[MARMAM] More on marine mammals vs fisheries interactions
lyne.morissette at globetrotter.net
Wed Aug 6 03:50:39 PDT 2008
After my message posted last week, I received many requests and
comments on our 'marine mammals vs fisheries' work. In line with
that, I would thus want to recommend you this earlier paper on the
"The trophic role of marine mammals in the Northern Gulf of St.
Mike O. Hammill
This paper is available in Marine Mammal Science 22(1): 74-103
The trophic role of apex predators was evaluated in the northern Gulf
of St. Lawrence ecosystem. An Ecopath model was developed for the
1985-1987 period prior to the collapse of commercially exploited
demersal fish stocks in this area. Marine mammal trophic levels were
estimated by the model at 4.1 for cetaceans, 4.4 for harp seals
(Phoca groenlandica), 4.7 for hooded seals (Cystophora cristata), 4.5
for gray seals (Halichoerus grypus), and 4.3 for harbor seals (Phoca
vitulina). Harp seals were the third most important predator on
vertebrate prey following large Atlantic cod (Gadus morhua) and
redfish (Sebastes spp.). Different seal species preyed on different
levels of the food chain. Harp seals preyed on most trophic groups,
whereas larger seals, such as gray seals and hooded seals, mainly
consumed higher trophic levels. The model suggested that apex
predators had a negative effect on their dominant prey, the higher
trophic level fish, but an indirect positive feedback on the prey of
their preferred prey, mainly American plaice (Hippoglossoides
platessoides), flounders, skates, and benthic invertebrates. Our
results suggest that both marine mammals and fisheries had an impact
on the trophic structure.
Keywords: Ecosystem model, predation, harp seal, gray seal, harbor
seal, hooded seal, cetaceans, predation, Gulf of St. Lawrence, food web.
PDF is also available upon request at: lyne.morissette at globetrotter.net.
Lyne Morissette, Ph.D.
Arizona State University
email: lyne.morissette at asu.edu
University of British Columbia
e-mail: l.morissette at fisheries.ubc.ca
Lenfest Ocean Program
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the MARMAM