A trophic model of a Galápagos subtidal rocky reef for evaluating fisheries and conservation strategies

By T. Okey, S. Banks, A. Born, R. Bustamante, M. Calvopiña, G. Edgar, E. Espinoza, J. Fariña, L. E. Garske, G. Reck and 4 more. 2004

168 citations recorded by the source corpus.

A balanced trophic model of a Galapagos rocky reef system was constructed using Ecopath and Ecosim. The Ecopath approach allowed characterization of food web structure through integration of disparate ecosystem information derived from many years of study of Galapagos shallow-water rocky reefs. Ecosim and Ecospace routines enabled us to explore various hypotheses about system dynamics as well as potential solutions to conservation concerns about overfishing. A full series of functional group removal simulations resulted in estimations of interaction strengths and ‘keystone’ potentials for each of the 42 living functional groups in the model. Relative interaction strengths in a pristine unfished system are likely to be quite different from interaction strengths indicated by this present-day model. At present, humans extract food from very low trophic levels (mean trophic level = 2.3) in Galapagos rocky reef systems because sea cucumbers and detritivorous mullets comprised 71 and 15%, respectively, of the total fisheries catch. Catch rates of sea cucumbers ( Stichopus fuscus; referred to here as ‘pepinos’) are shown to be unsustainable, and the population should be declining rapidly. The exclusion of fishing from 23% of the total reef area, representing a hypothetical non-extractive zone, prevented the functional extinction of pepinos that our analysis predicted to occur with no areas protected (given 1999–2000 capture rates). Even with 23% of the hypothetical area protected, pepinos were predicted to decline overall to a stable 36% of their current estimated biomass. Pepino biomass was predicted to increase to eight times that of current levels if pepino fishing were stopped altogether. © 2003 Elsevier B.V. All rights reserved.

Subfields: Ecology, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/83841df5716bffa06f8ec9a3aeb090e8c6c3fd19

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Citations in the corpus

El Niño, grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species (2010, background): “This Vulnerable species of grouper has been characterized as functionally extinct in the central region of Galapagos (Ruttenberg, 2001; Okey et al., 2004).”
Keystone species: toward an operational concept for marine biodiversity conservation (2015, methodology): “A trophic model of a AUDREY VALLS ET AL.46 Ecological Monographs Vol. 85, No. 1 R E V IE W S Galápagos subtidal rocky reef for evaluating fisheries and conservation strategies.”
Effects of body size, age and maturity stage on diet in a large shark: ecological and applied implications (2008, background): “As a result, both theoretical (Stevens et al. 2000; Okey et al. 2004; Frid et al. 2008) and empirical (Ward and Myers 2005; Shepherd and Myers 2005; Myers et al.”
Identifying important species: Linking structure and function in ecological networks (2008, unknown): “E-mail addresses: jordan.ferenc@gmail.com (F. Jordán), tokey@bms.bc.ca (T.A. Okey), b baver@yahoo.de (B. Bauer), slibralato@ogs.trieste.it (S. Libralato). gets for conservation practice (e.g. keystone species, Paine, 1966; Power et al., 1996).”
Food-web structure of and fishing impacts on the Gulf of Cadiz ecosystem (South-western Spain) (2013, background): “auly et al. (1998a) suggested that the mean trophic level of the atch (TLc) can decline in an exploited ecosystem as a consequence f overexploitation of the highest trophic levels corresponding to arge and slow growing long-lived predators.”
A method for identifying keystone species in food web models (2006, methodology): “…elimination of functional groups from a trophic web and evaluating impacts on the other functional groups using a graph theoretical method (Jordan et al., 1999; Jordan, 2001; Solé and Montoya, 2001), or evaluating changes in the biomass of ecosystem with dynamic models (Okey et al., 2004a).”