John P. Hoolihan Fisheries Research 78 (2006) 218–226 Reporter ：林圻鴻 指導教授：王勝平

1. Age and growth of Indo-Pacific sailfish, Istiophorus platypterus,from the Arabian Gulf　　－　阿拉伯海灣雨傘旗魚的年齡成長 John P. Hoolihan Fisheries Research 78 (2006) 218–226 Reporter：林圻鴻 指導教授：王勝平

2. Introduction

3. 中文名：雨傘旗魚 • 學　名：Istiophorus platypterus • 英文名：Sailfish

4. 棲息深度：0~50公尺 • 棲所生態：大洋性中上層洄游性魚類，一般皆發現在溫躍層之上的水域，常成群出現於島嶼周遭的水域。游泳速度快。具繁殖洄游之習性。 • 食　　性：魚類、甲殼類、頭足類等。 • 漁　　法：包括表層的延繩釣、流刺網、定置網、拖網或使用標槍法 (即鏢旗魚)。 　

5. Sailfish are highly regarded by recreational fishers for their spectacular gamefish characteristics. • This is apparent in the Gulf nation of the United Arab Emirates (UAE) where, sailfish represent an economic asset for the recreational fishing and tourism sectors.

6. A decline in Gulf sailfish capture rates suggests overexploitation, thus raising concerns that a unique genetic component of Gulf biodiversity may be threatened. • (Hunter, 1982) :Geographically,the 239,000 km2 area of the Gulf is relatively small and limits the size of this genetically isolated stock. • Therefore emphasizes the importance of obtaining basic sailfish biology and life history information that will enable development of sound conservation management strategies.

7. Understanding age and growth characteristics ranks among the most important components of fishery population analysis required for accurate stock assessment and management • this information has not been previously documented for sailfish from inside the Gulf. • Standard aging techniques that rely on counting incremental growth patterns in hard structures • such as otoliths, fin spines, and vertebrae have been investigated in billfish

8. The small size of billfish otoliths makes them difficult to analyze by the usual transverse sectioning methods. • Radtke and Dean (1981) used scanning electron microscopy (SEM) to examine the external morphologyof sailfish otoliths

9. Validation of band formation periodicity in dorsal spines using marginal increment ratio (MIR) analysis • reported for sailfish from the Gulf of California (Alvarado-Castillo and F´elix-Uraga, 1996) and Taiwan (Chiang et al.,2004). • Both studies reported a 1-year cycle to form a pair of opaque and translucent growth bands in the fourth dorsal fin spine.

10. This study evaluates the utility • Using structural growth increments in dorsal and anal fin spine sections, along with examining somatic growth patterns • Establishing key demographic characteristics of Gulf sailfish that could benefit future conservation management strategies.

11. Materials & Methods

12. Allometry • 採樣時間：2000年11月至2003年12月 • 總樣本數：101 • 60% female and 44% male collect from UAM waters using rod and reel with troll • Commercial gillnet at the Iranian ports of Busher and Dayyer

13. Commercial gillnet troll

14. Allometry • Growth relationships between LJFL and other morphometric traits • Estimated by non-linear regression for males, females and pooled sexes with the allometric growth equation: • Y is trait to be compared to LJFL(X)

15. Allometry • Linear regression slopes comparing LJFL to other morphometric traits • subjected to analysis of covariance and a modified t-test • determine if allometric growth varied between sexes.

16. Allometry • Least-squares linear regression • used in analyses of allometric growth trait relationships • the assumption of linearity was tested using graphical methods.

17. Aging • 樣本收集 • Fin spines collected from 85 sailfish (51 females, 34males) • Spines from the first dorsal (no. 4) and anal fins (nos. 2 and 3) were collected along with measurement of LJFL,TW and girth.

18. Age – 外部型態

19. Aging • 樣本處理 • Spines were placed in polyethylene bags and stored frozen at −18 ◦C • thawing, soft tissue was manually removed with a knife • Residual tissue was removed by soaking spines in sodium hypochlorite for 3–10 min • Spines were then stored in paper envelopes for drying and later embedded in epoxyresin

20. Age • 樣本處理 • Transverse sections (∼0.5mm thickness) were cut on a lowspeed lapidary saw with diamond wafering blades • viewed using transmitted light under a stereoscope at 10–20× magnification • direct digital image capturing to a PC with a microscope mounted camera.

21. Sections were placed on a glass microscope slide and heated rapidly (1–2 s) on a laboratory hot plate with a surface temperature around 100 ◦C. • Digital computer enhancement of brightness and contrast, as well as image inverting, provided alternative perspectives that aided scoringof ambiguous sections.

22. Theoretical growth parameters were estimated by fitting the von Bertalanffy (1938) growth function (VBGF), • Using standard non-linear least squares regression, to the backcalculated lengths (LJFL) at age: • Lt is the LJFL at age • L∞ the theoretical asymptotic LJFL • k the rate at which L∞ is approached • t0 is the theoretical age when fish length = 0

23. Results

24. Aging

25. Aging

26. 75%

27. Growth

31. Discussion

32. Jolley (1977) in Atlantic sailfish • female (8) and male (6) • Chiang et al. (2004) in Taiwanese sailfish • females(12) and males(11). • Freire et al. (1998) dorsal spine analysis of 51 Atlantic sailfish from Brazilian waters showed • maximum year class of 10 for pooled sexes

33. The ANOVA comparison of group 1 (year classes 0+and 1) with group 2 (years classes 2–8) indicated variable growth rates between sexes. • Group 1: no significant differences between female and male • Group 2: overall faster growth rate for females • Chiang et al. (2004) : analysis of 1135 sailfish from Taiwan waters • Jolley (1974) : length–weight relationships of 412 female and male Atlantic sailfishes.

34. The availability of spines varied with the fourth dorsal and the second and third anal spines • resulting in an overall lack of continuity for spine type. • Multiple spines samples were available for an individual, identical band counts were observed. • Jolley (1977) : reported similar results when comparing dorsal and anal fin spines of Atlantic sailfish.

35. Chiang et al. (2004) : used marginal increment ratio analysis of the fourth dorsal fin of sailfish to back-calculate estimated ages of older fish, presumed to be missing early rings. • Chiang et al. (2004) were able to increase estimated maximum ages • Males from 8 to 11 years • Females form 8 to 12 years.

36. For the present study, the combination of not having uniform spine types or complete spines prevented an analysis of marginal increment ratios.

37. Conclusion

38. 由其採樣數可得知，在阿拉伯海灣對雨傘旗魚的開發是屬於嚴重過魚的現象。由其採樣數可得知，在阿拉伯海灣對雨傘旗魚的開發是屬於嚴重過魚的現象。 • 阿拉伯海灣的雨傘旗魚與其他地區的雨傘旗魚一樣，均具有早期成長快速、雌性具有較大體長、體長與體長及體長與體重具有相關性。 • 經由外部型態的分析及年齡成長的研究可以提供未來在研究雨傘旗魚或是對其保育提供有效的資料。

39. Thank you for your attention