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Fishery induces sperm depletion and reduction in male reproductive potential for crab species under male-biased harvest strategy.

Pardo LM, Rosas Y, Fuentes JP, Riveros MP, Chaparro OR - PLoS ONE (2015)

Bottom Line: A manipulative experiment was performed in the laboratory to estimate vasa deferentia weight and VSI from just-mated males in order to obtain a reference point for the potential effects of the fishery on sperm reserves.Sperm storage capacity is significantly affected by fisheries; during the mating season vasa deferentia from localities with low fishery intensity were heavier than those from high intensity fisheries, and these differences were even more evident in large males.Males from localities with high fishery intensity showed little capacity to recover sperm reserves and the VSI of these males remained below the values of the just-mated males.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.

ABSTRACT
Sperm depletion in males can occur when polygynous species are intensively exploited under a male-biased management strategy. In fisheries involving crabs species, the effects of this type of management on the reproductive potential is far from being understood. This study tests whether male-biased management of the principal Chilean crab fishery is able to affect the potential capacity of Metacarcinus edwardsii males to transfer sperm to females. Five localities in southern Chile, recording contrasting crab fishery landing, were selected to assess the potential of sperm depletion triggered by fishery. Seasonally, male crabs from each locality were obtained. Dry weight and histological condition of vasa deferentia and the Vaso-Somatic Index (VSI) were determined in order to use them as proxies for sperm depletion and male reproductive condition. A manipulative experiment was performed in the laboratory to estimate vasa deferentia weight and VSI from just-mated males in order to obtain a reference point for the potential effects of the fishery on sperm reserves. Sperm storage capacity is significantly affected by fisheries; during the mating season vasa deferentia from localities with low fishery intensity were heavier than those from high intensity fisheries, and these differences were even more evident in large males. Histological section showed that this disparity in vasa deferentia weight was explained principally by differences in the quantity of spermatophores rather than other seminal material. VSI was always higher in males from localities with low fishery intensity. Males from localities with high fishery intensity showed little capacity to recover sperm reserves and the VSI of these males remained below the values of the just-mated males. Detriment in the capacity of males to transfer sperm is the first step to sperm limitation in an exploited population, thus detection of sperm depletion can be an alert to introduce changes in the current management of crabs.

No MeSH data available.


Related in: MedlinePlus

Seasonal mean Vaso-Somatic Index (VSI) and standard errors for Metacarcinus edwardsii males from localities with contrasting fishery intensity.Lines indicate mean (continuous) and confidence limit (95%, dashed) of VSI from just-mated laboratory males. Los Molinos and Calbuco are categorized as low fishery intensity and Ancud, Dalcahue and Quellon are categorized as high fishery intensity.
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pone.0115525.g006: Seasonal mean Vaso-Somatic Index (VSI) and standard errors for Metacarcinus edwardsii males from localities with contrasting fishery intensity.Lines indicate mean (continuous) and confidence limit (95%, dashed) of VSI from just-mated laboratory males. Los Molinos and Calbuco are categorized as low fishery intensity and Ancud, Dalcahue and Quellon are categorized as high fishery intensity.

Mentions: The VSI showed significant differences among localities, regardless of the season analyzed. In all cases, the two low fishery intensity localities had higher values of VSI in comparison to high fishery intensity localities (Fig. 6). Within localities of the same category differences were not found, except between Ancud and Quellon in fall and Los Molinos and Calbuco in spring (Table 1). In general, the VSI of males from high intensity fishing localities was 49% lower than those from low intensity fishing localities. The values were poorly dependent on male CW (Regression, F1,551 = 55.1, p = 0.001, r = 0.301). The VSI of males from experimental matings exhibited a range of 0.023 to 0.146, with a mean of 0.055 (Confidence Interval95% = 0.049–0.061, n = 53) (Fig. 6).


Fishery induces sperm depletion and reduction in male reproductive potential for crab species under male-biased harvest strategy.

Pardo LM, Rosas Y, Fuentes JP, Riveros MP, Chaparro OR - PLoS ONE (2015)

Seasonal mean Vaso-Somatic Index (VSI) and standard errors for Metacarcinus edwardsii males from localities with contrasting fishery intensity.Lines indicate mean (continuous) and confidence limit (95%, dashed) of VSI from just-mated laboratory males. Los Molinos and Calbuco are categorized as low fishery intensity and Ancud, Dalcahue and Quellon are categorized as high fishery intensity.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359117&req=5

pone.0115525.g006: Seasonal mean Vaso-Somatic Index (VSI) and standard errors for Metacarcinus edwardsii males from localities with contrasting fishery intensity.Lines indicate mean (continuous) and confidence limit (95%, dashed) of VSI from just-mated laboratory males. Los Molinos and Calbuco are categorized as low fishery intensity and Ancud, Dalcahue and Quellon are categorized as high fishery intensity.
Mentions: The VSI showed significant differences among localities, regardless of the season analyzed. In all cases, the two low fishery intensity localities had higher values of VSI in comparison to high fishery intensity localities (Fig. 6). Within localities of the same category differences were not found, except between Ancud and Quellon in fall and Los Molinos and Calbuco in spring (Table 1). In general, the VSI of males from high intensity fishing localities was 49% lower than those from low intensity fishing localities. The values were poorly dependent on male CW (Regression, F1,551 = 55.1, p = 0.001, r = 0.301). The VSI of males from experimental matings exhibited a range of 0.023 to 0.146, with a mean of 0.055 (Confidence Interval95% = 0.049–0.061, n = 53) (Fig. 6).

Bottom Line: A manipulative experiment was performed in the laboratory to estimate vasa deferentia weight and VSI from just-mated males in order to obtain a reference point for the potential effects of the fishery on sperm reserves.Sperm storage capacity is significantly affected by fisheries; during the mating season vasa deferentia from localities with low fishery intensity were heavier than those from high intensity fisheries, and these differences were even more evident in large males.Males from localities with high fishery intensity showed little capacity to recover sperm reserves and the VSI of these males remained below the values of the just-mated males.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.

ABSTRACT
Sperm depletion in males can occur when polygynous species are intensively exploited under a male-biased management strategy. In fisheries involving crabs species, the effects of this type of management on the reproductive potential is far from being understood. This study tests whether male-biased management of the principal Chilean crab fishery is able to affect the potential capacity of Metacarcinus edwardsii males to transfer sperm to females. Five localities in southern Chile, recording contrasting crab fishery landing, were selected to assess the potential of sperm depletion triggered by fishery. Seasonally, male crabs from each locality were obtained. Dry weight and histological condition of vasa deferentia and the Vaso-Somatic Index (VSI) were determined in order to use them as proxies for sperm depletion and male reproductive condition. A manipulative experiment was performed in the laboratory to estimate vasa deferentia weight and VSI from just-mated males in order to obtain a reference point for the potential effects of the fishery on sperm reserves. Sperm storage capacity is significantly affected by fisheries; during the mating season vasa deferentia from localities with low fishery intensity were heavier than those from high intensity fisheries, and these differences were even more evident in large males. Histological section showed that this disparity in vasa deferentia weight was explained principally by differences in the quantity of spermatophores rather than other seminal material. VSI was always higher in males from localities with low fishery intensity. Males from localities with high fishery intensity showed little capacity to recover sperm reserves and the VSI of these males remained below the values of the just-mated males. Detriment in the capacity of males to transfer sperm is the first step to sperm limitation in an exploited population, thus detection of sperm depletion can be an alert to introduce changes in the current management of crabs.

No MeSH data available.


Related in: MedlinePlus