Distribution, Habitat Use, and Movements of Juvenile Smalltooth Sawfish, Pristis Pectinata, in the Charlotte Harbor Estuarine System, Florida PDF Download

Author: Gregg Richard Poulakis
Publisher:
ISBN:
Category : Pristis pectinata
Languages : en
Pages : 330

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Author: Lisa Hollensead
Publisher:
ISBN:
Category : Conservation biology
Languages : en
Pages :

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ABSTRACT: Habitat use studies can be used to both investigate ecological and behavioral patterns of animals as well as provide a useful management tool for conservation planners. However, essential habitat can be difficult to determine for highly mobile marine animals, especially when these species are rare or endangered. While critical habitat has been very broadly delineated for the endangered smalltooth sawfish (Pristis pectinata), essential fish habitat (EFH) within the nursery has not been fully described. I used telemetry methods to determine daily activity spaces and rates of movement (ROM) of juvenile P. pectinata in a nursery in southwest Florida. These results were tested for differences in diel and tidal patterns of activity. Seven juvenile animals ranging in size from 85 - 175 cm fork length were tagged in April - September 2011. Overall, activity spaces ranged from 0.07 - 0.17 km2 using 95% Minimum Convex Polygons (MCP), 0.01 - 0.16 km2 based on 50% kernel density estimates (KDE), and 0.08 - 0.68 km2 based on 95% (KDE). Average ROMs ranged from 2.4 - 6.1 meters/min. Activity space and ROMs reflected the morphology of the bay in which the animal was tracked such that fish in small bays had small activity spaces and ROMs. There were no detectable differences in activity space or ROM between ebb and flood tide or high or low tide. Activity space decreased and ROM increased at night indicating possible foraging behavior at night. A home range (1.7 km2) was calculated for one animal. Daily asymptotes in space used were reached for all other tracks suggesting daily activity spaces were determined despite relatively short tracking durations. Bays, estuaries, and other discrete coastal habitats are highly productive and serve as nurseries for a variety of marine fishes. Nurseries are particularly crucial for batoids whose life histories are dependent on rapid growth in the first year, and they may be especially important for rare or endangered species within the group. The smalltooth sawfish, Pristis pectinata, are an endangered marine elasmobranch that makes use of specific nurseries in southwest Florida. While habitat and environmental parameters have been described within the nursery, specific characteristics of the habitats, such as mangrove morphology and sediment types associated with habitat use have not been identified. Two mangrove characteristics (prop root density and limb overhang) and two sediment characteristics (percent organic and percent silt) were used as independent variables to construct a habitat model. Acoustic monitoring was used to examine long term (weeks or months) patterns in habitat use in nursery areas during the critical first year of life. Twenty young-of-the-year sawfish were acoustically tagged between April and October of 2011, and detected by an array of 32 VEMCO VR2w receivers in a documented nursery within Everglades National Park. Presence in the array for individual smalltooth sawfish ranged from one day to 197 days, and overall P. pectinata were present within the acoustic array for 334 days. There was also evidence of overwintering specifically in Chokoloskee Bay. In the back water region (Turner River, Mud Bay, Cross Bays, Wilderness Waterway, and Lopez River), residency times were longer in tidal bays rather than creeks or rivers. A potential emigration corridor from the back water region was observed through the Lopez River. Using receiver data for animals moving between neighboring areas, a step wise logistic regression model in a generalized linear model framework for receiver hits per hour was significant for mangrove prop root density (Stepwise GLM- Partial R square = 0.22, C(p) = 6.02 p = 0.023). This model indicated a higher probability of seeing a juvenile smalltooth sawfish when mangrove prop root density was high.

