GAIA has approximately 400 members in the British Isles and Southern Ireland, and focuses on three skill disciplines; single-handed casting, double-handed casting, and fly dressing. Each of these disciplines has two levels of competence; GAIC (Game Angling Instructors Certificate) and APGAI (Advanced Professional Game Angling Instructors), which are internally assessed to very strict guidelines. It is possible to join GAIA as an Associate Member, which is the starting point for the learning path that leads to an instructor qualification and, ultimately, to becoming a GAIA Mentor and/or GAIA Assessor.

GAIA participates in a number of activities, such as providing casting clinics at most of the major game fairs, frequent Continuous Personal Professional Development (CPPD) workshops and assessment days which are held bi-annually around the UK. A good proportion of our members work full time as fishing guides and casting instructors, whilst all of the members have an avid interest in game fishing of all sorts including salt-water, reservoir, still-water, and moving water for species including trout, grayling, bass, pike, bone-fish, steelhead, and salmon. Members who have specialist knowledge in these various branches of fly-fishing are only too willing to pass this on to other members.

Other benefits include insurance for qualified instructors.

Additional information