Lot of missing information in the post.
I assume that Check_Bait_Squid (et. al) is the name of the checkbox control which reurns true or false
Might give you some ideas
Sub test()
Dim s As String
If Check_Bait_Squid Then s = "Squid,"
If Check_Bait_Sard Then s = s & "Sard,"
If Check_Bait_Prawn Then s = s & "Prawn,"
If Check_Bait_Redbait Then s = s & "Redbait,"
If Check_Bait_Worm Then s = s & "Worm,"
If Check_Bait_Mussel Then s = s & "Mussel,"
If Check_Bait_Mullet Then s = s & "Mullet,"
If Right(s, 1) = "," Then s = Left(s, Len(s) - 1)
Range("S1234").Value = s
End Sub