John Neilson results 19
· Newest (Page 1/1, per page 25)
Author: John Neilson ×Clear All Filters
Search Results
Animals within social groups respond to costs and benefits of sociality by adjusting the proportion of time they spend in close proximity to other individuals in the group (cohesion). Variation in cohesion between individuals, in turn, shapes important group‐level processes such as subgroup formation and fission–fusion dynamics. Although critical to animal sociality, a comprehensive understanding of the factors influencing coh...
We delineated and scored Biologically Important Areas (BIAs) for cetacean species in the Gulf of Alaska region. BIAs represent areas and times in which cetaceans are known to concentrate for activities related to reproduction, feeding, and migration, and also the known ranges of small and resident populations. This National Oceanic and Atmospheric Association (NOAA)-led effort uses structured expert elicitation principles to b...
Broadbill swordfish ( Xiphias gladius ) foraging and vertical movements in the n orth‐west A tlanticNARA Subscribed
The northern edge of Georges Bank is an important seasonal foraging habitat for swordfish ( Xiphias gladius ) in the North Atlantic, where aggregations support commercial pelagic longline and harpoon fisheries. Following a period of overfishing during the 1990s, the North Atlantic X. gladius stock underwent a period of recovery during the early 2000s and was considered rebuilt in 2009. We analysed stomach contents from X. glad...
Humpback whales interfering when mammal‐eating killer whales attack other species: Mobbing behavior and interspecific altruism?NARA Subscribed
Humpback whales ( Megaptera novaeangliae ) are known to interfere with attacking killer whales ( Orcinus orca ). To investigate why, we reviewed accounts of 115 interactions between them. Humpbacks initiated the majority of interactions (57% vs . 43%; n = 72), although the killer whales were almost exclusively mammal‐eating forms ( MEKW s, 95%) vs . fish‐eaters (5%; n = 108). When MEKW s approached humpbacks ( n = 27), they at...
Environmental influences on A tlantic bluefin tuna ( Thunnus thynnus ) catch per unit effort in the southern G ulf of S t. L awrenceNARA Subscribed
The A tlantic bluefin tuna ( T hunnus thynnus ) population in the western A tlantic supports substantial commercial and recreational fisheries. Despite quota establishment and management under the auspices of the International Commission for the Conservation of A tlantic T unas, only small increases in population growth have been estimated. In contrast to other western bluefin tuna fisheries indices, contemporary estimates of...
Stable carbon (Δ 13 C) and oxygen (Δ 18 O) in the otolith cores of Atlantic bluefin tuna ( Thunnus thynnus ) vary temporally, with changes that quantitatively follow interdecadal variation in atmospheric and oceanic reservoirs. Both carbon and oxygen isotopic signatures vary significantly by year of birth over the range investigated (1947‐2006), with Δ 13 C decreasing and Δ 18 O increasing (‐2.56 × 10 −2 ‰ and 4.3 × 10 −3 ‰ yr...
Bottom‐up forcing and the decline of Steller sea lions ( Eumetopias jubatus ) in Alaska: assessing the ocean climate hypothesisNARA Subscribed
Declines of Steller sea lion ( Eumetopias jubatus ) populations in the Aleutian Islands and Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976–77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality, and accessibility of prey, which in turn may have affected the rates of birth and death of sea lions. Recent studies of the spatial an...
Wind‐wave development across a large shallow intertidal estuary: A case study of Manukau Harbour, New ZealandNARA Subscribed
Locally generated wind‐waves in estuaries play an important role in the sediment dynamics and the transport of biota. Wave growth in estuaries is complicated by tidally varying depth, fetch, and currents. Wave development was studied at six sites along a transect across Manukau Harbour, New Zealand, which is a large intertidal estuary with a tidal range of up to 4 m. Three meteorological masts were also deployed across the mea...
Previous1Next