Identifying Suitable Habitat for Three Highly Migratory Sharks (Great Hammerhead, Tiger, and Bull) and Assessing Their Spatial Vulnerability to Commercial Longline Fishing in the Southwest Atlantic Ocean and Gulf of Mexico PDF Download
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Author: Hannah Calich Publisher: ISBN: Category : Languages : en Pages :
Book Description
Aquatic highly migratory species (HMS) are economically and ecologically important, however, their highly migratory nature makes them difficult to study and thus there are knowledge gaps relating to their movement and habitat use patterns. Highly migratory sharks are likely to interact with commercial longline fishing gear and be caught as target or bycatch, which can threaten their populations. Understanding the environmental factors that influence and drive the movements of highly migratory sharks may help researchers better predict their presence and subsequently identify areas where they are vulnerability to fisheries. Here I evaluated the overlap between habitat suitability and gear restricted zones for three co-occurring apex predatory sharks in the Southwest Atlantic Ocean and Gulf of Mexico (great hammerhead Sphyrna mokarran, tiger Galeocerdo cuvier, and bull sharks Carcharhinus leucas) to identify areas in this region where these species are vulnerable to and protected from commercial longline fishing. This research was accomplished in three integrated steps. First, I reviewed and summarized what is known about the environmental drivers of great hammerhead, tiger, and bull shark habitat use and movement patterns. Second, I used the results of this review to parameterize and subsequently generate habitat suitability models for these three species. Third, I used these models to spatially compare where each species' highly suitable habitat overlaps with longline gear restricted areas within the Southwest Atlantic Ocean and Gulf of Mexico, to identify regions where these species were both vulnerable to and protected from longline fishing gear. The results of this thesis have implications to the management of these species as well as for the conservation of other highly migratory aquatic species.
Author: Hannah Calich Publisher: ISBN: Category : Languages : en Pages :
Book Description
Aquatic highly migratory species (HMS) are economically and ecologically important, however, their highly migratory nature makes them difficult to study and thus there are knowledge gaps relating to their movement and habitat use patterns. Highly migratory sharks are likely to interact with commercial longline fishing gear and be caught as target or bycatch, which can threaten their populations. Understanding the environmental factors that influence and drive the movements of highly migratory sharks may help researchers better predict their presence and subsequently identify areas where they are vulnerability to fisheries. Here I evaluated the overlap between habitat suitability and gear restricted zones for three co-occurring apex predatory sharks in the Southwest Atlantic Ocean and Gulf of Mexico (great hammerhead Sphyrna mokarran, tiger Galeocerdo cuvier, and bull sharks Carcharhinus leucas) to identify areas in this region where these species are vulnerable to and protected from commercial longline fishing. This research was accomplished in three integrated steps. First, I reviewed and summarized what is known about the environmental drivers of great hammerhead, tiger, and bull shark habitat use and movement patterns. Second, I used the results of this review to parameterize and subsequently generate habitat suitability models for these three species. Third, I used these models to spatially compare where each species' highly suitable habitat overlaps with longline gear restricted areas within the Southwest Atlantic Ocean and Gulf of Mexico, to identify regions where these species were both vulnerable to and protected from longline fishing gear. The results of this thesis have implications to the management of these species as well as for the conservation of other highly migratory aquatic species.
Author: Michael L. Domeier Publisher: CRC Press ISBN: 1439848408 Category : Nature Languages : en Pages : 571
Book Description
Inspired by the International White Shark Symposium in 2010, Global Perspectives on the Biology and Life History of the White Shark incorporates the most important contemporary research findings into a single peer-reviewed book. This beautifully illustrated reference represents a historic change in the context of White Shark (Carcharodon carcharias) research. Once considered one of the most poorly understood and difficult sharks to study, this timely book recognizes a new sophisticated focus on the White Shark, raising its status from obscurity to enlightenment. The Global Perspectives on the Biology and Life History of the White Shark celebrates the White Shark as the most studied shark in the sea. Within the chapters one can find new insights into a vast range of topics, such as behavior, physiology, migration patterns, habitat preferences, daily activity patterns, molecular genetics, reproductive biology and new research methods. The book also delves into population monitoring and policy options for managers and researchers.
