First record of a spawning aggregation for the tropical eastern Pacific endemic grouper <i>Mycteroperca olfax</i> in the Galapagos Marine Reserve

Salinas‐de‐León, Pelayo; Rastoin, Etienne; Acuña-Marrero, David

doi:10.1111/jfb.12703

Cited by 19 publications

(17 citation statements)

References 28 publications

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“…Fishery effects on bacalao quite likely also include impacts on the adult sex ratio and size-at-sex change. The highly skewed sex ratio we observed (0.015 M:F) is consistent with those previously reported (0.021: Coello & Grimm, 1993 ; 0.017: Reck, 1983 ), suggesting that the adult sex ratio had likely been altered by fishing down of the larger bacalao prior to the 1980s, especially by targeting spawning aggregations ( Salinas-de-León, Rastoin & Acuña-Marrero, 2015 ). Although there has not been a decline in catch rates in the bacalao fishery over time ( Nicolaides et al, 2002 ), this might represent expansion of the fishery to new unfished areas.…”

Section: Discussionsupporting

confidence: 91%

“…While logistical constraints restricted our sampling to the period of October–February, the GSI attained the highest values in the month of December. Additionally, the first recorded evidence of a spawning aggregation for bacalao was in the month of November ( Salinas-de-León, Rastoin & Acuña-Marrero, 2015 ). Although there is not clear consensus on reproductive periodicity, sufficient information exists to establish a closed season from October to April, which would protect bacalao during much of the spawning season.…”

Section: Discussionmentioning

confidence: 99%

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Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouperMycteroperca olfax(Jenyns, 1840)

Usseglio

Friedlander

DeMartini

et al. 2015

PeerJ

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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.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouperMycteroperca olfax(Jenyns, 1840)

Usseglio

Friedlander

DeMartini

et al. 2015

PeerJ

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“…Nicolaides (2002) [13] did not find differences in the abundance of bacalao among the 13 main islands in the archipelago. A recent discovery of a bacalao spawning aggregation in the northern islands revealed a mean observed TL of 71 cm at the aggregation site [61]. While differentiation of landings from different zones goes beyond the scope of this paper, it is acknowledged that landings from the northern islands may bias the results from the most recent datasets as individuals there might be larger.…”

Section: Discussionmentioning

confidence: 95%

“…This suggests a need to incorporate biological information such as juvenile nursery habitats, spawning aggregation sites, and essential fish habitat for adults in the design of no-take zones specific for bacalao. Positive work has already started with the recent declaration of a no-take area around the northern islands of Darwin and Wolf, which has potential to enhance fisheries given the fact that there is as least one known spawning aggregation for bacalao within the new MPA [61]…”

Section: Discussionmentioning

confidence: 99%

So Long and Thanks for All the Fish: Overexploitation of the Regionally Endemic Galapagos Grouper Mycteroperca olfax (Jenyns, 1840)

et al. 2016

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The regionally endemic Galapagos Grouper, locally known as bacalao, is one of the most highly prized finfish species within the Galapagos Marine Reserve (GMR). Concerns of overfishing, coupled with a lack of fishing regulations aimed at this species raises concerns about the current population health. We assessed changes in population health over a 30-year period using three simple indicators: (1) percentage of fish below reproductive size (Lm); (2) percentage of fish within the optimum length interval (Lopt); and (3) percentage of mega-spawners in the catch. Over the assessed period, none of the indicators reached values associated with healthy populations, with all indicators declining over time. Furthermore, the most recent landings data show that the vast majority of the bacalao caught (95.7%,) were below Lm, the number of fish within the Lopt interval was extremely low (4.7%), and there were virtually no mega-spawners (0.2%). Bacalao fully recruit to the fishery 15 cm below the size at which 50% of the population matures. The Spawning Potential Ratio is currently 5% of potential unfished fecundity, strongly suggesting severe overfishing. Our results suggest the need for bacalao-specific management regulations that should include minimum (65 cm TL) and maximum (78 cm TL) landing sizes, slot limits (64–78 cm TL), as well as a closed season during spawning from October to January. It is recognized that these regulations are harsh and will certainly have negative impacts on the livelihoods of fishers in the short term, however, continued inaction will likely result in a collapse of this economically and culturally valuable species. Alternative sources of income should be developed in parallel with the establishment of fishing regulations to limit the socio-economic disruption to the fishing community during the transition to a more sustainable management regime.

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“…including the direct targeting of spawning aggregations, over the last century (Reck, 1983;Coello & Grimm, 1993;Salinas-de-León, Rastoin & Acuña-Marrero, 2015;Usseglio et al, 2015Usseglio et al, , 2016.…”

Section: Discussionmentioning

confidence: 99%

Effects of the 2016 El Niño on the Galapagos artisanal coastal fin-fish fishery

Jarrín

Salinas‐de‐León

2018

Preprint

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El Niño events heavily influence physical characteristics in the Tropical Eastern Pacific and lead to a decrease in nutrient and phytoplankton concentrations and to variation in the composition of the marine trophic chain. However, El Niño events can also provide an opportunity to evaluate the possible effects climate change may have on marine ecosystems. The Galapagos Marine Reserve coastal fin-fish fishery supports approximately 400 fishers that target species that include benthic/demersal predatory fish such as the endemic Galapagos whitespotted sandbass (Paralabrax albomaculatus), the regional endemic sailfin grouper (Mycteroperca olfax) and mottled scorpion fish (Pontinus clemensi), and the misty grouper (Hyporthodon mystacinus). The first two species are listed as vulnerable and endangered, respectively, on the IUCN red list of threatened species. Despite their potential effects on the biota, at present it is unclear how El Niño events influence artisanal fin-fish fisheries in the Galapagos. To study the impacts of El Niño events on the fishery, numerical percentage catch composition at the largest dock in Santa Cruz Island was recorded during March and April 2013, 2014 and 2016 and compared. Compositions were significantly different between 2016 and both 2013 and 2014, but not between 2013 and 2014. These differences appear to have been due to the appearance of uncommon demersal/benthic predatory fish such as Grape eye seabass (Hemilutjanus macrophthalmos) and Pacific dog snapper (Lutjanus novemfasciatus). Size frequency distributions also varied, with significantly larger sizes of several species observed in 2016 when compared to 2013 or 2014. These changes in catch composition and size may be a product of a reduction in nutrient concentration and primary production that led to an increase in water clarity and decrease in prey biomass that forced these benthic fish species to change their feeding behavior and strike at baits that usually would not be easily detected. Because of the conservative life history many of these benthic predatory fish exhibit and the absence of any form of management for fish species in the GMR, El Niño events may have profound effects on their populations due to the elimination of the largest individuals. Management actions, such as size and catch limits and closures, directed at reducing the impact of the fishery on these important fish populations in the near- (El Niños) and long-term (climate change) future should be encouraged.

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First record of a spawning aggregation for the tropical eastern Pacific endemic grouper Mycteroperca olfax in the Galapagos Marine Reserve

Cited by 19 publications

References 28 publications

Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouperMycteroperca olfax(Jenyns, 1840)

Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouperMycteroperca olfax(Jenyns, 1840)

So Long and Thanks for All the Fish: Overexploitation of the Regionally Endemic Galapagos Grouper Mycteroperca olfax (Jenyns, 1840)

Effects of the 2016 El Niño on the Galapagos artisanal coastal fin-fish fishery

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