Protection of functionally important parrotfishes increases their biomass but fails to deliver enhanced recruitment

O'Farrell, Shay, Harborne, Alastair R., Bozec, Yves-Marie, Luckhurst, Brian E. and Mumby, Peter J. (2015) Protection of functionally important parrotfishes increases their biomass but fails to deliver enhanced recruitment. Marine Ecology Progress Series, 522 245-254. doi:10.3354/meps11134

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Author O'Farrell, Shay
Harborne, Alastair R.
Bozec, Yves-Marie
Luckhurst, Brian E.
Mumby, Peter J.
Title Protection of functionally important parrotfishes increases their biomass but fails to deliver enhanced recruitment
Journal name Marine Ecology Progress Series   Check publisher's open access policy
ISSN 0171-8630
Publication date 2015-03-02
Year available 2015
Sub-type Article (original research)
DOI 10.3354/meps11134
Open Access Status File (Publisher version)
Volume 522
Start page 245
End page 254
Total pages 10
Place of publication Oldendorf, Germany
Publisher Inter-Research
Collection year 2016
Language eng
Formatted abstract
Burgeoning threats to coral reefs have prompted calls for management actions that can enhance ecosystem resilience, such as restoring herbivore populations whose grazing is critical to maintaining ecological function. However, lack of longitudinal datasets has hindered objective assessment of strategies aimed at recovering herbivory. Addressing this gap, we investigated the response of the Bermuda fish assemblage to a trapping ban that amounted to de facto protection of herbivorous parrotfishes (Scaridae). Hook-and-line fishing for piscivores continued during the ban, creating a natural experiment that freed scarids from both fishing mortality and adult-stage predation. Over the 9 yr study period, biomass of piscivores remained low because of the hook-and-line fishery, with the exception of trumpetfish Aulostomus maculatus whose biomass increased more than 6-fold. Although scarid post-recruit biomass increased by a factor of 3.7, there was no increase in recruits (<5 cm), contrary to our expectation of observing a stock–recruitment relationship (SRR) in a demographically closed system such as Bermuda. Although the unavoidable lack of a before-after-control-impact design in our study precludes making strong mechanistic inferences, we hypothesize that the observed increase in scarid biomass may indeed have driven a commensurate increase in larval settlement within this closed system, but density of settlers was subsequently regulated by A. maculatus, a predator of small fish that was free to respond to prey enrichment owing to the absence of large predators. Our results provide compelling evidence that scarid populations can rapidly recover from overfishing once protected, even if any SRR is decoupled.
Keyword Aulostomus maculatus
Coral reefs
Fish traps
Population regulation
Post-settlement mortality
Prey enrichment
Stock recruitment
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Biological Sciences Publications
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Created: Tue, 31 Mar 2015, 01:35:38 EST by System User on behalf of School of Biological Sciences