Author: Fiona Graham Publisher: ISBN: Category : Languages : en Pages :
Book Description
Marine protected areas (MPAs) are effective at employing ecosystem-based management as a conservation tool, however these networks of protected zones must be carefully chosen. Therefore, strategic area placement and size is crucial for the best conservation outcome. While the benefits of implementing clear protected zones are obvious for species that live sedentary lifestyles, the proportion of habitat protection that they offer to wide-ranging species is less clear. Here, we analyze satellite telemetry data in order to determine key habitat areas for three wide-ranging shark species in both the south Florida and Bahamas regions, and then quantify the level of potential habitat protection that is offered to these species by both management zones within Florida and The Bahamas EEZ. We further assess their movements and habitat use with regards to habitat preference, specifically water column depth and distance from land. The three species selected for this study are the great hammerhead (Sphyrna mokarran), tiger shark (Galeocerdo cuvier), and bull shark (Carcharhinus leucas). These species were selected primarily because, as a group, they are the apex predators in the region, are representative of the region's marine megafauna, and they rank as a conservation priority. The study area encompasses a number of different MPAs, each differing in qualities such as purpose, management agency, level of protection, and restrictions on human uses. However, for this study we are most concerned with locational boundaries and level of protection offered. More specifically, we primarily look at those areas that restrict fishing, which is a major anthropogenic threat to the study species. To accomplish this analysis, we use ArcGIS, a geographical information systems program, to overlay MPA data in the study region with analysis of satellite telemetry data. Core activity space was determined using kernel density estimates, and the 50% kernel density estimate isolpleth was considered "critical habitat." The proportion of critical habitat that is protected for each target species was then calculated by determining the percent overlap of the critical habitat area with protected areas relevant to each species. To supplement this assessment, we then evaluate habitat preference based on overlap of critical habitat use areas and physical factors, where bathymetry data is overlaid with kernel density estimate isopleths. Mean and max distance from land was also calculated for all interpolated points for each species, and all interpolated points within defined critical habitat boundaries. This analysis allowed us to quantify habitat use with regards to water column depth and distance from shore. Finally, we created separate seasonal kernel density estimates for all species for the wet and dry seasons, in order to evaluate seasonal habitat preference. Results from 26 tagged bull sharks demonstrate that Biscayne and Everglades National Parks are high use areas for these sharks, and that none of their critical habitat is currently within areas that protect the species from fishing pressure, more specifically prohibiting the landing of the species. Analysis of data from 22 tagged great hammerhead sharks illustrates that 17.88% of their critical habitat is currently protected, almost all of which is due to regulations that prohibit the landing of the species within Florida state waters. Finally, 34.74% of tagged tiger shark (n=44) critical habitat is currently protected, due to regulations that prohibit the landing of the species within Florida state waters and regulations prohibiting shark fishing within The Bahamas EEZ. Habitat preference results are consistent with our previous analysis, and show that bull sharks prefer depths of less than 10 meters and are, on average, very close to land. We found that mean distance to shore for all interpolated bull shark points was 6.4 km, and mean distance to shore for all interpolated bull shark points that lie within their defined critical habitat area was 4.3 km. Data from our 44 tagged tiger sharks demonstrated that 78.25% of their critical habitat consists of depths greater than 100 meters and mean distance from land for all points was furthest for this species, at 176.6. Average distance to shore for all points within the tiger shark critical habitat was 71.9. We found that great hammerhead critical habitat was split relatively evenly between each depth range, and their mean distance to shore for all points and for only those points within their critical habitat was 82.8km and 16.6km, respectively. Finally, seasonal kernel density estimates created for the wet and dry seasons showed that habitat use does indeed seem to vary by season. Many wide-ranging marine top predators are experiencing population declines globally (Pauly et al. 1998, Myers & Worm 2003, Hampton et al. 2005, Dulvy et al. 2008). Marine reserves are the first step toward evaluating how effective these MPAs are as conservation tools and understanding how we can work to improve them. The results from this study have valuable implications for marine conservation planning and help to develop an understanding of the current and potential level of protection for the top predator species that play integral roles in south Florida's and The Bahamas' ecosystems.
Author: C. Herb Ward Publisher: Springer ISBN: 1493934562 Category : Technology & Engineering Languages : en Pages : 948
Book Description
This book is open access under a CC BY-NC 2.5 license. The Gulf of Mexico is an open and dynamic marine ecosystem rich in natural resources but heavily impacted by human activities, including agricultural, industrial, commercial and coastal development. The Gulf of Mexico has been continuously exposed to petroleum hydrocarbons for millions of years from natural oil and gas seeps on the sea floor, and more recently from oil drilling and production activities located in the water near and far from shore. Major accidental oil spills in the Gulf are infrequent; two of the most significant include the Ixtoc I blowout in the Bay of Campeche in 1979 and the Deepwater Horizon Oil Spill in 2010. Unfortunately, baseline assessments of the status of habitats and biota in the Gulf of Mexico before these spills either were not available, or the data had not been systematically compiled in a way that would help scientists assess the potential short-term and long-term effects of such events. This 2-volume series compiles and summarizes thousands of data sets showing the status of habitats and biota in the Gulf of Mexico before the Deepwater Horizon Oil Spill. Volume 2 covers historical data on commercial and recreational fisheries, with an analysis of marketing trends and drivers; ecology, populations and risks to birds, sea turtles and marine mammals in the Gulf; and diseases and mortalities of fish and other animals that inhabit the Gulf of Mexico.
Author: Ramón Bonfil Publisher: Food & Agriculture Org. ISBN: 9789251050453 Category : Nature Languages : en Pages : 112
Book Description
This volume presents a fully illustrated field guide for the identification of the sharks and rays most relevant to the fisheries of the Red Sea and Gulf of Aden. An extensive literature review and two field surveys in the region were carried out for the preparation of this document. A total of 49 sharks and 45 batoids reliably reported for the region are listed and those common in the fisheries or likely to be found through fisheries operations are fully treated. The guide includes sections on technical terms and measurements for sharks and batoids, and fully illustrated keys to those orders and families that occur in the region. Color plates for a large number of the species are included.
Author: Judith Denkinger Publisher: Springer Science & Business Media ISBN: 3319027697 Category : Technology & Engineering Languages : en Pages : 322
Book Description
This book focuses on how marine systems respond to natural and anthropogenic perturbations (ENSO, overfishing, pollution, tourism, invasive species, climate-change). Authors explain in their chapters how this information can guide management and conservation actions to help orient and better manage, restore and sustain the ecosystems services and goods that are derived from the ocean, while considering the complex issues that affect the delicate nature of the Islands. This book will contribute to a new understanding of the Galapagos Islands and marine ecosystems.
Author: Hannah Calich
Author: Hannah Calich
Author: Michael L. Domeier
Author: Fiona Graham
Author: C. Herb Ward
Author: Alexander Dragovich
Author: Mark F. L. Smith
Author: Ramón Bonfil
Author: Judith Denkinger
Author: 
Author: Mohamed Nejmeddine Bradai