Recipe for Chum
Chum is bait, made up especially from chopped fish offal, then scattered on the water to attract seabirds. I have been asked for a formula for chum. The most successful mix I’ve used was ‘floating chum’, developed by Hadoram Shirihai, which was used on the Fiji Petrel expedition 2008 and made up in Dick Watling’s back yard (though more water will be added to the mix next year - see comment, bottom of recipe)
Must be frozen blocks that are chucked overboard!
Here’s the recipe:
Dick’s Chum Recipe (‘as good as a BigMac….though even tastier’)
Commercial fishmeal (15% water content) and soya bean oil (large drum)
(4/5 kilos fishmeal added to the oil, this stirred daily to infuse the oil that becomes ‘fish oil’)
Fish ‘dust’ (from sawing and cutting)
Shark’s liver (if possible – though does appear important!)
30% fishmeal, 15% oil, 55% water
Fishmeal and oil increased, to 25% water
Mix 3 – the best!
Mix equally 25% fish ‘dust’ (known as ‘sawdust’ from cutting) and 25% fishmeal to become 50% of total mix, adding 15% of oil (is this the oil mixed with fishmeal already, as above?) and 35% water
Additional bags required: Oilfish and oilfish ‘dust’ (from cutting), shark’s liver (the latter most important as snack, and loved by seabirds)
(3) Prepare for sea
Make up the mixes into plastic bags at 10/12 kilo each and then freeze.
(4) Use at sea
Note - Must be frozen blocks that are chucked overboard – these float and pieces break away gradually. Can heave to at about 80yds and view – the chum slick will be obvious, even in quite rough seas. Once birds start appearing throw in shark’s liver, pieces of oilfish, popcorn etc
Important supplementary note from Dick Watling:
'In view of the problem we had with some chum sinking off Taveuni, I would recommend our third mix only (where we used solely fish dust, oil, water). If I was going to use fishmeal again I would double the amount of water added'.
Also Dimethyl sulphide can be purchased, which petrels find irresistible. Usually called simply DMS, this chemical is naturally produced (when phytoplankton are grazed by zooplankton) and, for procellariiforms particularly, is a widespread feature of the olfactory landscape of the oceans. It is often associated with upwellings and seamounts.
Click below to read the paper:
‘Sensitivity to dimethyl sulphide suggests a mechanism for olfactory navigation by seabirds’
(Gabrielle A Nevitt and Francesco Bonadonna)