Sperm limitation: possible impacts of large male-selective harvesting on reproduction of the coconut crab Birgus latro

Sato, Taku; Yoseda, Kenzo; Okuzawa, Koichi; Suzuki, Nobuaki

doi:10.3354/ab00263

Cited by 28 publications

(7 citation statements)

References 40 publications

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“…This is the case in most crab fisheries, which typically select for large, dominant males. This selective pressure leads to changes in sex ratios in favor of females [ 1 ] and possibly sperm limitation [ 2 – 4 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…There are no obvious answers or references to solve this question since P. trituberculatus fishing in China is non-selective, which differs from other exploited decapod fisheries such as Chionoecetes opilio (SainteMarie et al 2002), Callinectes sapidus (Kendall et al 2001, Carver et al 2005, Pseudocarcinus gigas (Gardner & Williams 2002), Paralithodes brevipes (Sato et al 2007) and Birgus latro (Sato et al 2010), which are generally male-only and/or size-limited. However, since the 1990s, the spawning stock of P. trituberculatus has been under continual, intensive over-fishing (Yu et al 2003(Yu et al , 2004, and individual crab size and body weight have declined noticeably (Song et al1988, Zhen et al 2003.…”

Section: Discussionmentioning

confidence: 99%

“…In species with direct sperm transfer, sperm limitation may arise naturally from spatial or temporal variability in the population demographic structure (Pitnick 1993), while anthropogenic effects caused by selective harvesting may aggravate any underlying natural causes. For example, an increasing number of studies report the existence or possibility of various degrees of sperm limitation under sex-(male only) and/or size-selective (size limit) management for several exploited decapod crustacean species, including Chionoecetes opilio (Sainte-Marie & Lovrich 1994, Sainte-Marie et al 2002, Cancer magister (Hankin et al 1997), Callinectes sapidus (Kendall et al 2001, Hines et al 2003, Carver et al 2005, Pseudocarcinus gigas (Gardner & Williams 2002), Paralithodes brevipes (Sato et al , 2007 and Birgus latro (Sato et al 2010). Such cases of selective fishing can change the population structure by reducing the average size and density of males, as well as reducing the operational sex ratio (OSR) of males to females (Hines et al 2003, Carver et al 2005.…”

Section: Introductionmentioning

confidence: 99%

Current fishing practices may induce low risk of sperm limitation in female swimming crab Portunus trituberculatus in the East China Sea

Xuan¹,

Guan²,

Chengman³

et al. 2014

Aquat. Biol.

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Potential sperm limitation of the swimming crab Portunus trituberculatus was examined during the reproductive season from September 2006 to April 2007 in the East China Sea. We documented developmental variations between the spermatheca and ovary and distinguished these into 5 stages. We counted the number of stored sperm in paired spermathecae and found that more than 50% of sperm initially received during mating disappeared as the sperm plug degenerated; around 1.70 × 10 8 were used for final fertilization, and there was significant correlation between the final number of stored sperm and female carapace width. Lastly, using knowledge of the reproductive characteristics of P. trituberculatus, we calculated potential sperm:egg ratios of 221:1 or 153:1 for the first brood, and 55:1 or 38:1 for lifetime broods -either from the perspective of a fishery resource assessment or from the perspective of seed production. From comparison to sperm:egg ratios of Callinectes sapidus (for lifetime broods this ranges from 10:1 to 42:1), we can infer that female P. trituberculatus in the East China Sea may be at low risk of sperm limitation under current fishing practices. This may be the result of greater fishing mortality of females, causing an increase in the operational sex ratio. The present study improves our knowledge of sperm limitation in brachyurans as fishing management in China is non-selective, which differs from other exploited decapod crustacean species around the world. KEY WORDS: Portunus trituberculatus · Sperm limitation · Non-selective fishing · East China SeaResale or republication not permitted without written consent of the publisher Aquat Biol 20: 145-153, 2014 (OSR) of males to females (Hines et al. 2003, Carver et al. 2005. Therefore, sperm limitation can contribute to the structure of mating systems (Wedell et al. 2002), and knowledge of the process of sperm limitation may be beneficial to conservation and management efforts (Conover & Munch 2002, Sainte-Marie et al. 2002.A critical step in estimating the risk of sperm limitation in brachyurans is to determine whether the final quantities of sperm stored in female spermathecae are 'sufficient' to meet the possible minimum ratio of spermatozoon to oocyte for fertilization, to ensure reproductive success. However, there are relatively few reports concerning these important reproductive parameters. In Chionoecetes species, ratios for high fertilization success are reported to range from 'several' sperm per egg (Adams & Paul 1983) to actual expenditure of an estimated 70 stored sperm per egg for the first clutch extruded (SainteMarie & Lovrich 1994); females failed to extrude any eggs when the sperm:egg ratio was below 7:1 (SainteMarie & Lovrich 1994). In comparison, sperm:egg ratios in C. sapidus were estimated at 100:1 to 400:1 for the first brood, and only 20:1 to 30:1 for maximum lifetime broods over the 2 possible reproductive seasons, suggesting that approximately 67 × 10 6 sperm are used per brood of 3 × 10 6 eggs (Hines et al. 2003)....

