238 
Fishery Bulletin 114(2) 
comparative study of reef-fish landings and their eco- 
logical footprint concluded that 55% of coral reef fish- 
eries in 49 island countries were unsustainable, on the 
basis of the difference between actual reef-fish landings 
and an annual coral reef maximum sustainable yield 
value of 5 metric tons (t)/km 2 (Newton et al., 2007). 
A more recent study in just the western Pacific Ocean 
found a decline in catches of artisanal fisheries in most 
Pacific countries (Zeller et al., 2015). The potential, and 
evidently current, widespread overexploitation of reef 
fisheries highlights the need for proper management of 
these resources. 
We focused our study on trends in catch and effort 
of the reef-fish fishery of Guam, which is the largest 
island in Micronesia and the most southerly island of 
the Mariana Archipelago in the western Pacific Ocean. 
As in many other Pacific islands, fish have been impor- 
tant sources of food since the first human settlements 
(Hensley and Sherwood, 1993). From prehistoric to re- 
cent times, there have been at least 52 different fish- 
ing methods used on Guam (Kerr 1 ), and some of these 
traditional practices, such as the seasonal harvest of 
bigeye scad ( Selar crumenopthalmus ), fishing with sur- 
round nets, and throw- or cast-net fishing, are all still 
in use (Hensley and Sherwood, 1993). Modern fishing 
of reef fishes on Guam is best considered a recreational 
or subsistence fishery, and pelagic fisheries dominate 
the commercial landings there (Allen and Bartram 2 ). A 
study of households (van Beukering et al. 3 ) conducted 
in 2007 reported that 35-45% of respondents were ac- 
tive fishermen and that 28% of the fish consumed were 
caught by family members or friends (the 400 respon- 
dents in this study included the main ethnic and socio- 
economic groups in Guam). Fish make up an especially 
important source of food for large cultural events, such 
as baptisms, weddings, and village fiestas (Pinhey et 
al., 2006). 
Apart from their cultural and socioeconomic signifi- 
cance, reef-fish populations can play an impox’tant role 
in enhancing the resilience of reef ecosystems (i.e., the 
capacity of reef ecosystems to sustain and recover from 
a human-induced disturbance). For example, abundant 
and diverse assemblages of herbivorous fishes are ef- 
fective at reducing algal biomass and at opening up 
space for settlement of coral recruits (McClanahan, 
1997; Mumby et al., 2007a; Mumby and Harborne, 
2010; Graham et al., 2011, 2013; Mumby et al., 2013). 
Unlike many other countries and territories with 
coral reefs, Guam has long-term (>50 years) data for 
its coral reef fishery that have been obtained from creel 
1 Kerr, A. M. 2011. Fishing methods of the Mariana Is- 
lands, Micronesia. Univ. Guam Mar. Lab. Tech. Rep. 132, 44 
p. [Available at website.] 
2 Allen, S., and P. Bartram. 2008. Guam as a fishing com- 
munity. NOAA Pacific Islands Fish. Sci. Cent. Admin. Rep. 
H-08-01, 61 p. [Available at website.] 
3 van Beukering, P. (ed. ), W. Haider, M. Longland, H. Cesar, 
J. Sablan, S. Shjegstad, B. Beardmore, Y. Liu, G. O. Garc- 
es. 2007. The economic value of Guam’s coral reefs. Univ. 
Guam Mar. Lab. Tech. Rep. 116, 102 p. [Available at website.] 
surveys conducted by the Division of Aquatic and Wild- 
life Resources (DAWR), Guam Department of Agricul- 
ture. This creel survey program provides information 
on overall harvest and catch per unit of effort (CPUE). 
In the mid-1980s, DAWR adapted their existing creel 
survey program to better reflect changes in fishing 
practices. This survey program now encompasses an 
offshore boat-based fishery and an inshore shore-based 
fishery. The boat-based fishery focuses mainly on troll- 
ing for pelagic species and bottom fishing for species of 
commercial value in deepwater (depths >30 m), and the 
shore-based fishery targets reef fish in shallow-water 
(depths <30 m) primarily for recreational, subsistence, 
and cultural reasons (Appendix 1). 
Previous analysis of these creel survey data in- 
dicated that Guam has a low fishery yield compared 
with other Pacific islands (Dalzell, 1996). A more re- 
cent study concluded that there had been an 86-94% 
decline in recreational fish catches over the previous 
50 years (Zeller et ah, 2007, 2015). Other studies in 
Guam have documented a similar decreasing trend in 
both the numbers of fish landed and the mean size at 
capture (Myers, 1993; Mcllwain and Taylor 4 ; Lindfield 
et al., 2014). Hensley and Sherwood (1993) conducted 
a comprehensive analysis of just the shore-based fish- 
ery in Guam from 1982 through 1991. Their main con- 
clusions were that the fishery had changed because of 
the implementation of more modern fishing techniques 
and a switch from a traditional economic system (bar- 
ter, catch what you eat) to a more western one (dol- 
lar based, sell for profit) and that these changes led to 
more pressure on reef resources and to overharvesting 
the most frequently targeted species. 
The perception that reef-fish stocks in Guam are de- 
pleted has been corroborated by a recent large-scale 
study based on visual-survey data; this study conclud- 
ed that reef-fish biomass around Guam was 66% below 
what would be expected in the absence of human per- 
turbations (Williams et al., 2015). Other studies with 
visual-survey data have noted the relative scarcity of 
large-bodied fishes around Guam and other populated 
islands in the Mariana Archipelago, compared with 
the lightly or unpopulated islands in this archipelago 
(Richards et al., 2011; Williams et al., 2011). A paucity 
of large fishes often is indicative of overfishing (Fried- 
lander and DeMartini, 2002; Fenner, 2014). 
Although these studies reflect the declining trend in 
catch and a depletion of the reef-fish biomass at Guam 
and provide evidence of the effects of fishing on the life 
history of some taxa (e.g., parrotfishes [Chlorurus spp., 
Scarus spp.]; Taylor and Choat, 2014), time series for 
the total biomass of reef-fish populations and changes 
in the composition of reef-fish catches have not been 
4 Mcllwain, J. L., and B. M. Taylor. 2009. Parrotfish popula- 
tion dynamics from the Marianas Islands, with a description 
of the demographic and reproductive characteristics of Chlo- 
rurus sordidus: final report to the Western Pacific Regional 
Fishery Management Council, 61 p. Univ. Guam Mar. Lab., 
Mangilao, Guam. [Available at website] 
