Demartini NWHI Overview for CRSAW (Feb 1

NOWRAMP Overview

Ed DeMartini NOAA Fisheries, PIFSC

• Objectives • Design & Status of Surveys • Major Patterns Northwestern Hawaiian Islands

99 9 9 99 9 9 9 9 NWHI Survey Objectives

• Qualitative reconnaissance of ichthyofauna; describe relative abundance, assemblage structure • Initial quantitative assessment of both economic and ecologically interacting resources (corals, algae, macrobenthos as well as fishes); to provide baseline characterization of biota • Subsequent monitoring of target taxa at select representative stations; to enable detection of major changes over decadal time frame Summary of Design Elements

• Develop sampling and analysis designs; standardize data collection protocols – size- and species/taxon- specific tallies per unit area • graded bins: by cm (< 5 cm), by 5 cm (6-50 cm), …by 25 cm (> 100 cm TL) – station(=dive): 3, 25-m long x 4- or 8- m wide belt transects, plus 4, 10- m radius (5-min) SPCs, apportioned among 3 divers • belts: total 600 m2 area for “large” (> 20 cm Total Length, TL) fishes • belts: total 300 m2 area for “small” (< 20 cm TL) fishes • SPCs: total @ 1257 m2 area (fish > 25 cm TL only) – followed by @ 3,000 m2 Roving Diver Survey • Analysis Design – abundance (N, biomass) for baseline assessment – density for monitoring temporal change – stratified by major habitat within reef (eg, fore-, back-reef, lagoonal patch at atolls) Sampling & Analysis Design Summary (cont’d) – at least 50% hard substrate – number of stations proportional to reef-area (and variance of stratum) – all sampleable reef quadrants (emphasis on leeward for monitoring) – distribute among-observer bias (< 15%) across stations and tasks – control for seasonality (eg, in recruitment) by design • differs among NWHI and other reef-systems NOWRAMP Cruise-Effort

• 5-cruise baseline assessment • 25-mo period from Sep 00 to Oct 02 – Sep-Oct 00: NOAA’s Townsend Cromwell (TC00-10) & R/V Rapture – Sep 01: Cromwell (TC01-11); FFS, Maro Reef – Sep-Oct 02: Cromwell (TC02-07) & Rapture • Single monitoring cruise thus far – Jul-Aug 03: Oscar E. Sette (OES03-06) Summary: NOWRAMP Status

• Baseline assessment completed – late summer-early fall cruises – spanning 25-mo period from 2000-02 • Monitoring initiated – 1st survey completed in 2003 – 2nd survey scheduled for Sep 2004 Baseline Assessment Phase

• Identify important trophic/functional groups (eg, herbivores, apex predators), target species (Stegastes damselfish, giant trevally) and key pooled taxa (parrotfishes, surgeonfishes) • Evaluate variances of density estimates (eg, for select pooled taxa like herbivores) using prior (1992-2000) FFS and Midway data • Evaluate tractability based on sampling distributions and estimate effort necessary to estimate densities and abundances NWHI Baseline Effort (2000-02)

• Kure Atoll: 59 • Midway Atoll: 37 • Pearl & Hermes Atoll: 76 • Lisianki Island-Neva Shoal: 30 • Laysan island: 20 • Maro Reef: 43 • Gardner Pinnacles: 10 • French Frigate Shoals (FFS): 74 • Necker Island: 16 • Nihoa Island: 11 • TOTAL (ALL REEFs): 376 stations Subsequent Monitoring Phase

• Evaluate statistical power/identify testable hypotheses for monitoring – eg, power=80% to detect a gradual 50% change in biomass density of herbivorous fishes over a decade of annual surveys • Select monitoring stations from baseline assessment series – choose representative stations from among 376 stations surveyed for baseline assessment over a 25-mo (Sep 2000-Oct 2002) period – stratify selection by major habitat type (eg, forereef, backreef, lagoonal patch reef habitats at atolls) – base selection on representativeness of station (total fish biomass and assemblage structure) within habitat at a reef; repeat over habitats and reefs Monitoring (cont’d)

• Develop and implement balanced sampling design – randomly select constant number of stations to sample per habitat and reef on each survey; sample same stations on each subsequent survey • eg, 3 stations each in forereef, backreef, and lagoonal patch reef habitats at each atoll on each survey • on Jul-Aug 03 cruise completed 1st monitoring survey at 9 of 10 NWHI reefs (63 total stations) NWHI: Major Patterns

• Marked contrast in fish abundance betw NWHI & MHI – standing biomass in NWHI @ 2-3x MHI – apex predators @ order mag greater in NWHI • Apex predator effects on prey body size and related population characteristics – prey sizes skewed smaller where predators denser – labroid sizes at sex change smaller • Spatial patterns of endemism – latitudinal increase in numbers, biomass of endemics – proportionally greater recruitment at higher latitudes • Recruit-habitat relations (cf EFH/HAPC) – Higher recruit densities in sheltered habitats Comparison of Fish Biomass Densities between the Northwestern and the Main Hawaiian Islands

1.50 Northwestern Hawaiian Islands Main Hawaiian Islands 1.25

1.00

0.75

Biomass (mt/ha) 0.50

0.25

0.00 Apex predators Primary consumers Other consumers Consumer category Distribution of Reef Fish Biomass among Islands in the Hawaiian Archipelago 5.0 4.5 Herbivores 4.0 Other secondary consumers Apex predators 3.5 3.0 2.5 MHI NWHI 2.0 1.5 Biomass (mt/ha) 1.0 0.5 0.0

