We analyzed four decades of presence–absence data from a fishery-independent survey to characterize the long-term phenology of river herring (alewife, Alosa pseudoharengus; and blueback herring, Alosa aestivalis) spawning migrations in their southern distribution. We used logistic generalized additive models to characterize the average ingress, peak, and egress timing of spawning. In the 2010s, alewife arrived to spawning habitat 16 days earlier and egressed 27 days earlier (peak 12 days earlier) relative to the 1970s. Blueback herring arrived 5 days earlier and egressed 23 days earlier (peak 13 days earlier) in the 2010s relative to the 1980s. The changes in ingress and egress timing have shortened the occurrence in spawning systems by 11 days for alewife over four decades and 18 days for blueback herring over three decades. We found that the rate of vernal warming was faster during 2001–2016 relative to 1973–1988 and is the most parsimonious explanation for changes in spawning phenology. The influence of a shortened spawning season on river herring population dynamics warrants further investigation.

No abstract

Phenotypic flexibility is critical in determining fitness. As conditions change during ontogeny, continued responsiveness is necessary to meet the demands of the environment. Studies have shown that subsequent ontogenetic periods of development can interact with one another and shape developmental outcomes. The role genetic variation within populations plays in shaping these outcomes remains unclear. Four full-sib families of zebrafish Danio rerio were raised under for dietary regimes: high food rations for 60 days (HH), low food rations for 60 days (LL), high food rations for 30 days followed by low food rations for 30 (HL), and low food rations for 30 days followed by high food rations for 30 (LH). While the low ration diet significantly reduced body length at 30 days, diet was no longer a significant factor at day 60. Only family level variation influenced body length. Furthermore, there was significant family level variation in the manner in which swimming performance responded to fluctuating dietary conditions. Some families increased swimming performance in response to dietary change, while others did not. These results suggest that plastic responsiveness to subsequent environmental changes can be trait specific and vary significantly within populations.

We estimated rates of survival as well as effects of habitat on catch rates of juvenile yellow‐phase American Eels Anguilla rostrata in southeastern U.S. tidal creeks. We trapped and marked eels with PIT tags at 24 fixed sites in eight North Carolina tidal creeks and then recaptured and resighted the tagged individuals to estimate apparent survival. Separate Cormack–Jolly–Seber (CJS) models were fitted to mark–recapture data (eight creeks) versus mark–resight data (four creeks) to estimate apparent survival. Median annual apparent survival (Φ) was higher when the CJS model was fitted to mark–resight data (Φ = 0.15) than to mark–recapture data (Φ = 0.013). Negative binomially distributed models were fitted to catch rates of both tagged and untagged eels to test for habitat, development, and seasonal effects. The presence/absence of culverts and season were meaningful covariates of catch rates; greater catches were found at sites possessing culverts and during the spring. Other habitat and development factors at the site, creek, and watershed levels were not important covariates of catch rates. Partitioning the sources of loss of yellow‐phase American Eels from these systems into mortality versus emigration would be useful future research in the southeastern U.S. coastal region. Further study into how culverts affect yellow‐phase American Eel habitation and movement in southeastern U.S. estuaries is also warranted.