|Monitoring temporal and spatial variability in sandeel (Ammodytes hexapterus) abundance with pigeon guillemot (Cepphus columba) diets|
Litzow, M.A.; Piatt, J.F.; Abookire, A.A.; Prichard, A.K.; Robards, M.D. (2000). Monitoring temporal and spatial variability in sandeel (Ammodytes hexapterus) abundance with pigeon guillemot (Cepphus columba) diets. ICES J. Mar. Sci./J. Cons. int. Explor. Mer 57(4): 976-986
In: ICES Journal of Marine Science. Academic Press: London. ISSN 1054-3139, more
Alaska; Alaska; Aquatic birds; Biomonitors; Diet; Diets; Fish; Forage fish; Monitoring; Marine
|Authors|| || Top |
- Litzow, M.A.
- Piatt, J.F.
- Abookire, A.A.
- Prichard, A.K.
- Robards, M.D.
We evaluated pigeon guillemots (Cepphus columba) as monitors of nearshore fishabundance and community composition during 1995-1999 at Kachemak Bay, Alaska.We studied the composition of chick diets at 10 colonies and simultaneously measuredfish abundance around colonies with beach seines and bottom trawls. Sandeels(Ammodytes hexapterus) formed the majority of the diet at one group of colonies.Temporal variability in sandeel abundance explained 74% of inter-annual variability indiet composition at these colonies and 93% of seasonal variability. Diets at othercolonies were dominated by demersal fish. Among these colonies, 81% of thevariability in the proportion of sandeels in diets was explained by spatial differences insandeel abundance. Pigeon guillemots exhibited a non-linear functional response tosandeel abundance in the area where these fish were most abundant. Temporal andspatial variability in demersal fish abundance was not consistently reflected in diets.Spatial differences in the proportion of different demersal fishes in the diet may havebeen driven by differences in guillemot prey preference. Prey specialization byindividual pigeon guillemots was common, and may operate at the colony level.Inter-annual variability in sandeel abundance may have been tracked more accuratelybecause the magnitude of change (11-fold) was greater than that of demersal fish(three-fold).