[MARMAM] Fin and blue whales in the Porcupine Seabight, offshore Ireland
mickbaines at gmail.com
Mon Jun 26 10:33:06 PDT 2017
Dear list members,
We are happy to announce the publication of our paper:
*An autumn aggregation of fin (Balaenoptera physalus) and blue whales (B.
musculus) in the Porcupine Seabight, southwest of Ireland*
Mick Baines, Maren Reichelt & Donal Griffin.
Deep Sea Research Part II: Topical Studies in Oceanography, Volume 141,
July 2017, Pages 168–177
During a 16 week geophysical survey over the Porcupine Seabight (PSB)
southwest of Ireland in July to October 2013, marine mammal observers
logged 9382 km of effort. Balaenopterid whales comprised some 60% of a
total of 373 cetacean sighting events (s), with a cumulative count (n) of
392 whales. Fin whales (Balaenoptera physalus) were especially abundant
(s=111, n=209) and the number of blue whales (B. musculus) seen (s=12,
n=16) exceeded the total previously reported from Irish waters, but 43% of
balaenopterid sightings (s=98, n=172) were not identified to species level.
Data for all balaenopterid whales were pooled and generalised additive
models applied to identify environmental variables that predicted whale
density and to estimate abundance and the spatial distribution of density.
Depth range and chlorophyll-a concentration were significant predictors of
whale presence, and depth and sea floor rugosity were significant
predictors of group size. There appeared to be an influx of whales in
September and October and the predicted abundance peaked in October with an
estimate of 138 (95% CI 121–151) whales. Analysis of the direction of
movement of whales showed no significant bias in any one direction. Feeding
behaviour was observed in both whale species and circumstantial evidence
suggested that they were aggregating to exploit seasonally abundant
northern krill (Meganyctiphanes norvegica). Chasing behaviour observed
among fin whales was interpreted as evidence that this aggregation also
provided opportunities for social interaction related to their reproductive
cycle. The PSB may provide a link between the high latitude summer feeding
habitats of krill-feeding whales and a chain of highly productive habitats
in the Eastern Boundary Upwelling Ecosystems and we suggest that whales may
migrate southwards in autumn along this eastern route to the northwest
African upwelling zones, where productivity peaks in winter.
Copies are available from the publisher at:
Alternatively, contact mickbaines at gmail.com for a pdf file.
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