Efficacy of Varying Doses of Channel Catfish Pituitary Extract on Spawning Performance of Pinfish and Pigfish

Pinfish Lagodon rhomboides and Pigfish Orthopristis chrysoptera are commonly used as marine baitfish in the southeastern United States. Hormone efficacy studies for spawning induction have been conducted with both species, but spawning aids derived from piscine pituitary extracts have yet to be evaluated. Pituitary extract from Channel Catfish Ictalurus punctatus (CCPE) was chosen to determine its efficacy on spawning induction. The CCPE was dissolved in a saline solution and then injected into female broodfish at 5, 10, 20, or 40 mg/kg. The treated females were then paired with conspecific males receiving half the corresponding female dose. Ovaprim served as a positive control at a dose of 0.5 mL/kg for female broodfish and 0.25 mL/kg for males. A single pair of broodfish was randomly stocked according to treatment into separate 1,600-L tanks within recirculating systems. Broodfish were monitored daily over 72 h after injection for spawning occurrences, and qualitative characteristics including egg and larval morphometrics and viability were quantified. Channel Catfish pituitary extract failed to induce spawning in Pinfish among all dosages administered. All CCPE dosages induced at least one spawn in Pigfish. No significant differences were detected in spawning frequency among treatments although the 10- and 20-mg/kg CCPE dosages and the Ovaprim control each induced ≥50% of Pigfish females to spawn compared with only 16.7% of females treated with the 5- and 40-mg/kg dosages. Floating eggs from Pigfish females in the 10-mg/kg CCPE treatment were significantly larger than eggs produced using either the 20-mg/kg CCPE or Ovaprim treatment. Hatching success, larval survival to first feeding, larval length at hatch and first feeding, and oil droplet diameter of recently hatched Pigfish larvae were significantly greater for those larvae from the Ovaprim treatment than for those from the 10- and 20-mg/kg CCPE treatments. Data from these experiments demonstrate the potential use of CCPE to induce spawning in Pigfish, a popular marine baitfish species.