Greg Skomal

Massachusetts Division of Marine Fisheries · Fish and Game

Climate change is shifting animal distributions. However, the extent to which future global habitats of threatened marine megafauna will overlap existing human threats remains unresolved. Here we use global climate models and habitat suitability estimated from long-term satellite-tracking data of the world’s largest fish, the whale shark, to show t...

The white shark, Carcharodon carcharias, is an iconic apex predator, playing an important ecological role across its range. Persistent bycatch and overfishing led to white shark declines, but recent studies in the North Western Atlantic (NWA) revealed evidence for regional recovery, and highlighted the importance of Southeastern Florida and the Gul...

Basking sharks (Cetorhinus maximus) seasonally aggregate in coastal surface waters of the North Atlantic, providing opportunities for visual observation. While putative courtship displays have been observed, actual copulation has not been documented. Here we examine video collected by an unmanned aerial vehicle (“drone”) of novel behavioral interac...

The white shark (Carcharodon carcharias) is a globally distributed top predator. Due to its ecological importance and historical declining population trends, data contributing to conservation initiatives (e.g. habitat protections and resource management) pertaining to all life stages of this species are essential to facilitate population recovery....

Background To tag large marine vertebrates, without the need to catch them, avoiding using barbs for tag retention, and precisely controlling tag location, the remote Tag Attachment Device on a pole (TADpole) was developed. This allows single-pin tags (Finmount, Wildlife Computers) to be attached to the dorsal fins of free-swimming large marine ver...

The striped bass ( Morone saxatilis ) is one of the most important species for anglers along the Atlantic coast and a subject of intensive fisheries management. To promote best catch‐and‐release practices, understanding the physical and physiological consequences of angling is critical. We assessed the injury and stress of striped bass captured usi...

Objective Shark depredation, the full or partial consumption of a hooked fish by a shark before it is landed, is an increasing source of human–wildlife conflict in recreational fisheries. Reports of shark depredation in the catch‐and‐release Tarpon (also known as Atlantic Tarpon) Megalops atlanticus fishery in the Florida Keys are increasing, speci...

Many predator species make regular excursions from near-surface waters to the twilight (200 to 1,000 m) and midnight (1,000 to 3,000 m) zones of the deep pelagic ocean. While the occurrence of significant vertical movements into the deep ocean has evolved independently across taxonomic groups, the functional role(s) and ecological significance of t...

The present study provides the first estimate of abundance for the white shark at a new aggregation site in the western North Atlantic, which required the development of a novel modeling framework to accommodate the species’ migratory behavior. Estimates of abundance are needed to evaluate the performance of existing conservation measures for white...

Species distribution models (SDMs) are becoming an important tool for marine conservation and management. Yet while there is an increasing diversity and volume of marine biodiversity data for training SDMs, little practical guidance is available on how to leverage distinct data types to build robust models. We explored the effect of different data...

Species distribution models (SDMs) are becoming an important tool for marine conservation and management. Yet while there is an increasing diversity and volume of marine biodiversity data for training SDMs, little practical guidance is available on how to leverage distinct data types to build robust models. We explored the effect of different data...

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first globa...

Assessing progress for the endangered white shark (Carcharodon carcharias) relative to Canadian conservation objectives requires understanding distribution patterns. From the largest tagging data set in the Northwest Atlantic (2010–2020; 272 deployments), we determined the proportion of the population detected in Canadian waters, characterized patt...

Significance Global vessel traffic is increasing alongside world economic growth. The potential for rising lethal ship strikes on endangered species of marine megafauna, such as the plankton-feeding whale shark, remains poorly understood since areas of highest overlap are seldom determined across an entire species range. Here we show how satellite...

Interspecific interactions can play an essential role in shaping wildlife populations and communities. To date, assessments of interspecific interactions, and more specifically predator–prey dynamics, in aquatic systems over broad spatial and temporal scales (i.e., hundreds of kilometers and multiple years) are rare due to constraints on our abilit...

We conducted an interdisciplinary review of available information (i.e., genetics, life-history, and movement) to evaluate the stock structure of a previously targeted shark species, the porbeagle (Lamna nasus), in the North Atlantic. Most available information supports the conclusion that porbeagle consist of a single genetic population in the Nor...

Shark depredation, the full or partial removal of a hooked fish by a shark before it is landed, is anecdotally increasing in the United States. Perceptions of depredation by anglers and fishing guides may influence their behavior and have cascading effects on sharks and recreational fisheries. However, to date, these perceptions have not been broad...

The whale shark Rhincodon typus is found throughout the world's tropical and warm-temperate ocean basins. Despite their broad physical distribution, research on the species has been concentrated at a few aggregation sites. Comparing DNA sequences from sharks at different sites can provide a demographically neutral understanding of the whale shark's...

