摘要:

AbstractThe apparent lack of significant recovery of western North Atlantic right whale populations may be related to the availability of prey in exploitable densities. We have attempted to estimate the concentration of zooplankton required by right whales to obtain a net energetic benefit over the long term, using estimated values for body weight, metabolic rate, assimilation efficiency, time spent feeding, mouth size and swimming speed. The estimated range of required energy densities is 7.57 to 2,394 kcal m−3(3.17 × 104to 1.00 × 107joule m−3). These values are from one to more than three orders of magnitude greater than the densest concentration sampled in the vicinity of right whale aggregations in the Great South Channel. Right whales must seek out and exploit extremely dense patches of prey organisms in order to feed efficiently. The presence of such dense patches of zooplankton is likely to be a primary characteristic of spring, summer and fall right whale hab

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe incidental catch of northern sea lions (Eumetopias jubatus) in the walleye pollock (Theragra chalcogramma) joint‐venture fishery in Shelikof Strait, Alaska, was studied during 1982–1984 to assess the nature and magnitude of the catch. Data were obtained by placing U.S. observers on foreign processing vessels. Dead sea lions recovered from trawl nets were counted, sexed and measured, teeth were removed for age determination by dental laminae; and stomach contents were analyzed. Although the fishery has continued to expand both in number of boats and estimated total catch (74,136 metric tons [t] in 1982 to 171,539 t in 1984), the estimated incidental catch of northern sea lions has declined (ranging from 958 to 1,436 in 1982, 216 to 324 in 1983 and 237 to 355 in 1984). Of the sea lions processed, 73 percent were caught between 2000 and 0500 h, probably during net retrieval. Most caught sea lions were females ranging in age from 1–25 yr with a mean age of 6.43 yr; 79 percent of the females were sexually mature and probably part of the reproducing population. Males had a mean age of 4.8 yr and only 12 percent were old enough to obtain and defend territories. Analysis of stomach contents showed that the sea lions consumed pollock the same size as that taken by the commercial fishery. The impact of the incidental catch on the Gulf of Alaska sea lion population is un

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe authors review the literature on bottlenose dolphin ecology, behavior and social organization, focusing on data collected on free‐ranging animals. Most bottlenose dolphins studied to date have had definable home ranges, and behavioral, morphological and biochemical information indicates discrete stocks in some areas. Bottlenose dolphins appear to form relatively permanent social groups based on sex and age. Mother—calf bonds are long‐lasting. Movement patterns are extremely variable from location to location but are relatively predictable at any given site. Food resources are one of the most important factors affecting movements. Bottlenose dolphin behavior is very flexible, and these dolphins are generally active day and night. Feeding peaks in the morning and afternoon have been observed at several sites. Social behavior is an important component of daily activities. Sharks are the most significant predator on bottlenose dolphins in most areas, but captive and wild studies show that dolphins and sharks frequently live in harmony as well. Human activities may be helpful, harmful or neutral to bottlenose dolphins, but interactions with humans are frequent for these coastal ceta

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00026.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA school of 41 sperm whales,Physeter macrocephalus, that stranded near the mouth of the Siuslaw River, Oregon (43°59′N, 124°08′W), on 16 June 1979 consisted of 13 males and 28 females. Their ages were estimated by assuming that each postnatal dentin layer represents one year. The males were all sub‐adults, 9.3–11.5 m long and 14–21 yr old. The females were 9.3–11.4 m long, and 11 to about 58 yr old. Ten females were dissected; nine were sexually mature and three were carrying fetuses 2.64–4.62 m long. None of the 28 females was vi

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00027.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00028.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00029.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00030.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00031.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00032.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Book reviews in this article:TheGrayWhaleEschrichtiusRobustus. M. L. Jones, S. L. Swartz and S. Leatherwood (eds.).Diving andAsphyxia. R. Elsner and B. Gooden.Studies ofSeaMammals inSouthLatitudes. J. K. Ling and M. M. Bryden (eds.).LesPhoquesMoines—MonkSeal. K. Ronald and R. Duguy (eds.

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1986.tb00033.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY