Hawaii FEP - Western Pacific Fishery Council

goes due to the lack of available prey. With increasing depth, suspension feeders become lessabundant and deposit feeders become the dominant feeding type (Levington 1995).Although most of the deep seabed is homogenous and low in productivity, there are hot spotsteeming with life. In areas of volcanic activity such as the mid-oceanic ridge, thermal vents existthat spew hot water loaded with various metals and dissolved sulfide. Bacteria found in theseareas are able to make energy from the sulfide (chemotrophs) and are thus considered primaryproducers. A variety of organisms either feed on or contain these bacteria in their bodies withinspecial organs called “trophosomes.” Types of organisms found near these thermal vents includecrabs, limpets, tubeworms, and bivalves (Levington 1995).3.3.2.7.1 Benthic Species of Economic ImportanceCoral Reef Associated SpeciesThe most commonly harvested species of coral reef associated organisms include the following:surgeonfishes (Acanthuridae), triggerfishes (Balistidae), jacks (Carangidae), parrotfishes(Scaridae), soldierfishes/squirrelfishes (Holocentridae), wrasses (Labridae), octopus (Octopuscyanea, O. ornatus), and goatfishes (Mullidae). Studies on coral reef fisheries are relativelyrecent, commencing with the major study by Munro and his co-workers during the late 1960s inthe Caribbean (Munro 1983). Even today, only a relatively few examples are available of indepthstudies on reef fisheries.It was initially thought that the maximum sustainable yields for coral reef fisheries were in therange of 0.5–5 t km -2 yr -1 , based on limited data (Marten and Polovina 1982; Stevenson andMarshall 1974). Much higher yields of around 20 t km -2 yr -1 , for reefs in the Philippines (Alcala1981; Alcala and Luchavez 1981) and American Samoa (Wass 1982), were thought to beunrepresentative (Marshall 1980), but high yields of this order have now been independentlyestimated for a number of sites in the South Pacific and Southeast Asia (Dalzell and Adams1997; Dalzell et al. 1996). These higher estimates are closer to the maximum levels of fishproduction predicted by trophic and other models of ecosystems (Polunin and Roberts 1996).Dalzell and Adams (1997) estimated the average MSY for Pacific reefs to be approximately 16 tkm -2 yr -1 based on 43 yield estimates where the proxy for fishing effort was population density.However, Birkeland (1997b) has expressed some skepticism about the sustainability of the highyields reported for Pacific and Southeast Asian reefs. Among other examples, he noted that thehigh values for American Samoa reported by Wass (1982) during the early 1970s were followedby a 70 percent drop in coral reef fishery catch rates between 1979 and 1994. Saucerman (1995)ascribed much of this decline to a series of catastrophic events over the same period. This beganwith a crown of thorns infestation in 1978, followed by hurricanes in 1990 and 1991, whichreduced the reefs to rubble, and a coral bleaching event in 1994, probably associated with the ElNiño phenomenon. These various factors reduced live coral cover in American Samoa from amean of 60 percent in 1979 to between 3 and 13 percent in 1993.Furthermore, problems still remain in rigorously quantifying the effects of factors on yieldestimates such as primary productivity, depth, sampling area, or coral cover. Polunin and Roberts(1996) noted that there was an inverse correlation between estimated reef fishery yield and the63