Author:
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ISBN:
Category : Freshwater biology
Languages : en
Pages : 492

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Author: Michael Philip McCallister
Publisher:
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Category : Shark -- Dispersal -- Florida -- Jacksonville
Languages : en
Pages :

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Sharks are considered top predators in many marine ecosystems, and can play an important role in structuring those communities. As a result, it is necessary to understand the factors that influence their abundance and distribution. This is particularly important as fishery managers develop fishery management plans for sharks that identify areas that serve as essential fish habitat (EFH). This includes nursery habitat where sharks are born and juveniles spend the early part of their life. However, our understanding of shark habitat use in the northeast Florida waters is limited. The goal of this thesis was to characterize the abundance and distribution of sharks in northeast Florida estuaries, and to examine the effect of abiotic and biotic factors affecting shark habitat use. A bottom longline survey conducted from 2009 - 2011 indicated that 11 shark species use the estuarine waters of northeast Florida during summer months. Atlantic sharpnose (Rhizoprionodon terraenovae), blacktip (Carcharhinus limbatus), bonnethead (Sphyrna tiburo), and sandbar sharks (Carcharhinus plumbeus) were the most abundant species and made up 87.1% of the total catch. Month, bottom water temperature, and depth were the most important factors determining the presence and abundance of these species. This study also examined the role of prey abundance in determining the abundance of Atlantic sharpnose sharks. The probability of catching an Atlantic sharpnose shark, and the abundance of Atlantic sharpnose sharks, were most influenced by site. Neither potential prey abundance nor preferred prey abundance were not significant factors effecting Atlantic sharpnose abundance. This may be a result of prey sampling not providing an accurate measure of the true availability of prey resources. Other factors, such as predation risk, may better explain habitat use patterns of Atlantic sharpnose sharks. Continued sampling will give a better understanding of the factors influencing shark habitat use in this area.

Author: John Keith Carlson
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 15

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"Smalltooth sawfish, Pristis pectinata, historically were found from Texas to New York. However, the population today is approximately 5% of its original size and restricted primarily to the waters of southern Florida, especially Everglades National Park adn adjacent areas (Seitz and Poulakis, 2002; Poulakis and Seitz, 2004; Simpfendorfer and Wiley, 2005). The decline of smalltooth sawfish has been attributed to catch and bycatch in commercial and recreational fishing, habitat loss, and a vulnerable life history (Simpfendorfer, 2002, 2005). In response to the decline in the population, the National Marine Fisheries Service (NMFS) listed this species as Endangered under the US Endangered Species Act in April 2003 (68 FR 15674)"--Introduction.

Author: Cheston Thomas Peterson
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 0

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Drivers of animal movement, including abiotic factors such as environmental conditions or climate and biotic factors such as species interactions and reproduction, are classic topics in ecology and relevant to both basic and applied scientific questions. Understanding phenomena such as seasonal migrations are important in fisheries management, and describing habitat use and ecological interactions is a primary goal in fisheries ecology as the field moves toward holistic, ecosystem-based approaches. Here I present the results of research investigating the drivers of movement in coastal sharks, from scales of seasonal migrations and temporal patterns of abundance to fine-scale movement of a single species as it relates to the distribution and density of its prey and predators. I used a 10 year data set of long-term fishery-independent gillnet and longline surveys to explore the effects of abiotic variables on temporal patterns of community structure of fishes and correlates of migration at two seagrass shoals off the FSU Coastal and Marine Laboratory. I examined community structure using non-metric multidimensional scaling (NMDS) with environmental fitting, compared temporal community structure using permutational multivariate analysis of variance (PERMANOVA) of monthly catch rates in both gear types, and tested for cyclicity in community structure. I also used generalized additive models (GAMs) to explore the effects of environmental variables (e.g. temperature and photoperiod) on immigration and emigration phases of dominant taxa. I found strong seasonality and cyclicity in assemblages captured by both gear types, with depauperate winter communities and diverse assemblages in warmer month - especially late summer and fall. My results suggest temperature may determine the timing of immigration and duration of the residency period of dominant taxa, including the juvenile life stages of some coastal sharks, but photoperiod may cue immigration and emigration in adults when the purpose of those migrations includes predicable reproductive functions (e.g. parturition). I found evidence of partial migration in juvenile life stages of some coastal sharks, and hypothesize that rising temperatures due to climate change may have variable effects on residency patterns over ontogeny. I conducted similar fishery-independent sampling in Apalachicola Bay from 2018 to 2020 during the summer to study habitat overlap in multiple life stages of a group of sympatric coastal sharks. I also used data shared with me by the Florida Fish and Wildlife Conservation Commission to explore the relationship of habitat use in coastal sharks to prey distribution and density. My analyses suggested this relationship may vary among species and life stage, as predation risk or environmental tolerances may drive habitat use in early life stages of some species. Prey distribution may be more important for dietary specialists. Interestingly, habitat use of species life stages with increasing reported dietary overlap appeared to converge. Using acoustic telemetry, I described movement and habitat use of bull sharks (Carcharhinus leucas), bonnetheads (Sphyrna tiburo), and gafftopsail catfish (Bagre marinus) in Apalachicola Bay and St. George Sound. I used linear mixed models (LMM) to integrate the tracking information with blue crab (Calinectes sapidus) density data from the same fishery-independent surveys conducted by FWC to explore the predator-prey dynamics of blue crabs, bonnetheads, and bull sharks. All three fishes were resident throughout the summer and were philopatric. Bull sharks used more of the habitat than bonnetheads or gafftopsail catfish. Bonnetheads mainly used seagrass habitats, while gafftopsail catfish used muddy habitats around freshwater inputs. There were relationships of size and the proportion of the acoustic array each species used, with a positive correlation of size and space used in both species of sharks and a negative correlation in gafftopsail catfish, which may be driven my differences between sexes. Bonnetheads were not detected in habitats where blue crabs were most dense, but the probability of bull shark presence was highest. Results of the LMM analyses suggested a significant negative relationship of bonnethead habitat use and bull shark presence probability, as well as a significant negative relationship of the interaction of bull shark presence and salinity (bull shark presence probability was highest at sites with the lowest average salinities). These results suggest habitat use in bonnetheads may follow predictions of optimal foraging theory and the ideal free distribution under the constraint of predation risk, which may be informative in understanding the roles of predation and prey availability in the habitat use of marine mesopredators.

