title: Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouper Mycteroperca olfax (Jenyns, 1840).
abstract: The Galapagos Sailfin grouper, Mycteroperca olfax, locally known as bacalao and listed as vulnerable by the IUCN, is culturally, economically, and ecologically important to the Galapagos archipelago and its people. It is regionally endemic to the Eastern Tropical Pacific, and, while an important fishery resource that has shown substantial declines in recent years, to date no effective management regulations are in place to ensure the sustainability of the Galapagos fishery for this species. Previous estimates of longevity and size at maturity for bacalao are inconsistent with estimates for congeners, which brings into question the accuracy of prior estimates. We set out to assess the age, growth, and reproductive biology of bacalao in order to provide more accurate life history information to inform more effective fisheries management for this species. The oldest fish in our sample was 21 years old, which is 2-3 times greater than previously reported estimates of longevity. Parameter estimates for the von Bertalanffy growth function (k = 0.11, L ∞ = 110 cm TL, and to = - 1.7 years) show bacalao to grow much slower and attain substantially larger asymptotic maximum length than previous studies. Mean size at maturity (as female) was estimated at 65.3 cm TL, corresponding to a mean age of 6.5 years. We found that sex ratios were extremely female biased (0.009 M:1F), with a large majority of the individuals in our experimental catch being immature (79%). Our results show that bacalao grow slower, live longer, and mature at a much larger size and greater age than previously thought, with very few mature males in the population. These findings have important implications for the fishery of this valuable species and provide the impetus for a long-overdue species management plan to ensure its long-term sustainability.
authors.affiliation: Fisheries Ecology Research Lab, University of Hawai'i at Manoa , Honolulu, Hawai'i , USA ; Fundacion In-Nova Castilla la Mancha , Toledo , España.
authors.forename: Paolo
authors.initials: P
authors.lastname: Usseglio
authors.affiliation: Fisheries Ecology Research Lab, University of Hawai'i at Manoa , Honolulu, Hawai'i , USA ; Pristine Seas, National Geographic Society , Washington, DC , USA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Friedlander
authors.affiliation: NOAA Fisheries-Pacific Islands Fisheries Science Center, Fisheries Research and Monitoring Division, Life History Program , Honolulu, Hawai'i , USA ; Hawai'i Institute of Marine Biology, University of Hawai'i, School of Earth Science and Technology , Kaneohe, Hawai'i , USA.
authors.forename: Edward E
authors.initials: EE
authors.lastname: DeMartini
authors.affiliation: Department of Marine Sciences, Charles Darwin Research Station , Galapagos Islands , Ecuador ; University of British Columbia , Vancouver, British Columbia , Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Schuhbauer
authors.affiliation: Fisheries Ecology Research Lab, University of Hawai'i at Manoa , Honolulu, Hawai'i , USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Schemmel
authors.affiliation: Department of Marine Sciences, Charles Darwin Research Station , Galapagos Islands , Ecuador.
authors.forename: Pelayo
authors.initials: P
authors.lastname: Salinas de Léon
keywords: Age; Age and growth; Galapagos grouper; Growth; Life history; Management; Maturity