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“…Kepiting kelapa memiliki rasa daging yang enak sehingga digemari masyarakat. Populasinya juga mengalami penurunan dan terancam punah (Amesbury 1980;Kessler 2006;Sato & Yoseda 2010;Buden 2012).…”

Section: Pendahuluanunclassified

Spatial and Temporal Distributions of Coconut Crab (Birgus latro Linn 1767) in Daeo Morotai Distric, North Maluku

Serosero

Sulistiono

Butet

et al. 2018

JIPI

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Penelitian ini bertujuan untuk menggambarkan distribusi ukuran kepiting kelapa secara spasial dan temporal di Daeo, Pulau Morotai, Maluku Utara. Penangkapan dilakukan pada tiga stasiun, yaitu di daerah yang berdekatan dengan permukiman penduduk (stasiun 1), di daerah terjal dengan vegetasi yang bervariasi (stasiun 2), dan di daerah dangkal yang terdiri atas berbagai vegetasi dan pohon kelapa (stasiun 3). Pengumpulan sampel dilakukan dengan menggunakan umpan kelapa dan penangkapan secara langsung dengan menggunakan tangan. Kepiting kelapa hasil tangkapan diukur panjang cephalotorax tambah rostrum (CP+r) dan panjang dada (PD) serta ditimbang bobotnya. Selain itu, dilakukan juga pengukuran tekstur substrat dan pengamatan vegetasi alaminya. Data perbedaan hasil tangkapan (spasial) dianalisis dengan uji non-parametrik Mann-Whitney (α0,05), sedangkan secara temporal dengan uji Kruskal Wallis (α0,05). Hasil penelitian menemukan 581 individu kepiting kelapa (314 jantan dan 267 betina). Kisaran ukuran bobot berkisar 50990 dan 50520 g. Kisaran ukuran Cp+r pada kepiting kelapa jantan dan betina secara berturut-turut adalah 4,98114,72 mm dan 43,9890,67 mm. Kisaran PD pada kepiting kelapa jantan dan betina secara berturut-turut adalah 19,5654,86 mm dan 19,5648,65 mm. Uji non-parametrik Mann-Whitney secara spasial menunjukkan bahwa hasil tangkapan di stasiun 1 dari hasil tangkapan di stasiun 2 dan 3 (P<0,05), namun tidak berbeda secara temporal (P>0,05). Nilai kualitas lingkungan secara spasial tidak berbeda (P>0,05) dan secara temporal berbeda nyata (P<0,05) kecuali pH. Stasiun 3 memiliki vegetasi yang lebih padat dibandingkan dengan stasiun 1 dan 2. Kata kunci: distribusi spasial temporal, kepiting kelapa, Maluku Utara, Morotai

show abstract

Sperm limitation: possible impacts of large male-selective harvesting on reproduction of the coconut crab Birgus latro

Cited by 28 publications

References 40 publications

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

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

Current fishing practices may induce low risk of sperm limitation in female swimming crab Portunus trituberculatus in the East China Sea

Spatial and Temporal Distributions of Coconut Crab (Birgus latro Linn 1767) in Daeo Morotai Distric, North Maluku

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