Interannual variation in the summer diets of harbour seals Phoca vitulina at Mousa, Shetland (UK)

E. G. Brown, Graham John Pierce, J. R. G. Hislop, Maria Begona Santos Vazquez

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The main prey species in the summer (July-September) diets of harbour seals (Phoca vitulina) on the Island of Mousa (Shetland, UK), 1994-1997, were waiting (Merlangius merlangus), herring (Clupea harengus), sandeel (Ammodytidae) and garfish (Belone belone). Norway pout (Triopterus esmarkii) was numerically important but comprised no more than 11% of prey weight in any year. There were marked bet,, een-year fluctuations in the relative importance of these prey, with whiting comprising 16-34% (by weight) of the diet, herring 12-28%, sandeels 7-18% and garfish 7-22%, Additional data on spring (April-June) diet were available for 1995-1997: sandeels were the most important prey (% weight) in all three years (51-60% of the diet), while herring (8-48%) and gadids (2-22%) varied in importance. The average size of fish eaten was larger than that reported in comparable studies from other areas. Harbour seals appear to have selected larger sandeels, whiting and Norway pout than (lie average size available in the area, as indicated by survey trawls, although between-year changes in the size of Norway pout in the diet did to some extent reflect availability. Interannual variation in the importance of Norway pout in the diet appeared to track trend,) in abundance, although the short time series precluded detection of a statistically significant correlation. Thus, sonic of our results are consistent with harbour seals feeding opportunistically while others point to selectivity, particularly for prey size. Estimated consumption of fish by the 500 harbour seals on Mousa during summer ranged from 152-195 tonnes.

Original languageEnglish
Pages (from-to)325-337
Number of pages12
JournalJournal of the Marine Biological Association of the United Kingdom
Volume81
Publication statusPublished - 2001

Keywords

  • SEASONAL-VARIATION
  • PREY ABUNDANCE
  • MORAY-FIRTH
  • GREY SEALS
  • NORTH-SEA
  • FUR SEALS
  • SCOTLAND
  • CONSUMPTION
  • ATLANTIC
  • ISLAND

Cite this

Interannual variation in the summer diets of harbour seals Phoca vitulina at Mousa, Shetland (UK). / Brown, E. G.; Pierce, Graham John; Hislop, J. R. G.; Santos Vazquez, Maria Begona.

In: Journal of the Marine Biological Association of the United Kingdom, Vol. 81, 2001, p. 325-337.

Research output: Contribution to journalArticle

Brown, E. G. ; Pierce, Graham John ; Hislop, J. R. G. ; Santos Vazquez, Maria Begona. / Interannual variation in the summer diets of harbour seals Phoca vitulina at Mousa, Shetland (UK). In: Journal of the Marine Biological Association of the United Kingdom. 2001 ; Vol. 81. pp. 325-337.
@article{eadb9673a1714f6cbd5fb24fa2f7b97b,
title = "Interannual variation in the summer diets of harbour seals Phoca vitulina at Mousa, Shetland (UK)",
abstract = "The main prey species in the summer (July-September) diets of harbour seals (Phoca vitulina) on the Island of Mousa (Shetland, UK), 1994-1997, were waiting (Merlangius merlangus), herring (Clupea harengus), sandeel (Ammodytidae) and garfish (Belone belone). Norway pout (Triopterus esmarkii) was numerically important but comprised no more than 11{\%} of prey weight in any year. There were marked bet,, een-year fluctuations in the relative importance of these prey, with whiting comprising 16-34{\%} (by weight) of the diet, herring 12-28{\%}, sandeels 7-18{\%} and garfish 7-22{\%}, Additional data on spring (April-June) diet were available for 1995-1997: sandeels were the most important prey ({\%} weight) in all three years (51-60{\%} of the diet), while herring (8-48{\%}) and gadids (2-22{\%}) varied in importance. The average size of fish eaten was larger than that reported in comparable studies from other areas. Harbour seals appear to have selected larger sandeels, whiting and Norway pout than (lie average size available in the area, as indicated by survey trawls, although between-year changes in the size of Norway pout in the diet did to some extent reflect availability. Interannual variation in the importance of Norway pout in the diet appeared to track trend,) in abundance, although the short time series precluded detection of a statistically significant correlation. Thus, sonic of our results are consistent with harbour seals feeding opportunistically while others point to selectivity, particularly for prey size. Estimated consumption of fish by the 500 harbour seals on Mousa during summer ranged from 152-195 tonnes.",
keywords = "SEASONAL-VARIATION, PREY ABUNDANCE, MORAY-FIRTH, GREY SEALS, NORTH-SEA, FUR SEALS, SCOTLAND, CONSUMPTION, ATLANTIC, ISLAND",
author = "Brown, {E. G.} and Pierce, {Graham John} and Hislop, {J. R. G.} and {Santos Vazquez}, {Maria Begona}",
year = "2001",
language = "English",
volume = "81",
pages = "325--337",
journal = "Journal of the Marine Biological Association of the United Kingdom",
issn = "0025-3154",
publisher = "Cambridge University Press",

