An integrated tagging model to estimate mortality rates of Albemarle Sound – Roanoke River striped bass

We developed an integrated tagging model to estimate mortality rates and run sizes of Albemarle Sound – Roanoke River striped bass (Morone saxatilis), including (i) a multistate component for telemetered fish with a high reward external tag; (ii) tag return components for fish with a low reward external or PIT tag; and (iii) catch-at-age data. Total annual instantaneous mortality was 1.08 for resident (458–899 mm total length, TL) and 0.45 for anadromous (≥900 mm TL) individuals. Annual instantaneous natural mortality was higher for resident (0.70) than for anadromous (0.21) fish due to high summer mortality in Albemarle Sound. Natural mortality for residents was substantially higher than currently assumed for stock assessment. Monthly fishing mortality from multiple sectors (including catch-and-release) corresponded to seasonal periods of legal harvest. Run size estimates were 499 000–715 000. Results and simulation suggest increasing sample size for the multistate component increases accuracy and precision of annual estimates and low reward tags are valuable for estimating monthly fishing mortality rates among sectors. Our results suggest that integrated tagging models can produce seasonal and annual mortality estimates needed for stock assessment and management.

Tracking Ontogenentic Food Habits of Early Life Stages of White and Yellow Perch in Albemarle Sound, North Carolina

White Perch (Morone americana) and Yellow Perch (Perca flavescens) are percid fishes common to the Albemarle Estuarine System (AES) in North Carolina. Both species have well established recreational and commercial fisheries in the AES. The juvenile stages of these two species commonly occur in the same areas and likely share food resources. We investigated the feeding habits of juvenile White Perch and Yellow Perch in the AES from June through October 2005. The diets of both species were made up entirely of aquatic invertebrates, with copepods and cladocerans contributing (>90% by number) to the diet of juvenile White Perch. Mysid shrimp and amphipods were the primary source of White Perch dietary weight. Juvenile White Perch exhibited a marked change in prey with increased size, switching from smaller pelagic prey (e.g., copepods and cladocerans) to larger epibenthic prey (e.g., mysid shrimp and amphipods). Amphipods also were the primary prey of juvenile Yellow Perch, which differs from the majority of published data on the diet of juvenile Yellow Perch. The results of this study also provide evidence of little dietary overlap between the species, which was primarily explained by the timing of spawning and the size differences between the two species.