Process parsley, shallots, capers, lemon rind and juice in a food processor until finely chopped. Add half the avocado and pulse to form a paste.
Heat a large non-stick frying pan over a medium-high heat. Add salmon. Cook for 3 minutes. Turn and cook for a further 3 minutes or until cooked to your liking. Remove and flake into large pieces.
Meanwhile, cook spaghetti in a large saucepan of boiling water following packet directions. Reserve ½ cup pasta water, then drain.
Transfer spaghetti and reserved pasta water to a medium bowl. Add flaked salmon, avocado mixture, olives and rocket leaves. Season with freshly ground pepper and toss gently to combine.
Divide into 4 serving bowls. Top with remaining thinly sliced avocado. Sprinkle with pine nuts.