Sprinkle fish evenly with salt and 1/8 teaspoon pepper.
Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray.
Add 2 fillets to pan; saut 1 1/2 minutes or until browned. Carefully turn fillets; saut 1 1/2 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness.
Place fillets on a plate; keep warm. Repeat procedure with cooking spray and remaining fillets.
Melt butter in pan; cook 2 minutes or just until lightly browned.
Add shallots to butter; saut 45 seconds, stirring frequently.
Remove from heat; stir in remaining 1/8 teaspoon pepper, capers, and fresh lemon juice.