Demersal spawning in capelin (Mallotus villosus) on the Northeast coast of Newfoundland.

摘要

I investigated the physical characteristics of spawning sites and early life history stages of demersally spawning capelin (Mallotus villosus) on the Northeast coast of Newfoundland. I found that the eleven demersal spawning sites discovered during this study (2003-2005) were located primarily in depressions. Site use was associated with the suitability of both the thermal habitat and sediment distribution, demonstrating the importance of these features to the characterization of favourable spawning habitat in demersally spawning capelin. Egg abundance at demersal sites was similar to or higher than at a nearby beach site and egg mortality was higher at the beach in both years of this study. Developmental rates observed at demersal sites in this study do not support previous findings on egg development at the beach. Egg development was slower than at the beach, resulting in demersally spawned eggs hatching 8-10 days later than predicted. Environmental cues that stimulate the release of larvae from the sediment at beaches in Newfoundland occur at demersal spawning sites, but do not appear to stimulate larval emergence. Instead, larvae in good condition appeared to emerge continuously from the sediment. Results from this study suggest that demersal spawning is a viable reproductive mode on the Northeast coast of Newfoundland.