Trade-offs between size and energy reserves reflect alternative strategies for optimizing larval survival potential in rockfish

Abstract

Reproductive strategies balancing offspring size and offspring number have been well documented in empirical tests of life-history theory. Here we found an additional trade-off between offspring size and offspring condition. Among 5 species of live-bearing rockfishes (Sebastes spp.) from central Californian populations, we observed a negative relationship between larval length at parturition and the size of their oil globule (a triacylglycerol-rich energy reserve). When compared with a variety of performance variables (resistance to starvation, growth, startle-escape performance and routine activity levels), it appears that this trade-off leads to a conflict when trying to optimize survival potential, with differing benefits to each trait. A large oil globule greatly increases resistance to starvation, whereas larger body size is associated with numerous performance benefits likely to synergistically decrease predation-based mortality and increase success at capturing prey (increased startle speeds and distances, as well as more rapid onset of growth and larger size at age). The tradeoff between energy reserves and body size is further reflected in the seasonal patterns of parturition of the 5 species, with larvae having large oil globules and small body size being released in winter, when productivity in the California Current is low but transport is generally onshore, and those with small oil globule reserves and large body size released in late spring, when productivity is high but transport is generally offshore. These 2 apparent reproductive strategies also reflect subgeneric phylogenetic relationships, suggesting a potential lineage-specific basis for the contrast in larval traits. The results highlight the importance of measuring both physical and performance traits of larvae, as well as considering multiple attributes of both, when evaluating progeny quality.

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

“…In marine fishes, susceptibility to starvation, one of the major factors determining survival of offspring in larval phase (Bailey and Houde 1989), decreases with increasing larval body size. The larval survival period in the absence of food increases with increasing oil globule or yolk sac volume (Berkeley et al 2004;Fisher et al 2007;Higashitani et al 2007) and larger and older females produce larvae with larger oil globule or yolk sacs (Berkeley et al 2004;Higashitani et al 2007). Coconut crab larvae hatched from larger females would have a greater amount of energy in their yolk than larvae hatched from smaller ones and thus would have superior abilities to survive starvation in unpredictable, patchy and meager foraging conditions in the field and to recruit the resources successfully.…”

Offspring size and maternal environments mediate the early juvenile performance of two congeneric whelks

“…For a range of taxa across a variety of habitats, individuals that start juvenile life with a large size often perform better than smaller conspecifics. This pattern has been shown for gastropods (Spight 1976, Gosselin 1997, Moran & Emlet 2001, mussels (Phillips 2002), barnacles (Thiyagarajan et al 2003), ascidians (Marshall et al , 2006, beetles (Fox 2000, Clark et al 2011, isopods (Tsai & Dai 2001), spiders (Walker et al 2003), fish (Green & McCormick 2005, Fisher et al 2007, and birds (Krist 2011). Therefore, intraspecific variation in offspring size is of fundamental ecological and evolutionary importance (Marshall & Keough 2008).…”

Maternal influence on timing of parturition, fecundity, and larval quality in three shelf rockfishes (Sebastes spp.)

“…Although they are a shelf species, yellowtail rockfish migrate vertically to feed (Pereyra et al 1969, Pearcy 1992 and, in contrast to most Sebastes species, can purge their swim bladders quickly upon ascent (Love et al 2002), reducing barotrauma-related injuries. Adult females have successfully been held in the laboratory until parturition, allowing the assessment of larval quality, timing of parturition, and fecundity (Eldridge et al 2002, Fisher et al 2007, Sogard et al 2008. Results from laboratory studies of yellowtail rock fish are compared with predictions made from preparturition yellowtail rockfish embryos in this study.…”

“…Knowledge of species-specific reproductive phenologies and factors determining both the quality and quantity of offspring is integral to evaluating reproductive success. All nearshore Sebastes species researched to date have exhibited some significant effect of maternal size or age on reproductive traits (Berkeley et al 2004a, Bobko & Berkeley 2004, Fisher et al 2007, Sogard et al 2008, Rodgveller et al 2012). This study extends our understanding of maternal effects to deep-water rockfishes, examining the timing of parturition, fecundity, and larval quality.…”

“…1) comprised of triacylglycerol lipids (Norton & MacFarlane 1999). At parturition, larvae have absorbed their yolk, but a portion of their oil globule remains, sustaining the larvae after extrusion until they are able to locate prey and feed (Fisher et al 2007). In laboratory experiments, rockfish larvae from older, larger mothers had larger oil globules and exhibited increased resistance to starvation compared to larvae from younger, smaller mothers (Berkeley et al 2004a, Sogard et al 2008.…”