Fishery Induces Sperm Depletion and Reduction in Male Reproductive Potential for Crab Species under Male-Biased Harvest Strategy

Pardo, Luis Miguel; Rosas, Yenifer; Fuentes, Juan Pablo; Riveros, Marcela; Chaparro, Óscar R.

doi:10.1371/journal.pone.0115525

Cited by 30 publications

(28 citation statements)

References 24 publications

(48 reference statements)

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“…edwardsii is the most important artisanal crab fishery in Chile; which makes it important to understand the current state of the species in order to understand the effect of the fishery on its future. This study was conducted in the most intense crab fishing area in the country [35] (Concepción, Los Molinos and Calbuco are low fishery intensity localities, while Ancud, Dalcahue and Quellón are high fishery intensity localities), so the conclusions made here are valid for future management plans. Our results indicate that the larvae produced in unexploited areas are naturally connected with exploited areas, aiding to avoid the reduction of stocks and irreversible loss of genetic diversity.…”

Section: Discussionmentioning

confidence: 99%

“…edwardsii and there was no evidence for a recent bottleneck, we explored the factors that would affect this pattern in a scenario of increased fishing. Currently, around five thousand tons of this species are harvested every year from southern Chile, affecting the population size [35]. Migration rates could be influenced by changes in both oceanographic circulation and upwelling processes [61].…”

Section: Methodsmentioning

confidence: 99%

“…In Chile, M . edwardsii represents around 70% of national crab landings in artisanal fisheries [34]; exploitation is concentrated mainly around Chiloe Island in southern Chile [35]. The pelagic larval development of this species lasts three months (at 14±0.5°C) with five zoea larval stages and one megalopa stage [36] that settle mainly between November and December [37].…”

Section: Introductionmentioning

confidence: 99%

“…While previous studies have described aspects of the species reproductive biology [39,40], larva identification [41] and the effects of the fisheries on the reproductive potential of males [35], this information must be related to population genetics studies in order to be integrated in measures of protection for exploited populations. Our study covered 700 km of coastline, considering different sites and individuals sampled over 4 different years, in order to describe the spatial and temporal genetic structure of M .…”

Section: Introductionmentioning

confidence: 99%

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Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

et al. 2016

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For marine invertebrates with a benthic adult form and a planktonic larva phase, the connectivity among populations is mainly based on larval dispersal. While an extended larval phase will promote gene flow, other factors such as an intensive fishery and geographical barriers could lead to changes in genetic variability. In this study, the population genetic structure of the commercial crab Metacarcinus edwardsii was analyzed along 700 km of the Chilean coast. The analysis, based on eight microsatellite loci genotyped from megalopae and adult crabs, considered temporal and spatial patterns of genetic variation. The results showed no evidence of spatial patterns in genetic structure, suggesting high connectivity among the sampling sites. The temporal analysis showed no evidence of changes in allele frequencies and no evidence of a recent bottleneck. The lack of spatial structure and allele variation over time could be explained by the interaction of factors such as i) low reproductive variance due to the capability of females to store sperm in the seminal receptacle, which can be used for successive broods, ii) high larval dispersal and iii) high individual reproductive output. Using our data as priors, a genetic modelling approach coincided, predicting this temporal and spatial stability. The same analysis showed that a reduction in population size leads to the loss of genetic variability in populations, as well as of the genetic cohesiveness between populations, pointing out the importance management for species under exploitation, such as M. edwardsii.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

et al. 2016

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“…In harvested crabs, like M. edwardsii, the low capacity of males to allocate their ejaculates prudently depending on future mating opportunities could explain why this species undergoes ejaculate depletion under a female-biased sex ratio triggered by intense fishery (Pardo et al 2015). Ejaculate depletion in males promotes sperm limitation in females, which has also been detected in this species in populations with high exploitation rates (Pardo et al 2017).…”

Section: Discussionmentioning

confidence: 78%

Ejaculate allocation in Brachyura: What do males of Metacarcinus edwardsii respond to?

Pardo¹,

Riveros²,

Chaparro³

et al. 2018

Aquat. Biol.

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In polygynous species, the sperm economy hypothesis predicts that males can adjust the amount of their ejaculate during copulation in response to (1) individual traits of females according to potential female fecundity, (2) future mating opportunities, and (3) risk of sperm competition. We tested this hypothesis in the crab Metacarcinus edwardsii by performing laboratory mating experiments to compare the response of males (sperm number and ejaculate weight delivered) in 3 sex-ratio scenarios: (1) equal, 1 female:1 male; (2) male-biased, 1 female:2 males; and (3) female-biased, 2 females:1 male. First, we determined if any variable, or an interaction between variables, could explain the variation in sperm or ejaculate amount delivered under an equal sex ratio. Second, we contrasted the ejaculate allocation among different sex-ratio scenarios. Under an equal sex ratio, males of M. edwardsii did not adjust their ejaculate allocation in response to any female trait. Male size was positively related to ejaculate delivery, indicating that the pair of vasa deferentia has ejaculate reserves that scale exponentially with male size. However, larger males delivered disproportionally more seminal fluid than sperm. Under a female-biased sex ratio, males did not show plasticity in their ejaculate allocation, but they increased their ejaculate investment (23%) per female under a male-biased sex ratio (i.e. risk of sperm competition). M. edwardsii presented a low level of ejaculate allocation, responding only when competitive males were perceived. In species with trans-molt sperm retention and long ejaculate storage, the risk of sperm competition is present all the time; therefore, males do not economize ejaculate even if more receptive females are available.

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Effects of size‐ and sex‐selective harvesting: An integral projection model approach

Stubberud

Vindenes

Vøllestad

et al. 2019

Ecology and Evolution

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Harvesting is often size‐selective, and in species with sexual size dimorphism, it may also be sex‐selective. A powerful approach to investigate potential consequences of size‐ and/or sex‐selective harvesting is to simulate it in a demographic population model. We developed a population‐based integral projection model for a size‐ and sex‐structured species, the commonly exploited pike (Esox lucius). The model allows reproductive success to be proportional to body size and potentially limited by both sexes. We ran all harvest simulations with both lower size limits and slot limits, and to quantify the effects of selective harvesting, we calculated sex ratios and the long‐term population growth rate (λ). In addition, we quantified to what degree purely size‐selective harvesting was sex‐selective, and determined when λ shifted from being female to male limited under size‐ and sex‐selective harvesting. We found that purely size‐selective harvest can be sex‐selective, and that it depends on the harvest limits and the size distributions of the sexes. For the size‐ and sex‐selective harvest simulations, λ increased with harvest intensity up to a threshold as females limited reproduction. Beyond this threshold, males became the limiting sex, and λ decreased as more males were harvested. The peak in λ, and the corresponding sex ratio in harvest, varied with both the selectivity and the intensity of the harvest simulation. Our model represents a useful extension of size‐structured population models as it includes both sexes, relaxes the assumption of female dominance, and accounts for size‐dependent fecundity. The consequences of selective harvesting presented here are especially relevant for size‐ and sex‐structured exploited species, such as commercial fisheries. Thus, our model provides a useful contribution toward the development of more sustainable harvesting regimes.

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Fishery Induces Sperm Depletion and Reduction in Male Reproductive Potential for Crab Species under Male-Biased Harvest Strategy

Cited by 30 publications

References 24 publications

Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

Ejaculate allocation in Brachyura: What do males of Metacarcinus edwardsii respond to?

Effects of size‐ and sex‐selective harvesting: An integral projection model approach

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