@article{johnson_eggleston_2010, title={Population density, survival and movement of blue crabs in estuarine salt marsh nurseries}, volume={407}, ISSN={["0171-8630"]}, DOI={10.3354/meps08574}, abstractNote={MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 407:135-147 (2010) - DOI: https://doi.org/10.3354/meps08574 Population density, survival and movement of blue crabs in estuarine salt marsh nurseries Eric G. Johnson1,2,*, David B. Eggleston1 1North Carolina State University, Department of Marine, Earth and Atmospheric Sciences, Raleigh, North Carolina 27695-8208, USA 2Present address: Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, Maryland 21037, USA *Email: johnsoneg@si.edu ABSTRACT: The importance of a broad suite of complex structured habitats as nurseries for estuarine fauna is well recognized. In contrast, recent evidence indicates the nursery value of salt marshes and contiguous unvegetated mud flats for blue crabs are underestimated. To assess the nursery value of salt marsh tidal creeks for the blue crab Callinectes sapidus in coastal North Carolina, USA, we quantified population density, survival and movement patterns of juvenile blue crabs in 2 tidal salt marsh creeks during summer and fall. Survival rates of blue crab juveniles were high (0.98 d–1) and similar in both creek systems. Juvenile crabs exhibited a high degree of site fidelity to a given marsh creek during summer–fall, suggesting that losses were predominantly due to mortality, not emigration. Our study provides critical information on the demographic processes underlying the importance of salt marshes as nurseries for estuarine-dependent species, and was novel in that it: (1) measured density, survival and emigration concurrently; and (2) enabled the identification of individuals, which allowed for the assessment of the relationship between blue crab size, survival and capture probability. We conclude that the observed patterns of abundance, survival and habitat utilization of blue crabs within tidal salt marsh creeks in North Carolina are consistent with the hypothesis that salt marsh creeks are important nurseries for blue crabs. Further, the relatively high use of the marsh surface by juvenile blue crabs, combined with a general lack of directed sampling within these complex habitats, suggests that crab densities may be even higher in salt marshes than previously thought. KEY WORDS: Blue crab · Callinectes sapidus · Mark-recapture · Survival · Salt marsh Full text in pdf format Supplementary material PreviousNextCite this article as: Johnson EG, Eggleston DB (2010) Population density, survival and movement of blue crabs in estuarine salt marsh nurseries. Mar Ecol Prog Ser 407:135-147. https://doi.org/10.3354/meps08574Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 407. Online publication date: May 20, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.}, journal={MARINE ECOLOGY PROGRESS SERIES}, author={Johnson, Eric G. and Eggleston, David B.}, year={2010}, pages={135–U150} }
 @article{eggleston_parsons_kellison_plaia_johnson_2008, title={Functional response of sport divers to lobsters with application to fisheries management}, volume={18}, ISSN={["1939-5582"]}, DOI={10.1890/06-1409.1}, abstractNote={Fishery managers must understand the dynamics of fishers and their prey to successfully predict the outcome of management actions. We measured the impact of a two-day exclusively recreational fishery on Caribbean spiny lobster in the Florida Keys, USA, over large spatial scales (>100 km) and multiple years and used a theoretical, predator–prey functional response approach to identify whether or not sport diver catch rates were density-independent (type I) or density-dependent (type II or III functional response), and if catch rates were saturated (i.e., reached an asymptote) at relatively high lobster densities. We then describe how this predator–prey framework can be applied to fisheries management for spiny lobster and other species. In the lower Keys, divers exhibited a type-I functional response, whereby they removed a constant and relatively high proportion of lobsters (0.74–0.84) across all pre-fishing-season lobster densities. Diver fishing effort increased in a linear manner with lobster prey densities, as would be expected with a type-I functional response, and was an order of magnitude lower in the upper Keys than lower Keys. There were numerous instances in the upper Keys where the density of lobsters actually increased from before to after the fishing season, suggesting some type of "spill-in effect" from surrounding diver-disturbed areas. With the exception of isolated reefs in the upper Keys, the proportion of lobsters removed by divers was density independent (type-I functional response) and never reached saturation at natural lobster densities. Thus, recreational divers have a relatively simple predatory response to spiny lobster, whereby catch rates increase linearly with lobster density such that catch is a reliable indicator of abundance. Although diver predation is extremely high (∼80%), diver predation pressure is not expected to increase proportionally with a decline in lobster density (i.e., a depensatory response), which could exacerbate local extinction. Furthermore, management actions that reduce diver effort should have a concomitant and desired reduction in catch. The recreational diver–lobster predator–prey construct in this study provides a useful predictive framework to apply to both recreational and commercial fisheries, and on which to build as management actions are implemented.