MEASURING AMOUNTS, SIZES, AND TYPES OF AQUACULTURE GEAR IN MARINE DEBRIS IN HAWAII

Hawaii windward beaches accumulate large amounts of marine debris composed mainly of low-density polymers that float in seawater. While unidentifiable fragments from larger items are the most common type of marine debris washing ashore in Hawaii, many pieces can also be identified as once being used in fishing industries. Here we assess marine debris on Hawaiian beaches that could be tracked back to bivalve aquaculture.  We collected 11,708 pieces of marine debris from 9 windward and 5 leeward Hawaiian beaches.  Type, color, longest dimension (cm), and mass (g) of each individual pieces was collected.  A large subset of these pieces (n = 9,758) were also analyzed using Fourier transform infrared spectroscopy (FTIR) to  determine their polymer composition. All pieces have been archived and information collected for each piece has been stored in a large database.  From the 11,708 pieces catalogued , 2.77% were identified as being from bivalve aquaculture (e.g. oyster or scallop spacers). This is likel y an underestimate as spacers can break down into fragment s and not be identified as  the whole item.  The sizes ranged from 1 .1 - 32 cm with the majority measuring between 1.4 and 2.5 cm .  Since the use of spacers in bivalve aq uaculture  is not  active in Hawaii,  these items must have traveled more than 4000 km from continental America or  Asia to reach Hawaii's shores. 93.47 % were identified as polyethylene (PE) while 3.78 % were composed of ethylene vinyl acetate (EVA) (Figure 1), which are floating  polymers and hence can be transported long distances by wind and currents. Spacers made of high-density,  sinking polymers such as polyvinyl chloride  were originally used  in the industry  and their presence on Hawaiian shorelines suggest they are still persisting and transporting  slowly  in the environment. Releasing spacers made of long-lasting plastic polymers, regardless of whether they float or sink, will result in habitat damage and should be avoided. There is great interest in collaborating with industry to discuss and explore alternatives (e.g. bamboo spacers) to help mitigate the impact  of the global marine debris issue.