Donovan Et Al. 2015
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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/279532948 Ecology and niche specialization of two bonefish species in Hawai‘i ARTICLE in ENVIRONMENTAL BIOLOGY OF FISHES · JUNE 2015 Impact Factor: 1.57 · DOI: 10.1007/s10641-015-0427-z CITATION READS 1 54 7 AUTHORS, INCLUDING: Mary K Donovan Alan Friedlander University of Hawaiʻi at Mānoa University of Hawaiʻi at Mānoa 16 PUBLICATIONS 116 CITATIONS 178 PUBLICATIONS 3,671 CITATIONS SEE PROFILE SEE PROFILE Eva Schemmel University of Hawaiʻi at Mānoa 5 PUBLICATIONS 4 CITATIONS SEE PROFILE Available from: Mary K Donovan Retrieved on: 07 April 2016 Environ Biol Fish DOI 10.1007/s10641-015-0427-z Ecology and niche specialization of two bonefish species in Hawai‘i Mary K. Donovan & Alan M. Friedlander & Kimberlee K. Harding & Eva M. Schemmel & Alexander Filous & Keith Kamikawa & Natalie Torkelson Received: 8 November 2014 /Accepted: 8 June 2015 # Springer Science+Business Media Dordrecht 2015 Abstract Bonefishes are a cryptic species complex that management strategies. We found that the wide-ranging are a prized sportfish in many places around the world. In species, A. glossodonta had a larger mean size, length at a Hawai‘i they have a long history of use and today have given weight, and size at maturity than the endemic, important recreational, and cultural value. In the early A. virgata. We found differences in prey preferences 1980s, two distinct species of bonefishes were deter- between the two species that support our hypothesis that minedtoinhabitHawaiianwaters(Albula glossodonta differences in jaw morphologies and habitat preferences Bround jaw^,andA. virgata Bsharp jaw^). Little is known translate to dissimilarities in diet. This study contributes about the life histories of these two species, hindering to our knowledge about these species and provides an population assessments and relevant fisheries manage- example of niche specialization in two closely related and ment guidelines. In addition, no ecological studies have cohabiting species. been conducted to examine interactions or separation between these species. This research assesses how differ- Keywords Bonefishes . Life history. Niche ences in size, abundance, diet, growth, reproduction, and specialization . Hawai‘i habitat preference of the two bonefish species in Hawai‘i can explain the coexistence and persistence of these two closely related species. Differences in size structure, Introduction growth rates, and spawning patterns for each species provides species-specific life history information that Bonefishes are highly prized recreationally in many parts differentiates them ecologically and is useful for popula- of the world, contributing significantly to local econo- tion assessments and in developing species-specific mies (Ault 2007;Fedler2013). In Hawai‘i, bonefishes, locally known as ‘ō‘io, are an important target of recrea- tional fisheries and have cultural significance (Kahaulelio M. K. Donovan (*) : A. M. Friedlander : K. K. Harding : E. M. Schemmel : A. Filous : K. Kamikawa : N. Torkelson 2006). Bonefishes were an important food item for early Fisheries Ecology Research Lab, Department of Biology, Hawaiian civilization, being both wild-caught and cul- University of Hawai‘iatMānoa, Honolulu, HI 96822, USA tured in fish ponds (Titcomb 1972). In modern Hawai‘i, e-mail: [email protected] bonefish continue to play an important cultural role A. M. Friedlander through recreation and subsistence as a commonly Pristine Seas, National Geographic Society, Washington, DC targeted resource species by non-commercial fishers 20036, USA (Kamikawa et al. 2015). Despite the high recreational importance placed on bonefishes, they have limited K. K. Harding Department of Natural Sciences, Hawai‘i Pacific University, economic value as a recreational species and only mar- Honolulu, HI 96813, USA ginal commercial value in Hawai‘i. The commercial sale Environ Biol Fish of bonefishes in Hawai‘i is permitted, there are no recre- between the two species (Colborn et al. 2001). There is ational harvest limits, and the minimum legal harvest size also a significant difference in the number of gill rakers is 31.4 cm (14 in), with no distinction between the two on the lower limb of the first gill arch (Shaklee and bonefish species found in Hawai‘i, Albula glossodonta Tamaru 1981). Therefore we hypothesize that differ- and A. virgata (DAR 2012). By comparison, the state of ences in feeding apparatuses could translate to dissimi- Florida estimates that>$460 million dollars per year is larities in prey preferences following evidence from a addedtothestate’s economy through direct and indirect wide range of coral reef fish taxa (Wainwright 1988; expenditures