Dewayne A. Fox's research while affiliated with Delaware State University and other places

Publications (48)

Article
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Differential migration—increased migration propensity with increasing individual size—is common in migratory species. Like other forms of partial migration, it provides spatial buffering against regional differences in habitat quality and sources of mortality. We investigated differential migration and its consequences to survival and reproductive...
Article
Species distribution models (SDMs) are often empirically developed on spatially and temporally biased samples and then applied over much larger spatial scales to test ecological hypotheses or to inform management. Underlying this approach is the assumption that the statistical relationships between species observations and environmental predictors...
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There is considerable interest in evaluating the status and trends of sturgeon populations, yet many traditional approaches to estimating the abundance of fishes are intractable due to their biology and rarity. Side-scan sonar has recently emerged as an effective tool for censusing sturgeon in rivers, yet challenges remain for censusing open popula...
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Animals utilize various habitats throughout their life to optimize growth, fitness, and survival. Identifying environmental conditions and locations where animals exhibit different movement behaviors can be used to infer the relative importance of habitat types. In the case of threatened and endangered species, such as the Atlantic Sturgeon Acipens...
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Background: Acoustic biotelemetry sensors have been fully integrated into a broad range of mobile autonomous platforms; however, estimates of detection efficiency in different environmental conditions are rare. Here, we examined the role of environmental and vehicle factors influencing detection range for two common acoustic receivers, the VEMCO mo...
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The popularity of recreational shark fishing appears to be on the rise in recent years, with current policies often failing to address the direct targeting of protected species in this sector. Examination of catch trends from the past decade revealed that more than 66 million sharks were caught by recreational anglers along the U.S. eastern coast a...
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Complex social networks and behaviors are difficult to observe for free-living marine species, especially those that move great distances. Using implanted acoustic transceivers to study the inter- and intraspecific interactions of sand tiger sharks Carcharias taurus, we observed group behavior that has historically been associated with higher order...
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We developed a long-term tagging method that can be used to understand species assemblages and social groupings associated with large marine fishes such as the Sand Tiger shark Carcharias taurus. We deployed internally implanted archival VEMCO Mobile Transceivers (VMTs; VEMCO Ltd. Nova Scotia, Canada) in 20 adult Sand Tigers, of which two tags were...
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Categorical landscapes are powerful environmental partitions that index complex biogeochemical processes that drive terrestrial species distributions. However, translating landscapes into seascapes requires that the dynamic nature of the fluid environment be reflected in spatial and temporal boundaries such that seascapes can be used in marine spec...
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Partial migration, by which contingents within populations undertake divergent migrations, is common in marine fishes but remains poorly documented. Intrapopulation groups of fish with similar seasonal migration behaviors were noted early in the fisheries literature and have attracted increased interest for their role in population resilience to en...
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http://www.tandfonline.com/eprint/RKdxWnaeYCqc8Xd5euUV/full Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus was federally listed under the U.S. Endangered Species Act as five distinct population segments (DPS). Currently, at least 18 estuaries coastwide host spawning populations and the viability of these vary, requiring differing levels of prote...
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Globally, population declines for the sand tiger shark (Carcharias taurus) have resulted in calls for informed management of populations, including in the western North Atlantic, where they have been listed as a Species of Concern by NOAA Fisheries. However, information on movements and habitat use, critical for informed management of this sand tig...
Conference Paper
The 2012 Endangered Species Act listing emphasized the need for improved understanding of Atlantic Sturgeon marine habitat requirements. To aid in this understanding and facilitate management, we developed a spatial prediction for occurrence by linking detections of 395 telemetered adult and sub-adult Atlantic Sturgeon with water classes assignment...
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Temperatures are rising at an unprecedented rate in the Arctic, and affecting the sensitive hydrological cycle with increased freshwater inputs to the marine environment. A deep-time analogue often used to understand and predict the environmental and ecological impacts of global warming is the early-middle Eocene greenhouse (ca. 53-38 Ma). Although...
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The coastal migratory stock of Striped Bass Morone saxatilis has supported fisheries off the Massachusetts (MA) coast for centuries. However, despite this historical importance, limited information is available regarding Striped Bass seasonal movement patterns or migratory pathways within MA coastal waters and beyond. Using passive acoustic telemet...
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Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) experienced severe declines due to habitat destruction and overfishing beginning in the late 19(th) century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeo...
