Kelp culture in integrated multi-trophic aquaculture: expanding the temporal limitations.




Blasco, Nathanial

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In integrated multi-trophic aquaculture (IMTA) production of cultured species may not align temporally. For instance, at an IMTA site in Kyuquot Sound, BC where the cultured species are Anoplopoma fimbria (sablefish), Plactopentin yesoensis (Japanese scallop) and Saccharina latissima (sugar kelp), sablefish are grown year round while the kelp culturing lasts from winter to summer. Kelp sporophytes become visible in early spring while harvest takes place in July. This indicates that at Surprise Island the time period of nutrient extraction by the kelp is limited to only a few months per year. Two potentials methods to lengthen the time in which the kelp component was on site were employed and evaluated: 1. the use of multiple kelp species with potentially differing seasonal growth strategies and; 2. outplanting kelp seed at four different times of the year. The first method involved outplanting seed of four kelp species, Saccharina latissima, Costaria costata, Alaria marginata and Saccharina groenlandica and monitoring growth parameters (blade length and yield). For the second method, a modified seed production method of Merrill and Gillingham (1991) with Luning and Dring (1973) successfully provided seed throughout the year. Seasonally out-planted seed was also monitored for growth parameters. Results were marginal for experiments and were confounded by the lack of growth rates due to infrastructure problems, grazing by naturally setting marine snails and seemingly poor environmental conditions for kelp culturing at the farm site. However, data indicated that certain species in co-culture may slightly increase the time period, and strategically entered kelp seed may do the same. In particular the co-culture of C. costaria and S. groenlandica or biannual seed outplanting in fall and spring may increase the length of growth period of kelp provided certain limitations found during this experiment are overcome (i.e. pressures of grazing). Additional potential benefits with these kelp production strategies are the diversification of final kelp products, additional kelp harvests and increased production.



kelp aquaculture, integrated multi-trophic aquaculture, kelp farming