Ectosymbionts, such as bacteria and parasites, are found on the surface of organisms throughout the world’s ecosystems. Hosts have evolved a variety of mechanisms across ecosystems to rid themselves of ectoparasites or other skin irritants including chafing behavior, whereby an organism curves their body to rub the convex portion of their body alon...

106,107 ✉ replying to A. V. Harry & J. M. Braccini Nature https://doi.org/10.1038/s41586-021-03463-w (2021) Our global analysis 1 estimated the overlap and fishing exposure risk (FEI) using the space use of satellite-tracked sharks and longline fishing effort monitored by the automatic identification system (AIS). In the accompanying Comment, Harry...

This article is a response to Murua et al.'s Matters Arising article in Nature, "Shark mortality cannot be assessed by fishery overlap alone," which arose from arising from N. Queiroz et al. Nature https://doi.org/10.1038/s41586-019-1444-4 (2019).

Data from the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, and sister networks, were used to evaluate fish movements in the Florida Keys—an extensive reef fish ecosystem just north of Cuba connecting the Atlantic Ocean and Gulf of Mexico. We analysed ~2 million detections for 23 species, ranging from reef fish such a...

Resource selection functions (RSFs) have been widely applied to animal tracking data to examine relative habitat selection and to help guide management and conservation strategies. While readily used in terrestrial ecology, RSFs have yet to be extensively used within marine systems. As acoustic telemetry continues to be a pervasive approach within...

Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the...

Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the...

ContextOver the past decade, the coastal waters off Cape Cod, Massachusetts, have emerged as the only known aggregation site for the white shark (Carcharodon carcharias) in the western North Atlantic. During periods of seasonal residency, white sharks patrol the shoreline in search of pinniped prey, bringing them in close proximity to popular beach...

Novel, non-lethal approaches are needed to improve our current understanding of the reproductive biology and ecology of the white shark Carcharodon carcharias . Previous studies have demonstrated that concentrations of reproductive hormones in muscle tissue can be used as reliable indicators of reproductive status for many vertebrate species, inclu...

The porbeagle (Lamna nasus) is a large, highly migratory endothermic shark broadly distributed in the higher latitudes of the Atlantic, South Pacific, and Indian Oceans. In the North Atlantic, the porbeagle has a long history of fisheries exploitation and current assessments indicate that this stock is severely overfished. Although much is known of...

Over the past decade, drones have become a popular tool for wildlife management and research. Drones have shown significant value for animals that were often difficult or dangerous to study using traditional survey methods. In the past five years drone technology has become commonplace for shark research with their use above, and more recently, bel...

Broad-scale movements (10s–100s km) of highly migratory species, such as sharks, present unique management challenges as fish migrate across international boundaries, thereby exposing them to different levels of anthropogenic pressure. Lemon sharks and blacktip sharks are well-studied throughout their range in the western North Atlantic, but broad-...

White sharks Carcharodon carcharias and gray seals Halichoerus grypus are re-establishing their ecological roles within the Northwestern Atlantic Ocean, presenting an opportunity to understand gray seal movement and at-sea behavior under predation risk. As with other shark-seal hotspots, movements to and from terrestrial haul outs can be risky for...

Broadbill swordfish (Xiphias gladius) is a key species in commercial fisheries, but management efforts continue to be hindered by data gaps in their basic biology, including ongoing debate over stock boundaries and movement between management zones. We deployed 20 pop-up satellite archival transmitting (PSAT) tags on juvenile swordfish in the Azore...

Whale sharks (Rhincodon typus) are typically dispersed throughout their circumtropical range, but the species is also known to aggregate in specific coastal areas. Accurate site descriptions associated with these aggregations are essential for the conservation of R. typus, an Endangered species. Although aggregations have become valuable hubs for r...

Effective ocean management and the conservation of highly migratory species depend on resolving the overlap between animal movements and distributions, and fishing effort. However, this information is lacking at a global scale. Here we show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fle...

Mesoscale eddies are critical components of the ocean’s “internal weather” system. Mixing and stirring by eddies exerts significant control on biogeochemical fluxes in the open ocean, and eddies may trap distinctive plankton communities that remain coherent for months and can be transported hundreds to thousands of kilometers. Debate regarding how...

Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology,...

White sharks, Carcharodon carcharias, are often described as elusive, with little information available due to the logistical difficulties of studying large marine predators that make long-distance migrations across ocean basins. Increased understanding of aggregation patterns, combined with recent advances in technology have, however, facilitated...

Telemetry transmitters incorporating accelerometers have recently emerged as powerful tools for investigating the activity patterns of individuals and groups of individuals in nearshore environments. Data obtained from these devices provide not only a time series of animal occurrence at acoustic receivers, but also a direct measure of animal activi...

