Place split peas in a large bowl with enough water to cover by 2 inches; let stand for 6 hours or overnight.
Drain split peas, and transfer to a large stockpot. Add clam juice, water, and onion; bring to a boil, reduce heat, and simmer, stirring occasionally, until peas soften, 35 to 40 minutes.
Stir in baby peas, and simmer for 5 minutes. Let soup cool slightly. Place in the bowl of a food processor, working in batches, if necessary; puree until smooth. Press through a fine sieve into a large saucepan, and keep warm over low heat.
In a large bowl, stir together shrimp, garlic, lemon zest, paprika, and salt. Melt butter in a nonstick medium skillet over medium-high heat. Add shrimp, and cook, stirring, until they begin to turn pink and opaque. Add lemon juice, and stir for 1 minute more. Remove from heat, and stir in tarragon.
Ladle bisque into six shallow soup plates, and place a mound of shrimp in the center of each serving.