Heterogeneity and the mark–recapture assessment of the Scotian Shelf population of northern bottlenose whales (Hyperoodon ampullatus)

2005 ◽  
Vol 62 (11) ◽  
pp. 2573-2585 ◽  
Author(s):  
Hal Whitehead ◽  
Tonya Wimmer
Keyword(s):  
High Probability ◽  
Temporal Trend ◽  
Parametric Bootstrap ◽  
Estimation Procedure ◽  
Submarine Canyon ◽  
Mixed Population ◽  
Scotian Shelf ◽  
Mark Recapture ◽  
Northern Bottlenose Whales ◽  
Hyperoodon Ampullatus

A population of northern bottlenose whales (Hyperoodon ampullatus) inhabits the waters along the edge of the Scotian Shelf. The most important habitat of this population is the Gully, a large submarine canyon, where animals were photographically identified between 1988 and 2003. Open mark–recapture models, including mixture models that allow for heterogeneity in identifiability and (or) mortality among individuals, were fitted to identification-history data. Models without heterogeneity in identifiability had poor fit to the data and underestimated population size. The population is estimated to contain about 163 animals (95% confidence interval 119–214), with no statistically significant temporal trend. About 12% of the population has a high probability of being identified within the Gully in any year. Many of them are mature males. The remainder is less likely to be identified in the Gully during any year, spend generally shorter periods in the Gully even in years when they are found, and are more likely to be female. This and other work indicate a poorly mixed population inhabiting the canyons and other deeper waters off the Scotian Shelf. Non parametric bootstrap methods were used to validate the estimation procedure and to estimate the efficiency of future fieldwork scenarios.

Distribution and behaviour of male sperm whales on the Scotian Shelf, Canada

1992 ◽  
Vol 70 (5) ◽  
pp. 912-918 ◽  
Author(s):  
Hal Whitehead ◽  
Sebastian Brennan ◽  
David Grover
Keyword(s):  
Social Organization ◽  
Submarine Canyon ◽  
Mature Male ◽  
Consistent Pattern ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Scotian Shelf ◽  
Male Sperm ◽  
Northern Bottlenose Whales ◽  
The Tropics

Studies of mature male sperm whales (Physeter macrocephalus) were carried out on the Scotian Shelf during the summers of 1986, 1988, 1989, and 1990. Sperm whales were found principally along the edge of the Shelf, although there were some encounters in water less than 100 m deep. Within the Gully, a prominent submarine canyon, sperm whales showed a consistent pattern of distribution between years, distinct from that of northern bottlenose whales (Hyperoodon ampullatus). Some male sperm whales were individually identified in the Gully after periods of 2–47 days, and in one case, after 2 years. The male sperm whales showed little evidence of social organization and rarely performed aerial behaviour. However, their diving behaviour was similar to that observed from female sperm whales in the tropics. On one occasion a group of presumed female and immature sperm whales entered the Gully, attracting the attention of resident mature males.

scholarly journals Movements and distribution of northern bottlenose whales, Hyperoodon ampullatus, on the Scotian Slope and in adjacent waters

2004 ◽  
Vol 82 (11) ◽  
pp. 1782-1794 ◽  
Author(s):  
Tonya Wimmer ◽  
Hal Whitehead
Keyword(s):  
Deep Water ◽  
Optimal Foraging ◽  
Submarine Canyon ◽  
Optimal Foraging Theory ◽  
Primary Resource ◽  
Depth Contour ◽  
Endangered Population ◽  
Northern Bottlenose Whales ◽  
Important Habitat ◽  
Hyperoodon Ampullatus

