Yellow tang Zebrasoma flavescens is the primary coral reef fish species taken in Hawaii for the aquarium trade. As part of an extensive adaptive management effort that included a network of marine protected areas that prohibited commercial aquarium fishing, an emphasis was placed on obtaining habitat-and sex-specific life history information for this valuable species. Using otolith and capture-mark-recapture methods we examined sexual differences in ontogenetic patterns of habitat use, growth rate, size dimorphism and longevity. Age validation using tetracycline to mark otoliths provided evidence that a single annulus formed each year. Yellow tang are a long-lived species (the oldest individual collected was 41 yr old) and display an asymptotic growth pattern typical of the family Acanthuridae. Median size and age at the transition between deeper coral-rich and shallow turfdominated habitat use were about 20 mm longer and about 2 yr older for males than females and coincided with an increase in reproductive output. The sexual difference in size at habitat transition, combined with sexual size dimorphism (mean asymptotic maximum length -male: 179 mm; female 156 mm) results in differences in the size distributions of both sexes in the 2 habitats. Sexual size dimorphism resulted from a higher growth rate for males through the juvenile period.KEY WORDS: Ontogenetic habitat use · Hawaiian aquarium fishery · Acanthuridae · Model selection · Otolith · Capture-mark-recapture · Growth · Coral reef fish Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 389: [245][246][247][248][249][250][251][252][253][254][255] 2009 information is combined with ontogenetic patterns of habitat use. Most studies on ontogenetic variation of habitat use have compared size distributions between habitats (Gillanders et al. 2003), and therefore have not considered age structure, sex-specific habitat use patterns or the duration of the lifespan spent in each habitat. When available, information about age-based habitat use can improve conservation planning and design of MPAs (Mumby 2006, Parnell et al. 2006) and lead to an understanding of how the amount of available juvenile and adult habitat may influence population size -a potential key to conservation and area-based fisheries management (Halpern et al. 2005).Many species of coral reef fish, including several species of surgeonfish, make ontogenetic shifts in habitat use-an important factor in the organization of fish communities (Robertson 1988, Lawson et al. 1999, Lecchini & Galzin 2005, Robertson et al. 2005, Pratchett et al. 2008. Yellow tang in West Hawaii settle primarily into middepth (10 to 25 m) reef habitat with a high percentage of coral cover (hereafter deeper coral-rich habitat). At some as yet undetermined point in their lifespan, larger individuals shift to spending daytime foraging in adjacent, shallow, complex habitats (reef flats and boulders) characterized by a high percentage of exposed rock covered by turf algae (h...

Reproduction was investigated in relation to lunar and annual cycles in a population of yellow tang Zebrasoma flavescens, a popular aquarium species commercially harvested in Hawaii. Lunar periodicity was determined to be an inherent characteristic of reproduction; peaks in mean daily egg production, female gonado-somatic index (I(G)) and the fraction of females with eggs were observed at the full moon of each sampled month. An increase in the fraction of late-stage vitellogenic oocytes within the ovaries was also observed at the full moon. Reproductive effort peaked in the late spring and summer as indicated by high values of mean daily egg production, female I(G) and the recorded incidence of females spawning for at least two consecutive days. Mean daily egg production and I(G) of monthly samples were lowest in November to February, although some level of egg production continued throughout the year. Large individual variation in batch fecundity was observed, with a range from 44 to > 24,000 eggs per female produced on a single sampling date. Smaller females, 80-120 mm standard length (L(S)), produced limited numbers of eggs, while females > or = 120 mm L(S) were capable of maximal egg production (> 20,000 eggs per batch). In contrast to trends observed in many fish species, no significant relationship between batch fecundity and adult L(S) > 120 mm was observed in female Z. flavescens. An estimate of annual fecundity (mean +/-S.E. 1,055,628 +/- 120,596 eggs) was also generated using a simple model of the lunar variability in egg production. This study illustrates the importance of accounting for potential variation in egg production over time, especially with respect to diel and lunar cycles, in the design of reproductive studies of multiple-spawning fishes. Greater insight into the environmental factors that regulate reproductive activity may be gained by determining the relative reproductive investment allocated at each spawning event. The ability to estimate annual fecundity for more multiple-spawning species will facilitate examination of the effects of fishing on the reproductive characteristics of these populations and permit examination of life-history evolution across a broader suite of fishes.

Passive acoustic telemetry and conventional tag/re-sight techniques were used to study daily movement patterns of adult yellow tang, Zebrasoma flavescens, over a period of months. Range testing and visual observations revealed the limitations of using small acoustic transmitters to monitor movements of small coral reef fish in a topographically complex and noisy coral reef environment. Visual observations of conventionally tagged and albino fish suggest individuals return each day to forage over the same few hundred m 2 of shallow, turf algae dominated boulder and reef flat habitat for periods of at least weeks to months. Acoustic telemetry data suggest lower frequency of repeated use of daytime foraging, nighttime refuge and sunset spawning sites. However, integration of observation and acoustic telemetry data revealed that many fish were not detected while they were within the empirically tested range of the receivers. These observations indicate that data from passive acoustic telemetry can underestimate the frequency and duration of repeated use of specific areas. Yellow tang adults made daily crepuscular migrations of up to 600 m between foraging and spawning or sheltering sites at consistent times relative to sunset and sunrise. While there was high individual variability in migration distance, almost all individuals moved in the same direction (from south to north) at sunset. This study provided valuable information for evaluating ongoing fishery management efforts using marine protected areas in Hawaii.