I always try to work upstream. The fish has eyes in its head, not its ass. Sneaking up behind them is always easier. Plus natural food will drift downstream. If I cast upstream the fly comes back down to me, naturally. Trout will always be suspicious of a mayfly swimming upstream.
Sex is fairly easy. The head gives it away. The short nose and jaw of a female (hen) is always going to be smaller. The jacks (males) will have a longer snout and jaw, with the larger males getting quite a hook at the end of the jaw.
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