Monster Seminar Jam - Reproductive strategies in rockfishes: how mothers hedge their bets in the California Current
Dr. Susan Sogard, Ecology Branch, SWFSC
All Sebastes are primitively viviparous, allowing them to have high fecundity, but larvae are small (4-6 mm) and poorly developed at parturition. With some exceptions, individual females spawn only once per year, releasing all of their larvae on a single date. My research focuses on reproductive strategies and trade-offs within and across different species of rockfishes, and how those strategies are shaped by the vagaries of the California Current. Across species, there is an apparent trade-off between larval size, which influences swimming capabilities, and larval condition, which influences starvation resistance. This trade-off in larval performance is associated with the season of spawning and the expected oceanographic conditions encountered by larvae. Most rockfish species are long-lived, with an individuals reproductive effort spread across many years as a presumed bet-hedging strategy against long periods of poor larval survival. Within species, we have found that older mothers can be better mothers, producing larvae that survive and grow better than those from younger mothers. In addition, older mothers tend to release larvae earlier in the season. These maternal effects are not consistent across species, however, and are more evident in winter-spawning than spring/summer-spawning species. The enhanced contributions of older females to recruitment success have led to compelling arguments for maintaining age diversity in rockfish populations, and indicate that spawning stock biomass alone is an insufficient metric of a populations reproductive potential.
Date and Time:
January 17, 2008,
11:00 am - 12:30 pm