Conference Paper
Worldwide, sturgeons are recognized as one of the most imperiled groups of organisms. In 2012, Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were listed under the ESA due to concerns over population declines. In June 2013, through a combination of passive mobile telemetry and high-resolution side-scan sonar, we assessed the distribution of re...
Conference Paper
In 2012, five Distinct Population Segments of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were listed under the Endangered Species Act. A preceding Status Review concluded that bycatch in sink-gillnets was a significant hurdle to Atlantic sturgeon recovery. Over three field seasons (2010-2012), we worked collaboratively with commercial harv...
Conference Paper
Bottom longlines are commonly used to in commercial fisheries as well as research studies sample sharks and although much attention has been focused on longline configuration (e.g. baits, hook type/size, and soak time) little information is available on the potential injury of targeted species. Sand tiger sharks (Carcharias taurus) although conside...
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Multibeam imaging sonars have considerable potential for use in fisheries surveys because the video-like images are easy to interpret, and they contain information about fish size, shape, and swimming behavior, as well as characteristics of occupied habitats. We examined images obtained using a dual-frequency identification sonar (DIDSON) multibeam...
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Physical processes in the coastal Mid-Atlantic create a complex and dynamic seascape. Understanding how coastal fishes respond to this complexity has been a major motivation in establishing coastal biotelemetry arrays. Most coastal arrays maximize the probability offish detection by positioning hydrophones near geophysical bottlenecks. The developm...
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One of the largest impediments to the conservation of freshwater mussels is the absence of host-fish data. Suitable hosts must be present in sufficient numbers and occur at the appropriate time for successful mussel recruitment. Habitat degradation and fragmentation caused by dams and other anthropogenic alterations may reduce host availability. Ho...
Conference Paper
Passive acoustic telemetry is a relatively low cost and reliable method to examine patterns of habitat utilization, behavior, and movement over multiple spatial scales. With the highly migratory nature of some aquatic organisms, and continued technological advances, issues including equipment compatibility, standardization, and data ownership/excha...
Conference Paper
Choctawhatchee Bay, FL provides critical foraging habitats for the federally protected Gulf sturgeon (Acipenser oxyrinchus desotoi). The Choctawhatchee River remains free flowing, allowing access to spawning sites, and is one factor that likely contributes to the relative health of the Gulf sturgeon population utilizing the system. Like many estuar...
Conference Paper
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Despite its highly industrialized and urbanized setting, the lower Hudson River Estuary is an important habitat for striped bass Morone saxatilis, contributing to important fisheries throughout the Hudson River, NY Harbor, and well beyond in coastal Atlantic waters. Based upon previous otolith chemistry and telemetry research we hypothesized that t...
Conference Paper
In order to best manage human activities in a way that populations of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) may recover fully, it is necessary to understand the association between sub-adult Atlantic sturgeon and their ocean/estuarine habitat. With the recent listing under the ESA, the identification of key movements and habitat use i...
Conference Paper
In 2012, five DPSs of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were listed under the ESA. The preceding Status Review concluded that bycatch in sink-gillnets was a significant hurdle to Atlantic sturgeon recovery. Over two field seasons (2010, 2011), we worked with commercial fishermen on sink gillnet modifications to achieve reductions...
Conference Paper
Recovery of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) will likely requirea better understanding of the physical and biological factors that drive habitat utilization at critical life stages. Recent collaborative research in the Delaware River Estuary has produced spatial datasets of the biotic and abiotic composition of its benthos which...
Article
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In 2007, a team of U. S. scientists performed a status review of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus and concluded that the species would likely become endangered (U. S. Endangered Species Act 1973, as amended) in the foreseeable future over much of its range, including populations of the New York Bight, which is comprised of the Huds...
Conference Paper
Choctawhatchee Bay, Florida has been designated critical habitat for the federally protected Gulf sturgeon (Acipenser oxyrinchus desotoi); it is an important area for foraging and migration. Like many Gulf coast estuaries, the Choctawhatchee Bay watershed has been significantly impacted by dramatic rises in human population in recent years. Associa...
Conference Paper
Recently Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were proposed for listing under the ESA with a final ruling due to be released in October 2011. Once supporting a tremendous caviar and flesh fishery, Atlantic sturgeon populations suffered from severe overharvest and habitat destruction beginning in the late 19th century and have since s...
