Browsing School of Arts and Sciences by Subject "aquaculture"
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Conditions for staggering and delaying outplantings of the kelps Saccharina latissima and Alaria marginata for maricultureWe describe a method for production of kelp using meiospore seeding creating flexibility for extended storage time prior to outplanting. One bottleneck to expansion of the kelp farming industry is the lack of flexibility in timing of seeded twine production, which is dependent on the fertility of wild sporophytes. We tested methods to slow gametophyte growth and reproduction of early life stages by manipulating temperature of the kelp Saccharina latissima. Reducing temperature from 12 C to 4 C reduced gametophyte size, sporophyte size, egg production, and sporophyte production and subsequently was the best candidate condition for storage experiments of seeded twine. Next, we examined how storage of Alaria marginata and S. latissima seeded twine at 4 C under differing nutrient concentrations affected the viability of sporelings after being moved into optimal growth conditions. Seeded twine storage at 4 C with no alteration to culturing media showed no negative effects in sporophyte density and sporophyte length for both species. This method for seeded twine storage, “cold banking,” allowed seeded twine storage for at least an additional 36 days compared to standard methods, with a total of 56 days spent in the hatchery providing opportunity for outplanting timing and staggering to enhance aquaculture efficiency.
Humpback whales feed on hatchery-released juvenile salmonHumpback whales are remarkable for the behavioural plasticity of their feeding tactics and the diversity of their diets. Within the last decade at hatchery release sites in Southeast Alaska, humpback whales have begun exploiting juvenile salmon, a previously undocumented prey. The anthropogenic source of these salmon and their important contribution to local fisheries makes the emergence of humpback whale predation a concern for the Southeast Alaska economy. Here, we describe the frequency of observing humpback whales, examine the role of temporal and spatial variables affecting the probability of sighting humpback whales and describe prey capture behaviours at five hatchery release sites. We coordinated twice daily 15 min observations during the spring release seasons 2010–2015. Using logistic regression, we determined that the probability of occurrence of humpback whales increased after releases began and decreased after releases concluded. The probability of whale occurrence varied among release sites but did not increase significantly over the 6 year study period. Whales were reported to be feeding on juvenile chum, Chinook and coho salmon, with photographic and video records of whales feeding on coho salmon. The ability to adapt to new prey sources may be key to sustaining their population in a changing ocean.