Lee M. Paramore

A combined telemetry - tag return approach to estimate fishing and natural mortality rates of an estuarine fish

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum (Sciae- nops ocellatus) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry - tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based pri- marily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry - tag return approach can be an effective approach for estimat- ing F and M as long as several key assumptions of the model are met.

Multi-way analysis of trace elements in fish otoliths to track migratory patterns

Abstract Spawning striped bass in the Shubenacadie watershed of Nova Scotia, Canada exhibit three dorsal coloration patterns: green, indicative of fish from the ocean; black, indicative of fish that overwinter in a fresh headwater lake, and mottled fish of unknown origin. Microchemical analysis of growth rings in fish otoliths (calcareous particles found in the inner ear of certain lower vertebrates), measured by laser ablation-inductively coupled plasma/mass spectrometry (LA-ICP/MS), from fish captured during the 1999 Shubenacadie spawning period were analyzed by Tucker-3 multi-way principal component models. Using this technique, multidimensional patterns were discovered in the trace element measurements indicating that migratory patterns of individual striped bass can be tracked from the time-dependent trace element record deposited in the otoliths. Of the nine fish analyzed by LA-ICP/MS, trace element composition at year 0 suggested that all nine fish originated from the same locale. Differentiation in the trace element record was observed in subsequent years. Clustering of the trace element data for six fish unambiguously coincided with dorsal coloration. The three remaining fish exhibited trace element patterns that suggested migration between freshwater and marine conditions at one or more periods during life.

Recruitment of Juvenile Red Drum in North Carolina: Spatiotemporal Patterns of Year‐Class Strength and Validation of a Seine Survey

Abstract Sixteen years of data from a North Carolina Division of Marine Fisheries seining survey were analyzed to assess the validity of the survey, describe spatial and temporal patterns in recruitment of red drum Sciaenops ocellatus, and evaluate factors that potentially contribute to recruitment variation. Overall, 11,817 age-0 red drum (total length = 11–104 mm) were collected in the survey during 1991–2006. Annual estimates of red drum recruitment were variable over time and showed no long-term trend. The dome-shaped catch-per-unit-effort (CPUE) pattern of all annual cohorts indicated that the seine survey captured peak abundance levels each year; the spatial coverage of the survey also appeared to be adequate. Regional correlations within North Carolina were strongest for areas that were adjacent to one another, and the North Carolina statewide index was not correlated with indices from Florida or Texas, suggesting that factors controlling recruitment of red drum operate at a scale of tens to hundre...

An Age-Dependent Tag Return Model for Estimating Mortality and Selectivity of an Estuarine-Dependent Fish with High Rates of Catch and Release

Abstract Red drum Sciaenops ocellatus support commercial and recreational fisheries in North Carolina, but the stock was overfished in the 1980s because fishing was unregulated. Subsequent fishery regulations increased subadult survival into adult age-classes, but overall stock status is difficult to assess because of migration to ocean waters, prohibited harvest of older fish, and relative importance of catch and release. We analyzed 24 years of tagging data from the North Carolina Division of Marine Fisheries to assess the effects of two regulation changes (effected in 1991 and 1998) on fishing mortality rate (F) and selectivity (SEL) patterns of red drum. We used an age-dependent tag return model that accounted for both harvest and catch-and-release fishing. Using external estimates of natural mortality (M) and annual tag retention rate, we obtained precise estimates of annual F; an overall tag reporting rate (λ); and fate-specific, age-specific, and regulation-period-specific SEL. Estimated F of fully...

Dorsal coloration as an indicator of different life history patterns for striped bass within a single watershed of Atlantic Canada

Abstract The striped bass Morone saxatilis spawning within a single river system are generally considered to be members of a single population unit. For some rivers in Canada, however, fishers have reported different-colored groups of striped bass in the watershed during the prespawning and spawning seasons, which suggests the existence of population subgroups. We examined this “colormorph” phenomenon for a striped bass population in the Shubenacadie watershed of Nova Scotia, Canada. Spawning fish had three dorsal coloration patterns: green, which was indicative of fish from the ocean; black, which was indicative of fish that overwinter in a freshwater headwater lake; and mottled, which were fish of unknown origin. Body morphology appeared to be similar among the three groups. Although the age structures of the spawning populations revealed a wider range of age-classes among greenbacked fish, the growth aspects (e.g., length, weight, and length at age) were similar. We estimated that during the prespawnin...

Delineation and mapping of coastal shark habitat within a shallow lagoonal estuary

Estuaries function as important nursery and foraging habitats for many coastal species, including highly migratory sharks. Pamlico Sound, North Carolina, is one of the largest estuaries in the continental United States and provides a variety of potential habitats for sharks. In order to identify and spatially delineate shark habitats within Pamlico Sound, shark catch and environmental data were analyzed from the 2007–2014 North Carolina Division of Marine Fisheries (NCDMF) gillnet and longline surveys conducted within the estuary. Principal species were identified and environmental data recorded at survey sites (depth, temperature, salinity, dissolved oxygen, submerged aquatic vegetation (SAV) distance, and inlet distance) were interpolated across Pamlico Sound to create seasonal environmental grids with a 90-m2 cell size. Boosted Regression Tree (BRT) analysis was used to identify the most important environmental factors and ranges associated with presence of each principal species, and the resulting models were used to predict shark capture probability based on the environmental values within the grid cells. The Atlantic Sharpnose Shark (Rhizoprionodon terraenovae), Blacktip Shark (Carcharhinus limbatus), Bull Shark (Carcharhinus leucas), Sandbar Shark (Carcharhinus plumbeus), Smooth Dogfish (Mustelus canis), and Spiny Dogfish (Squalus acanthias) were the principal species in Pamlico Sound. Most species were associated with proximity to the inlet and/or high salinity, and warm temperatures, but the Bull Shark preferred greater inlet distances and the Spiny Dogfish preferred lower temperatures than the other species. Extensive Smooth Dogfish habitat overlap with seagrass beds suggests that seagrass may be a critical part of nursery habitat for this species. Spatial delineation of shark habitat within the estuary will allow for better protection of essential habitat and assessment of potential interactions with other species.