Lifetime reproductive potential of female blue crabs Callinectes sapidus in North Carolina, USA

Abstract

We examined lifetime clutch production and size at maturity for blue crabs Callinectes sapidus Rathbun in North Carolina, USA. Female crabs were collected at terminal molt and confined individually in the field for the duration of their lifetime. Crabs were monitored weekly for the presence of eggs. Clutch quality and larval viability were assessed for each clutch. Crabs produced up to 7 clutches over 1 to 2 spawning seasons and survived up to 394 d after the terminal molt. Time to first clutch and time between clutches were positively correlated with carapace width and best described by degree-days, physiological time calculated as a thermal integral. Size at maturity was negatively correlated with water temperature on the day of the terminal molt. Egg lipid content (mean = 79.2% of dry mass), egg diameter (mean = 267.5 µm), larval carapace width (mean = 278.4 µm), and larval survival time without food (mean = 3.4 d) were similar for all clutches. The percentage of embryos developing normally decreased 40% from Clutch 1 to 4, and clutch volume decreased 50% from Clutch 1 to 5. Thus, most of a crab's reproductive output is from the first few clutches. Realistic estimates of fecundity and reproductive potential are essential for accurate spawning stock assessment and population modeling. KEY WORDS: Blue crab · Callinectes sapidus · Reproductive potential · Spawning biology · Fecundity · Multiple clutches · Degree-days Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 394: [153][154][155][156][157][158][159][160][161][162][163] 2009 serves to reduce the risk of predation and sperm competition (Jivoff 1997). Thus, the duration of the postcopulatory embrace depends on the presence of conspecific predators, sex ratio, and male size and density (Jivoff 1997). Approximately 12% of females mate with at least a second male (Jivoff 1997). Females mate only following the terminal molt (Van Engel 1958); thus, all clutches produced by a female must be fertilized by stored sperm. Sufficient sperm is stored to fertilize up to a dozen clutches of eggs . Wolcott et al. (2005) found that the number and viability of sperm transferred during mating are independent of male and female body size. Female crabs then forage, develop mature ovaries, extrude a first clutch, and undertake a seaward spawning migration (Van Engel 1958, Tankersley et al. 1998, Turner et al. 2003, Forward et al. 2005) using both ebb-tide transport and directed walking during flood tides (Forward et al. 2003. Spawning females produce multiple clutches, and migratory behavior continues between clutches, ensuring that spawning females are continually moving seaward throughout the spawning season , Forward et al. 2005.Studies of crab and lobster reproductive potential have traditionally examined fecundity for only a single clutch (e.g. Pillay & Nair 1971, Hines 1982, Campbell & Robinson 1983, Jones & Simons 1983, Dugan et al. 1994, Medina Mantelatto & Fransozo 1997, presumably due to the difficulty of obser...

Impacts of Large Male-Selective Harvesting on Reproduction: Illustration with Large Decapod Crustacean Resources

“…Also in species in which females show determinate growth and terminal molt, females can use the sperm in their spermatheca over their reproductive lifespan and produce multiple clutches (e.g. blue crab, Darnell et al 2009;snow crab, Kon and Adachi 2005). Sperm storage would give females the opportunity to accumulate sperm from several males, and sperm storage across spawning seasons potentially releases females from the obligation to mate.…”

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

“…In the East China Sea, the final number of stored sperm in Portunus trituberculatus females is approximately 1.70 × 10 8 , which is far less than observed with Callinectes sapidus (belonging to the Portunidae), which receives about 9.3 × 10 8 sperm, even after mating with a recently-mated male (Kendall et al 2002). However, considering the almost 50% sperm attrition prior to ovulation , the fact that most of a crab's reproductive output is from the first few broods, and that the percentage of embryos developing normally and brood volume are de creased with successive broods (Darnell et al 2009), the sperm:egg ratio of C. sapidus would be estimated to be 50:1 to 200:1 for the first brood. That estimate would be even less than 10:1 to 42:1 for the last few broods due to its ability to produce multiple broods over 2 reproductive seasons (6 to 18 broods; Hines et al 2003).…”

Evolution of maternal effect senescence

“…Similar studies of age-specific maternal IGEs are lacking from the literature. However, as discussed above, there is good evidence to suggest maternal effects and IGEs are widespread and important in nature (29)(30)(31) and that maternal age is a powerful predictor of a range of offspring traits (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Given that age-specific maternal effects have been detected and estimated in a wild mammal system (59), the estimation of age-specific IGEs in other experimental and observational studies should be feasible.…”

“…Amid the many studies of senescing traits, a clear pattern is emerging that relates maternal age to the health, fitness, and lifespan of their progeny across widely diverse taxa including humans (8), birds (9, 10), mammals (11,12), Drosophila species (13)(14)(15) and other arthropods (16)(17)(18), and plants (19). Although observations suggest that maternal effect senescence may not proceed at the same rate as fertility senescence (12,(20)(21)(22)(23)(24), there is no evolutionary theory yet capable of explaining maternal effect senescence or its distinction from fertility senescence.…”