A small, apparently isolated, and endangered population of ~130 northern bottlenose whales (Hyperoodon ampullatus Forster, 1770) is found on the Scotian Slope south of Nova Scotia, Canada. Virtually all previous information on these animals had come from the Gully, a large submarine canyon where the northern bottlenose whales can be reliably found. A ship survey along the 1000 m depth contour in 2001 showed northern bottlenose whales only in the Gully, Shortland canyon (50 km east of the Gully), and Haldimand canyon (100 km east of the Gully). Studies in 2002 reconfirmed the presence of the whales in these other canyons, although densities were about 50% lower than in the Gully. Photo-identifications showed that individuals moved between the Gully and Shortland and Haldimand canyons over periods from days to years, with mean stays in any canyon of about 22 days. However, the population was not fully mixed: at least some individuals had preferences for particular canyons. The sex ratios were similar in all canyons, but males had higher rates of movement between canyons. These results are consistent with the expectations of optimal foraging theory, when the primary resource for females, deep-water squid of the genus Gonatus Gray, 1849, is more temporally stable than the primary resource for males, which is assumed to be receptive females. Haldimand and Shortland canyons are clearly important habitat for this species, and should receive appropriate protection.

Stomach contents of northern bottlenose whales Hyperoodon ampullatus stranded in the North Sea

2001 ◽  
Vol 81 (1) ◽  
pp. 143-150 ◽  
Author(s):  
M.B. Santos ◽  
G.J. Pierce ◽  
C. Smeenk ◽  
M.J. Addink ◽  
C.C. Kinze ◽  
...  
Keyword(s):  
The Netherlands ◽  
Stomach Contents ◽  
Important Species ◽  
North East ◽  
The North ◽  
Northern Latitudes ◽  
The North Sea ◽  
Fish Remains ◽  
Northern Bottlenose Whales ◽  
Hyperoodon Ampullatus

This paper presents information on the stomach contents of four northern bottlenose whales Hyperoodon ampullatus (Odontoceti: Ziphiidae) from the north-east Atlantic, an area for which there are few recent data on the feeding ecology of this species. Two of these whales were relatively recent strandings, a female stranded in August 1993 at Hargen (the Netherlands) and a male stranded in February 1997 on the island of Tåsinge (Denmark). Stomach content samples were also examined from a juvenile male stranded in November 1885 at Dunbar (Scotland) and a female stranded in August 1956 on the island of Texel (the Netherlands).  Food remains from the four samples consisted almost entirely of cephalopod beaks. Some fish remains were also found in the stomach of the Hargen and Tåsinge whales, and the latter also had crustacean remains in the stomach. The cephalopod prey consisted mainly of oceanic cephalopods: Gonatus sp. (probably G. fabricii, Cephalopoda: Teuthoidea), Taoniuspavo and Histioteuthis sp. for the Dunbar whale; Gonatus and Teuthowenia megalops for the Texel whale; Gonatus for the Hargen whale and Gonatus, T. megalops and Taonius pavo for the Tåsinge whale. Other prey species found in the Tåsinge specimen included the squid Histioteuthis reversa, H. arcturi, and the octopods Vampiroteuthis infernalis and Vitreledonella richardi. Based on the size of the lower beaks, the squid eaten included juvenile and mature individuals of the most important species (Gonatus and Teuthowenia megalops). The fish remains consisted of vertebrae of Gadidae and fish eye lenses (Hargen whale) and two Trisopterus otoliths (Tåsinge whale).  The results from this study are in agreement with those of previous authors in that cephalopods in general, and G. fabricii in particular, are the main prey of the northern bottlenose whale and other toothed whales in northern latitudes.

scholarly journals A Two-Player Iterated Survival Game

2018 ◽  
Author(s):  
John Wakeley ◽  
Martin Nowak
Keyword(s):  
Overall Survival ◽  
High Probability ◽  
Evolutionary Games ◽  
Single Step ◽  
Mixed Population ◽  
Pairwise Interactions ◽  
Player Game ◽  
Expected Payoffs ◽  
Number Of Iterations ◽  
Over Time

