R. Keller Kopf

Photograph by: William Boyce Age and growth of striped marlin:

Hawaiian-based longline fishery  PFRP funded in 2010 with sample collections by NOAA PIFSC

Southwest Pacific Ocean  PhD thesis confirmed 2010 Primary distribution (dark blue), Occasional distribution (light blue) Study regions (red circles)

-Most widely distributed species of marlin, sailfish, and spearfish (Istiophoridae)

-Two - five semi-independent stocks in the Pacific Ocean

-Most commercially valuable species of Istiophorid billfish caught in longline fisheries

~ 4000 mt harvested per year in US Western and Central Pacific

- Biomass of striped in the north Pacific has declined to approximately 6% -16% of 1952 levels (Piner et al. 2007; Brodziak and Piner 2010) 30% HA. COMM. LL Mean=1776 mm LJFL ~35 kg whole weight 25% AUS. COMM. LL Mean=2229 mm LJFL ~78 kg whole weight 20%

15% Percent 10%

5%

0% 1050 1250 1450 1650 1850 2050 2250 2450 2650 2850 250 450 650 850 50

LJFL (mm) First dorsal and anal fin spines (N=425) cleaned, dried, and embedded in polyester resin. Sections made relative to maximum condyle width (Kopf et al. 2010)

Transverse sections of otoliths from juveniles ground and polished by hand. Micro- Dorsal and anal fin spine sections increments viewed at ~1500X Kopf and Davie (In-Press) magnification and counted on digital images made along the counting path. 200 180 160 140 120 100 y = 9.686x + 24.572

ForkLength (cm) 80 1_4 CW - R² = 0.9566 60 Eye 2CM CW y = 10.833x + 47.716 40 R² = 0.948 20 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Fin spine diameter (mm) First yearly annulus formed at about 301 days after hatching Observed Spine Radius of First Annulus 5.35 ± 0.62mm

Mean marginal increment showed that a new annulus was formed annually each spring FIRST ANNULUS AGE 383 DAYS OLD

SOUTHWEST PACIFIC OCEAN ?

HAWAII Striped marlin growth averaged 4.5mm per day during first 12 months of life

Rapid growth in terms of length (not mass): -Dolphin fish, Coryphaena hippurus = 3.6 and 4.7 mm per day (Oxenford and Hunter 1983; Bentivoglio 1988) . 1220 Lower Jaw Fork Length - Blue marlin, Makaira nigricans Caught – 15 April 2008 Estimated hatch date - 28 October 2007 = 4.8 mm per day (Prince et al. 1991). Significant differences in Von B growth curves developed for 3500 striped marlin. Are they real? 3000 2500 SWPO – validated: 2000 Southwest Pacific LJFL (mm) LJFL 1500  Rapid early growth with 70- New Zealnand 75% of maximum body length 1000 Mexico 500 Hawaii female (L∞=2722 ♀, 2581mm LJFL ♂ ) Hawaii male during the first two years of 0 Otolith daily life 0 1 2 3micro4 5 -6increments7 8 9 10111213 Age

 Ages ranged from 130 estimated days in a 4kg whole Previous von Bertalanffy growth curves developed for striped marlin weight (1120 mm, LJFL) male to eight estimated years in a 168kg (2871 mm, LJFL) female North Pacific (Mexico) ~30 kg Southwest Pacific Ocean Age 7-8 years 124 kg Age 8 years Melo-Barrera et al. (2003) Kopf (2010)  Regional age-structure was dependent on latitude (Χ2=3409.78; P < 0.001) and longitude (Χ2=1833.55; P < 0.001)

 Age progressively increased between the equator and 45°S Lat. Young of the year most common in tropics while the oldest (5-8yrs) and largest Striped marlin age contour adults most frequent in sub- tropical and temperate waters plot summer 1998-2008 SWPO SWPO (Kopf 2010) stock assessment (Langley et al. 2006) Age classes (years) 0-8 0-10 L∞ 2749mm LJFL 2750 - 3500mm LJFL Growth rate (k) 0.44 0.23-0.65 Growth rate (K) 0.09 - Length-at-age one 1606mm LJFL 650mm LJFL % mature at age (female) Age 1, 2, 3, 4.. Age 1, 2, 3, 4... % 0.03, 0.60, 0.97, 1.0 % 0, 0.5, 0.75, 1.0 Sex-specific differences Yes No Single spring spawning period Yes Yes Latitudinal stratification within fisheries Yes No -Despite the relatively rapid growth rate and early maturity, the sustainability of current fishing practices for striped marlin remains uncertain

-Regional time-area fisheries management measures could be effectively used to conserve particular age-classes, reproductive stages, or pelagic environments (eg. post-spawning feeding grounds) that are important to the species Central-north Pacific  Pelagic Fisheries Research Program  NOAA , Pacific Islands Fisheries Science Center  Pacific Island Regional Observer Program

Southwest Pacific  Charles Sturt University, Australia  Australian Fisheries Management Authority (AFMA) and Fisheries Research and Development Corporation (FRDC)  CSIRO  New South Wales Department of Primary Industries (DPI), Recreational Fishing Trusts  Secretariat of the Pacific Community (SPC)  Fiji Regional Observer Programme  New Zealand Ministry of Fisheries  Blue Water Marine Research, NZ  Central Ageing Facility, Queenscliff DPI