Event Title
Unusual Open Water Grouping Behavior in Salish Sea Harbor Seals (Phoca vitulina richardii)
Streaming Media
Presentation Abstract
Most pinniped species are relatively solitary when in water, but some species, most notably the otariids, will form large groupings (referred to as rafts) in open water for thermoregulation or rest, as well as participating in group foraging behaviors. Alternatively, individuals of many species may concentrate in one area, forming foraging aggregations when prey are in high abundance. Open water grouping behavior that is distanced from haulout sites is less common in phocid species, and in particular has not been documented in the literature for harbor seals (Phoca vitulina richardii). In the Salish Sea, the inland waters of Washington, United States and British Columbia, Canada, harbor seals are the most abundant pinniped species. Recent observations in two locations in the south and central Salish Sea have documented large groupings ranging from 6 to 50 individuals (x=23.9) not located near haulout sites (more than at least 1 mile from known large group haulout locations). These observations occurred only in April/May 2019-2020 off Fidalgo Island (n=14) and in February 2017 and January 2019 in southern Puget Sound (n=2). These groups consisted of only adults/juveniles floating together within 1-2 body lengths of each other, unlike larger aggregations where individuals are in the same area, but not necessarily as a group. Some observations included systematic diving where individuals took turns periodically diving, appearing to be foraging, while others remained at the surface. This behavior appears to differ from the rafting behavior observed in otariids. Though harbor seals are known to habitually haul out together on beaches or islands, grouping behavior while in the water, like that observed here, has not been previously described. The purpose of such large groupings is unknown and continued monitoring of these occurrences and further analysis of behavior is needed.
Session Title
Poster Session 2: The Salish Sea Food Web and Cycles of Life
Conference Track
SSE14: Posters
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-posters-202
Start Date
26-4-2022 4:30 PM
End Date
26-4-2022 5:00 PM
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Unusual Open Water Grouping Behavior in Salish Sea Harbor Seals (Phoca vitulina richardii)
Most pinniped species are relatively solitary when in water, but some species, most notably the otariids, will form large groupings (referred to as rafts) in open water for thermoregulation or rest, as well as participating in group foraging behaviors. Alternatively, individuals of many species may concentrate in one area, forming foraging aggregations when prey are in high abundance. Open water grouping behavior that is distanced from haulout sites is less common in phocid species, and in particular has not been documented in the literature for harbor seals (Phoca vitulina richardii). In the Salish Sea, the inland waters of Washington, United States and British Columbia, Canada, harbor seals are the most abundant pinniped species. Recent observations in two locations in the south and central Salish Sea have documented large groupings ranging from 6 to 50 individuals (x=23.9) not located near haulout sites (more than at least 1 mile from known large group haulout locations). These observations occurred only in April/May 2019-2020 off Fidalgo Island (n=14) and in February 2017 and January 2019 in southern Puget Sound (n=2). These groups consisted of only adults/juveniles floating together within 1-2 body lengths of each other, unlike larger aggregations where individuals are in the same area, but not necessarily as a group. Some observations included systematic diving where individuals took turns periodically diving, appearing to be foraging, while others remained at the surface. This behavior appears to differ from the rafting behavior observed in otariids. Though harbor seals are known to habitually haul out together on beaches or islands, grouping behavior while in the water, like that observed here, has not been previously described. The purpose of such large groupings is unknown and continued monitoring of these occurrences and further analysis of behavior is needed.