related to recreational catch-and-release Bond 1996; Wainwright et al. 2004). bonefish fishing and commercial harvest is prohibited Most of the research on bonefishes has been conduct- (Fedler 2013). ed in Florida and the Bahamas, where they are highly Bonefishes are cosmopolitan fishes with few prized in the sport fishing industry (Colton and Alevizon distinguishing morphological differences across species 1983;Crabtreeetal.1996, 1997, 1998; Pfeiler et al. (Colborn et al. 2001). Early researchers believed that the 2000; Humston et al. 2005; Adams et al. 2007; genus Albula consisted of only two species, A. vulpes and Danylchuk et al. 2011). Little is known about the life A. nemoptera (Whitehead 1986; Colborn et al. 2001; history of bonefishes in the Pacific despite their long Bowen et al. 2007). Shaklee and Tamaru (1981) history of use and continued cultural importance in questioned the validity of this classification, and distin- many islands throughout the region today (Friedlander guished two bonefish species in Hawai‘i, (A. glossodonta et al. 2007; Allen 2014). This study is the first to and A. virgata) which was subsequently confirmed by examine size, age, growth, diet, spawning, reproduction, other researchers (Randall and Bauchot 1999; Colborn recruitment and habitat use of two closely related spe- et al. 2001; Bowen et al. 2007;Hidakaetal.2008). cies of bonefishes in Hawai‘i and includes a discussion Because research showed no evidence of gene flow on how differences in the characteristics of their biology betweenthetwospecies,theywereconsideredsympat- influence niche specialization and species persistence. ric species capable of coexisting in the same habitat due Further, this study serves to provide important life his- to an inferred difference in their preferred prey items; tory information for the management of these fisheries however this theory was never tested (Colborn et al. by providing species-specific information that can be 2001). Differences in morphological characteristics used to develop more sustainable harvest strategies. (e.g., mouth shapes and size, mean body lengths) and ecological characteristics (e.g., habitat use) have been suggested as indicators of resource partitioning, there- Methods fore allowing closely related species to coexist in the same geography while minimizing competition (Hutch- Species identification inson and MacArthur 1959; Van Valen 1965; Schoener 1974;Ross1986). However, simply comparing re- Two species of bonefishes are found in Hawaiian wa- source use of two species does not provide enough ters, which can easily be distinguished by external mor- information to demonstrate niche partitioning resulting phological characteristics (Shaklee and Tamaru 1981). from selection pressures by evolutionary mechanisms A. glossodonta derives its common name, round jaw, (Walter 1991). Connell (1980)arguedthattoconclude from its rounded lower jaw compared to A. virgata,the whether the coexistence of two species is a result of sharp jaw, that has an angular, sharp pointed lower jaw. competition alone, field experiments must be performed The jaw measurement, the distance from the tip of the to test if another mechanism is involved. Therefore, we snout to the posterior end of the maxilla, of discuss niche specialization, rather than partitioning, by A. glossodonta is shorter relative to the length of the comparing the two species of bonefishes in Hawai‘i. head compared to A. virgata (Fig. 1). The ratio of head A difference in the feeding apparatus of the Hawaiian length to the jaw measurement for A. glossodonta is bonefish species indicates they could preferentially be 3.03–3.31 compared to 2.65–2.87 for A. virgata feeding on different prey items. Both species possess (Randall 2007). Other distinguishing characteristics in- enlarged molariform teeth positioned as patches in both clude a yellow spot on the axil of the pectoral fins in the upper and lower mouth, but the size of the individual A. virgata and 65–66 lateral-line scales in A. virgata teeth and shape of the patches are significantly different compared to 72–75 in A. glosssodonta (Randall 2007). Environ Biol Fish Fig. 1 Comparison of two bonefish species that inhabit Hawaiian waters, ratio of head to jaw length is from Randall (2007), fork lengths are means (Table 1) Collections scaling constant. Analysis of covariance (ANCOVA) of log-log data was used to compare the relationship be- Beginning in 2008, samples were collected as part of the tween the two species. ‘Ō‘io Tagging Project (http://www.hawaii.edu/ oiotaggingproject/), on the island of Oahu, Hawai‘i Growth (see Kamikawa et al. 2015). Adult fishes were obtained by hook-and-line, fly-fishing, or gill net, and were largely Sagittal otoliths were extracted from a subset of