}

TY - JOUR

T1 - Interannual variation in the summer diets of harbour seals Phoca vitulina at Mousa, Shetland (UK)

AU - Brown, E. G.

AU - Pierce, Graham John

AU - Hislop, J. R. G.

AU - Santos Vazquez, Maria Begona

PY - 2001

Y1 - 2001

N2 - The main prey species in the summer (July-September) diets of harbour seals (Phoca vitulina) on the Island of Mousa (Shetland, UK), 1994-1997, were waiting (Merlangius merlangus), herring (Clupea harengus), sandeel (Ammodytidae) and garfish (Belone belone). Norway pout (Triopterus esmarkii) was numerically important but comprised no more than 11% of prey weight in any year. There were marked bet,, een-year fluctuations in the relative importance of these prey, with whiting comprising 16-34% (by weight) of the diet, herring 12-28%, sandeels 7-18% and garfish 7-22%, Additional data on spring (April-June) diet were available for 1995-1997: sandeels were the most important prey (% weight) in all three years (51-60% of the diet), while herring (8-48%) and gadids (2-22%) varied in importance. The average size of fish eaten was larger than that reported in comparable studies from other areas. Harbour seals appear to have selected larger sandeels, whiting and Norway pout than (lie average size available in the area, as indicated by survey trawls, although between-year changes in the size of Norway pout in the diet did to some extent reflect availability. Interannual variation in the importance of Norway pout in the diet appeared to track trend,) in abundance, although the short time series precluded detection of a statistically significant correlation. Thus, sonic of our results are consistent with harbour seals feeding opportunistically while others point to selectivity, particularly for prey size. Estimated consumption of fish by the 500 harbour seals on Mousa during summer ranged from 152-195 tonnes.

AB - The main prey species in the summer (July-September) diets of harbour seals (Phoca vitulina) on the Island of Mousa (Shetland, UK), 1994-1997, were waiting (Merlangius merlangus), herring (Clupea harengus), sandeel (Ammodytidae) and garfish (Belone belone). Norway pout (Triopterus esmarkii) was numerically important but comprised no more than 11% of prey weight in any year. There were marked bet,, een-year fluctuations in the relative importance of these prey, with whiting comprising 16-34% (by weight) of the diet, herring 12-28%, sandeels 7-18% and garfish 7-22%, Additional data on spring (April-June) diet were available for 1995-1997: sandeels were the most important prey (% weight) in all three years (51-60% of the diet), while herring (8-48%) and gadids (2-22%) varied in importance. The average size of fish eaten was larger than that reported in comparable studies from other areas. Harbour seals appear to have selected larger sandeels, whiting and Norway pout than (lie average size available in the area, as indicated by survey trawls, although between-year changes in the size of Norway pout in the diet did to some extent reflect availability. Interannual variation in the importance of Norway pout in the diet appeared to track trend,) in abundance, although the short time series precluded detection of a statistically significant correlation. Thus, sonic of our results are consistent with harbour seals feeding opportunistically while others point to selectivity, particularly for prey size. Estimated consumption of fish by the 500 harbour seals on Mousa during summer ranged from 152-195 tonnes.

KW - SEASONAL-VARIATION

KW - PREY ABUNDANCE

KW - MORAY-FIRTH

KW - GREY SEALS

KW - NORTH-SEA

KW - FUR SEALS

KW - SCOTLAND

KW - CONSUMPTION

KW - ATLANTIC

KW - ISLAND

M3 - Article

VL - 81

SP - 325

EP - 337

JO - Journal of the Marine Biological Association of the United Kingdom

JF - Journal of the Marine Biological Association of the United Kingdom

SN - 0025-3154

ER -