Controlling for Survey Effort Is Worth the Effort: Comparing Bottlenose Dolphin (Tursiops truncatus) Habitat Use Between Standardized and Opportunistic Photographic-Identification Surveys

McBride-Kebert, Shauna; Taylor, J. Sneyd; Lyn, Heidi; Moore, Frank R.; Sacco, Donald F.; Kar, Bandana; Kuczaj, Stan A.

doi:10.1578/am.45.1.2019.21

Cited by 2 publications

(4 citation statements)

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“…How to best quantify monitoring efforts for demographics studies is an ongoing challenge in ecology (e.g., Symons et al, 2018;McBride-Kebert et al, 2019). Effects of effort on demographics data for live animals have been well studied in fisheries and some targeted marine mammal research (McCluskey and Lewison, 2008;McBride-Kebert et al, 2019;Tiongson et al, 2021), but these approaches typically cannot be applied to marine mammal stranding data. Stranding data typically rely on opportunistic public reporting rather than regular targeted monitoring of a given location.…”

Section: Introductionmentioning

confidence: 99%

Human influence on bottlenose dolphin (Tursiops truncatus) strandings in the northern Gulf of Mexico

Carmichael

Hodanbosi

Russell

et al. 2022

Front. Environ. Sci.

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Human activity affects marine mammal stranding rates in two major ways; through human interaction (HI) that may lead to mortality and through search and response efforts that enable carcass detection. To better quantify the combined effects of these interacting human influences, we analyzed strandings for bottlenose dolphins (Tursiops truncatus) in the northern Gulf of Mexico (nGOM), an area of high cetacean strandings. To identify hotspots of human influence, we first determined the number of total and HI-related bottlenose dolphin strandings normalized to shoreline length in each nGOM U.S. state, which represent major response areas. To estimate the effects of response effort on stranding numbers (for HI and non-HI strandings), we used the Deepwater Horizon oil spill (DWHOS) as an established benchmark to compare periods of lower (pre-spill) and higher (post-spill) response effort. Strandings in Alabama waters were used as a case study to detail spatial and temporal variation due to human influences during the 39-year period of retrospective study. We found an increase in strandings from Louisiana through Alabama following the DWHOS. Non-oil related HI strandings increased in total number in AL, and they increased as a proportion of total strandings in Alabama (16%) and the Florida panhandle (12%). The increase in HI-related strandings in Alabama was driven by mortality of many types, but particularly fishery interactions and cases of apparent intentional harm. The Alabama case study clearly detected lower stranding numbers during periods of low or intermittent response coverage. Our findings are consistent with an overall increase in stranding numbers due to a combination of increased stranding occurrence and response effort following the DWHOS. Importantly, we provide evidence that HI-related standings increased independently from the DWHOS, with ongoing increases in at least one hotspot (Alabama). These findings provide a first step to parsing out different effects of human influences on stranding data for a common coastal cetacean. Our approach establishes baselines for future damage and recovery assessments, identifies areas where resources can be focused for management and education, and highlights the power of response and monitoring agencies to positively influence stranding datasets.

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Section: Introductionmentioning

confidence: 99%

Human influence on bottlenose dolphin (Tursiops truncatus) strandings in the northern Gulf of Mexico

Carmichael

Hodanbosi

Russell

et al. 2022

Front. Environ. Sci.

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“…Additionally, dolphin prey species seasonally migrate to offshore Atlantic waters during winter to spawn and return to estuarine waters during the spring and summer (Gannon & Waples, 2004). McBride-Kebert et al (2019) found that from late spring to early fall, Roanoke Sound dolphins frequently used the southern region of the sound containing the estuary mouth for feeding and traveling. This finding suggests that the dolphins may use Roanoke Sound as a seasonal foraging area and travel corridor between estuaries and Atlantic coastal waters.…”

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confidence: 99%

“…This finding suggests that the dolphins may use Roanoke Sound as a seasonal foraging area and travel corridor between estuaries and Atlantic coastal waters. However, McBride-Kebert et al (2019) did not examine the relationship between habitat characteristics and dolphin distribution, and more information is needed to determine why dolphins seasonally migrate to Roanoke Sound. Our objective was to expand on the study by McBride-Kebert et al (2019) in order to increase our understanding of the interaction between dolphin distribution and habitat characteristics.…”

mentioning

confidence: 99%

“…However, McBride-Kebert et al (2019) did not examine the relationship between habitat characteristics and dolphin distribution, and more information is needed to determine why dolphins seasonally migrate to Roanoke Sound. Our objective was to expand on the study by McBride-Kebert et al (2019) in order to increase our understanding of the interaction between dolphin distribution and habitat characteristics. Specifically, we (1) identified areas that were frequently used by dolphins, (2) determined which activities were observed most often in these frequently used areas, and (3) determined if habitat characteristics and environmental variables were associated with dolphin distribution and activity in Roanoke Sound, North Carolina.…”

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confidence: 99%

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Common Bottlenose Dolphin, Tursiops truncatus, SeasonalHabitat Use and Associations with Habitat Characteristics inRoanoke Sound, North Carolina

McBride-Kebert¹,

Taylor²,

Wilkinson³

et al. 2019

IJCP

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Understanding how habitat characteristics influence common bottlenose dolphin, Tursiops truncatus, distribution and behavior can be useful for conservation. The dolphin community in Roanoke Sound, North Carolina primarily exhibits seasonal residency and there is limited information on their habitat use. The objectives of this study were to increase habitat use knowledge and determine the relationship between habitat characteristics and dolphin distribution using standardized photographic-identification data (2009 – 2017). A hot spot (Getis-Ord Gi*) analysis showed dolphins frequently use the southern region containing the mouth of the estuary for feeding and traveling. Habitat characteristics were modeled with zero-altered gamma (ZAG), generalized linear (GLM), and generalized additive (GAM) models to predict dolphin group density. Models showed that groups were more likely to be present in areas with greater benthic slope variation and shallow areas closer to land, and that different habitat characteristics were associated with feed, social, and travel activities. This study suggests that Roanoke Sound provides a seasonal foraging area and travel corridor between the estuaries and coastal waters. This information contributes baseline knowledge of how habitat potentially influences dolphin distribution and behavior which can be useful for management and conservation, especially in areas where habitat changes and impacts need to be assessed.

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Controlling for Survey Effort Is Worth the Effort: Comparing Bottlenose Dolphin (Tursiops truncatus) Habitat Use Between Standardized and Opportunistic Photographic-Identification Surveys

Cited by 2 publications

References 0 publications

Human influence on bottlenose dolphin (Tursiops truncatus) strandings in the northern Gulf of Mexico

Human influence on bottlenose dolphin (Tursiops truncatus) strandings in the northern Gulf of Mexico

Common Bottlenose Dolphin, Tursiops truncatus, SeasonalHabitat Use and Associations with Habitat Characteristics inRoanoke Sound, North Carolina

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