The shortfin mako shark Isurus oxyrinchus is one of the fastest sharks, reaching speeds of up to 70 km/h. Belonging to family Lamnidae it is the second-most common oceanic shark caught by high seas longlines, mainly because of the high value of shortfin mako fins and meat. North Atlantic reported catches currently exceed 3300 tons annually and the...

Inaccurate age estimates can have severe consequences in the management of elasmobranchs. Numerous studies in shark age validation have demonstrated a disconnect between band pair counts and age, resulting in age underestimation, particularly in older individuals. To investigate the relationship between band pairs, vertebral shape and growth, we qu...

The blacktip shark (Carcharhinus limbatus) is a common coastal species in tropical and subtropical waters around the world. To examine the fine-scale movement ecology of this species in a Caribbean nursery, 17 neonate blacktip sharks were acoustically tagged in May, 2012 and tracked for one year in Coral Bay, St John, USVI. By quantifying linear mo...

Satellite-tracking of mature white sharks (Carcharodon carcharias) has revealed open-ocean movements spanning months and covering tens of thousands of kilometers. But how are the energetic demands of these active apex predators met as they leave coastal areas with relatively high prey abundance to swim across the open ocean through waters often cha...

Significance Understanding the key drivers of animal movement is crucial to assist in mitigating adverse impacts of anthropogenic activities on marine megafauna. We found that movement patterns of marine megafauna are mostly independent of their evolutionary histories, differing significantly from patterns for terrestrial animals. We detected a rem...

Basking shark (Cetorhinus maximus) populations are considered “vulnerable” globally and “endangered” in the northeast Atlantic by the International Union for the Conservation of Nature (IUCN). Much of our knowledge of this species comes from surface observations in coastal waters, yet recent evidence suggests the majority of their lives may be spen...

Understanding population dynamics is essential for implementing effective conservation and management of coastal sharks. Fisheries-independent surveys can offer valuable information for such data-limited situations. A 12-year (2004-2015) standardized, shallow water longline survey was conducted monthly in the coastal waters of Bimini, Bahamas. Each...

In the western North Atlantic, much of what is known about the movement ecology of the white shark Carcharodon carcharias is based on historical fisheries-dependent catch records, which portray a shelf-oriented species that moves north and south seasonally. In this study, we tagged 32 white sharks (16 females, 7 males, 9 unknown), ranging from 2.4...

The blacktip shark (Carcharhinus limbatus) is the most commonly captured species in the Florida recreational shark fishery. We aimed to quantify the postrelease mortality of blacktip sharks and to determine whether hook type (circle or J) had any impact on survival. We measured capture variables (e.g., fight time, animal condition, etc.), blood gas...

Striped bass (Morone saxatilis) are important in commercial and recreational fisheries along the western Atlantic coastline. Although there is a good understanding of their seasonal migration patterns, less is known about the short-term movements of striped bass once they have reached New England coastal embayments during the summer months. Movemen...

In recent years, great technological subsurface advancements have been made to observe and study Carcharodon carcharias, white sharks with autonomous underwater vehicles (AUVs) [1]. Prior to 2011, tracking pelagic predators like sharks was limited to using active tracking from boats [2] and passive acoustic arrays [3]. These aforementioned techniqu...

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...

The presence of whale sharks Rhincodon typus were recorded around Shib Habil, a small, coastal reef off the Red Sea coast of Saudi Arabia, from 2010 to 2015. A total of 267 suitable photographs resulting in the identification of 136 individuals, were documented from 305 encounters. Sharks were divided evenly between the sexes with no evidence of te...

It is a golden age for animal movement studies and so an opportune time to assess priorities for future work. We assembled 40 experts to identify key questions in this field, focussing on marine megafauna, which include a broad range of birds, mammals, reptiles, and fish. Research on these taxa has both underpinned many of the recent technical deve...

It is a golden age for animal movement studies and so an opportune time to assess priorities for future work. We assembled 40 experts to identify key questions in this field, focussing on marine megafauna, which include a broad range of birds, mammals, reptiles, and fish. Research on these taxa has both underpinned many of the recent technical deve...

Large pelagic fishes like sharks, tuna, swordfish, and billfish spend a portion of their lives in the open ocean, yet their spatial distribution in this vast habitat remains relatively unknown. Mesoscale ocean eddies, rotating vortices with radius scales of approximately 100 km, structure open ocean ecosystems from primary producers to apex predato...

Background The Red Sea has received little study when compared to other areas. This holds true for sharks in general and for whale sharks in particular. The discovery of a seasonal aggregation off the Saudi Arabian coast has made the targeted study of Red Sea whale sharks more feasible. Assessing the size and structure of this aggregation is a firs...

Background A recent global study of whale shark population genetics has allowed for better understanding of genetic connections between aggregations in both the Indo-Pacific and Atlantic. This overview included an aggregation found within the Red Sea near Al Lith, Saudi Arabia, however the Mafia Island, Tanzania, aggregation was not part of the stu...