~ Pacific Islands

Pacific IslandThe tropical and subtropical marine ecosystems of the U.S. Pacific Islands – Hawaii, American Samoa, Guam, the Northern Mariana Islands, and other smaller islands – will experience various climate impacts, from degradation of important coral reef fish habitat to shifting of commercially viable populations, in response to ocean warming and changes in circulation. Some of the greatest impacts are likely to be due to increasing sea temperatures. For example, coral reefs are a major habitat type of Pacific Island marine ecosystems, and warming temperatures are likely to lead to increased frequency and severity of coral bleaching events (Guidry and Mackenzie 2011; Keener et al. 2012).

Additionally, ocean acidification will decrease rates of coral reef formation and reefs may erode quickly, further hindering the ability of reefs to withstand compounding stressors (Leong et al. 2014). Declines in coral health will negatively impact reef fish populations, which are valuable to commercial, recreational, and subsistence fishermen. Reef fish that use corals for spawning, foraging habitat, protection, and feeding are likely to experience declines as corals degrade (Leong et al. 2014). Changing ocean circulation patterns may also disturb the ecological connectivity of coral reef populations, further limiting the ability of corals to recover after bleaching events (Keener et al. 2012). Mangrove and seagrass coastal ecosystems, which other fish species also use as key nursery and foraging habitat, may decline due to sea level rise and increases in the intensity and severity of tropical storms (Keener et al. 2012; Leong et al. 2014).

Impacts on Commercial Fisheries

Commercially valuable fisheries in the Pacific Islands include nearshore pelagic and reef fish species, which are particularly vulnerable to changes in temperature and ocean circulation and ocean acidification. Large pelagic species, such as skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye (T. obesus), and South Pacific albacore (T. alalunga) tuna populations, respond strongly to shifts in temperature and ocean conditions (e.g., El Niño Southern Oscillation [ENSO] events) (Keener et al. 2012; Leong et al. 2014). By 2100, western Pacific skipjack and bigeye tuna catch may decrease, while eastern Pacific fisheries may see an increase for skipjack and decrease for bigeye (Lehodey et al. 2011 in Keener et al. 2012).

Equatorial tuna populations have also been observed to move eastward during the warm phase of ENSO events as upwelling patterns weaken and primary production decreases (Guidry and Mackenzie 2011). These shifts will likely continue as ENSO events become longer and more intense under changing climatic conditions (Guidry and Mackenzie 2011; Leong et al. 2014). Smaller-scale fishing operations will likely have more difficulty adjusting to these range shifts than large commercial fishing fleets.

Reef fish tend to live near the upper end of their thermal tolerance limit and experience physiological and developmental impacts (e.g., increased metabolic rates, decreased reproduction) (Guidry and Mackenzie 2011) and range shifts due to increases in sea temperature (Leong et al. 2014). The additional stress of decreased coral reef and mangrove habitats could lead to large declines in reef fish populations and limit the availability of species for commercial fishermen.

Impacts on Recreational Fisheries

Recreational fishing is an important industry in the U.S. Pacific Islands. For instance, in Hawaii, shorebased recreational fishing supported 1,176 jobs and total sales of $110 million, while boat fishing supported 466 jobs with total sales of $49 million in 2006 (NOAA 2011). Key recreational species include yellowfin tuna, mahi mahi (Coryphaena hippurus), ono (Acanthocybium solandri), big-eye skad (akule, Selar crumenophthalmus), yellow-stripe goatfish (Parupeneus chrysopleuron), and flagtail fish (aholehole, Kuhlia spp.) (NOAA 2011). There is limited literature regarding the effects of climate change on recreational anglers in the U.S. Pacific Islands.

However, changes in reef fish and pelagic species abundance due to rising sea temperature, ocean acidification, and other compounding climate stressors are likely to limit recreational fishing opportunities. Pacific coral reefs are already stressed by coastal sediment input, nutrient runoff, destructive fishing practices, and increased incidence of disease (Keener et al. 2012), decreasing the potential for recovery after coral bleaching events and resistance to acidification. Recreational anglers and operators could respond to shifting species by travelling greater distances, but this would lead to increased costs and potential revenue declines.

Impacts on Subsistence & Traditional Fisheries

Many Pacific Island communities depend on reef fish for subsistence as a major source of protein, and as an important cultural resource (Keener et al. 2012). Subsistence and traditional fishermen will be affected by climate impacts on traditionally fished stocks, such as sea urchins, snappers, groupers, and surgeonfish (Guidry and Mackenzie 2011; Keener et al. 2012; Leong et al. 2014). For migratory stocks, such as tuna, where commercial operators may be able to follow shifting tuna populations to new locations, subsistence fishermen are geographically limited and may no longer be able to access these important resources (Keener et al. 2012).

Impacts on Aquaculture

There is limited information available about the scope of aquaculture production in the U.S. Pacific Islands. In Hawaii, aquaculture is an expanding industry, doubling in size and revenue since the early 2000s (Naomasa et al. 2013). Farmed species include crustaceans and mollusks, as well as food fish species, such as amberjack, Pacific threadfin, and bigeye and yellowfin tuna. Although changing ocean conditions and sea level rise may affect the viability of local coastal and aquaculture facilities, unfavorable conditions in other regions of the United States may cause some aquaculture operators to seek new opportunities in Hawaii. For instance, due to the increasingly acidic conditions in Pacific Northwest waters, some operators, such as Washington’s Goose Point Oysters, have shifted their nursery hatchery operations to Hawaii, where the waters are less acidic and temperatures are optimal for oyster larval development (Holmyard 2014).

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