The clean waters and protected bays along Alaska's remote and protected coastline provide a bounty of suitable areas for mariculture, especially for farming of oysters and blue mussels (mystilus trossulus). Mariculture may provide an enriched or altered living environment compared to that which existed prior to the farming operation. While an altered environment may be viewed as a source of pollution and reduced biodiversity, it may, at the same time, benefit certain adaptable species by allowing them to thrive under newly specialized conditions. Benthic communities are often used to assess pollution in the water column, with past studies examining factors that affect how mussel farms influence these communities — particularly the age of the farm, the density of organisms living on the farms' ropes, the physical construction of the farms, hydrodynamics of the water surrounding the farms and sedimentation below them.
Human illness due to consumption of contaminated mussels (caused by contaminants retained from these bivalves filtering up to 25 gallons of seawater a day) is a concern to seafood consumers; so mussels harvested from the relatively pure waters of Alaska are especially favored by shellfish connoisseurs. Over the past decade Kachemak Bay mariculture sites, including several in Jakolof Bay, have produced both blue mussels and Pacific oysters with a reputation for outstanding taste.
To learn more about the environmental conditions that Kachemak Bay shellfish farmers operate in and may ultimately alter, shellfish farm sites in Jakolof Bay were studied and compared this past spring. As a researcher in the University of Alaska Fairbanks 2005 Scientific Diving Class, I conducted a field study to compare abandoned and active farming sites in terms of species biodiversity and abundance. Nine dives were made under three active mariculture sites and one abandoned site, with sampling conducted along underwater transects 30 meters in length. At increments of 5 meters, samples were extracted from the sea floor using a PVC coring device that measured approximately 4 inches in diameter and collected 3 inches of substrate. Screening and processing of substrate samples was then conducted at the Kasitsna Bay Lab using No. 10 and No. 4 wire mesh screening sieves to isolate infauna (organisms that live in tubes or burrows beneath the surface of the sea floor) and epifauna (animals that live on the sea floor or attached to other animals or objects under water) from the substrate.
Both site types contained annelid worms, brittle stars, mussels and shrimp along the transect lines. The abandoned site — in this state for four years — contained a vast array of sea anemones, tube worms, and echinoderms living on the surface of the abandoned farming gear. Results from my portion of the study showed that there was not a significant difference in abundance of species between the sites — at each of the active sites, I found a total of 10 invertebrate species; nine were found at the abandoned site.
To learn more about the Kachemak Bay Research Reserve, please visit www.kbayrr.org.
Will Smith was assisting in a March 2005 comparative study of shellfish farm impacts in Jakolof Bay as an undergraduate student in the School of Fisheries and Ocean Sciences at the University of Alaska Fairbanks.
Alaska's shellfish aquaculture (or mariculture) industry has a relatively long history, beginning in 1910 with introduction of the Pacific oyster (crassostrea gigas) for cultivation along beaches from Ketchikan to Kachemak Bay. The industry continued until 1961, with oysters growing best in Southeast Alaska, and then started again in the late 1970s with reintroduction of oyster spat (juvenile oysters) into a few shellfish farms near Wrangell. By 1992, better permit processing, improved state agency coordination and permit regulation changes had led to the establishment of 72 aquatic farms permitted to culture seaweeds, bivalves, abalones and urchins.
