Search Results (3)

Walleye Sander vitreus is a valued sportfish in eastern North America, including the upper New River of Virginia, where individuals can grow to a large size (>7 kg). After construction of dams, especially Claytor Dam in 1939, the population declined and non-native walleye were stocked. Stocking of non-native walleye was stopped in 1997, and molecular marker data showed that the presumptive native population had persisted. To restore the native stock, selection of broodstock candidates bearing native marker alleles and hatchery-based augmentation have been practiced over a 20-year period. We evaluated the success of the marker-assisted selection and hatchery-based augmentation program. Marker-assisted selection of native New River walleye began with mean frequencies of marker alleles at microsatellite loci Svi17 and Svi33 of ~30%, and continuing selection has driven marker allele frequencies to ~65–70%. Numbers of walleye collected in fall gillnet and spring electrofishing surveys were responsive to augmentations with hatchery fish 2–3 years earlier. Stocking was not practiced in 2012–2013, and a decrease in walleye catch rates was noted in 2016, suggesting that the native New River walleye population still depends upon hatchery-based augmentation. We recommend the development of a small panel of single nucleotide polymorphism markers for more rigorous selection of broodstock representative of the native walleye population. Full article

Coastal habitats are declining worldwide, which has impacted economically important fisheries, especially in the Indian River Lagoon, Florida. As a result, extensive intertidal oyster reef and living shoreline restoration projects have been implemented. Restoration can also theoretically benefit predator populations, but this relationship is understudied. Here, the impact of habitat restoration on juvenile predatory fish (i.e., sportfish) populations (abundance) and communities (species richness, diversity, and assemblage) was assessed prior to and following oyster reef restoration and living shoreline stabilization for up to three years, and incorporated the influence of 17 environmental predictor variables. Juvenile sportfish abundance and richness (n = 11) were variable over time but collectively higher on restored oyster reefs compared to controls, and similar between control and stabilized shorelines. Sportfish abundance was best described by a combination of biotic features of the site (e.g., reef height and benthic substrate cover), prey abundance, decreasing distance to the nearest ocean inlet and dissolved oxygen. Results suggest future restoration site selection should emphasize adequate dissolved oxygen (~6 mg/L), oyster densities above 50/m² and reef height above 55 mm, and minimum shoreline vegetation coverage of 50% to support macrofaunal prey and subsequently attract sportfish. These findings can help natural resource managers better use habitat restoration as a tool for enhancing fish populations in the future. Full article

Invasive species often cause negative ecological and economic effects. Florida has >20 established invasive fish species but only seven exist in saltwater. The present study examined Belonesox belizanus (Pike Killifish), a Central American euryhaline fish introduced to Tampa Bay (west-central Florida) in the early 1990s, which has quantifiably reduced populations of small-bodied native fishes and may compete with prized sportfish juveniles in estuarine nursery habitat. Long-term monitoring revealed that B. belizanus occurs in estuarine waterbodies along a 31-km stretch of the bay’s eastern fringe, with a second, smaller population in two western tributaries. Spread rate was estimated to be 5.5–13 km year⁻¹, intermediate among invasive poeciliids. A novel implementation of boosted regression tree modeling to assess B. belizanus habitat predictability found greater probability of presence with decreasing water depth and pH, whereas presence tended to be greatest at polyhaline salinity. It is hypothesized that B. belizanus distribution in Tampa Bay is constrained by deep, seawall habitats acting as ecological barriers. Further B. belizanus spread therefore may be most likely to occur by human release (from aquaria or bait buckets) or bird carry-off. Newly restored tidal habitat within the current range probably will be invaded quite quickly by B. belizanus. Full article