AbstractWe describe an iterated game between two players, in which the payoff is to survive a number of steps. Expected payoffs are probabilities of survival. A key feature of the game is that individuals have to survive on their own if their partner dies. We consider individuals with hardwired, unconditional behaviors or strategies. When both players are present, each step is a symmetric two-player game. The overall survival of the two individuals forms a Markov chain. As the number of iterations tends to infinity, all probabilities of survival decrease to zero. We obtain general, analytical results for n-step payoffs and use these to describe how the game changes as n increases. In order to predict changes in the frequency of a cooperative strategy over time, we embed the survival game in three different models of a large, well-mixed population. Two of these models are deterministic and one is stochastic. Offspring receive their parent’s type without modification and fitnesses are determined by the game. Increasing the number of iterations changes the prospects for cooperation. All models become neutral in the limit (n → ∞). Further, if pairs of cooperative individuals survive together with high probability, specifically higher than for any other pair and for either type when it is alone, then cooperation becomes favored if the number of iterations is large enough. This holds regardless of the structure of pairwise interactions in a single step. Even if the single-step interaction is a Prisoner’s Dilemma, the cooperative type becomes favored. Enhanced survival is crucial in these iterated evolutionary games: if players in pairs start the game with a fitness deficit relative to lone individuals, the prospects for cooperation can become even worse than in the case of a single-step game.

scholarly journals Pollock (Pollachius virens) stock structure in the Canadian Maritimes inferred from mark-recapture studies

2006 ◽  
Vol 63 (4) ◽  
pp. 749-765 ◽  
Author(s):  
John D. Neilson ◽  
Wayne T. Stobo ◽  
Peter Perley
Keyword(s):  
Gulf Of Maine ◽  
Atlantic Coast ◽  
Fishing Effort ◽  
Management Unit ◽  
Bay Of Fundy ◽  
Stock Structure ◽  
Scotian Shelf ◽  
Current Management ◽  
Mark Recapture ◽  
Novel Method

Abstract The current management unit for pollock on the Canadian Atlantic coast is large compared with other gadoid resources, and includes the Scotian Shelf, the Bay of Fundy, and the Canadian portion of Georges Bank. Based on an analysis of mark-recapture studies conducted in the Canadian Maritimes and off southwestern Newfoundland and a review of other published studies providing data relevant to stock identification, the stock structure of pollock in Canadian Atlantic waters was re-assessed. The analysis also includes a novel method for using the spatial distribution of standardized fishing effort to predict the distribution of tag returns. It is concluded that three stocks co-occur within the current management unit. The larger population components exist in the western Scotian Shelf (including the eastern Bay of Fundy) and on the eastern Scotian Shelf. There is a coastal population in the western Gulf of Maine that overlaps into Canadian waters, but its size is likely to be relatively small. There is a need to revise the current management unit boundaries to protect the eastern Scotian Shelf stock, which on the basis of growth rate data, appears to be the least productive component of the pollock resource in Canadian Atlantic waters.

Distribution and habitat partitioning by small odontocetes in the Gully, a submarine canyon on the Scotian Shelf

1995 ◽  
Vol 73 (9) ◽  
pp. 1599-1608 ◽  
Author(s):  
Shannon Gowans ◽  
Hal Whitehead
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Submarine Canyon ◽  
Sea Surface ◽  
Scotian Shelf ◽  
Sea Floor ◽  
Delphinus Delphis ◽  
Pilot Whales ◽  
Summer Distribution ◽  
Common Dolphins

In this paper we examine the summer distribution of three species of small odontocetes in the highly productive waters in and near the Gully, a submarine canyon on the edge of the Scotian Shelf. Atlantic white-sided dolphins (Lagenorhynchus acutus) and common dolphins (Delphinus delphis) were not randomly distributed with respect to depth, sea-floor relief, month of sighting, or sea-surface temperature. Long-finned pilot whales (Globicephala melas) were not randomly distributed with respect to month or sea-surface temperature. These species used the Gully slightly differently, although there was overlap. White-sided dolphins were seen only in the core of the canyon, but were sighted at all temperatures, depths, and sea-floor reliefs and throughout the summer field season. Common dolphins had a modest range throughout the deeper waters and were not seen in the summer before July, when the water warms. Pilot whales ranged widely over the study area, preferring areas with fairly flat relief and were more common later in the summer, when the waters were warmer. It appears that white-sided and common dolphins partition the Gully temporally but not geographically.

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