High temperature is detrimental to captive lumpfish (Cyclopterus lumpus, L) reproductive performance

Summary

There is increased commercial interest in the production of Lumpfish (Cyclopterus lumpus, Linnaeus, 1758) as a biological control for sea lice infections in Atlantic salmon farming. To ensure sustainability, reliable captive breeding is required however, optimal husbandry conditions for broodstock performance remain unknown. The present study investigated the effects of holding temperature on spawning productivity and gamete quality in captivity reared lumpfish. Sexually mature lumpfish (15 month old) were held on three temperature regimes (6 °C, 9 °C and 14 °C) from the onset of first spawning. Holding mature lumpfish at high temperatures (14 °C) resulted in a notable reduction in spawning activity with a significant reduction in sperm density (50% reduction compared to pre-treatment levels) and furthermore resulted in the production of non-viable oocytes (0% to eyeing rate). Holding lumpfish at 9 °C and 6 °C did not have a similar negative impact on gamete quality, however the spawning season for the 6 °C treatment was twice as long as the 9 °C treatment. These results indicate that holding temperature for lumpfish broodstock should not reach the 14 °C degree threshold, with a possible thermal optimum below 10 °C. The current findings are the first step in identifying optimal rearing conditions for captive Lumpfish broodstock.