Analysis of humpback whale sounds from the Southern Ocean.


Contact
Ilse.van.Opzeeland [ at ] awi.de

Abstract

Humpback whales are a highly vocal baleen whale species. Alongside social sounds produced by both sexes, male humpback whales also produce song, which is thought to play a role in reproduction processes during the breeding season. Humpback whales are traditionally thought to seasonally migrate between winter breeding areas in lower latitudes and summer feeding areas in higher latitudes. Evidence of offseason humpback whale (Megaptera novaeangliae) acoustic presence in high latitude feeding areas is accumulating for Northern Hemisphere waters. For the Southern Ocean seasonal patterns in humpback whale vocal behaviour have to date only been investigated for a coastal site. This study provides preliminary year-round baseline data from 2011 from three offshore recording sites on humpback whale vocal behaviour on Antarctic feeding grounds. Passive acoustic recorders were located along a transect from the Greenwich meridian to the Antarctic continent, at 59’S (AWI227- 11_SV0002), at 64’S (AWI229-9_SV1000) and 66’S (AWI230-7_SV1001). Humpback whales were found to be acoustically present from January to August (AWI227- 11_SV0002), from January to June (AWI229-9_SV1000) and from January until May (AWI230-7_SV1001). Acoustic presence was most pronounced (>80% of recording days containing calls) from May to August (AWI227- 11_SV0002), and April to May (AWI229-9_SV1000 and AWI230-7_SV1001) concurring with substantial local increases in ice cover. From January to March acoustic presence was sparser (<35% of recording days containing calls). Calls were divided into 27 call categories with a maximum of 10 subtypes per category. For all three recorders 4 to 8 call categories made up <80% of all calls, three call categories of which were the same for all three recorders. The vocal repertoire was more diverse in March, April and May compared to January, February, June, July and August in all three recorders. Furthermore, humpback whale song was present at all three recording sites, at AWI227- 11_SV0002 in May and June, AWI229-9_SV1000 in April and May and AWI230-7_SV1001 in April. This study presents new insights with respect to the spatio- temporal patterns in presence of humpback whale acoustic presence on Southern Ocean feeding grounds, showing that at least part of the population resides in Antarctic waters into the seasonal breeding season. It seems that humpback whales move further north with extending ice coverage, as they were present until the end of May on the southernmost recording site at 66°S and left this area possibly by the influence of expanding ice.



Item Type
Thesis (Master)
Authors
Divisions
Primary Division
Programs
Primary Topic
Research Networks
Peer revision
Not peer-reviewed
Publication Status
Published
Eprint ID
49002
Cite as
Mueller, S. (2017): Analysis of humpback whale sounds from the Southern Ocean. , Master thesis, University of Oldenburg.


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