The final requirement is that the employee on the fishing vessel
must be employed in ``the first processing, canning or packing'' of the
marine products. The meaning and scope of these operations when
performed at sea as an incident to the fishing operations of the vessel
are set forth in Secs. 784.133 to 784.135. To be ``employed in'' such
operations the employee must, as previously explained (see Secs. 784.106
and 784.121), be engaged in work which is clearly part of the named
activity.