Men like to fish. It is relaxing for them, they can bond and as tranquility is a main ingredient, awkward silences are embraced. Sammy, who is now turning into Frank Zappa but is sensibly dressed in wellington boots, fills one of these silences by saying that he seems to be forgetting things, but he can't forget things that much as he is quite specific with the number of things he is forgetting. He knows full well that he is forgetting names and faces, but with the amount of people in this town it is forgiveable. Sammy is usually drunk when meeting these people and everyone knows when you get to Sammy's age you only need to know the name of your wife and best friend. Sammy's forgetfulness is not causing a problem yet, although we wonder now if he'd been to the Barker's Summer party before.
The fact that he has forgotten the third thing that he keeps forgetting makes it redundant. Does it matter that he can't remember it? He knows he has to address the names and faces problem, perhaps with the use of a notebook, but if he truly has forgotten the very thing he keeps forgetting then maybe it doesn't matter. However, Sammy may descend into a spiral by continually forgetting the very thing he keeps forgetting. This may be a philosophical matter and could drive him mad.
There is one more explanation for the final forgetting. Just as George asks Sammy about the third item, Sammy appears to get a bite on his line. This violent downforce on the rod that he holds may have assisted in his mild amnesia. Suddenly his train of thought was lost as he bravely grapples with the mighty beast of the deep. George doesn't seem too concerned so neither should we. Alzheimer's takes a while to take hold so I think Sammy has a good few years yet until he forgets his own name and face.