SURVIVAL FOR SPECIFIC LIFE INTERVALS OF SMALLMOUTH BASS, MICROPTERUS-DOLOMIEU, DURING PARENTAL CARE

We tested whether daily mortality rates (DMR) of smallmouth bass offsp ring were influenced by life interval, offspring density and growth, p arental male attributes, and selected mortality factors during parenta l care in a regulated Virginia stream. Mortality averaged 9.5% per day (range 5.2-13.9%) and 94.1% total (range 80.9-99.5%) from egg deposit ion to the juvenile period (29-36 d) for individual broods. Offspring losses were primarily attributed to fungus (Saprolegnia parasitica) in fection of eggs and to American eel, Anguilla rostrata, predation. DMR were significantly higher for the interval from swim-up of larvae to metamorphosis relative to earlier and later intervals. There was no si gnificant autocorrelation of DMR among life intervals for individual b roods, indicating that relative mortality rates were inconsistent amon g broods through time. DMR were also uncorrelated with the number of o ffspring per brood, offspring growth rates, and parental male attribut es, except during egg and embryo intervals. Daily egg mortality was ne gatively related to male size and positively related to the number of eggs per nest, suggesting that density-dependent egg mortality may hav e been partially offset in nests of larger males. Larger males receive d more eggs, tended to maintain larger broods throughout parental care , and contributed a high proportion of the total number of juveniles r eared.