Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
Fishery and ecological interactions for selected cetaceans, off the northeast United States of America
Abstract
Conservation and management of marine mammal populations requires information on direct and indirect affects of anthropogenic activities, population dynamics, habitat requirements and behavioral ecology. For most populations, particularly the non-hunted smaller whales and dolphins, programs designed to collect these data are relatively new (i.e., two decades old or less). This study utilizes data collected from several recent research programs to address some specific scientific and management issues. Pilot whale by-catch relative to distant-water fleet Atlantic mackerel fishing operations was examined. Although incidental mortality was not correlated to mackerel catch and effort statistics, it was associated with fishing season and depth. By-catch is highest during spring in shelf edge waters when mackerel, fishing activity, and pilot whales are concentrated along a linear habitat. Further, pilot whale behavior in the vicinity of fishing trawlers is an important component of the by-catch problem. Seasonal and spatial overlap patterns between selected cetaceans and prey resources off the northeast U.S. indicate trophic relationships are likely broader than previously hypothesized. The degree of overlap suggests that cetacean trophic requirements are likely buffeted from stock collapse of one or more prey species. However, broad scale correlations were not observed between most cetaceans and prey spatial and temporal abundance data. A dynamic patch model incorporating energetic requirements, probability of mortality "by-catch" and finding food, food value, and habitat type was used to simulate the behavioral ecology of a hypothetical pilot whale in mid-Atlantic shelf edge waters. The model suggested that the forager will make risky decisions at low state (i.e., fat reserves) levels. The general trend was to select the safer patches at high state levels. Reducing food gain versus increasing mortality or travel costs produced the most variability in model results. This variability provides some insight into pilot whale foraging around fishing vessels, since it is assumed that, although the risk of mortality is higher, the energetic costs are lower.
Subject Area
Forestry|Zoology|Oceanography|Ecology
Recommended Citation
Waring, Gordon Thayer, "Fishery and ecological interactions for selected cetaceans, off the northeast United States of America" (1995). Doctoral Dissertations Available from Proquest. AAI9524761.
https://scholarworks.umass.edu/dissertations/AAI9524761