}, number={1}, journal={ECOLOGICAL APPLICATIONS}, author={Eggleston, David B. and Parsons, Darren M. and Kellison, G. Todd and Plaia, Gayle R. and Johnson, Eric G.}, year={2008}, month={Jan}, pages={258–272} }
 @article{eggleston_dahlgren_johnson_2004, title={Fish density, diversity, and size-structure within multiple back reef habitats of Key West National Wildlife Refuge}, volume={75}, number={2}, journal={Bulletin of Marine Science}, author={Eggleston, D. B. and Dahlgren, C. P. and Johnson, E. G.}, year={2004}, pages={175–204} }
 @article{eggleston_johnson_kellison_nadeau_2003, title={Intense removal and non-saturating functional responses by recreational divers on spiny lobster Panulirus argus}, volume={257}, ISSN={["1616-1599"]}, DOI={10.3354/meps257197}, abstractNote={MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 257:197-207 (2003) - doi:10.3354/meps257197 Intense removal and non-saturating functional responses by recreational divers on spiny lobster Panulirus argus David B. Eggleston1,*, Eric G. Johnson1, G. Todd Kellison1,2, David A. Nadeau1 1North Carolina State University, Department of Marine, Earth and Atmospheric Sciences, Raleigh, North Carolina 27695-8208, USA 2Present address: Biscayne National Park, 9700 SW 328th Street, Homestead, Florida 33033, USA *Email: eggleston@ncsu.edu ABSTRACT: The effects of recreational fishing often go undetected, yet can lead to the collapse of fishery populations. Fishery managers must understand the dynamics of recreational fishers and their prey to successfully predict the outcome of management actions. We measured the impact of a 2 d exclusively recreational fishery on the Caribbean spiny lobster Panulirus argus in the Florida Keys, USA, and used a theoretical, predator-prey functional response approach to identify whether or not sport diver catch rates were density-independent or -dependent (Types I, II or III functional response), and if catch rates were saturated (i.e. reached an asymptote) at relatively high lobster densities. Herein, we describe how this predator-prey framework could be applied to fisheries management for the spiny lobster. Our approach consisted of SCUBA diver surveys of lobster distribution and abundance patterns immediately before and after the 2 d recreational Œmini-season¹ coupled with counts of recreational boats and divers to assess the aggregative response of divers to lobster density. During the mini-season, the density of boats along coral patch reefs and patch heads was over 900x higher than during the regular fishing season ~3 wk later. Overall, there was a 95 and 79% decline in mean lobster densities in the patch reef and patch head habitats, respectively. Fishing effort was 10x greater on patch heads than on reefs, probably due to ~100-fold higher lobster densities in patch-head habitats. In both patch reefs and heads, the proportion of lobsters removed by divers was density-independent (Type I functional response). Diver catch never reached saturation at natural lobster densities. Thus, recreational divers have a relatively simple predatory response to spiny lobsters, whereby catch rates increase linearly with lobster density such that catch is a reliable indicator of abundance. A major concern is that the current levels of lobster exploitation by sport divers are extremely high (~90%); however, diver predation pressure is not expected to increase proportionally with a decline in lobster density, which could exacerbate local extinction. Management actions that reduce diver effort should have a concomitant reduction in catch. The recreational diver-lobster predator-prey construct in this study provides a useful predictive framework on which to build as the spatiotemporal scales of measurements expand, management actions are implemented, and the lobster population varies. KEY WORDS: Caribbean spiny lobster · Density-independence · Fishery management · Recreational fishing impacts · Florida Keys · Functional response · Maximum likelihood · Overfishing · Predator-prey theory Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 257. Online publication date: August 07, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.}, number={2003}, journal={MARINE ECOLOGY PROGRESS SERIES}, author={Eggleston, DB and Johnson, EG and Kellison, GT and Nadeau, DA}, year={2003}, pages={197–207} }