Clay As a Greenwater Alternative for Larval Sablefish Anoplopoma fimbria

In aquaculture and stock enhancement settings, most marine species require water to be supplemented with algae (“greenwater”) so that larvae can see live feed and orient themselves properly. Greenwater application can be laborious, expensive, inconsistent, and may contribute to bacterial growth, but there are few well researched alternatives. 

We studied first-feeding sablefish (Anoplopoma fimbria) reared in greenwater or claywater under three conditions: 1) greenwater for both weeks, 2) claywater for both weeks, and 3) greenwater for the first week then claywater for the second week.

Clay created the same turbidity as greenwater at 1% the cost. In both greenwater and claywater treatments, larvae appeared to orient themselves properly (indicated by a lack of wall-nosing) and see live feed (indicated by “coil and strike” feeding behavior, and prolonged survival beyond yolk sac depletion). Greenwater during the first week produced triple the survival when compared to claywater. In contrast, during the second week after first feeding, claywater led to 60% greater growth compared to greenwater. A later one-week additive experiment confirmed that greenwater leads to greater survival and growth during the first week. We will discuss potential mechanisms and implications for rearing sablefish.