Author: Jeffrey Cohen Carpenter
Publisher:
ISBN:
Category : Fisheries -- Gear selectivity -- Physiological effect
Languages : en
Pages :

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Gill nets and longlines were compared as shark nursery sampling methodologies in inshore waters of Georgia to (1) assess differences in gear selectivity, bias, and stress of capture and (2) determine potential relationships between habitat features and shark distribution and abundance. Gear selectivity varied between gears as a function of both species and life stage resulting in significantly different estimates of species and life stage compositions. Juvenile bonnetheads (Sphyrna tiburo) and young of the year blacktip sharks (Carcharhinus limbatus) experienced significantly higher stress from gill net capture than longline. Major sources of bias are thought to result from dietary preferences and individual size. Juvenile sandbar shark (C. plumbeus) distribution revealed a potential preference for creeks rather than sounds, between 0.32-0.8km wide and 4.02-8.05km from the ocean. Adult Atlantic sharpnose sharks (Rhizoprionodon terraenovae) appear to prefer larger, open sound waters closer to the ocean. A potential preference for locations in close proximity to jetties over those near oyster reefs was also observed for adult Atlantic sharpnose sharks, and while statistical significance was observed, a stronger pattern may exist, as sample sizes in this study were relatively small yet still able to detect a difference. Future investigations that quantify proportions of habitat availability and shark abundance in a given area may be more useful for identifying preferences for the structures observed in this study. This study also provides strong evidence of finetooth shark (C. isodon) primary and potentially secondary nursery habitat in areas that had not yet been documented. Findings from these investigations can be useful for managers seeking to maintain healthy coastal shark populations.

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Category :
Languages : en
Pages :

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Author: Stephen A. Bortone
Publisher: CRC Press
ISBN: 1420040790
Category : Nature
Languages : en
Pages : 329

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The spotted seatrout is an important species not only for recreational and commercial fisheries, but also as an integral part of many estuarine ecosystems. As one of the few fishes that live its entire life within an estuarine system, the species has tremendous potential as a monitor or sentinel for estuarine conditions. Prepared by the foremost au

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Category :
Languages : en
Pages :

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The National Marine Fisheries Service of the U.S. National Oceanic and Atmospheric Administration (NOAA), headquartered in Silver Spring, Maryland, provides information on domestic threatened species. These species are likely to become endangered. The service discusses the population, range, biology, distribution, and major threats and impacts on the smalltooth sawfish. A photograph of the smalltooth sawfish is included.