O'Malley et al.: Effects of exploitation evident in age-based demography of Pristipomoides flavipinnis and P. auricilla 
323 
and lack of life history information restricts options for 
quantitative stock assessment and, hence, the accurate 
determination of stock status needed for sustainable 
management. 
In species of Pristipomoides, size and age can become 
decoupled because asymptotic size is reached at a young 
age relative to maximum age (Newman et al., 2016). 
Although fishery-dependent size information is relatively 
easy and cost effective to obtain compared with age data 
derived from collecting and analyzing aging structures, 
this decoupling may result in biased assessments when 
length data are used to define cohorts within stock assess¬ 
ments. As such, fishing impacts may not be readily identi¬ 
fiable by examining changes in fish size, highlighting the 
importance of age information. Hence, there is a need for 
accurate and timely information on age structure and age- 
based life history of deepwater snappers. Age-based demog¬ 
raphy furthers our understanding of deepwater snapper 
life history and facilitates stock assessment models and 
sustainable harvest strategies for these species (Brodziak 
et al., 2011a; Newman et al., 2016). 
Species-specific life history parameters important for 
assessments and development of harvest strategies include 
growth, maturity, maximum size and age, and mortality 
(Quinn and Deriso, 1999; Maunder et al., 2016). Estimat¬ 
ing natural mortality (Pauly, 1980; Then et al., 2015) is 
particularly important and exceedingly difficult. In data- 
poor situations, such as those of many deepwater snapper 
fisheries, total mortality is typically estimated by using 
catch curve analysis, and natural mortality is calculated 
indirectly by using empirical formulae (hereafter referred 
to as natural mortality estimators ) derived from correlation 
with life history parameters or maximum age from a collec¬ 
tion of species (Pauly, 1980; Kenchington, 2014; Then et al., 
2015). Because of the lack of life history information, none 
of these natural mortality estimators were derived by using 
information specific to tropical deepwater snappers. The 
lack of this information is concerning because many stud¬ 
ies show life history parameters vary among taxa (Thorson 
et al., 2014; Nadon and Ault, 2016) and among populations 
within species (Brown, 1995; Newman et al., 1996; Williams 
et al., 2007, 2017; Cappo et al., 2013). Further, Kenching¬ 
ton (2014), in a review of indirect methods, postulated that 
none of these natural mortality estimators are sufficiently 
precise to use in an analytical stock assessment. 
The spatial extents of the Samoa and Mariana Archipel¬ 
agoes present the opportunity to compare life history and 
population dynamics between exploited and unexploited 
populations of deepwater snappers and to test the suitabil¬ 
ity of natural mortality estimators for assessing deepwater 
snapper stocks. Deepwater snapper populations surround 
the populated islands, as well as the uninhabited islands 
and offshore seamounts, within the Samoa and Mariana 
Archipelagoes (Fig. 1). 
The history of American Samoa’s deepwater snapper 
fishery is detailed in Itano (1996) and WPRFMC * 2 and is 
2 WPRFMC (Western Pacific Regional Fishery Management 
Council). 2009. Fishery ecosystem plan for the American Samoa 
briefly described here. There were 2 periods of expansion 
and subsequent decline in landings and effort, both due 
to the availability of fishing vessels (subsidized by the 
local government) and advances in technology. The first 
was in 1972, when the “dory fleet” began the commercial 
exploitation of shallow-water snappers and emperors (e.g., 
Lutjanus spp. and Lethrinus spp.) and, to a limited extent, 
deepwater snappers (e.g., Pristipomoides spp. and Etelis 
spp.) around the populated Tutuila Island and Manua 
Islands (Tau, Ofu, and Olosega). However, the number of 
dories quickly declined in 1977 to near zero. 
A new period of exploitation began in 1978 with the 
advent of a new vessel design (called alia), which extended 
fishing to the offshore banks (South Bank, East Bank, Two 
Percent Bank, Northeast Bank, and Rose Atoll). Signifi¬ 
cant quantities of deepwater snappers, particularly Etelis 
coruscans and E. carbunculus, were landed in the early 
1980s. Etelis carbunculus is now known to be composed 
of 2 distinct, non-interbreeding lineages (Andrews et al., 
2016). Both species occur in the Samoa Archipelago, and 
they were likely both captured by fishermen in the 1980s 
but reported as one species. By 1989, fishing of deepwa¬ 
ter snappers stopped on the offshore banks (Moffitt 3 4 5 ) for 
reasons generally attributed to typhoons destroying ves¬ 
sels, fishermen leaving the deepwater snapper fishery for 
other fisheries, and market competition from imported 
fish (Levine and Allen, 2009). The results of discussions 
with fishermen and creel surveys (WPacFIN 4,5 ) indicate 
that little to no deepwater snapper fishing has occurred 
for the past 29 years at the offshore banks of American 
Samoa but that fishing continues around the populated 
islands throughout this archipelago. 
The deepwater snapper fishery in the Mariana Archi¬ 
pelago occurs primarily in the southern portion of the 
archipelago from Santa Rosa Reef north to Zeelandia 
Bank. This area includes offshore banks (Santa Rosa Reef, 
Galvez Banks, Eleven-Mile Bank, and Esmerelda Bank), 
populated islands (Guam, Rota, Tinian, and Saipan), and 
unpopulated islands (Farallon de Medinilla, Anatahan, 
and Sarigan) (WPRFMC 6 ; Fig. 1). The islands to the north 
of Zealandia Bank (Guguan, Alamagan, Pagan, Agrihan, 
Asuncion, Maug, and Farallon de Pajaros) have had very 
little historical and contemporary fishing because of the 
economics of traveling long distances. 
Archipelago, 202 p. WPRFMC, Honolulu, HI. [Available from 
website.] 
! Moffitt, R. B. 1989. Analysis of the depletion of bottom fishes at 
2% Bank, American Samoa. NOAA, Natl. Mar. Fish. Serv., South¬ 
west Fish. Cent., Honol. Lab. Manuscr. Rep. MRF-002-89H, 9 p. 
4 WPacFIN (Western Pacific Fishery Information Network). 2018. 
Boat-based creel survey of the Am. Samoa Dep. Mar. Wildl. 
Resour. [Available from website.] 
5 WPacFIN (Western Pacific Fisheries Information Network). 
2017. Unpubl. data. Confidential data from boat-based creel 
surveys. WVacFIN, Pac. Isl. Fish. Sci. Cent., Natl. Mar. Fish. 
Serv., NOAA. 1845 Wasp Blvd., Bldg. 176, Honolulu, HI 96818. 
6 WPRFMC (Western Pacific Regional Fishery Management 
Council). 2009. Fishery ecosystem plan for the Mariana 
Archipelago, 231 p. WPRFMC, Honolulu, HI. [Available from 
website.] 
