Here is how to get there:
Taking Taipei Rapid Transit (MRT) along the Danshui Line (denoted as Red Line) 
North bound from Taipei Main Station to Danshui Station.
Transfer to Shuttle Bus Route Red-26, 836 or 837 at Danshui Station and get off at Fisherman's Wharf stop.
Schedule for the Shuttle Bus: 
Weekdays: 
08:00-08:30 Every 7-8 min. 
08:30-16:30 Every 15 min. 
16:30-18:30 Every 7-8 min. 
20:00-24:00 Every hour 
Last bus arrive at Danshui Station around 24:55 
Weekends: 
08:00-08:30 Every 20 min. 
08:30-19:00 Every 15 min. 
19:00-21:00 Every 20 min. 
21:00-24:00 Every hour 
Last bus arrive at Danshui Station around 24:55 
Bus Route map for your reference:
thanks to weiwei