Conference Paper
American eels (Anguilla rostrata) serve key roles in the ecological and economic health of the mid-Atlantic region. Resource managers facing a combination of declining landings and changing environmental regimes are in need of information on the factors influencing American eel movement. In the spring of 2009, a combined mark-recapture and biotelem...
Conference Paper
Monkfish (Lophius americanus) support a lucrative fishery primarily centered in the waters of the mid-Atlantic and northeast US. Monkfish are targeted primarily through trawls and sink-gillnets. Overharvest coupled with habitat loss and alteration lead to a wholesale decline of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the early 1900s....
Conference Paper
Recently fishery managers have begun to combine mark-recapture and telemetry modeling approaches to provide estimates of survival, mortality and emigration. In the spring of 2009, a combined mark-recapture and telemetry study was initiated in the St. Jones River, Delaware. Monthly mark-recapture events took place using fixed locations (n = 40) stra...
Conference Paper
Passive acoustic telemetry is a relatively low cost and reliable method to examine large scale patterns of habitat utilization, behavior, and movement. The highly migratory nature of some fishes coupled with the recent advent of this technology raises issues including equipment compatibility, data ownership and exchange. The Atlantic Cooperative Te...
Conference Paper
The decline of traditional spring fisheries in Delaware has lead to the rapid development of a targeted black drum fishery. Delaware currently has no black drum regulations and concern over increased effort has led to calls for a standardized management approach with New Jersey. Sagittal otoliths and morphometric data were collected from both recre...
Conference Paper
Choctawhatchee Bay serves as important foraging habitat for Gulf sturgeon (Acipenser oxyrinchus desotoi) during periods of estuarine residence. Such habitats are critical to Gulf sturgeon, as they depend exclusively upon them for growth. In recent years, the Choctawhatchee watershed has undergone significant anthropogenic landscape-level changes co...
Conference Paper
Atlantic sturgeon were plentiful along the Atlantic seaboard prior to their precipitous decline in the early 20th century resulting from over harvest. By utilizing new capture techniques and standardized telemetry equipment, we were able to implant acoustic transmitters into 51 Atlantic sturgeon off the Delaware coast and follow their marine moveme...
Conference Paper
Although found globally in most temperate and tropical marine waters Delaware Bay is relatively unique as one of few locations in North America where sand tigers are commonly encountered. There are growing concerns over the trends in sand tiger abundance leading to our focus on the role of Delaware Bay in this species’ successful management. We imp...
Article
Larger nektonic fishes, many of which are economically important, comprise a large portion of the biomass in estuaries and may influence energy flow through their migrations and feeding, yet we know relatively little of this faunal component. To elucidate the patterns of species composition, distribution, and abundance in Delaware Bay, we sampled (...
Article
Modification of brackish marshes by nonindigenousPhragmites australis has occurred across a broad geographical area in eastern North America. Among its effects on marsh processes,Phragmites may be increasingly unfavorable to marsh surface fishes as its invasion progresses within an estuary. We assessed the effect of thePhragmites invasion on reside...

Citations

... Despite the model assumptions and a limited amount of 355 available Atlantic Sturgeon of ages 0-1, we found evidence of a remnant spawning population in the Delaware River and identified important nursery habitat based on the presence of individuals of ages 0-1. Similarly, Simpson and Fox (2006) suggested the existence of a contemporary spawning popula-360 tion in the Delaware River at much lower levels than historical population abundances (Secor and Waldman 1999). Spawning adults are believed to aggregate at areas with flowing waters (optimal flows of 46-76 cm/s) between the salt front and the fall line of large rivers at depths from 11 to 27 m (Borodin 365 1925;Leland 1968;Scott and Crossman 1973;Crance 1987;Bain et al. 2000) and deposit adhesive eggs on hard substrate (Gilbert 1989;Smith and Clungston 1997). ...
... Atlantic Sturgeon form large aggregations within feeding locations and this study provided evidence Table 2 Description of dyads detected within Minas Basin during 2012-2014, including the mean (± Standard Deviation; SD) simple ratio index (SRI), the mean (± SD) nodal degree, and the characteristics of the dyads (genetic river of origin and initial capture date) that some Atlantic Sturgeon preferentially co-occur with other individuals. Sturgeons' co-occurrence behavior may be similar to that reported for several species of shark [39][40][41] which have been thought to undergo solitary marine migrations but preferentially co-occur at feeding sites [5]. Most behavioral studies examining cooccurrence behavior have focused on teleost fishes [6,10] and may not be directly comparable to more primitive chondrostei such as the Atlantic Sturgeon. ...
