Comparison of three techniques for the capture and transport of impounded subyearling American shad

Abstract

A comparison of three techniques for the capture of impounded juvenile American shad ( Alosa sapidissima ; 50–100 mm total length) showed a 1‐m‐diameter entrainment net to be an order of magnitude more efficient than a black rectangular tank, which relied on a light source to attract the fish at night. A third technique, pond drawdown, was by far the most efficient, but it also resulted in high (>50%) short‐term mortality. American shad captured by the first two techniques were transported a short distance and placed in circular holding tanks (1.22 or 2.44 m in diameter). After initial treatment with 0.5% sea salts for 1 d and continued culture in 13–15°C water, these fish schooled and fed normally within 1 week, and there was no mortality within 48 h after transfer. Weekly overall mortality rates ranged from 1.8 to 8.4%. Regression analysis showed a significant inverse relation between weekly mortality and number of fish per tank, suggesting that relatively large numbers offish in transport or holding tanks may reduce mortality by promoting stress‐mitigating schooling behavior.