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Hatch J.M.,Integrated Statistics Inc. | Wiley D.,Stellwagen Bank National Marine Sanctuary | Murray K.T.,National Oceanic and Atmospheric Administration | Welch L.,U.S. Fish and Wildlife Service
Conservation Letters | Year: 2016

Identifying the overlap of commercial fishing grounds and seabird habitat can suggest areas of high bycatch risk and inform management and mitigation measures. We used Bayesian state space modeling to describe the movements of 10 satellite-tagged Great Shearwaters and a bivariate kernel density technique to investigate spatial overlap with commercial fishing effort to predict areas of high bycatch in the Gulf of Maine. We then used contemporaneous fishery observer data to test the validity of our predictions, highlighting an area constituting 1% of the Gulf of Maine as having the highest bycatch risk that accounted for 50% of observed takes. Fishery observer data also provided insights into characteristics of the seabird-fishery interactions. Our results indicate that a relatively small number of satellite-tagged seabirds, when combined with fishery-dependent data, can lead to identifying high-bycatch areas, particular fishing practices that might increase risk, and fishing communities that could be targeted for education/mitigation. © 2016 Wiley Periodicals, Inc. Source


Stanistreet J.E.,Northeast Fisheries Science Center | Stanistreet J.E.,Duke University | Risch D.,Integrated Statistics Inc. | Van Parijs S.M.,Northeast Fisheries Science Center
PLoS ONE | Year: 2013

Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring. Source


Elvin S.S.,Integrated Statistics Inc.
Environmental Development | Year: 2014

As an apex predator dependent on sea ice as habitat for catching prey, polar bears (Ursus maritimus) are threatened in terms of survival rates due to the loss of sea ice in relation to climate change. Current management plans have made modest progress in providing adequate assessment and management of the 19 polar bear subpopulations in the five nations containing the subpopulations: Canada, Russia, Greenland, Norway, and the USA. Polar bears are distributed across Large Marine Ecosystems (LMEs) where changes in ice cover are affecting their survival. This paper describes the utility of a transboundary ecosystem-based adaptive management approach to sustain polar bear subpopulations during climate change. The LME framework provides a means to measure change in five modules (productivity, fish and fisheries and marine mammals, pollution and ecosystem health, socioeconomics, and governance) and assess changes in environmental conditions to initiate conservation and recovery. In particular, this paper demonstrates that the LME approach can provide a means of diagnostic analyses and strategic planning for transboundary polar bear conservation in Arctic LMEs during climate change. © 2014 Elsevier B.V. Source


McElroy W.D.,Integrated Statistics Inc. | Wuenschel M.J.,National Oceanic and Atmospheric Administration | Towle E.K.,Integrated Statistics Inc. | McBride R.S.,National Oceanic and Atmospheric Administration
Journal of Sea Research | Year: 2015

Potential annual fecundity (PAF) was estimated over three years (2010-2012) for yellowtail flounder with individuals from the three stocks off the northeast U.S. coast. Down-regulation of PAF, the resorption of oocytes during development, was evident as the vitellogenic cohort advanced, so we directly measured atresia of vitellogenic oocytes using stereological techniques. PAF models including relative fish condition, stock area, year, and oocyte diameter of the leading cohort explained more variation than models with just size alone based on Akaike information criteria. In a given year, Gulf of Maine females had lower PAF at size than southern New England females. Interannual differences were evident: PAF of both stocks was higher in 2010 and lower in 2012, with 2011 showing less synchronization between these stocks. Differences in size at age and relative condition suggested that energy available for somatic and reproductive growth was lower in some years in the Gulf of Maine and Georges Bank, especially in 2011. Georges Bank PAF and condition were intermediate to the other stocks or more similar to the Gulf of Maine, varying annually. A latitudinal gradient in PAF is evident based on our results and relative to earlier studies that included Canadian stocks. The magnitude of down-regulation was variable across stocks and typically 3-25% of PAF. This can be accounted for in fecundity estimates, by the seasonal schedule of sampling and use of an oocyte diameter term in the fecundity model. Theoretical models of atresia patterns suggested variable rates over the later portion of clutch development. The timing of down-regulation varied among years, and its intensity was influenced by female relative condition. Fecundity was related to fish size, but was also affected by fish condition and oocyte diameter (a proxy for time until spawning), and spatial and temporal effects. A longer time series of PAF may identify environmental drivers that modulate annual stock reproductive potential. © 2015 Elsevier B.V. Source


McElroy W.D.,Integrated Statistics Inc. | McElroy W.D.,National Oceanic and Atmospheric Administration | Wuenschel M.J.,National Oceanic and Atmospheric Administration | Towle E.K.,Integrated Statistics Inc. | And 2 more authors.
Journal of Sea Research | Year: 2016

Potential annual fecundity (PAF) was estimated over three years (2010-2012) for yellowtail flounder with individuals from the three stocks off the northeast U.S. coast. Down-regulation of PAF, the resorption of oocytes during development, was evident as the vitellogenic cohort advanced, so we directly measured atresia of vitellogenic oocytes using stereological techniques. PAF models including relative fish condition, stock area, year, and oocyte diameter of the leading cohort explained more variation than models with just size alone based on Akaike information criteria. In a given year, Gulf of Maine females had lower PAF at size than southern New England females. Interannual differences were evident: PAF of both stocks was higher in 2010 and lower in 2012, with 2011 showing less synchronization between these stocks. Differences in size at age and relative condition suggested that energy available for somatic and reproductive growth was lower in some years in the Gulf of Maine and Georges Bank, especially in 2011. Georges Bank PAF and condition were intermediate to the other stocks or more similar to the Gulf of Maine, varying annually. A latitudinal gradient in PAF is evident based on our results and relative to earlier studies that included Canadian stocks. The magnitude of down-regulation was variable across stocks and typically 3-25% of PAF. This can be accounted for in fecundity estimates, by the seasonal schedule of sampling and use of an oocyte diameter term in the fecundity model. Theoretical models of atresia patterns suggested variable rates over the later portion of clutch development. The timing of down-regulation varied among years, and its intensity was influenced by female relative condition. Fecundity was related to fish size, but was also affected by fish condition and oocyte diameter (a proxy for time until spawning), and spatial and temporal effects. A longer time series of PAF may identify environmental drivers that modulate annual stock reproductive potential. © 2015 Elsevier B.V.. Source

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