Lipid Dynamics in Relation to the Annual Reproductive Cycle in Yellowtail Rockfish (Sebastes flavidus)

Abstract

In yellowtail rockfish (Sebastes fiavidus), lipids that accumulated in mesenteries and liver during the summer and early fall upwelling were subsequently translocated to developing ovaries during late fall and winter. Tissue and serum lipids were assessed by stage of ovary maturation from fish collected monthly over six annual reproductive cycles (1985–91) from Cordell Bank, a seamount off central California. Lipids were primarily transported to ovaries prior to fertilization. Energetic lipids (triglycerides, nonesterified fatty acids) were maximal in serum during yolk accumulation stages and declined significantly during embryonic stages. Between fertilization and parturition, lipid and protein content of ovaries declined by about 21%, a value approaching the minimum for lecithotrophy (i.e. ovoviviparity). During gestation, however, serum phospholipids and calcium (vitellogenin surrogate) were significantly elevated relative to male levels, suggesting matrotrophic contributions. A reproductive mode that is primarily lecithotrophic but supplemented by maternal inputs during embryogenesis would be beneficial to viviparous fishes of the California coast. This strategy may optimize reproduction by coupling the disparate times of food abundance and gestation, yet allow for provision of nutrients late in the reproductive cycle should they be available.

Metabolic costs of viviparity in yellowtail rockfish,Sebastes flavidus

“…In this study, respirometrically measured embryos and larvae of S. flavidus required only 3.4% of their energy from exogenous sources versus 12 to 92% in three other Sebastes species. Our observations confirm findings of MacFarlane et al (1993) who concluded from studies of protein and lipids in tissues of adult yel- Table 2. Comparison of energy requirements per embryo, change in caloric content and weight change data (dry weight for S. caurinus, ash free dry weight for all others) per embryo during gestation in four species of Sebasfes where matrotrophic contribution (energy requirement from external sources) has been estimated.…”

Reproductive biology of ningu, Labeo victorianus (Pisces : Cyprinidae), in the Kagera and Sio Rivers, Uganda

“…Similar findings are reported in O. mykiss where the liver plays a small role in lipid storage (Nassour & Le´ger 1989). MacFarlane et al (1993) investigated the role of accumulated lipids in the mesentery of the yellowtail rockfish, Sebastes flavidus, and showed that a greater proportion was incorporated in the developing ovaries. The sharp decline in the mesenteric fat index in L. victorianus during spawning periods suggests that the mesenteric fat deposits are the major source of energy for reproduction.…”

“…The sharp decline in the mesenteric fat index in L. victorianus during spawning periods suggests that the mesenteric fat deposits are the major source of energy for reproduction. Accumulation of mesenteric fat as reported in some fishes (MacFarlane et al 1993, Okuda 2001) is important since lipids are known to play a number of roles such as formation of vitellogenin, insulation of organs, buoyancy and several other physiological functions (Weigand 1996). Reproduction in the Kagera River population conformed to the 'normal' labeine reproductive pattern -synchronisation of spawning with the raining season.…”

Physical characteristics, and proximate composition of oocytes, liver and muscle of wild caught and tank-reared Macquarie perch

“…The liver is the main storage organ, and as maturation takes place a significant proportion of the nutrition needed by the oocytes is supplied by the liver. Consequently, as maturation is completed one would expect the liver reserves to be depleted and hence the HSI to be lower (Eliassen and Vahl, 1982;MacFarlane et al, 1993). The I-N in tank-raised Macquarie perch was considerably higher than in wild fish suggesting that nourishment provided by the liver to the oocytes in the former group was inadequate.…”