5
#2Phil W. Atkinson (British Trust for Ornithology)H-Index: 6
Last. Jonathan A. Green (University of Liverpool)H-Index: 24
view all 7 authors...
The at-sea distribution of seabirds primarily depends on the distance from their breeding colony, and the abundance, distribution and predictability of their prey, which are subject to strong spatial and temporal variation. Many seabirds have developed flexible foraging strategies to deal with this variation, such as increasing their foraging effort or switching to more predictable, less energy dense, prey, in poor conditions. These responses may vary both within and between individuals, and und...
8 CitationsSource
#1Amélie Lescroël (University of Montpellier)H-Index: 17
#2Raphaël Mathevet (University of Montpellier)H-Index: 18
Last. David Grémillet (University of Montpellier)H-Index: 48
view all 7 authors...
Seeing the ocean through the eyes of seabirds could help meet the challenges of managing common-pool marine resources both in protected and unprotected areas. First, seabirds are top-predators, exposed to all threats affecting the oceans, and this makes them ideal sentinel organisms for monitoring changes within marine ecosystems. Second, seabirds cross both ecological and political boundaries, and following their movements should help making interdependencies within and between marine ecosystem...
10 CitationsSource
Cited By0