Effectiveness of fish waste management strategies in reducing seabird attendance at a trawl vessel

TitleEffectiveness of fish waste management strategies in reducing seabird attendance at a trawl vessel
Publication TypeJournal Article
Year of Publication2009
AuthorsAbraham, ER, Pierre JP, Middleton DAJ, Cleal J, Walker NA, Waugh SM
Volume95
Pagination210–219
Abstract

The risk of seabird bycatch in trawl fisheries is increased by high numbers of seabirds attending vessels to feed on fish waste discharged. We conducted an experimental test of whether mincing fish waste prior to its discharge from a factory trawler reduced the number of seabirds attending the vessel. The trial was conducted on a mid-water trawler targeting hoki (Macruronus novaezelandiae) in New Zealand waters, and the experiment compared three treatments (1) discharging ‘unprocessed’ waste (fish offal and whole discards), (2) mincing all waste to a small particle size before discharge, or, (3) converting all waste to fishmeal and reducing discharge to sump water. The response to the experimental treatments was determined using seabird abundance within a 40 m-radius semi-circular area centred on the vessel stern. Mincing reduced the numbers of large albatrosses (Diomedea spp.) feeding astern of the vessel, but had no significant effect on other groups of seabirds. In contrast, reducing discharge to sump water resulted in a significant reduction in numbers of all groups of seabirds. In particular, the abundance of the small albatross group (principally Thalassarche spp.), and some smaller procellarids (e.g. sooty shearwater, Puffinus griseus, and white-chinned petrel, Procellaria aequinoctialis), was reduced to less than five percent of the number that were within the sweep area when unprocessed discharge was released. While mincing significantly reduced the abundance of large albatrosses at the vessel stern, relatively small numbers of these birds attend trawl vessels in New Zealand waters and associated bycatch rates are low. In contrast, reducing the quantity of fish waste discharge by mealing resulted in reduced abundances of a wide range of seabirds at the vessel. Therefore, compared to mincing, we recommend fish waste retention as a more effective management strategy for reducing seabird bycatch.

DOIdoi:10.1016/j.fishres.2008.08.014

Publications by Edward Abraham

Abraham, ER, Pierre JP, Middleton DAJ, Cleal J, Walker NA, Waugh SM. 2009. Effectiveness of fish waste management strategies in reducing seabird attendance at a trawl vessel. Fisheries Research. 95: 210–219
Waugh, DW, Abraham ER. 2008. Stirring in the global surface ocean. Geophysical Research Letters. 35:
Abraham, ER. 2007. Sea-urchin feeding fronts. Ecological Complexity. 4: 161–168
Waugh, DW, Abraham ER, Bowen MM. 2006. Spatial Variations of Stirring in the Surface Ocean: A Case Study of the Tasman Sea. Journal of Physical Oceanography. 36: 526–542
Bakker, DCE, BOYD PW, Abraham ER, Charette MA, Gall MP, Hall JA, LAW CS, Nodder SD, Safi K, Singleton DJ et al.. 2006. Matching carbon pools and fluxes for the Southern Ocean Iron Release Experiment (SOIREE). Deep-Sea Research Part I. 53: 1941–1960
LAW, CS, Crawford WR, Smith MJ, BOYD PW, Wong CS, Nojiri Y, Robert M, Abraham ER, Johnson WK, Forsland V et al.. 2006. Patch evolution and the biogeochemical impact of entrainment during an iron fertilisation experiment in the sub-Arctic Pacific. Deep-Sea Research Part II. 53: 2012–2033