Jaguar Panthera onca (Linnaeus, 1758) (Mammalia: Carnivora: Felidae) presumably feeding on Flathead Catfish Pylodictis olivaris (Rafinesque, 1818) (Actinopterygii: Siluriformes: Ictaluridae) at Aros and Yaqui rivers, Sonora, Mexico

Despite the abundant literature on the feeding preferences of the Jaguar Panthera onca throughout its range in America, few studies report fish consumed as prey by Jaguars. This paper reports two accounts of Jaguars presumably feeding on the introduced Flathead Catfish Pylodictis olivaris at the Aros and Yaqui rivers in Sonora, northwestern Mexico.

Optimization of a suite of flathead catfish (Pylodictis olivaris) microsatellite markers for understanding the population genetics of introduced populations in the northeast United States

Objective Flathead catfish are rapidly expanding into nonnative waterways throughout the United States. Once established, flathead catfish may cause disruptions to the local ecosystem through consumption and competition with native fishes, including species of conservation concern. Flathead catfish often become a popular sport fish in their introduced range, and so management strategies must frequently balance the need to protect native and naturalized fauna while meeting the desire to maintain or enhance fisheries. However, there are currently few tools available to inform management of invasive flathead catfish (Pylodictis olivaris). We describe a suite of microsatellite loci that can be used to characterize population structure, predict invasion history, and assess potential mitigation strategies for flathead catfish. Results Our panel of 13 microsatellite loci were polymorphic and appear to be informative for population genetic studies of flathead catfish. We found moderate levels of diversity in four nonnative collections of flathead catfish in the Pennsylvania and Maryland sections of the Susquehanna River and the Schuylkill River, Pennsylvania. Analyses suggested patterns of genetic differentiation within- and among-rivers, highlighting the utility of this marker panel for understanding the structure and assessing the degree of connectivity among flathead catfish populations.

Flathead Catfish (Pylodictis olivaris) reproduction in Canada

Eleven Flathead Catfish (Pylodictis olivaris), representing at least five age classes, were collected between 2016 and 2018 in the lower Thames River, Ontario, Canada. The capture of two juveniles (total lengths 78 mm and 82 mm), the first records of juveniles in Canada, is a strong indication that reproduction has occurred. Previous records were thought to be individuals that dispersed from known populations in American waters of Lake Erie. Flathead Catfish is currently designated as data deficient by the Committee on the Status of Endangered Wildlife in Canada. These new findings may provide sufficient data to reconsider the conservation status of this species.

Effect of Drying Methods and Pre Treatments on Nutritional Value and Sensory Quality of Fish (Oreochromis niloticus, Pylodictis olivaris and Cyprinus carpio) Species Commonly Used in Gambella Region

This study was conducted to assess the effect of drying methods and pre-treatments on nutritional content and sensory quality of dried fish. The experiment was conducted in factorial arrangement of 2×3×2 with two drying methods (sun and oven drying), three fish species (tilapia, cat fish and carp) and two preservatives treatment (garlic and ginger juice) laid out in Completely Randomized Design (CRD). Fresh fillets were analysed for their nutritional value and sensory quality. The compositions of the fresh fillets were 6.50-7.59% for ash, 74.20-76.67% for protein, 8.06-9.09% for fat and 8.47-9.12% for total carbohydrates. Drying reduced the moisture contents from 74.74-75.81% to between 7.76-8.25%, making it safe for storage. The ash content changed from 7.11 to 7.34 and from 6.50% to 6.34% for cat fish and tilapia, respectively, with statistical significance whereas no change was observed in carp with 7.60% because of drying. Drying method had no difference in ash and protein contents while increase in fat from 7.75 to 9.44% and a decrease in carbohydrate from 9.37 to 8.13% were observed in sun dried samples than that of oven dried fillets. This study showed that nutritional values of dry fish did not statistically changed during storage period of 3 months.

Factors associated with the success of native and nonnative species in an unfragmented arid-land riverscape

Native fish persistence is threatened by the establishment and spread of nonnatives. Identifying environmental and biotic factors associated with the success of co-occurring native fishes and nonnative taxa is central to identifying mechanisms responsible for native declines and nonnative expansion. We related physicochemical variables, food resources, and community composition to the success (secondary production) of native and nonnative fishes, tadpoles, and crayfish across six sites in three reaches (tributary, canyon, and valley) during 2008–2011 in the Gila River, New Mexico. Native fish success was greater than nonnative success across a range of physicochemical conditions, basal resource supply rates, and nonnative communities, although nonnative fish, tadpole, and crayfish success could approach or exceed that of native fishes in canyon habitats, a warm-water tributary, or in downstream valley sites, respectively. Native fish success was lowest in canyon reaches, when flathead catfish (Pylodictis olivaris) and common carp (Cyprinus carpio) were highly productive. These results demonstrate the potential for native fish persistence in the presence of nonnatives in physically unmodified streams, highlighting the importance of habitat preservation for native conservation.