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Age, Growth, and Reproductive Dynamics of Striped Marlin, Kajikia

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Age, Growth, and Reproductive Dynamics of Striped Marlin, Kajikia 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) 2850 2650 2450 2250 2050 1850 1650 1450 LJFL(mm) 1250 Mean=1776 mm LJFL mm Mean=1776 weight whole kg ~35 LJFL mm Mean=2229 weight whole kg ~78 1050 850 650 450 250 HA. COMM. LL HA.COMM. AUS. COMM. LL 50 0% 5% 10% 15% 20% 25% 30% Percent 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 .
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