JFM99 Quarterly Rpt. sidebar
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(Quarterly Report for Jan-Feb-March 1999)
Gray
Whale Workshop
The National Marine Fisheries
Service (NMFS) sponsored a review of the status of the eastern North Pacific stock of gray
whales (Eschrichtius robustus). The workshop was held by the National Marine
Mammal Laboratory (NMML) in Seattle on 16-17 March 1999. Thirty-seven people
attended. The review concluded the 5-year assessment of the stock following the June 1994
delisting from the List of Endangered and Threatened Wildlife. Based on the
continued growth of this population (rising at 2.5% per year; currently at an estimated
26,600 individuals) and the lack of evidence of any imminent threats to the stock, the
participants recommended to continue this stocks classification as nonthreatened.
Other reports presented at the workshop showed that the widely reported delay in the
southbound migration and unusually high levels of strandings in Mexico this year were not
significantly different from other years. Those attending the workshop concluded that
abundance monitoring should continue and that, ideally, research should continue on human
impacts to critical habitats. This stocks annual migrations along the highly
populated coastline of the western United States and its concentration in limited winter
and summer areas may make it particularly vulnerable to impacts from commercial or
industrial development or local catastrophic events.
By Dave Rugh and Marcia Muto.
Pinniped
Predation on Endangered Salmonids
NMML staff are completing laboratory
analysis of harbor seal and sea lion food habits in the Columbia, Umpqua, and Ozette
Rivers in preparation for the workshop Assessing Impacts of Pinniped Predation
on Endangered Salmonids scheduled for 21 - 23 April in Newport, Oregon. The
objectives of the workshop are 1) to evaluate methods of estimating consumption of ESA
(Endangered Species Act)-listed salmon and 2) to evaluate salmon life history models for
evaluating the impact of measured predation on the recovery of listed fish runs.
At the workshop NMML staff will present the reports Food
habits of harbor seals in the lower Columbia River and Prey consumption
estimates for harbor seals in the lower Columbia River and the draft reports
Food habits of harbor seals from Umpqua River and Food habits of
harbor seals, California sea lions and Steller sea lions at Ozette River.
An interesting aspect of the studies
of harbor seals at the Umpqua River has been the potential harbor seal predation on the
endangered Umpqua River cutthroat trout. Scat collections from autumn of 1997 were
cleaned and the prey remains were identified. Samples contained a few salmonid
otoliths and identifiable bone. There was no indication of feeding on cutthroat
trout, although a number of the samples contained bone of salmonids which could not be
identified to species. In a collaborative effort, the Northwest Fisheries Science
Center (NWFSC) extracted DNA from those bone samples and has been able to provide species
identifications in almost all of the samples. The extraction of DNA from prey
remains is an important new tool which aids in distinguishing between species and perhaps
even stocks of salmonids in studies along the West Coast.
By Bob DeLong.
Steller Sea Lion
Prey and Foraging Studies
Scientists from NMFS and the U.S.
Fish and Wildlife Service (USFWS) conducted an echo integration-midwater trawl
survey for Steller sea lion (Eumetopias jubatus) prey at three sites in
Alaska waters during 2-25 March 1999 aboard the USFWS vessel Tiglax for a total of
23 sea days. The area of operations included the Kiska, Kasatochi, and Ugamak
rookeries and waters surrounding these sites.
A total of 401 km of transects were
run at the three sites, 276 km during the day and 125 km at night. At Kiska,
Kasatochi, and Ugamak 40%, 100%, and 90% of the transects were completed, respectively.
Long-line sets or midwater trawls were not conducted due to rough weather. One neuston
surface tow was made to verify echosign, verifying the presence of larval fish.
Preliminary estimates suggest that midwater biomass was greatest at Ugamak rookery and
declined to the west, but these data remain to be analyzed. Additionally, oceanographic
seabird and marine mammal sighting data were recorded throughout the trip, all of which
are currently being analyzed.
The cruise was moderately
successful, though rough weather conditions were more prevalent than in past trips.
The vessel and crew performed admirably during periods of stormy weather. The
vessel continues to provide an excellent platform for winter work.
By Kathryn Chumbley.
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