FFS Kauai Oahu Maui Kure Maro Nihoa P & H Hawaii Necker Laysan Molokai Lisianski Gardner Kahoolawe Uhu uliuli – Chlorurus perspicillatus

16 14 12 MHI 10 8 6 4 2 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

1.4 80 1.2 70 1 60 NWHI 0.8 50 0.6 40 0.4 30

Number per transect 0.2 20 0 10 MHI NWHI 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Total Length (cm) Frequency (station-surveys)

Percent presence 100 10 20 30 40 50 amongyearsspanning1992/93and1995-2000. Relative presence-absenceofgianttrevallyandomiluatFFSMidway 20 40 60 80 0 0 (A) Before FFS Caranx ignobilis 1992 (C) SpeciesbySiteTimeTrend After omilu, Midway giant trevally,Midway omilu, FFS giant trevally,FFS 1994 Midway Before Absence Presence After 1996 (B) Before FFS Caranx melampygus After 1998 Midway Before 2000 After Presence Absence Multiway G-test of Jack Frequency Occurrence Maximum-Likelihood Analysis-of-Variance Table Source df Chi-square Probability Species (ulua, omilu) 1 0.01 0.91 Site (FFS, Midway) 1 22.51 <0.0001 Survey period (B vs A) 1 2.20 0.14 Site x Survey period 1 5.24 0.022 T Likelihood ratio (=error) 3 1.25 0.74

Results of a posteriori tests

Species: omilu = white ulua

Site: FFS > MW

Site x Survey period: FFS,Before = FFS,After > MW,Before > MW,After Apex Predator Densities, by Reef

• Apex predators 2.5 2.5 (mostly white ulua) denser at PHR than 2.0 2.0 at either Kure or Midway atolls 1.5 1.5 • 1-way ANOVA; 1.0 1.0 P<0.001

0.5 0.5 Mean + se Biomass density (mT/ha)

KUR MID PHR LIS LAY MAR GAR FFS NEC NIH Body Size Distribution and Size-at- Sex Change of Select Labroids

• Body size distribution of 120 Hawaiian hogfish & 100 (A) Pearl & Hermes Atoll 80 All 311 fish > 25 cm TL 57 Terminal Phase only spectacled parrotfish 60 shifted left (SMALLER) at 40 20

PHR than at either Kure 0 20 30 40 50 60 70 or Midway atolls 100 (B) Kure Atoll – 2, 2-way K-S tests; 80 All 255 fish > 25 cm TL P<0.001 60 64 Terminal Phase only • Both species also change 40 20 Frequency Count

from IP female to TP 0 20 30 40 50 60 70 male at SMALLER size at 50 (C) Midway Atoll PHR than at either Kure 40 All 159 > 25 cm TL or Midway 30 35 Terminal Phase only 20

– K-S tests; P < 0.01 10

0 20 30 40 50 60 70 Total length class (TL, cm) Prey Reef Fish Length Distributions

2500 (A) Pearl & Hermes Atoll • All other taxa of prey 2000 9,478 fish < 75 cm TL 1500

fishes also SMALLER 1000 at PHR than at either 500 0 Kure or Midway atolls 10 20 30 40 50 60 70 1400

1200 (B) Kure Atoll • 2, 2-way K-S tests 1000 5,724 fish < 75 cm TL 800

600

• both P<0.01 400

Frequency Count 200

0 • Conclusion: Predation 10 20 30 40 50 60 70

1400

effects greater at 1200 (C) Midway Atoll

1000 4,026 fish < 75 cm TL PHR, where 800 600 predators are denser 400 200

0 0 10 20 30 40 50 60 70 Total length class (TL, cm) 70 70 174 124 Numbers 155 NumbersBiomass 60 163 60 174 BiomassSpecies 142 155 124 Species 163 178 50 50 131 142 178 124 125 40 131 40 124 125

30 30

Percent Endemism 20 20 127127

10 10

0 0 KUR MID PHR LIS LAY MAR GAR FFS NEC NIH 16 French Frigate Shoals 16

*

7 7

) Exposed barrier forereef 2 Semi-sheltered barrier backreef 6 Sheltered lagoonal patch reef 6

5 5 FFS: forereef--5 4 4 * backreef--5 patch reefs--22 3 3 Density (N per 100 m

2 * 2 * * 1 * 1 * * * * * * * * * * * * * * * * 0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 32 primary taxa, ranked by grand mean density (all habitats) * 24 24 Midway Atoll Exposed barrier forereef 15 Semi-sheltered barrier backreef 15 * Sheltered lagoonal patch reef 14 14

) 13 13 2 12 12 Midway: forereef--4 11 11 backreef--1 10 10 * patch reefs--30 9 * 9 8 G-test 8 Accept H : FFS = Midway 7 o 7 Reject H : (semi)sheltered = exposed 6 o 6 chi-squared = 43.3 w/ 2 df Density (N per 100 m 5 * 5 P < 0.001 4 4 3 3 2 * * 2 * 1 * * * 1 * * * * * * * * * * * * * * * * * * * 0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 1314 15 16 17 1819 20 21 22 2324 25 26 27 2829 30 31 32 3334 35 36 35 primary taxa, ranked by grand mean density (all habitats) Pertinent Publications

• DeMartini, Parrish & Parrish (1996) Bull Mar Sci 58:804-825 • Friedlander & DeMartini (2002) Mar Ecol Prog Ser 230:253-264 • DeMartini, Parrish & Boland (2002) NOAA Tech Memo NMFS-SWFSC-347 (Dec 2002) • DeMartini & Friedlander (2004, in press) Mar Ecol Prog Ser • DeMartini (in press) Bull Mar Sci • DeMartini, Friedlander & Holzwarth (in prep) Coral Reefs