... Throughout the 1990s and 2000s, the diet of juvenile and adult Weakfish was studied extensively in the Delaware Bay (Grecay and Targett 1996a;Lankford and Targett 1997;Paperno et al. 2000;Nemerson 2001;Nemerson and Able 2004;Able et al. 2009Able et al. , 2018 priority was placed on monitoring the diets of Weakfish over broad regional and spatial scales with "an emphasis on new studies within estuaries". Additionally, the fishery management priorities at the federal level emphasize an ecosystem-based fisheries management (EBFM) ...
... Impoundment typically results in the loss of half or more of the original mussel fauna, but impoundment-tolerant species often increase in abundance, and other impoundment-tolerant species not present historically may colonize the stream (Garner and McGregor 2001). Loss of a fish host can eliminate a particular mussel species while leaving the remainder of the fauna relatively unaffected (Smith 1985;Fritts et al. 2012). Many unimpounded streams have lost a substantial portion of their historical mussel species richness but continue to support large populations of apparently adaptable species (''opportunistic species'', Haag 2012; see ''Fauna-Wide Collapse''). ...
... Ad hoc approaches (e.g., analyses developed for a specific task) are frequently used to simultaneously incorporate space and time in models of individual movements [20,21], and survival [4], but those methods are not easily repeated and have not been used to identify movement structure at the population level. Few studies have used cluster analysis to identify structure (i.e., commonalities) within populations [2,22]. For example, Kessel et al. used supervised agglomerative clustering (i.e., detection histories were manually arranged along a similarity gradient) to identify migratory contingents within a population of lake sturgeon (Acipenser fulvescens). ...
... As a result, during a given year, only a subset of mature adults participates in a spawning migration to suitable freshwater habitats. Additionally, populations mix extensively within marine aggregations and can only be distinguished genetically (Dunton et al. 2012;Waldman et al. 2013;Wirgin et al. 2015). Since the coast-wide fishery moratorium instituted in 1998 by the Atlantic States Marine Fisheries Commission (ASMFC), no recent fishery-dependent data exist for US populations of Atlantic sturgeon aside from occasional bycatch records. ...
... It is one of the most efficient techniques for individual recognition and can be used to evaluate the fate of the stocked fish to improve conservation actions outcomes. So, it has been widely used for post-release monitoring in conservation stocking programs (Ebner and Thiem 2009;Grabowski and Jennings 2009;Mohler et al., 2012;Thompson et al., 2016). It is a reliable means to study spatial ecology of fish and it is used in several taxa Ingraham et al., 2014;Horká et al., 2015). ...
... Proxy records suggest that the Arctic Ocean was much fresher during the Eocene than the present day, with typical surface salinities around 20-25 psu and periodic excursions to very low salinity conditions (<10 psu) (Brinkhuis et al., 2006;Kim et al., 2014;Waddell and Moore, 2008). Outflow of this fresh surface water into the North Atlantic can potentially prohibit deep 315 water formation (Baatsen et al., 2020;Hutchinson et al., 2018). ...
... The STS is a coastal shark (Haulsee et al., 2016) that spends most of the time in shallow waters near caves and submerged reefs, between the surface and depths of up to 40 m (Otway & Ellis, 2011;Smith, Scarpaci, Scarr, & Otway, 2014). Juveniles tend to remain in shallow waters, seldom occurring at depths of greater than 80 m (Otway & Ellis, 2011;Teter et al., 2015). The recorded temperature range of the species is 12-26 C, but there is high variability across populations (Lucifora, Menni, & Escalante, 2002;Otway & Ellis, 2011;Smale, 2002;Teter et al., 2015). ...
... The relationship between Atlantic sturgeon and seascape class E has now been documented three times in three different seasons (i.e. southward fall migration MAB, Oliver et al., 2013;northward spring migration MAB, Breece et al., 2016;overwintering SAB, current study). In addition to seascape class E, we found the selection for seascape class F in the SAB; however, relationship between Atlantic sturgeon and seascape class F in the MAB is not clear (Breece et al., 2016). ...