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Summary
Euphausiids and salps
Image: Edin Whitehead ©
This project builds on past work on the indirect effects of commercial fishing on seabirds. A range of commercial fisheries target aggregations of surface shoaling fish, purse seining is commonly used to capture thse fish schools. The dense fish schools create a phenomenon known as fish work-ups. These work-ups drive up prey items to the sea surface and observations suggest that this forms an important food source for a range of seabird species.
There is currently poor knowledge of both the idet of surface-foraging seabirds and what prey items are being made available to seabirds from fish work-ups. This is currently limiting our understanding of the mechanisms through which changes in the distribution and/or abundance of fish work-ups may be dirving seabird population changes (population status and annual breeding success).
Field research was focussed on in the Hauraki Gulf, key sites such as the Noises, Tiritiri Matangi, Goat, Mokohinau, Hen and Chickens, Poor Knights, Three Kings and Tawharanui Regional Park where species such as red-billed gull, white-fronted tern, Australasian gannet, fairy prion, Buller's shearwater and fluttering shearwaters breed.
This project was comprised of 4 objectives:
- Identify the range of potential seabird prey species within fish work-ups
- Identify food fed to chicks of key surface feeding seabirds
- Compare prey availability in fish work-ups with the diet of the target seabird species
- Collect baseline population data on surface-nesting seabirds
Publication information
Gaskin, C., Kozmian-Ledward, L., Jeffs, A. (2019). Indirect effects on seabirds in the northern North Island region. Final report of at-sea fish shoal sampling prepared by NNZST for the Conservation Services Programme, Department of Conservation. POP2017-06. 40 p.
Gaskin, C., Kozmian-Ledward, L., Jeffs, A., Adams,N, Doyle, E. (2019). Indirect effects on seabirds in the northern North Island region. Final report of seabird diet sampling prepared by NNZST for the Conservation Services Programme, Department of Conservation. POP2017-06. 50 p.
Gaskin, C., Adams, N., Kozmian-Ledward, L., Jeffs, A. (2019). Indirect effects on seabirds in the northern North Island region. Final report on comparison of fish shoals and seabird diet prepared by NNZST for the Conservation Services Programme, Department of Conservation. POP2017-06. 48 p.
Gaskin, C., Frost, P., Friesen, M. (2019). Indirect effects on seabirds in the northern North Island region. Final report on seabird colony and population assessments prepared by NNZST for the Conservation Services Programme, Department of Conservation. POP2017-06. 23 p.