Weijerman et al. Trends in biomass of coral reef fishes, derived from creel surveys in Guam 
239 
quantified. These potential declines in fish populations 
reduce overall biomass, reproductive potential, and 
ecosystem function (Taylor et al., 2012; Mumby et al, 
2013; Williams et al., 2015). We aimed to improve our 
understanding of the effects of this socially and cul- 
turally important fishery, using the shore-based creel 
data 1 ) to compare catch composition in the early years 
(1985-2000) with the composition in the recent years 
(2007-2012) and 2) to reconstruct trends in the popu- 
lation biomass of functional groups of reef-fish species 
over the period 1985-2012 by using recent visual-sur- 
vey data as a relative index. 
Materials and methods 
Fishery data source: creel surveys 
The creel surveys conducted around Guam by the 
DAWR included 2 distinct fisheries: the shore-based 
fishery and the boat-based fishery. This division of the 
data and the terms used to describe its 2 parts are 
widely used in Guam, including among fishery manage- 
ment agencies; therefore, we used them in our study. 
It is important to note that the shore-based fishery 
includes fishing from boats when boats are launched 
from shore (Appendix 1). The shore-based fishery dif- 
fers from the boat-based fishery in several key aspects. 
In general, larger boats are used in the boat-based 
fishery, which primarily targets pelagic or bottomfish 
species, and predominantly is a commercial fishery. 
However, the boat-based fishery landings also include 
a substantial amount of reef fishes (Appendix 1). We 
chose not to include boat-based fishery results in our 
study for 2 reasons. First, boat-based fishing effort is 
recorded in trip hours, and shore-based fishing effort 
is recorded in gear hours; therefore, it was difficult to 
generate CPUE for just the fishing of reef fishes with 
the boat-based fishery to include in our analysis (Ap- 
pendix 1 Figure 1). Second, trends in the catch from 
spearfishing in the boat- and shore-based fisheries are 
very consistent, indicating that, at least for reef-fish 
species, these trends reflect changes that are common 
among the targeted stocks (Appendix 1 Figure 2). 
Categorization of species into functional groups 
We analyzed records in the catch database of the shore- 
based component of the creel survey program for Guam 
(DAWR data obtained from a database maintained by 
the Western Pacific Fisheries Information Network 
[WPacFIN 5 ], NOAA Pacific Islands Fisheries Science 
Center [PIFSC]). A total of 580 species or families ap- 
peared in the records. For some taxa, there were very 
little data; therefore, we grouped data of all taxa on the 
5 WPacFIN (Western Pacific Fishery Information Net- 
work). 2013. Guam shore-based creel survey. NOAA Pa- 
cific Islands Fish. Sci. Cent., Honolulu, HI. [Metadata avail- 
able at website.] 
basis of their taxonomy, ecological function, and impor- 
tance to fisheries, as shown in Table 1. 
Collection of catch and effort data 
The shore-based surveys of the DAWR creel survey 
program are designed to collect information on effort 
and catch for all shore-based fishing activities (Hensley 
and Sherwood, 1993; Zeller et al., 2007). There are 2 
parts in the shore-based fishery: 1) visual surveys to 
establish the number of people participating in fishing 
activities (which are called participation surveys) and 
to collect data on the type of fishing activities observed 
(effort data) and 2) interviews of a sample of fisher- 
men to collect data on the duration of fishing activities 
and numbers and sizes of fish caught (catch and effort 
data). Effort was recorded as hours fished per gear type 
(gear hour) and catch was recorded as the number and 
weights of fish caught per hour fished per gear type 
(Oram et al. 6 ). Data from restricted areas (Appendix 2) 
were collected during aerial surveys conducted on the 
same 2 days that the participation surveys took place 
(Oram et al. 6 ). 
Catch values for the shore-based fishery are provid- 
ed on a voluntary basis by fishermen to creel surveyors. 
Effort primarily is based on the visual surveys of fish- 
erman participating in fishing activities, with details 
about the actual hours of fishing coming from inter- 
views. When conducting surveys, DAWR staff attempt 
to interview fishermen for each type of gear observed 
during the participation surveys (Appendix 3 Table 1). 
However, interviewers are not always able to collect in- 
formation on all types of gear. For example, since 2005, 
many spear fishermen have refused to participate in 
the creel surveys (Lindfield et al., 2014). Consequently, 
the number of snorkel-spear interviews has declined 
from an average of 30 per year in 1985-90 to an av- 
erage below 8 interviews per year during 2007-2012 
(Appendix 3 Table 1), and this decline is unfortunate 
because counts of observations made during participa- 
tion surveys indicate that spearfishing represents one 
of the most used fishing method of the shore-based fish- 
ery in terms of effort (Bak 7 ). Because collecting data on 
CPUE for most of the taxa and for most of the gears 
was difficult and infrequent, results dependent on the 
CPUE statistics were grouped at the family taxon level 
and are best considered as relative measures. 
Estimates of total catch, total effort, and catch per unit of effort 
The staff of the PIFSC program WPacFIN who col- 
laborates with the DAWR, use an expansion algorithm 
6 Oram, R., T. Flores Jr., B. Tibbatts, J. Gutierrez, J. R Gesner, 
S. Wusstig, A. Regis, D. Hamm, M. Quach, and P. Tao. In 
press. Guam shore-based creel survey. NOAA Pac. Islands 
Fish. Sci. Cent. Admin. Rep., 25 p. 
7 Bak, S. 2012. Evaluation of creel survey program in the 
western Pacific region (Guam, CNMI, and American Samoa), 
58 p. Unpubl. report prepared for the Western Pacific Re- 
gional Fishery Management Council, Honolulu, HI 96813. 
